plperl.c

Go to the documentation of this file.

/**********************************************************************
 * plperl.c - perl as a procedural language for PostgreSQL
 *
 *    src/pl/plperl/plperl.c
 *
 **********************************************************************/

#include "postgres.h"
/* Defined by Perl */
#undef _

/* system stuff */
#include <ctype.h>
#include <fcntl.h>
#include <unistd.h>
#include <locale.h>

/* postgreSQL stuff */
#include "access/htup_details.h"
#include "access/xact.h"
#include "catalog/pg_language.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "commands/trigger.h"
#include "executor/spi.h"
#include "funcapi.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "parser/parse_type.h"
#include "storage/ipc.h"
#include "tcop/tcopprot.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/guc.h"
#include "utils/hsearch.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/rel.h"
#include "utils/syscache.h"
#include "utils/typcache.h"

/* define our text domain for translations */
#undef TEXTDOMAIN
#define TEXTDOMAIN PG_TEXTDOMAIN("plperl")

/* perl stuff */
#include "plperl.h"
#include "plperl_helpers.h"

/* string literal macros defining chunks of perl code */
#include "perlchunks.h"
/* defines PLPERL_SET_OPMASK */
#include "plperl_opmask.h"

EXTERN_C void boot_DynaLoader(pTHX_ CV *cv);
EXTERN_C void boot_PostgreSQL__InServer__Util(pTHX_ CV *cv);
EXTERN_C void boot_PostgreSQL__InServer__SPI(pTHX_ CV *cv);

PG_MODULE_MAGIC;


/**********************************************************************
 * Information associated with a Perl interpreter.  We have one interpreter
 * that is used for all plperlu (untrusted) functions.  For plperl (trusted)
 * functions, there is a separate interpreter for each effective SQL userid.
 * (This is needed to ensure that an unprivileged user can't inject Perl code
 * that'll be executed with the privileges of some other SQL user.)
 *
 * The plperl_interp_desc structs are kept in a Postgres hash table indexed
 * by userid OID, with OID 0 used for the single untrusted interpreter.
 * Once created, an interpreter is kept for the life of the process.
 *
 * We start out by creating a "held" interpreter, which we initialize
 * only as far as we can do without deciding if it will be trusted or
 * untrusted.  Later, when we first need to run a plperl or plperlu
 * function, we complete the initialization appropriately and move the
 * PerlInterpreter pointer into the plperl_interp_hash hashtable.  If after
 * that we need more interpreters, we create them as needed if we can, or
 * fail if the Perl build doesn't support multiple interpreters.
 *
 * The reason for all the dancing about with a held interpreter is to make
 * it possible for people to preload a lot of Perl code at postmaster startup
 * (using plperl.on_init) and then use that code in backends.  Of course this
 * will only work for the first interpreter created in any backend, but it's
 * still useful with that restriction.
 **********************************************************************/
typedef struct plperl_interp_desc
{
    Oid         user_id;        /* Hash key (must be first!) */
    PerlInterpreter *interp;    /* The interpreter */
    HTAB       *query_hash;     /* plperl_query_entry structs */
} plperl_interp_desc;


/**********************************************************************
 * The information we cache about loaded procedures
 *
 * The refcount field counts the struct's reference from the hash table shown
 * below, plus one reference for each function call level that is using the
 * struct.  We can release the struct, and the associated Perl sub, when the
 * refcount goes to zero.
 **********************************************************************/
typedef struct plperl_proc_desc
{
    char       *proname;        /* user name of procedure */
    TransactionId fn_xmin;      /* xmin/TID of procedure's pg_proc tuple */
    ItemPointerData fn_tid;
    int         refcount;       /* reference count of this struct */
    SV         *reference;      /* CODE reference for Perl sub */
    plperl_interp_desc *interp; /* interpreter it's created in */
    bool        fn_readonly;    /* is function readonly (not volatile)? */
    bool        lanpltrusted;   /* is it plperl, rather than plperlu? */
    bool        fn_retistuple;  /* true, if function returns tuple */
    bool        fn_retisset;    /* true, if function returns set */
    bool        fn_retisarray;  /* true if function returns array */
    /* Conversion info for function's result type: */
    Oid         result_oid;     /* Oid of result type */
    FmgrInfo    result_in_func; /* I/O function and arg for result type */
    Oid         result_typioparam;
    /* Conversion info for function's argument types: */
    int         nargs;
    FmgrInfo    arg_out_func[FUNC_MAX_ARGS];
    bool        arg_is_rowtype[FUNC_MAX_ARGS];
    Oid         arg_arraytype[FUNC_MAX_ARGS];   /* InvalidOid if not an array */
} plperl_proc_desc;

#define increment_prodesc_refcount(prodesc)  \
    ((prodesc)->refcount++)
#define decrement_prodesc_refcount(prodesc)  \
    do { \
        if (--((prodesc)->refcount) <= 0) \
            free_plperl_function(prodesc); \
    } while(0)

/**********************************************************************
 * For speedy lookup, we maintain a hash table mapping from
 * function OID + trigger flag + user OID to plperl_proc_desc pointers.
 * The reason the plperl_proc_desc struct isn't directly part of the hash
 * entry is to simplify recovery from errors during compile_plperl_function.
 *
 * Note: if the same function is called by multiple userIDs within a session,
 * there will be a separate plperl_proc_desc entry for each userID in the case
 * of plperl functions, but only one entry for plperlu functions, because we
 * set user_id = 0 for that case.  If the user redeclares the same function
 * from plperl to plperlu or vice versa, there might be multiple
 * plperl_proc_ptr entries in the hashtable, but only one is valid.
 **********************************************************************/
typedef struct plperl_proc_key
{
    Oid         proc_id;        /* Function OID */

    /*
     * is_trigger is really a bool, but declare as Oid to ensure this struct
     * contains no padding
     */
    Oid         is_trigger;     /* is it a trigger function? */
    Oid         user_id;        /* User calling the function, or 0 */
} plperl_proc_key;

typedef struct plperl_proc_ptr
{
    plperl_proc_key proc_key;   /* Hash key (must be first!) */
    plperl_proc_desc *proc_ptr;
} plperl_proc_ptr;

/*
 * The information we cache for the duration of a single call to a
 * function.
 */
typedef struct plperl_call_data
{
    plperl_proc_desc *prodesc;
    FunctionCallInfo fcinfo;
    Tuplestorestate *tuple_store;
    TupleDesc   ret_tdesc;
    MemoryContext tmp_cxt;
} plperl_call_data;

/**********************************************************************
 * The information we cache about prepared and saved plans
 **********************************************************************/
typedef struct plperl_query_desc
{
    char        qname[24];
    MemoryContext plan_cxt;     /* context holding this struct */
    SPIPlanPtr  plan;
    int         nargs;
    Oid        *argtypes;
    FmgrInfo   *arginfuncs;
    Oid        *argtypioparams;
} plperl_query_desc;

/* hash table entry for query desc  */

typedef struct plperl_query_entry
{
    char        query_name[NAMEDATALEN];
    plperl_query_desc *query_data;
} plperl_query_entry;

/**********************************************************************
 * Information for PostgreSQL - Perl array conversion.
 **********************************************************************/
typedef struct plperl_array_info
{
    int         ndims;
    bool        elem_is_rowtype;    /* 't' if element type is a rowtype */
    Datum      *elements;
    bool       *nulls;
    int        *nelems;
    FmgrInfo    proc;
} plperl_array_info;

/**********************************************************************
 * Global data
 **********************************************************************/

static HTAB *plperl_interp_hash = NULL;
static HTAB *plperl_proc_hash = NULL;
static plperl_interp_desc *plperl_active_interp = NULL;

/* If we have an unassigned "held" interpreter, it's stored here */
static PerlInterpreter *plperl_held_interp = NULL;

/* GUC variables */
static bool plperl_use_strict = false;
static char *plperl_on_init = NULL;
static char *plperl_on_plperl_init = NULL;
static char *plperl_on_plperlu_init = NULL;

static bool plperl_ending = false;
static OP  *(*pp_require_orig) (pTHX) = NULL;
static char plperl_opmask[MAXO];

/* this is saved and restored by plperl_call_handler */
static plperl_call_data *current_call_data = NULL;

/**********************************************************************
 * Forward declarations
 **********************************************************************/
Datum       plperl_call_handler(PG_FUNCTION_ARGS);
Datum       plperl_inline_handler(PG_FUNCTION_ARGS);
Datum       plperl_validator(PG_FUNCTION_ARGS);
Datum       plperlu_call_handler(PG_FUNCTION_ARGS);
Datum       plperlu_inline_handler(PG_FUNCTION_ARGS);
Datum       plperlu_validator(PG_FUNCTION_ARGS);
void        _PG_init(void);

static PerlInterpreter *plperl_init_interp(void);
static void plperl_destroy_interp(PerlInterpreter **);
static void plperl_fini(int code, Datum arg);
static void set_interp_require(bool trusted);

static Datum plperl_func_handler(PG_FUNCTION_ARGS);
static Datum plperl_trigger_handler(PG_FUNCTION_ARGS);

static void free_plperl_function(plperl_proc_desc *prodesc);

static plperl_proc_desc *compile_plperl_function(Oid fn_oid, bool is_trigger);

static SV  *plperl_hash_from_tuple(HeapTuple tuple, TupleDesc tupdesc);
static SV  *plperl_hash_from_datum(Datum attr);
static SV  *plperl_ref_from_pg_array(Datum arg, Oid typid);
static SV  *split_array(plperl_array_info *info, int first, int last, int nest);
static SV  *make_array_ref(plperl_array_info *info, int first, int last);
static SV  *get_perl_array_ref(SV *sv);
static Datum plperl_sv_to_datum(SV *sv, Oid typid, int32 typmod,
                   FunctionCallInfo fcinfo,
                   FmgrInfo *finfo, Oid typioparam,
                   bool *isnull);
static void _sv_to_datum_finfo(Oid typid, FmgrInfo *finfo, Oid *typioparam);
static Datum plperl_array_to_datum(SV *src, Oid typid, int32 typmod);
static ArrayBuildState *array_to_datum_internal(AV *av, ArrayBuildState *astate,
                        int *ndims, int *dims, int cur_depth,
                        Oid arraytypid, Oid elemtypid, int32 typmod,
                        FmgrInfo *finfo, Oid typioparam);
static Datum plperl_hash_to_datum(SV *src, TupleDesc td);

static void plperl_init_shared_libs(pTHX);
static void plperl_trusted_init(void);
static void plperl_untrusted_init(void);
static HV  *plperl_spi_execute_fetch_result(SPITupleTable *, int, int);
static char *hek2cstr(HE *he);
static SV **hv_store_string(HV *hv, const char *key, SV *val);
static SV **hv_fetch_string(HV *hv, const char *key);
static void plperl_create_sub(plperl_proc_desc *desc, char *s, Oid fn_oid);
static SV  *plperl_call_perl_func(plperl_proc_desc *desc,
                      FunctionCallInfo fcinfo);
static void plperl_compile_callback(void *arg);
static void plperl_exec_callback(void *arg);
static void plperl_inline_callback(void *arg);
static char *strip_trailing_ws(const char *msg);
static OP  *pp_require_safe(pTHX);
static void activate_interpreter(plperl_interp_desc *interp_desc);

#ifdef WIN32
static char *setlocale_perl(int category, char *locale);
#endif

/*
 * convert a HE (hash entry) key to a cstr in the current database encoding
 */
static char *
hek2cstr(HE *he)
{
    /*-------------------------
     * Unfortunately,  while HeUTF8 is true for most things > 256, for values
     * 128..255 it's not, but perl will treat them as unicode code points if
     * the utf8 flag is not set ( see The "Unicode Bug" in perldoc perlunicode
     * for more)
     *
     * So if we did the expected:
     *    if (HeUTF8(he))
     *        utf_u2e(key...);
     *    else // must be ascii
     *        return HePV(he);
     * we won't match columns with codepoints from 128..255
     *
     * For a more concrete example given a column with the name of the unicode
     * codepoint U+00ae (registered sign) and a UTF8 database and the perl
     * return_next { "\N{U+00ae}=>'text } would always fail as heUTF8 returns
     * 0 and HePV() would give us a char * with 1 byte contains the decimal
     * value 174
     *
     * Perl has the brains to know when it should utf8 encode 174 properly, so
     * here we force it into an SV so that perl will figure it out and do the
     * right thing
     *-------------------------
     */
    SV         *sv = HeSVKEY_force(he);

    if (HeUTF8(he))
        SvUTF8_on(sv);
    return sv2cstr(sv);
}

/*
 * This routine is a crock, and so is everyplace that calls it.  The problem
 * is that the cached form of plperl functions/queries is allocated permanently
 * (mostly via malloc()) and never released until backend exit.  Subsidiary
 * data structures such as fmgr info records therefore must live forever
 * as well.  A better implementation would store all this stuff in a per-
 * function memory context that could be reclaimed at need.  In the meantime,
 * fmgr_info_cxt must be called specifying TopMemoryContext so that whatever
 * it might allocate, and whatever the eventual function might allocate using
 * fn_mcxt, will live forever too.
 */
static void
perm_fmgr_info(Oid functionId, FmgrInfo *finfo)
{
    fmgr_info_cxt(functionId, finfo, TopMemoryContext);
}


/*
 * _PG_init()           - library load-time initialization
 *
 * DO NOT make this static nor change its name!
 */
void
_PG_init(void)
{
    /*
     * Be sure we do initialization only once.
     *
     * If initialization fails due to, e.g., plperl_init_interp() throwing an
     * exception, then we'll return here on the next usage and the user will
     * get a rather cryptic: ERROR:  attempt to redefine parameter
     * "plperl.use_strict"
     */
    static bool inited = false;
    HASHCTL     hash_ctl;

    if (inited)
        return;

    /*
     * Support localized messages.
     */
    pg_bindtextdomain(TEXTDOMAIN);

    /*
     * Initialize plperl's GUCs.
     */
    DefineCustomBoolVariable("plperl.use_strict",
                             gettext_noop("If true, trusted and untrusted Perl code will be compiled in strict mode."),
                             NULL,
                             &plperl_use_strict,
                             false,
                             PGC_USERSET, 0,
                             NULL, NULL, NULL);

    /*
     * plperl.on_init is marked PGC_SIGHUP to support the idea that it might
     * be executed in the postmaster (if plperl is loaded into the postmaster
     * via shared_preload_libraries).  This isn't really right either way,
     * though.
     */
    DefineCustomStringVariable("plperl.on_init",
                               gettext_noop("Perl initialization code to execute when a Perl interpreter is initialized."),
                               NULL,
                               &plperl_on_init,
                               NULL,
                               PGC_SIGHUP, 0,
                               NULL, NULL, NULL);

    /*
     * plperl.on_plperl_init is marked PGC_SUSET to avoid issues whereby a
     * user who might not even have USAGE privilege on the plperl language
     * could nonetheless use SET plperl.on_plperl_init='...' to influence the
     * behaviour of any existing plperl function that they can execute (which
     * might be SECURITY DEFINER, leading to a privilege escalation).  See
     * http://archives.postgresql.org/pgsql-hackers/2010-02/msg00281.php and
     * the overall thread.
     *
     * Note that because plperl.use_strict is USERSET, a nefarious user could
     * set it to be applied against other people's functions.  This is judged
     * OK since the worst result would be an error.  Your code oughta pass
     * use_strict anyway ;-)
     */
    DefineCustomStringVariable("plperl.on_plperl_init",
                               gettext_noop("Perl initialization code to execute once when plperl is first used."),
                               NULL,
                               &plperl_on_plperl_init,
                               NULL,
                               PGC_SUSET, 0,
                               NULL, NULL, NULL);

    DefineCustomStringVariable("plperl.on_plperlu_init",
                               gettext_noop("Perl initialization code to execute once when plperlu is first used."),
                               NULL,
                               &plperl_on_plperlu_init,
                               NULL,
                               PGC_SUSET, 0,
                               NULL, NULL, NULL);

    EmitWarningsOnPlaceholders("plperl");

    /*
     * Create hash tables.
     */
    memset(&hash_ctl, 0, sizeof(hash_ctl));
    hash_ctl.keysize = sizeof(Oid);
    hash_ctl.entrysize = sizeof(plperl_interp_desc);
    hash_ctl.hash = oid_hash;
    plperl_interp_hash = hash_create("PL/Perl interpreters",
                                     8,
                                     &hash_ctl,
                                     HASH_ELEM | HASH_FUNCTION);

    memset(&hash_ctl, 0, sizeof(hash_ctl));
    hash_ctl.keysize = sizeof(plperl_proc_key);
    hash_ctl.entrysize = sizeof(plperl_proc_ptr);
    hash_ctl.hash = tag_hash;
    plperl_proc_hash = hash_create("PL/Perl procedures",
                                   32,
                                   &hash_ctl,
                                   HASH_ELEM | HASH_FUNCTION);

    /*
     * Save the default opmask.
     */
    PLPERL_SET_OPMASK(plperl_opmask);

    /*
     * Create the first Perl interpreter, but only partially initialize it.
     */
    plperl_held_interp = plperl_init_interp();

    inited = true;
}


static void
set_interp_require(bool trusted)
{
    if (trusted)
    {
        PL_ppaddr[OP_REQUIRE] = pp_require_safe;
        PL_ppaddr[OP_DOFILE] = pp_require_safe;
    }
    else
    {
        PL_ppaddr[OP_REQUIRE] = pp_require_orig;
        PL_ppaddr[OP_DOFILE] = pp_require_orig;
    }
}

/*
 * Cleanup perl interpreters, including running END blocks.
 * Does not fully undo the actions of _PG_init() nor make it callable again.
 */
static void
plperl_fini(int code, Datum arg)
{
    HASH_SEQ_STATUS hash_seq;
    plperl_interp_desc *interp_desc;

    elog(DEBUG3, "plperl_fini");

    /*
     * Indicate that perl is terminating. Disables use of spi_* functions when
     * running END/DESTROY code. See check_spi_usage_allowed(). Could be
     * enabled in future, with care, using a transaction
     * http://archives.postgresql.org/pgsql-hackers/2010-01/msg02743.php
     */
    plperl_ending = true;

    /* Only perform perl cleanup if we're exiting cleanly */
    if (code)
    {
        elog(DEBUG3, "plperl_fini: skipped");
        return;
    }

    /* Zap the "held" interpreter, if we still have it */
    plperl_destroy_interp(&plperl_held_interp);

    /* Zap any fully-initialized interpreters */
    hash_seq_init(&hash_seq, plperl_interp_hash);
    while ((interp_desc = hash_seq_search(&hash_seq)) != NULL)
    {
        if (interp_desc->interp)
        {
            activate_interpreter(interp_desc);
            plperl_destroy_interp(&interp_desc->interp);
        }
    }

    elog(DEBUG3, "plperl_fini: done");
}


/*
 * Select and activate an appropriate Perl interpreter.
 */
static void
select_perl_context(bool trusted)
{
    Oid         user_id;
    plperl_interp_desc *interp_desc;
    bool        found;
    PerlInterpreter *interp = NULL;

    /* Find or create the interpreter hashtable entry for this userid */
    if (trusted)
        user_id = GetUserId();
    else
        user_id = InvalidOid;

    interp_desc = hash_search(plperl_interp_hash, &user_id,
                              HASH_ENTER,
                              &found);
    if (!found)
    {
        /* Initialize newly-created hashtable entry */
        interp_desc->interp = NULL;
        interp_desc->query_hash = NULL;
    }

    /* Make sure we have a query_hash for this interpreter */
    if (interp_desc->query_hash == NULL)
    {
        HASHCTL     hash_ctl;

        memset(&hash_ctl, 0, sizeof(hash_ctl));
        hash_ctl.keysize = NAMEDATALEN;
        hash_ctl.entrysize = sizeof(plperl_query_entry);
        interp_desc->query_hash = hash_create("PL/Perl queries",
                                              32,
                                              &hash_ctl,
                                              HASH_ELEM);
    }

    /*
     * Quick exit if already have an interpreter
     */
    if (interp_desc->interp)
    {
        activate_interpreter(interp_desc);
        return;
    }

    /*
     * adopt held interp if free, else create new one if possible
     */
    if (plperl_held_interp != NULL)
    {
        /* first actual use of a perl interpreter */
        interp = plperl_held_interp;

        /*
         * Reset the plperl_held_interp pointer first; if we fail during init
         * we don't want to try again with the partially-initialized interp.
         */
        plperl_held_interp = NULL;

        if (trusted)
            plperl_trusted_init();
        else
            plperl_untrusted_init();

        /* successfully initialized, so arrange for cleanup */
        on_proc_exit(plperl_fini, 0);
    }
    else
    {
#ifdef MULTIPLICITY

        /*
         * plperl_init_interp will change Perl's idea of the active
         * interpreter.  Reset plperl_active_interp temporarily, so that if we
         * hit an error partway through here, we'll make sure to switch back
         * to a non-broken interpreter before running any other Perl
         * functions.
         */
        plperl_active_interp = NULL;

        /* Now build the new interpreter */
        interp = plperl_init_interp();

        if (trusted)
            plperl_trusted_init();
        else
            plperl_untrusted_init();
#else
        elog(ERROR,
             "cannot allocate multiple Perl interpreters on this platform");
#endif
    }

    set_interp_require(trusted);

    /*
     * Since the timing of first use of PL/Perl can't be predicted, any
     * database interaction during initialization is problematic. Including,
     * but not limited to, security definer issues. So we only enable access
     * to the database AFTER on_*_init code has run. See
     * http://archives.postgresql.org/pgsql-hackers/2010-01/msg02669.php
     */
    newXS("PostgreSQL::InServer::SPI::bootstrap",
          boot_PostgreSQL__InServer__SPI, __FILE__);

    eval_pv("PostgreSQL::InServer::SPI::bootstrap()", FALSE);
    if (SvTRUE(ERRSV))
        ereport(ERROR,
                (errmsg("%s", strip_trailing_ws(sv2cstr(ERRSV))),
        errcontext("while executing PostgreSQL::InServer::SPI::bootstrap")));

    /* Fully initialized, so mark the hashtable entry valid */
    interp_desc->interp = interp;

    /* And mark this as the active interpreter */
    plperl_active_interp = interp_desc;
}

/*
 * Make the specified interpreter the active one
 *
 * A call with NULL does nothing.  This is so that "restoring" to a previously
 * null state of plperl_active_interp doesn't result in useless thrashing.
 */
static void
activate_interpreter(plperl_interp_desc *interp_desc)
{
    if (interp_desc && plperl_active_interp != interp_desc)
    {
        Assert(interp_desc->interp);
        PERL_SET_CONTEXT(interp_desc->interp);
        /* trusted iff user_id isn't InvalidOid */
        set_interp_require(OidIsValid(interp_desc->user_id));
        plperl_active_interp = interp_desc;
    }
}

/*
 * Create a new Perl interpreter.
 *
 * We initialize the interpreter as far as we can without knowing whether
 * it will become a trusted or untrusted interpreter; in particular, the
 * plperl.on_init code will get executed.  Later, either plperl_trusted_init
 * or plperl_untrusted_init must be called to complete the initialization.
 */
static PerlInterpreter *
plperl_init_interp(void)
{
    PerlInterpreter *plperl;

    static char *embedding[3 + 2] = {
        "", "-e", PLC_PERLBOOT
    };
    int         nargs = 3;

#ifdef WIN32

    /*
     * The perl library on startup does horrible things like call
     * setlocale(LC_ALL,""). We have protected against that on most platforms
     * by setting the environment appropriately. However, on Windows,
     * setlocale() does not consult the environment, so we need to save the
     * existing locale settings before perl has a chance to mangle them and
     * restore them after its dirty deeds are done.
     *
     * MSDN ref:
     * http://msdn.microsoft.com/library/en-us/vclib/html/_crt_locale.asp
     *
     * It appears that we only need to do this on interpreter startup, and
     * subsequent calls to the interpreter don't mess with the locale
     * settings.
     *
     * We restore them using setlocale_perl(), defined below, so that Perl
     * doesn't have a different idea of the locale from Postgres.
     *
     */

    char       *loc;
    char       *save_collate,
               *save_ctype,
               *save_monetary,
               *save_numeric,
               *save_time;

    loc = setlocale(LC_COLLATE, NULL);
    save_collate = loc ? pstrdup(loc) : NULL;
    loc = setlocale(LC_CTYPE, NULL);
    save_ctype = loc ? pstrdup(loc) : NULL;
    loc = setlocale(LC_MONETARY, NULL);
    save_monetary = loc ? pstrdup(loc) : NULL;
    loc = setlocale(LC_NUMERIC, NULL);
    save_numeric = loc ? pstrdup(loc) : NULL;
    loc = setlocale(LC_TIME, NULL);
    save_time = loc ? pstrdup(loc) : NULL;

#define PLPERL_RESTORE_LOCALE(name, saved) \
    STMT_START { \
        if (saved != NULL) { setlocale_perl(name, saved); pfree(saved); } \
    } STMT_END
#endif   /* WIN32 */

    if (plperl_on_init && *plperl_on_init)
    {
        embedding[nargs++] = "-e";
        embedding[nargs++] = plperl_on_init;
    }

    /*
     * The perl API docs state that PERL_SYS_INIT3 should be called before
     * allocating interpreters. Unfortunately, on some platforms this fails in
     * the Perl_do_taint() routine, which is called when the platform is using
     * the system's malloc() instead of perl's own. Other platforms, notably
     * Windows, fail if PERL_SYS_INIT3 is not called. So we call it if it's
     * available, unless perl is using the system malloc(), which is true when
     * MYMALLOC is set.
     */
#if defined(PERL_SYS_INIT3) && !defined(MYMALLOC)
    {
        static int  perl_sys_init_done;

        /* only call this the first time through, as per perlembed man page */
        if (!perl_sys_init_done)
        {
            char       *dummy_env[1] = {NULL};

            PERL_SYS_INIT3(&nargs, (char ***) &embedding, (char ***) &dummy_env);

            /*
             * For unclear reasons, PERL_SYS_INIT3 sets the SIGFPE handler to
             * SIG_IGN.  Aside from being extremely unfriendly behavior for a
             * library, this is dumb on the grounds that the results of a
             * SIGFPE in this state are undefined according to POSIX, and in
             * fact you get a forced process kill at least on Linux.  Hence,
             * restore the SIGFPE handler to the backend's standard setting.
             * (See Perl bug 114574 for more information.)
             */
            pqsignal(SIGFPE, FloatExceptionHandler);

            perl_sys_init_done = 1;
            /* quiet warning if PERL_SYS_INIT3 doesn't use the third argument */
            dummy_env[0] = NULL;
        }
    }
#endif

    plperl = perl_alloc();
    if (!plperl)
        elog(ERROR, "could not allocate Perl interpreter");

    PERL_SET_CONTEXT(plperl);
    perl_construct(plperl);

    /* run END blocks in perl_destruct instead of perl_run */
    PL_exit_flags |= PERL_EXIT_DESTRUCT_END;

    /*
     * Record the original function for the 'require' and 'dofile' opcodes.
     * (They share the same implementation.) Ensure it's used for new
     * interpreters.
     */
    if (!pp_require_orig)
        pp_require_orig = PL_ppaddr[OP_REQUIRE];
    else
    {
        PL_ppaddr[OP_REQUIRE] = pp_require_orig;
        PL_ppaddr[OP_DOFILE] = pp_require_orig;
    }

#ifdef PLPERL_ENABLE_OPMASK_EARLY

    /*
     * For regression testing to prove that the PLC_PERLBOOT and PLC_TRUSTED
     * code doesn't even compile any unsafe ops. In future there may be a
     * valid need for them to do so, in which case this could be softened
     * (perhaps moved to plperl_trusted_init()) or removed.
     */
    PL_op_mask = plperl_opmask;
#endif

    if (perl_parse(plperl, plperl_init_shared_libs,
                   nargs, embedding, NULL) != 0)
        ereport(ERROR,
                (errmsg("%s", strip_trailing_ws(sv2cstr(ERRSV))),
                 errcontext("while parsing Perl initialization")));

    if (perl_run(plperl) != 0)
        ereport(ERROR,
                (errmsg("%s", strip_trailing_ws(sv2cstr(ERRSV))),
                 errcontext("while running Perl initialization")));

#ifdef PLPERL_RESTORE_LOCALE
    PLPERL_RESTORE_LOCALE(LC_COLLATE, save_collate);
    PLPERL_RESTORE_LOCALE(LC_CTYPE, save_ctype);
    PLPERL_RESTORE_LOCALE(LC_MONETARY, save_monetary);
    PLPERL_RESTORE_LOCALE(LC_NUMERIC, save_numeric);
    PLPERL_RESTORE_LOCALE(LC_TIME, save_time);
#endif

    return plperl;
}


/*
 * Our safe implementation of the require opcode.
 * This is safe because it's completely unable to load any code.
 * If the requested file/module has already been loaded it'll return true.
 * If not, it'll die.
 * So now "use Foo;" will work iff Foo has already been loaded.
 */
static OP  *
pp_require_safe(pTHX)
{
    dVAR;
    dSP;
    SV         *sv,
              **svp;
    char       *name;
    STRLEN      len;

    sv = POPs;
    name = SvPV(sv, len);
    if (!(name && len > 0 && *name))
        RETPUSHNO;

    svp = hv_fetch(GvHVn(PL_incgv), name, len, 0);
    if (svp && *svp != &PL_sv_undef)
        RETPUSHYES;

    DIE(aTHX_ "Unable to load %s into plperl", name);
    /*
     * In most Perl versions, DIE() expands to a return statement, so the next
     * line is not necessary.  But in versions between but not including 5.11.1
     * and 5.13.3 it does not, so the next line is necessary to avoid a
     * "control reaches end of non-void function" warning from gcc.  Other
     * compilers such as Solaris Studio will, however, issue a "statement not
     * reached" warning instead.
     */
    return NULL;
}


/*
 * Destroy one Perl interpreter ... actually we just run END blocks.
 *
 * Caller must have ensured this interpreter is the active one.
 */
static void
plperl_destroy_interp(PerlInterpreter **interp)
{
    if (interp && *interp)
    {
        /*
         * Only a very minimal destruction is performed: - just call END
         * blocks.
         *
         * We could call perl_destruct() but we'd need to audit its actions
         * very carefully and work-around any that impact us. (Calling
         * sv_clean_objs() isn't an option because it's not part of perl's
         * public API so isn't portably available.) Meanwhile END blocks can
         * be used to perform manual cleanup.
         */

        /* Run END blocks - based on perl's perl_destruct() */
        if (PL_exit_flags & PERL_EXIT_DESTRUCT_END)
        {
            dJMPENV;
            int         x = 0;

            JMPENV_PUSH(x);
            PERL_UNUSED_VAR(x);
            if (PL_endav && !PL_minus_c)
                call_list(PL_scopestack_ix, PL_endav);
            JMPENV_POP;
        }
        LEAVE;
        FREETMPS;

        *interp = NULL;
    }
}

/*
 * Initialize the current Perl interpreter as a trusted interp
 */
static void
plperl_trusted_init(void)
{
    HV         *stash;
    SV         *sv;
    char       *key;
    I32         klen;

    /* use original require while we set up */
    PL_ppaddr[OP_REQUIRE] = pp_require_orig;
    PL_ppaddr[OP_DOFILE] = pp_require_orig;

    eval_pv(PLC_TRUSTED, FALSE);
    if (SvTRUE(ERRSV))
        ereport(ERROR,
                (errmsg("%s", strip_trailing_ws(sv2cstr(ERRSV))),
                 errcontext("while executing PLC_TRUSTED")));

    /*
     * Force loading of utf8 module now to prevent errors that can arise from
     * the regex code later trying to load utf8 modules. See
     * http://rt.perl.org/rt3/Ticket/Display.html?id=47576
     */
    eval_pv("my $a=chr(0x100); return $a =~ /\\xa9/i", FALSE);
    if (SvTRUE(ERRSV))
        ereport(ERROR,
                (errmsg("%s", strip_trailing_ws(sv2cstr(ERRSV))),
                 errcontext("while executing utf8fix")));

    /*
     * Lock down the interpreter
     */

    /* switch to the safe require/dofile opcode for future code */
    PL_ppaddr[OP_REQUIRE] = pp_require_safe;
    PL_ppaddr[OP_DOFILE] = pp_require_safe;

    /*
     * prevent (any more) unsafe opcodes being compiled PL_op_mask is per
     * interpreter, so this only needs to be set once
     */
    PL_op_mask = plperl_opmask;

    /* delete the DynaLoader:: namespace so extensions can't be loaded */
    stash = gv_stashpv("DynaLoader", GV_ADDWARN);
    hv_iterinit(stash);
    while ((sv = hv_iternextsv(stash, &key, &klen)))
    {
        if (!isGV_with_GP(sv) || !GvCV(sv))
            continue;
        SvREFCNT_dec(GvCV(sv)); /* free the CV */
        GvCV_set(sv, NULL);     /* prevent call via GV */
    }
    hv_clear(stash);

    /* invalidate assorted caches */
    ++PL_sub_generation;
    hv_clear(PL_stashcache);

    /*
     * Execute plperl.on_plperl_init in the locked-down interpreter
     */
    if (plperl_on_plperl_init && *plperl_on_plperl_init)
    {
        eval_pv(plperl_on_plperl_init, FALSE);
        if (SvTRUE(ERRSV))
            ereport(ERROR,
                    (errmsg("%s", strip_trailing_ws(sv2cstr(ERRSV))),
                     errcontext("while executing plperl.on_plperl_init")));

    }
}


/*
 * Initialize the current Perl interpreter as an untrusted interp
 */
static void
plperl_untrusted_init(void)
{
    /*
     * Nothing to do except execute plperl.on_plperlu_init
     */
    if (plperl_on_plperlu_init && *plperl_on_plperlu_init)
    {
        eval_pv(plperl_on_plperlu_init, FALSE);
        if (SvTRUE(ERRSV))
            ereport(ERROR,
                    (errmsg("%s", strip_trailing_ws(sv2cstr(ERRSV))),
                     errcontext("while executing plperl.on_plperlu_init")));
    }
}


/*
 * Perl likes to put a newline after its error messages; clean up such
 */
static char *
strip_trailing_ws(const char *msg)
{
    char       *res = pstrdup(msg);
    int         len = strlen(res);

    while (len > 0 && isspace((unsigned char) res[len - 1]))
        res[--len] = '\0';
    return res;
}


/* Build a tuple from a hash. */

static HeapTuple
plperl_build_tuple_result(HV *perlhash, TupleDesc td)
{
    Datum      *values;
    bool       *nulls;
    HE         *he;
    HeapTuple   tup;

    values = palloc0(sizeof(Datum) * td->natts);
    nulls = palloc(sizeof(bool) * td->natts);
    memset(nulls, true, sizeof(bool) * td->natts);

    hv_iterinit(perlhash);
    while ((he = hv_iternext(perlhash)))
    {
        SV         *val = HeVAL(he);
        char       *key = hek2cstr(he);
        int         attn = SPI_fnumber(td, key);

        if (attn <= 0 || td->attrs[attn - 1]->attisdropped)
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_COLUMN),
                     errmsg("Perl hash contains nonexistent column \"%s\"",
                            key)));

        values[attn - 1] = plperl_sv_to_datum(val,
                                              td->attrs[attn - 1]->atttypid,
                                              td->attrs[attn - 1]->atttypmod,
                                              NULL,
                                              NULL,
                                              InvalidOid,
                                              &nulls[attn - 1]);

        pfree(key);
    }
    hv_iterinit(perlhash);

    tup = heap_form_tuple(td, values, nulls);
    pfree(values);
    pfree(nulls);
    return tup;
}

/* convert a hash reference to a datum */
static Datum
plperl_hash_to_datum(SV *src, TupleDesc td)
{
    HeapTuple   tup = plperl_build_tuple_result((HV *) SvRV(src), td);

    return HeapTupleGetDatum(tup);
}

/*
 * if we are an array ref return the reference. this is special in that if we
 * are a PostgreSQL::InServer::ARRAY object we will return the 'magic' array.
 */
static SV  *
get_perl_array_ref(SV *sv)
{
    if (SvOK(sv) && SvROK(sv))
    {
        if (SvTYPE(SvRV(sv)) == SVt_PVAV)
            return sv;
        else if (sv_isa(sv, "PostgreSQL::InServer::ARRAY"))
        {
            HV         *hv = (HV *) SvRV(sv);
            SV        **sav = hv_fetch_string(hv, "array");

            if (*sav && SvOK(*sav) && SvROK(*sav) &&
                SvTYPE(SvRV(*sav)) == SVt_PVAV)
                return *sav;

            elog(ERROR, "could not get array reference from PostgreSQL::InServer::ARRAY object");
        }
    }
    return NULL;
}

/*
 * helper function for plperl_array_to_datum, recurses for multi-D arrays
 */
static ArrayBuildState *
array_to_datum_internal(AV *av, ArrayBuildState *astate,
                        int *ndims, int *dims, int cur_depth,
                        Oid arraytypid, Oid elemtypid, int32 typmod,
                        FmgrInfo *finfo, Oid typioparam)
{
    int         i;
    int         len = av_len(av) + 1;

    for (i = 0; i < len; i++)
    {
        /* fetch the array element */
        SV        **svp = av_fetch(av, i, FALSE);

        /* see if this element is an array, if so get that */
        SV         *sav = svp ? get_perl_array_ref(*svp) : NULL;

        /* multi-dimensional array? */
        if (sav)
        {
            AV         *nav = (AV *) SvRV(sav);

            /* dimensionality checks */
            if (cur_depth + 1 > MAXDIM)
                ereport(ERROR,
                        (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                         errmsg("number of array dimensions (%d) exceeds the maximum allowed (%d)",
                                cur_depth + 1, MAXDIM)));

            /* set size when at first element in this level, else compare */
            if (i == 0 && *ndims == cur_depth)
            {
                dims[*ndims] = av_len(nav) + 1;
                (*ndims)++;
            }
            else if (av_len(nav) + 1 != dims[cur_depth])
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                         errmsg("multidimensional arrays must have array expressions with matching dimensions")));

            /* recurse to fetch elements of this sub-array */
            astate = array_to_datum_internal(nav, astate,
                                             ndims, dims, cur_depth + 1,
                                             arraytypid, elemtypid, typmod,
                                             finfo, typioparam);
        }
        else
        {
            Datum       dat;
            bool        isnull;

            /* scalar after some sub-arrays at same level? */
            if (*ndims != cur_depth)
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                         errmsg("multidimensional arrays must have array expressions with matching dimensions")));

            dat = plperl_sv_to_datum(svp ? *svp : NULL,
                                     elemtypid,
                                     typmod,
                                     NULL,
                                     finfo,
                                     typioparam,
                                     &isnull);

            astate = accumArrayResult(astate, dat, isnull,
                                      elemtypid, CurrentMemoryContext);
        }
    }

    return astate;
}

/*
 * convert perl array ref to a datum
 */
static Datum
plperl_array_to_datum(SV *src, Oid typid, int32 typmod)
{
    ArrayBuildState *astate;
    Oid         elemtypid;
    FmgrInfo    finfo;
    Oid         typioparam;
    int         dims[MAXDIM];
    int         lbs[MAXDIM];
    int         ndims = 1;
    int         i;

    elemtypid = get_element_type(typid);
    if (!elemtypid)
        ereport(ERROR,
                (errcode(ERRCODE_DATATYPE_MISMATCH),
                 errmsg("cannot convert Perl array to non-array type %s",
                        format_type_be(typid))));

    _sv_to_datum_finfo(elemtypid, &finfo, &typioparam);

    memset(dims, 0, sizeof(dims));
    dims[0] = av_len((AV *) SvRV(src)) + 1;

    astate = array_to_datum_internal((AV *) SvRV(src), NULL,
                                     &ndims, dims, 1,
                                     typid, elemtypid, typmod,
                                     &finfo, typioparam);

    if (!astate)
        return PointerGetDatum(construct_empty_array(elemtypid));

    for (i = 0; i < ndims; i++)
        lbs[i] = 1;

    return makeMdArrayResult(astate, ndims, dims, lbs,
                             CurrentMemoryContext, true);
}

/* Get the information needed to convert data to the specified PG type */
static void
_sv_to_datum_finfo(Oid typid, FmgrInfo *finfo, Oid *typioparam)
{
    Oid         typinput;

    /* XXX would be better to cache these lookups */
    getTypeInputInfo(typid,
                     &typinput, typioparam);
    fmgr_info(typinput, finfo);
}

/*
 * convert Perl SV to PG datum of type typid, typmod typmod
 *
 * Pass the PL/Perl function's fcinfo when attempting to convert to the
 * function's result type; otherwise pass NULL.  This is used when we need to
 * resolve the actual result type of a function returning RECORD.
 *
 * finfo and typioparam should be the results of _sv_to_datum_finfo for the
 * given typid, or NULL/InvalidOid to let this function do the lookups.
 *
 * *isnull is an output parameter.
 */
static Datum
plperl_sv_to_datum(SV *sv, Oid typid, int32 typmod,
                   FunctionCallInfo fcinfo,
                   FmgrInfo *finfo, Oid typioparam,
                   bool *isnull)
{
    FmgrInfo    tmp;

    /* we might recurse */
    check_stack_depth();

    *isnull = false;

    /*
     * Return NULL if result is undef, or if we're in a function returning
     * VOID.  In the latter case, we should pay no attention to the last Perl
     * statement's result, and this is a convenient means to ensure that.
     */
    if (!sv || !SvOK(sv) || typid == VOIDOID)
    {
        /* look up type info if they did not pass it */
        if (!finfo)
        {
            _sv_to_datum_finfo(typid, &tmp, &typioparam);
            finfo = &tmp;
        }
        *isnull = true;
        /* must call typinput in case it wants to reject NULL */
        return InputFunctionCall(finfo, NULL, typioparam, typmod);
    }
    else if (SvROK(sv))
    {
        /* handle references */
        SV         *sav = get_perl_array_ref(sv);

        if (sav)
        {
            /* handle an arrayref */
            return plperl_array_to_datum(sav, typid, typmod);
        }
        else if (SvTYPE(SvRV(sv)) == SVt_PVHV)
        {
            /* handle a hashref */
            Datum       ret;
            TupleDesc   td;

            if (!type_is_rowtype(typid))
                ereport(ERROR,
                        (errcode(ERRCODE_DATATYPE_MISMATCH),
                  errmsg("cannot convert Perl hash to non-composite type %s",
                         format_type_be(typid))));

            td = lookup_rowtype_tupdesc_noerror(typid, typmod, true);
            if (td == NULL)
            {
                /* Try to look it up based on our result type */
                if (fcinfo == NULL ||
                get_call_result_type(fcinfo, NULL, &td) != TYPEFUNC_COMPOSITE)
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                        errmsg("function returning record called in context "
                               "that cannot accept type record")));
            }

            ret = plperl_hash_to_datum(sv, td);

            /* Release on the result of get_call_result_type is harmless */
            ReleaseTupleDesc(td);

            return ret;
        }

        /* Reference, but not reference to hash or array ... */
        ereport(ERROR,
                (errcode(ERRCODE_DATATYPE_MISMATCH),
         errmsg("PL/Perl function must return reference to hash or array")));
        return (Datum) 0;       /* shut up compiler */
    }
    else
    {
        /* handle a string/number */
        Datum       ret;
        char       *str = sv2cstr(sv);

        /* did not pass in any typeinfo? look it up */
        if (!finfo)
        {
            _sv_to_datum_finfo(typid, &tmp, &typioparam);
            finfo = &tmp;
        }

        ret = InputFunctionCall(finfo, str, typioparam, typmod);
        pfree(str);

        return ret;
    }
}

/* Convert the perl SV to a string returned by the type output function */
char *
plperl_sv_to_literal(SV *sv, char *fqtypename)
{
    Datum       str = CStringGetDatum(fqtypename);
    Oid         typid = DirectFunctionCall1(regtypein, str);
    Oid         typoutput;
    Datum       datum;
    bool        typisvarlena,
                isnull;

    if (!OidIsValid(typid))
        elog(ERROR, "lookup failed for type %s", fqtypename);

    datum = plperl_sv_to_datum(sv,
                               typid, -1,
                               NULL, NULL, InvalidOid,
                               &isnull);

    if (isnull)
        return NULL;

    getTypeOutputInfo(typid,
                      &typoutput, &typisvarlena);

    return OidOutputFunctionCall(typoutput, datum);
}

/*
 * Convert PostgreSQL array datum to a perl array reference.
 *
 * typid is arg's OID, which must be an array type.
 */
static SV  *
plperl_ref_from_pg_array(Datum arg, Oid typid)
{
    ArrayType  *ar = DatumGetArrayTypeP(arg);
    Oid         elementtype = ARR_ELEMTYPE(ar);
    int16       typlen;
    bool        typbyval;
    char        typalign,
                typdelim;
    Oid         typioparam;
    Oid         typoutputfunc;
    int         i,
                nitems,
               *dims;
    plperl_array_info *info;
    SV         *av;
    HV         *hv;

    info = palloc(sizeof(plperl_array_info));

    /* get element type information, including output conversion function */
    get_type_io_data(elementtype, IOFunc_output,
                     &typlen, &typbyval, &typalign,
                     &typdelim, &typioparam, &typoutputfunc);

    perm_fmgr_info(typoutputfunc, &info->proc);

    info->elem_is_rowtype = type_is_rowtype(elementtype);

    /* Get the number and bounds of array dimensions */
    info->ndims = ARR_NDIM(ar);
    dims = ARR_DIMS(ar);

    deconstruct_array(ar, elementtype, typlen, typbyval,
                      typalign, &info->elements, &info->nulls,
                      &nitems);

    /* Get total number of elements in each dimension */
    info->nelems = palloc(sizeof(int) * info->ndims);
    info->nelems[0] = nitems;
    for (i = 1; i < info->ndims; i++)
        info->nelems[i] = info->nelems[i - 1] / dims[i - 1];

    av = split_array(info, 0, nitems, 0);

    hv = newHV();
    (void) hv_store(hv, "array", 5, av, 0);
    (void) hv_store(hv, "typeoid", 7, newSViv(typid), 0);

    return sv_bless(newRV_noinc((SV *) hv),
                    gv_stashpv("PostgreSQL::InServer::ARRAY", 0));
}

/*
 * Recursively form array references from splices of the initial array
 */
static SV  *
split_array(plperl_array_info *info, int first, int last, int nest)
{
    int         i;
    AV         *result;

    /* since this function recurses, it could be driven to stack overflow */
    check_stack_depth();

    /*
     * Base case, return a reference to a single-dimensional array
     */
    if (nest >= info->ndims - 1)
        return make_array_ref(info, first, last);

    result = newAV();
    for (i = first; i < last; i += info->nelems[nest + 1])
    {
        /* Recursively form references to arrays of lower dimensions */
        SV         *ref = split_array(info, i, i + info->nelems[nest + 1], nest + 1);

        av_push(result, ref);
    }
    return newRV_noinc((SV *) result);
}

/*
 * Create a Perl reference from a one-dimensional C array, converting
 * composite type elements to hash references.
 */
static SV  *
make_array_ref(plperl_array_info *info, int first, int last)
{
    int         i;
    AV         *result = newAV();

    for (i = first; i < last; i++)
    {
        if (info->nulls[i])
        {
            /*
             * We can't use &PL_sv_undef here.  See "AVs, HVs and undefined
             * values" in perlguts.
             */
            av_push(result, newSV(0));
        }
        else
        {
            Datum       itemvalue = info->elements[i];

            /* Handle composite type elements */
            if (info->elem_is_rowtype)
                av_push(result, plperl_hash_from_datum(itemvalue));
            else
            {
                char       *val = OutputFunctionCall(&info->proc, itemvalue);

                av_push(result, cstr2sv(val));
            }
        }
    }
    return newRV_noinc((SV *) result);
}

/* Set up the arguments for a trigger call. */
static SV  *
plperl_trigger_build_args(FunctionCallInfo fcinfo)
{
    TriggerData *tdata;
    TupleDesc   tupdesc;
    int         i;
    char       *level;
    char       *event;
    char       *relid;
    char       *when;
    HV         *hv;

    hv = newHV();
    hv_ksplit(hv, 12);          /* pre-grow the hash */

    tdata = (TriggerData *) fcinfo->context;
    tupdesc = tdata->tg_relation->rd_att;

    relid = DatumGetCString(
                            DirectFunctionCall1(oidout,
                                  ObjectIdGetDatum(tdata->tg_relation->rd_id)
                                                )
        );

    hv_store_string(hv, "name", cstr2sv(tdata->tg_trigger->tgname));
    hv_store_string(hv, "relid", cstr2sv(relid));

    if (TRIGGER_FIRED_BY_INSERT(tdata->tg_event))
    {
        event = "INSERT";
        if (TRIGGER_FIRED_FOR_ROW(tdata->tg_event))
            hv_store_string(hv, "new",
                            plperl_hash_from_tuple(tdata->tg_trigtuple,
                                                   tupdesc));
    }
    else if (TRIGGER_FIRED_BY_DELETE(tdata->tg_event))
    {
        event = "DELETE";
        if (TRIGGER_FIRED_FOR_ROW(tdata->tg_event))
            hv_store_string(hv, "old",
                            plperl_hash_from_tuple(tdata->tg_trigtuple,
                                                   tupdesc));
    }
    else if (TRIGGER_FIRED_BY_UPDATE(tdata->tg_event))
    {
        event = "UPDATE";
        if (TRIGGER_FIRED_FOR_ROW(tdata->tg_event))
        {
            hv_store_string(hv, "old",
                            plperl_hash_from_tuple(tdata->tg_trigtuple,
                                                   tupdesc));
            hv_store_string(hv, "new",
                            plperl_hash_from_tuple(tdata->tg_newtuple,
                                                   tupdesc));
        }
    }
    else if (TRIGGER_FIRED_BY_TRUNCATE(tdata->tg_event))
        event = "TRUNCATE";
    else
        event = "UNKNOWN";

    hv_store_string(hv, "event", cstr2sv(event));
    hv_store_string(hv, "argc", newSViv(tdata->tg_trigger->tgnargs));

    if (tdata->tg_trigger->tgnargs > 0)
    {
        AV         *av = newAV();

        av_extend(av, tdata->tg_trigger->tgnargs);
        for (i = 0; i < tdata->tg_trigger->tgnargs; i++)
            av_push(av, cstr2sv(tdata->tg_trigger->tgargs[i]));
        hv_store_string(hv, "args", newRV_noinc((SV *) av));
    }

    hv_store_string(hv, "relname",
                    cstr2sv(SPI_getrelname(tdata->tg_relation)));

    hv_store_string(hv, "table_name",
                    cstr2sv(SPI_getrelname(tdata->tg_relation)));

    hv_store_string(hv, "table_schema",
                    cstr2sv(SPI_getnspname(tdata->tg_relation)));

    if (TRIGGER_FIRED_BEFORE(tdata->tg_event))
        when = "BEFORE";
    else if (TRIGGER_FIRED_AFTER(tdata->tg_event))
        when = "AFTER";
    else if (TRIGGER_FIRED_INSTEAD(tdata->tg_event))
        when = "INSTEAD OF";
    else
        when = "UNKNOWN";
    hv_store_string(hv, "when", cstr2sv(when));

    if (TRIGGER_FIRED_FOR_ROW(tdata->tg_event))
        level = "ROW";
    else if (TRIGGER_FIRED_FOR_STATEMENT(tdata->tg_event))
        level = "STATEMENT";
    else
        level = "UNKNOWN";
    hv_store_string(hv, "level", cstr2sv(level));

    return newRV_noinc((SV *) hv);
}


/* Set up the new tuple returned from a trigger. */

static HeapTuple
plperl_modify_tuple(HV *hvTD, TriggerData *tdata, HeapTuple otup)
{
    SV        **svp;
    HV         *hvNew;
    HE         *he;
    HeapTuple   rtup;
    int         slotsused;
    int        *modattrs;
    Datum      *modvalues;
    char       *modnulls;

    TupleDesc   tupdesc;

    tupdesc = tdata->tg_relation->rd_att;

    svp = hv_fetch_string(hvTD, "new");
    if (!svp)
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_COLUMN),
                 errmsg("$_TD->{new} does not exist")));
    if (!SvOK(*svp) || !SvROK(*svp) || SvTYPE(SvRV(*svp)) != SVt_PVHV)
        ereport(ERROR,
                (errcode(ERRCODE_DATATYPE_MISMATCH),
                 errmsg("$_TD->{new} is not a hash reference")));
    hvNew = (HV *) SvRV(*svp);

    modattrs = palloc(tupdesc->natts * sizeof(int));
    modvalues = palloc(tupdesc->natts * sizeof(Datum));
    modnulls = palloc(tupdesc->natts * sizeof(char));
    slotsused = 0;

    hv_iterinit(hvNew);
    while ((he = hv_iternext(hvNew)))
    {
        bool        isnull;
        char       *key = hek2cstr(he);
        SV         *val = HeVAL(he);
        int         attn = SPI_fnumber(tupdesc, key);

        if (attn <= 0 || tupdesc->attrs[attn - 1]->attisdropped)
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_COLUMN),
                     errmsg("Perl hash contains nonexistent column \"%s\"",
                            key)));

        modvalues[slotsused] = plperl_sv_to_datum(val,
                                          tupdesc->attrs[attn - 1]->atttypid,
                                         tupdesc->attrs[attn - 1]->atttypmod,
                                                  NULL,
                                                  NULL,
                                                  InvalidOid,
                                                  &isnull);

        modnulls[slotsused] = isnull ? 'n' : ' ';
        modattrs[slotsused] = attn;
        slotsused++;

        pfree(key);
    }
    hv_iterinit(hvNew);

    rtup = SPI_modifytuple(tdata->tg_relation, otup, slotsused,
                           modattrs, modvalues, modnulls);

    pfree(modattrs);
    pfree(modvalues);
    pfree(modnulls);

    if (rtup == NULL)
        elog(ERROR, "SPI_modifytuple failed: %s",
             SPI_result_code_string(SPI_result));

    return rtup;
}


/*
 * There are three externally visible pieces to plperl: plperl_call_handler,
 * plperl_inline_handler, and plperl_validator.
 */

/*
 * The call handler is called to run normal functions (including trigger
 * functions) that are defined in pg_proc.
 */
PG_FUNCTION_INFO_V1(plperl_call_handler);

Datum
plperl_call_handler(PG_FUNCTION_ARGS)
{
    Datum       retval;
    plperl_call_data *save_call_data = current_call_data;
    plperl_interp_desc *oldinterp = plperl_active_interp;
    plperl_call_data this_call_data;

    /* Initialize current-call status record */
    MemSet(&this_call_data, 0, sizeof(this_call_data));
    this_call_data.fcinfo = fcinfo;

    PG_TRY();
    {
        current_call_data = &this_call_data;
        if (CALLED_AS_TRIGGER(fcinfo))
            retval = PointerGetDatum(plperl_trigger_handler(fcinfo));
        else
            retval = plperl_func_handler(fcinfo);
    }
    PG_CATCH();
    {
        if (this_call_data.prodesc)
            decrement_prodesc_refcount(this_call_data.prodesc);
        current_call_data = save_call_data;
        activate_interpreter(oldinterp);
        PG_RE_THROW();
    }
    PG_END_TRY();

    if (this_call_data.prodesc)
        decrement_prodesc_refcount(this_call_data.prodesc);
    current_call_data = save_call_data;
    activate_interpreter(oldinterp);
    return retval;
}

/*
 * The inline handler runs anonymous code blocks (DO blocks).
 */
PG_FUNCTION_INFO_V1(plperl_inline_handler);

Datum
plperl_inline_handler(PG_FUNCTION_ARGS)
{
    InlineCodeBlock *codeblock = (InlineCodeBlock *) PG_GETARG_POINTER(0);
    FunctionCallInfoData fake_fcinfo;
    FmgrInfo    flinfo;
    plperl_proc_desc desc;
    plperl_call_data *save_call_data = current_call_data;
    plperl_interp_desc *oldinterp = plperl_active_interp;
    plperl_call_data this_call_data;
    ErrorContextCallback pl_error_context;

    /* Initialize current-call status record */
    MemSet(&this_call_data, 0, sizeof(this_call_data));

    /* Set up a callback for error reporting */
    pl_error_context.callback = plperl_inline_callback;
    pl_error_context.previous = error_context_stack;
    pl_error_context.arg = (Datum) 0;
    error_context_stack = &pl_error_context;

    /*
     * Set up a fake fcinfo and descriptor with just enough info to satisfy
     * plperl_call_perl_func().  In particular note that this sets things up
     * with no arguments passed, and a result type of VOID.
     */
    MemSet(&fake_fcinfo, 0, sizeof(fake_fcinfo));
    MemSet(&flinfo, 0, sizeof(flinfo));
    MemSet(&desc, 0, sizeof(desc));
    fake_fcinfo.flinfo = &flinfo;
    flinfo.fn_oid = InvalidOid;
    flinfo.fn_mcxt = CurrentMemoryContext;

    desc.proname = "inline_code_block";
    desc.fn_readonly = false;

    desc.lanpltrusted = codeblock->langIsTrusted;

    desc.fn_retistuple = false;
    desc.fn_retisset = false;
    desc.fn_retisarray = false;
    desc.result_oid = VOIDOID;
    desc.nargs = 0;
    desc.reference = NULL;

    this_call_data.fcinfo = &fake_fcinfo;
    this_call_data.prodesc = &desc;
    /* we do not bother with refcounting the fake prodesc */

    PG_TRY();
    {
        SV         *perlret;

        current_call_data = &this_call_data;

        if (SPI_connect() != SPI_OK_CONNECT)
            elog(ERROR, "could not connect to SPI manager");

        select_perl_context(desc.lanpltrusted);

        plperl_create_sub(&desc, codeblock->source_text, 0);

        if (!desc.reference)    /* can this happen? */
            elog(ERROR, "could not create internal procedure for anonymous code block");

        perlret = plperl_call_perl_func(&desc, &fake_fcinfo);

        SvREFCNT_dec(perlret);

        if (SPI_finish() != SPI_OK_FINISH)
            elog(ERROR, "SPI_finish() failed");
    }
    PG_CATCH();
    {
        if (desc.reference)
            SvREFCNT_dec(desc.reference);
        current_call_data = save_call_data;
        activate_interpreter(oldinterp);
        PG_RE_THROW();
    }
    PG_END_TRY();

    if (desc.reference)
        SvREFCNT_dec(desc.reference);

    current_call_data = save_call_data;
    activate_interpreter(oldinterp);

    error_context_stack = pl_error_context.previous;

    PG_RETURN_VOID();
}

/*
 * The validator is called during CREATE FUNCTION to validate the function
 * being created/replaced. The precise behavior of the validator may be
 * modified by the check_function_bodies GUC.
 */
PG_FUNCTION_INFO_V1(plperl_validator);

Datum
plperl_validator(PG_FUNCTION_ARGS)
{
    Oid         funcoid = PG_GETARG_OID(0);
    HeapTuple   tuple;
    Form_pg_proc proc;
    char        functyptype;
    int         numargs;
    Oid        *argtypes;
    char      **argnames;
    char       *argmodes;
    bool        istrigger = false;
    int         i;

    /* Get the new function's pg_proc entry */
    tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcoid));
    if (!HeapTupleIsValid(tuple))
        elog(ERROR, "cache lookup failed for function %u", funcoid);
    proc = (Form_pg_proc) GETSTRUCT(tuple);

    functyptype = get_typtype(proc->prorettype);

    /* Disallow pseudotype result */
    /* except for TRIGGER, RECORD, or VOID */
    if (functyptype == TYPTYPE_PSEUDO)
    {
        /* we assume OPAQUE with no arguments means a trigger */
        if (proc->prorettype == TRIGGEROID ||
            (proc->prorettype == OPAQUEOID && proc->pronargs == 0))
            istrigger = true;
        else if (proc->prorettype != RECORDOID &&
                 proc->prorettype != VOIDOID)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("PL/Perl functions cannot return type %s",
                            format_type_be(proc->prorettype))));
    }

    /* Disallow pseudotypes in arguments (either IN or OUT) */
    numargs = get_func_arg_info(tuple,
                                &argtypes, &argnames, &argmodes);
    for (i = 0; i < numargs; i++)
    {
        if (get_typtype(argtypes[i]) == TYPTYPE_PSEUDO &&
            argtypes[i] != RECORDOID)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("PL/Perl functions cannot accept type %s",
                            format_type_be(argtypes[i]))));
    }

    ReleaseSysCache(tuple);

    /* Postpone body checks if !check_function_bodies */
    if (check_function_bodies)
    {
        (void) compile_plperl_function(funcoid, istrigger);
    }

    /* the result of a validator is ignored */
    PG_RETURN_VOID();
}


/*
 * plperlu likewise requires three externally visible functions:
 * plperlu_call_handler, plperlu_inline_handler, and plperlu_validator.
 * These are currently just aliases that send control to the plperl
 * handler functions, and we decide whether a particular function is
 * trusted or not by inspecting the actual pg_language tuple.
 */

PG_FUNCTION_INFO_V1(plperlu_call_handler);

Datum
plperlu_call_handler(PG_FUNCTION_ARGS)
{
    return plperl_call_handler(fcinfo);
}

PG_FUNCTION_INFO_V1(plperlu_inline_handler);

Datum
plperlu_inline_handler(PG_FUNCTION_ARGS)
{
    return plperl_inline_handler(fcinfo);
}

PG_FUNCTION_INFO_V1(plperlu_validator);

Datum
plperlu_validator(PG_FUNCTION_ARGS)
{
    return plperl_validator(fcinfo);
}


/*
 * Uses mksafefunc/mkunsafefunc to create a subroutine whose text is
 * supplied in s, and returns a reference to it
 */
static void
plperl_create_sub(plperl_proc_desc *prodesc, char *s, Oid fn_oid)
{
    dSP;
    char        subname[NAMEDATALEN + 40];
    HV         *pragma_hv = newHV();
    SV         *subref = NULL;
    int         count;

    sprintf(subname, "%s__%u", prodesc->proname, fn_oid);

    if (plperl_use_strict)
        hv_store_string(pragma_hv, "strict", (SV *) newAV());

    ENTER;
    SAVETMPS;
    PUSHMARK(SP);
    EXTEND(SP, 4);
    PUSHs(sv_2mortal(cstr2sv(subname)));
    PUSHs(sv_2mortal(newRV_noinc((SV *) pragma_hv)));

    /*
     * Use 'false' for $prolog in mkfunc, which is kept for compatibility in
     * case a module such as PostgreSQL::PLPerl::NYTprof replaces the function
     * compiler.
     */
    PUSHs(&PL_sv_no);
    PUSHs(sv_2mortal(cstr2sv(s)));
    PUTBACK;

    /*
     * G_KEEPERR seems to be needed here, else we don't recognize compile
     * errors properly.  Perhaps it's because there's another level of eval
     * inside mksafefunc?
     */
    count = perl_call_pv("PostgreSQL::InServer::mkfunc",
                         G_SCALAR | G_EVAL | G_KEEPERR);
    SPAGAIN;

    if (count == 1)
    {
        SV         *sub_rv = (SV *) POPs;

        if (sub_rv && SvROK(sub_rv) && SvTYPE(SvRV(sub_rv)) == SVt_PVCV)
        {
            subref = newRV_inc(SvRV(sub_rv));
        }
    }

    PUTBACK;
    FREETMPS;
    LEAVE;

    if (SvTRUE(ERRSV))
        ereport(ERROR,
                (errcode(ERRCODE_SYNTAX_ERROR),
                 errmsg("%s", strip_trailing_ws(sv2cstr(ERRSV)))));

    if (!subref)
        ereport(ERROR,
        (errmsg("didn't get a CODE reference from compiling function \"%s\"",
                prodesc->proname)));

    prodesc->reference = subref;

    return;
}


/**********************************************************************
 * plperl_init_shared_libs()        -
 **********************************************************************/

static void
plperl_init_shared_libs(pTHX)
{
    char       *file = __FILE__;

    newXS("DynaLoader::boot_DynaLoader", boot_DynaLoader, file);
    newXS("PostgreSQL::InServer::Util::bootstrap",
          boot_PostgreSQL__InServer__Util, file);
    /* newXS for...::SPI::bootstrap is in select_perl_context() */
}


static SV  *
plperl_call_perl_func(plperl_proc_desc *desc, FunctionCallInfo fcinfo)
{
    dSP;
    SV         *retval;
    int         i;
    int         count;

    ENTER;
    SAVETMPS;

    PUSHMARK(SP);
    EXTEND(sp, desc->nargs);

    for (i = 0; i < desc->nargs; i++)
    {
        if (fcinfo->argnull[i])
            PUSHs(&PL_sv_undef);
        else if (desc->arg_is_rowtype[i])
        {
            SV         *sv = plperl_hash_from_datum(fcinfo->arg[i]);

            PUSHs(sv_2mortal(sv));
        }
        else
        {
            SV         *sv;

            if (OidIsValid(desc->arg_arraytype[i]))
                sv = plperl_ref_from_pg_array(fcinfo->arg[i], desc->arg_arraytype[i]);
            else
            {
                char       *tmp;

                tmp = OutputFunctionCall(&(desc->arg_out_func[i]),
                                         fcinfo->arg[i]);
                sv = cstr2sv(tmp);
                pfree(tmp);
            }

            PUSHs(sv_2mortal(sv));
        }
    }
    PUTBACK;

    /* Do NOT use G_KEEPERR here */
    count = perl_call_sv(desc->reference, G_SCALAR | G_EVAL);

    SPAGAIN;

    if (count != 1)
    {
        PUTBACK;
        FREETMPS;
        LEAVE;
        elog(ERROR, "didn't get a return item from function");
    }

    if (SvTRUE(ERRSV))
    {
        (void) POPs;
        PUTBACK;
        FREETMPS;
        LEAVE;
        /* XXX need to find a way to assign an errcode here */
        ereport(ERROR,
                (errmsg("%s", strip_trailing_ws(sv2cstr(ERRSV)))));
    }

    retval = newSVsv(POPs);

    PUTBACK;
    FREETMPS;
    LEAVE;

    return retval;
}


static SV  *
plperl_call_perl_trigger_func(plperl_proc_desc *desc, FunctionCallInfo fcinfo,
                              SV *td)
{
    dSP;
    SV         *retval,
               *TDsv;
    int         i,
                count;
    Trigger    *tg_trigger = ((TriggerData *) fcinfo->context)->tg_trigger;

    ENTER;
    SAVETMPS;

    TDsv = get_sv("main::_TD", 0);
    if (!TDsv)
        elog(ERROR, "couldn't fetch $_TD");

    save_item(TDsv);            /* local $_TD */
    sv_setsv(TDsv, td);

    PUSHMARK(sp);
    EXTEND(sp, tg_trigger->tgnargs);

    for (i = 0; i < tg_trigger->tgnargs; i++)
        PUSHs(sv_2mortal(cstr2sv(tg_trigger->tgargs[i])));
    PUTBACK;

    /* Do NOT use G_KEEPERR here */
    count = perl_call_sv(desc->reference, G_SCALAR | G_EVAL);

    SPAGAIN;

    if (count != 1)
    {
        PUTBACK;
        FREETMPS;
        LEAVE;
        elog(ERROR, "didn't get a return item from trigger function");
    }

    if (SvTRUE(ERRSV))
    {
        (void) POPs;
        PUTBACK;
        FREETMPS;
        LEAVE;
        /* XXX need to find a way to assign an errcode here */
        ereport(ERROR,
                (errmsg("%s", strip_trailing_ws(sv2cstr(ERRSV)))));
    }

    retval = newSVsv(POPs);

    PUTBACK;
    FREETMPS;
    LEAVE;

    return retval;
}


static Datum
plperl_func_handler(PG_FUNCTION_ARGS)
{
    plperl_proc_desc *prodesc;
    SV         *perlret;
    Datum       retval = 0;
    ReturnSetInfo *rsi;
    ErrorContextCallback pl_error_context;

    if (SPI_connect() != SPI_OK_CONNECT)
        elog(ERROR, "could not connect to SPI manager");

    prodesc = compile_plperl_function(fcinfo->flinfo->fn_oid, false);
    current_call_data->prodesc = prodesc;
    increment_prodesc_refcount(prodesc);

    /* Set a callback for error reporting */
    pl_error_context.callback = plperl_exec_callback;
    pl_error_context.previous = error_context_stack;
    pl_error_context.arg = prodesc->proname;
    error_context_stack = &pl_error_context;

    rsi = (ReturnSetInfo *) fcinfo->resultinfo;

    if (prodesc->fn_retisset)
    {
        /* Check context before allowing the call to go through */
        if (!rsi || !IsA(rsi, ReturnSetInfo) ||
            (rsi->allowedModes & SFRM_Materialize) == 0 ||
            rsi->expectedDesc == NULL)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("set-valued function called in context that "
                            "cannot accept a set")));
    }

    activate_interpreter(prodesc->interp);

    perlret = plperl_call_perl_func(prodesc, fcinfo);

    /************************************************************
     * Disconnect from SPI manager and then create the return
     * values datum (if the input function does a palloc for it
     * this must not be allocated in the SPI memory context
     * because SPI_finish would free it).
     ************************************************************/
    if (SPI_finish() != SPI_OK_FINISH)
        elog(ERROR, "SPI_finish() failed");

    if (prodesc->fn_retisset)
    {
        SV         *sav;

        /*
         * If the Perl function returned an arrayref, we pretend that it
         * called return_next() for each element of the array, to handle old
         * SRFs that didn't know about return_next(). Any other sort of return
         * value is an error, except undef which means return an empty set.
         */
        sav = get_perl_array_ref(perlret);
        if (sav)
        {
            int         i = 0;
            SV        **svp = 0;
            AV         *rav = (AV *) SvRV(sav);

            while ((svp = av_fetch(rav, i, FALSE)) != NULL)
            {
                plperl_return_next(*svp);
                i++;
            }
        }
        else if (SvOK(perlret))
        {
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("set-returning PL/Perl function must return "
                            "reference to array or use return_next")));
        }

        rsi->returnMode = SFRM_Materialize;
        if (current_call_data->tuple_store)
        {
            rsi->setResult = current_call_data->tuple_store;
            rsi->setDesc = current_call_data->ret_tdesc;
        }
        retval = (Datum) 0;
    }
    else
    {
        retval = plperl_sv_to_datum(perlret,
                                    prodesc->result_oid,
                                    -1,
                                    fcinfo,
                                    &prodesc->result_in_func,
                                    prodesc->result_typioparam,
                                    &fcinfo->isnull);

        if (fcinfo->isnull && rsi && IsA(rsi, ReturnSetInfo))
            rsi->isDone = ExprEndResult;
    }

    /* Restore the previous error callback */
    error_context_stack = pl_error_context.previous;

    SvREFCNT_dec(perlret);

    return retval;
}


static Datum
plperl_trigger_handler(PG_FUNCTION_ARGS)
{
    plperl_proc_desc *prodesc;
    SV         *perlret;
    Datum       retval;
    SV         *svTD;
    HV         *hvTD;
    ErrorContextCallback pl_error_context;

    /* Connect to SPI manager */
    if (SPI_connect() != SPI_OK_CONNECT)
        elog(ERROR, "could not connect to SPI manager");

    /* Find or compile the function */
    prodesc = compile_plperl_function(fcinfo->flinfo->fn_oid, true);
    current_call_data->prodesc = prodesc;
    increment_prodesc_refcount(prodesc);

    /* Set a callback for error reporting */
    pl_error_context.callback = plperl_exec_callback;
    pl_error_context.previous = error_context_stack;
    pl_error_context.arg = prodesc->proname;
    error_context_stack = &pl_error_context;

    activate_interpreter(prodesc->interp);

    svTD = plperl_trigger_build_args(fcinfo);
    perlret = plperl_call_perl_trigger_func(prodesc, fcinfo, svTD);
    hvTD = (HV *) SvRV(svTD);

    /************************************************************
    * Disconnect from SPI manager and then create the return
    * values datum (if the input function does a palloc for it
    * this must not be allocated in the SPI memory context
    * because SPI_finish would free it).
    ************************************************************/
    if (SPI_finish() != SPI_OK_FINISH)
        elog(ERROR, "SPI_finish() failed");

    if (perlret == NULL || !SvOK(perlret))
    {
        /* undef result means go ahead with original tuple */
        TriggerData *trigdata = ((TriggerData *) fcinfo->context);

        if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
            retval = (Datum) trigdata->tg_trigtuple;
        else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
            retval = (Datum) trigdata->tg_newtuple;
        else if (TRIGGER_FIRED_BY_DELETE(trigdata->tg_event))
            retval = (Datum) trigdata->tg_trigtuple;
        else if (TRIGGER_FIRED_BY_TRUNCATE(trigdata->tg_event))
            retval = (Datum) trigdata->tg_trigtuple;
        else
            retval = (Datum) 0; /* can this happen? */
    }
    else
    {
        HeapTuple   trv;
        char       *tmp;

        tmp = sv2cstr(perlret);

        if (pg_strcasecmp(tmp, "SKIP") == 0)
            trv = NULL;
        else if (pg_strcasecmp(tmp, "MODIFY") == 0)
        {
            TriggerData *trigdata = (TriggerData *) fcinfo->context;

            if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
                trv = plperl_modify_tuple(hvTD, trigdata,
                                          trigdata->tg_trigtuple);
            else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
                trv = plperl_modify_tuple(hvTD, trigdata,
                                          trigdata->tg_newtuple);
            else
            {
                ereport(WARNING,
                        (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
                         errmsg("ignoring modified row in DELETE trigger")));
                trv = NULL;
            }
        }
        else
        {
            ereport(ERROR,
                    (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
                  errmsg("result of PL/Perl trigger function must be undef, "
                         "\"SKIP\", or \"MODIFY\"")));
            trv = NULL;
        }
        retval = PointerGetDatum(trv);
        pfree(tmp);
    }

    /* Restore the previous error callback */
    error_context_stack = pl_error_context.previous;

    SvREFCNT_dec(svTD);
    if (perlret)
        SvREFCNT_dec(perlret);

    return retval;
}


static bool
validate_plperl_function(plperl_proc_ptr *proc_ptr, HeapTuple procTup)
{
    if (proc_ptr && proc_ptr->proc_ptr)
    {
        plperl_proc_desc *prodesc = proc_ptr->proc_ptr;
        bool        uptodate;

        /************************************************************
         * If it's present, must check whether it's still up to date.
         * This is needed because CREATE OR REPLACE FUNCTION can modify the
         * function's pg_proc entry without changing its OID.
         ************************************************************/
        uptodate = (prodesc->fn_xmin == HeapTupleHeaderGetXmin(procTup->t_data) &&
                    ItemPointerEquals(&prodesc->fn_tid, &procTup->t_self));

        if (uptodate)
            return true;

        /* Otherwise, unlink the obsoleted entry from the hashtable ... */
        proc_ptr->proc_ptr = NULL;
        /* ... and release the corresponding refcount, probably deleting it */
        decrement_prodesc_refcount(prodesc);
    }

    return false;
}


static void
free_plperl_function(plperl_proc_desc *prodesc)
{
    Assert(prodesc->refcount <= 0);
    /* Release CODE reference, if we have one, from the appropriate interp */
    if (prodesc->reference)
    {
        plperl_interp_desc *oldinterp = plperl_active_interp;

        activate_interpreter(prodesc->interp);
        SvREFCNT_dec(prodesc->reference);
        activate_interpreter(oldinterp);
    }
    /* Get rid of what we conveniently can of our own structs */
    /* (FmgrInfo subsidiary info will get leaked ...) */
    if (prodesc->proname)
        free(prodesc->proname);
    free(prodesc);
}


static plperl_proc_desc *
compile_plperl_function(Oid fn_oid, bool is_trigger)
{
    HeapTuple   procTup;
    Form_pg_proc procStruct;
    plperl_proc_key proc_key;
    plperl_proc_ptr *proc_ptr;
    plperl_proc_desc *prodesc = NULL;
    int         i;
    plperl_interp_desc *oldinterp = plperl_active_interp;
    ErrorContextCallback plperl_error_context;

    /* We'll need the pg_proc tuple in any case... */
    procTup = SearchSysCache1(PROCOID, ObjectIdGetDatum(fn_oid));
    if (!HeapTupleIsValid(procTup))
        elog(ERROR, "cache lookup failed for function %u", fn_oid);
    procStruct = (Form_pg_proc) GETSTRUCT(procTup);

    /* Set a callback for reporting compilation errors */
    plperl_error_context.callback = plperl_compile_callback;
    plperl_error_context.previous = error_context_stack;
    plperl_error_context.arg = NameStr(procStruct->proname);
    error_context_stack = &plperl_error_context;

    /* Try to find function in plperl_proc_hash */
    proc_key.proc_id = fn_oid;
    proc_key.is_trigger = is_trigger;
    proc_key.user_id = GetUserId();

    proc_ptr = hash_search(plperl_proc_hash, &proc_key,
                           HASH_FIND, NULL);

    if (validate_plperl_function(proc_ptr, procTup))
        prodesc = proc_ptr->proc_ptr;
    else
    {
        /* If not found or obsolete, maybe it's plperlu */
        proc_key.user_id = InvalidOid;
        proc_ptr = hash_search(plperl_proc_hash, &proc_key,
                               HASH_FIND, NULL);
        if (validate_plperl_function(proc_ptr, procTup))
            prodesc = proc_ptr->proc_ptr;
    }

    /************************************************************
     * If we haven't found it in the hashtable, we analyze
     * the function's arguments and return type and store
     * the in-/out-functions in the prodesc block and create
     * a new hashtable entry for it.
     *
     * Then we load the procedure into the Perl interpreter.
     ************************************************************/
    if (prodesc == NULL)
    {
        HeapTuple   langTup;
        HeapTuple   typeTup;
        Form_pg_language langStruct;
        Form_pg_type typeStruct;
        Datum       prosrcdatum;
        bool        isnull;
        char       *proc_source;

        /************************************************************
         * Allocate a new procedure description block
         ************************************************************/
        prodesc = (plperl_proc_desc *) malloc(sizeof(plperl_proc_desc));
        if (prodesc == NULL)
            ereport(ERROR,
                    (errcode(ERRCODE_OUT_OF_MEMORY),
                     errmsg("out of memory")));
        /* Initialize all fields to 0 so free_plperl_function is safe */
        MemSet(prodesc, 0, sizeof(plperl_proc_desc));

        prodesc->proname = strdup(NameStr(procStruct->proname));
        if (prodesc->proname == NULL)
        {
            free_plperl_function(prodesc);
            ereport(ERROR,
                    (errcode(ERRCODE_OUT_OF_MEMORY),
                     errmsg("out of memory")));
        }
        prodesc->fn_xmin = HeapTupleHeaderGetXmin(procTup->t_data);
        prodesc->fn_tid = procTup->t_self;

        /* Remember if function is STABLE/IMMUTABLE */
        prodesc->fn_readonly =
            (procStruct->provolatile != PROVOLATILE_VOLATILE);

        /************************************************************
         * Lookup the pg_language tuple by Oid
         ************************************************************/
        langTup = SearchSysCache1(LANGOID,
                                  ObjectIdGetDatum(procStruct->prolang));
        if (!HeapTupleIsValid(langTup))
        {
            free_plperl_function(prodesc);
            elog(ERROR, "cache lookup failed for language %u",
                 procStruct->prolang);
        }
        langStruct = (Form_pg_language) GETSTRUCT(langTup);
        prodesc->lanpltrusted = langStruct->lanpltrusted;
        ReleaseSysCache(langTup);

        /************************************************************
         * Get the required information for input conversion of the
         * return value.
         ************************************************************/
        if (!is_trigger)
        {
            typeTup =
                SearchSysCache1(TYPEOID,
                                ObjectIdGetDatum(procStruct->prorettype));
            if (!HeapTupleIsValid(typeTup))
            {
                free_plperl_function(prodesc);
                elog(ERROR, "cache lookup failed for type %u",
                     procStruct->prorettype);
            }
            typeStruct = (Form_pg_type) GETSTRUCT(typeTup);

            /* Disallow pseudotype result, except VOID or RECORD */
            if (typeStruct->typtype == TYPTYPE_PSEUDO)
            {
                if (procStruct->prorettype == VOIDOID ||
                    procStruct->prorettype == RECORDOID)
                     /* okay */ ;
                else if (procStruct->prorettype == TRIGGEROID)
                {
                    free_plperl_function(prodesc);
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("trigger functions can only be called "
                                    "as triggers")));
                }
                else
                {
                    free_plperl_function(prodesc);
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("PL/Perl functions cannot return type %s",
                                    format_type_be(procStruct->prorettype))));
                }
            }

            prodesc->result_oid = procStruct->prorettype;
            prodesc->fn_retisset = procStruct->proretset;
            prodesc->fn_retistuple = (procStruct->prorettype == RECORDOID ||
                                   typeStruct->typtype == TYPTYPE_COMPOSITE);

            prodesc->fn_retisarray =
                (typeStruct->typlen == -1 && typeStruct->typelem);

            perm_fmgr_info(typeStruct->typinput, &(prodesc->result_in_func));
            prodesc->result_typioparam = getTypeIOParam(typeTup);

            ReleaseSysCache(typeTup);
        }

        /************************************************************
         * Get the required information for output conversion
         * of all procedure arguments
         ************************************************************/
        if (!is_trigger)
        {
            prodesc->nargs = procStruct->pronargs;
            for (i = 0; i < prodesc->nargs; i++)
            {
                typeTup = SearchSysCache1(TYPEOID,
                        ObjectIdGetDatum(procStruct->proargtypes.values[i]));
                if (!HeapTupleIsValid(typeTup))
                {
                    free_plperl_function(prodesc);
                    elog(ERROR, "cache lookup failed for type %u",
                         procStruct->proargtypes.values[i]);
                }
                typeStruct = (Form_pg_type) GETSTRUCT(typeTup);

                /* Disallow pseudotype argument */
                if (typeStruct->typtype == TYPTYPE_PSEUDO &&
                    procStruct->proargtypes.values[i] != RECORDOID)
                {
                    free_plperl_function(prodesc);
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("PL/Perl functions cannot accept type %s",
                        format_type_be(procStruct->proargtypes.values[i]))));
                }

                if (typeStruct->typtype == TYPTYPE_COMPOSITE ||
                    procStruct->proargtypes.values[i] == RECORDOID)
                    prodesc->arg_is_rowtype[i] = true;
                else
                {
                    prodesc->arg_is_rowtype[i] = false;
                    perm_fmgr_info(typeStruct->typoutput,
                                   &(prodesc->arg_out_func[i]));
                }

                /* Identify array attributes */
                if (typeStruct->typelem != 0 && typeStruct->typlen == -1)
                    prodesc->arg_arraytype[i] = procStruct->proargtypes.values[i];
                else
                    prodesc->arg_arraytype[i] = InvalidOid;

                ReleaseSysCache(typeTup);
            }
        }

        /************************************************************
         * create the text of the anonymous subroutine.
         * we do not use a named subroutine so that we can call directly
         * through the reference.
         ************************************************************/
        prosrcdatum = SysCacheGetAttr(PROCOID, procTup,
                                      Anum_pg_proc_prosrc, &isnull);
        if (isnull)
            elog(ERROR, "null prosrc");
        proc_source = TextDatumGetCString(prosrcdatum);

        /************************************************************
         * Create the procedure in the appropriate interpreter
         ************************************************************/

        select_perl_context(prodesc->lanpltrusted);

        prodesc->interp = plperl_active_interp;

        plperl_create_sub(prodesc, proc_source, fn_oid);

        activate_interpreter(oldinterp);

        pfree(proc_source);
        if (!prodesc->reference)    /* can this happen? */
        {
            free_plperl_function(prodesc);
            elog(ERROR, "could not create PL/Perl internal procedure");
        }

        /************************************************************
         * OK, link the procedure into the correct hashtable entry
         ************************************************************/
        proc_key.user_id = prodesc->lanpltrusted ? GetUserId() : InvalidOid;

        proc_ptr = hash_search(plperl_proc_hash, &proc_key,
                               HASH_ENTER, NULL);
        proc_ptr->proc_ptr = prodesc;
        increment_prodesc_refcount(prodesc);
    }

    /* restore previous error callback */
    error_context_stack = plperl_error_context.previous;

    ReleaseSysCache(procTup);

    return prodesc;
}

/* Build a hash from a given composite/row datum */
static SV  *
plperl_hash_from_datum(Datum attr)
{
    HeapTupleHeader td;
    Oid         tupType;
    int32       tupTypmod;
    TupleDesc   tupdesc;
    HeapTupleData tmptup;
    SV         *sv;

    td = DatumGetHeapTupleHeader(attr);

    /* Extract rowtype info and find a tupdesc */
    tupType = HeapTupleHeaderGetTypeId(td);
    tupTypmod = HeapTupleHeaderGetTypMod(td);
    tupdesc = lookup_rowtype_tupdesc(tupType, tupTypmod);

    /* Build a temporary HeapTuple control structure */
    tmptup.t_len = HeapTupleHeaderGetDatumLength(td);
    tmptup.t_data = td;

    sv = plperl_hash_from_tuple(&tmptup, tupdesc);
    ReleaseTupleDesc(tupdesc);

    return sv;
}

/* Build a hash from all attributes of a given tuple. */
static SV  *
plperl_hash_from_tuple(HeapTuple tuple, TupleDesc tupdesc)
{
    HV         *hv;
    int         i;

    /* since this function recurses, it could be driven to stack overflow */
    check_stack_depth();

    hv = newHV();
    hv_ksplit(hv, tupdesc->natts);      /* pre-grow the hash */

    for (i = 0; i < tupdesc->natts; i++)
    {
        Datum       attr;
        bool        isnull,
                    typisvarlena;
        char       *attname;
        Oid         typoutput;

        if (tupdesc->attrs[i]->attisdropped)
            continue;

        attname = NameStr(tupdesc->attrs[i]->attname);
        attr = heap_getattr(tuple, i + 1, tupdesc, &isnull);

        if (isnull)
        {
            /*
             * Store (attname => undef) and move on.  Note we can't use
             * &PL_sv_undef here; see "AVs, HVs and undefined values" in
             * perlguts for an explanation.
             */
            hv_store_string(hv, attname, newSV(0));
            continue;
        }

        if (type_is_rowtype(tupdesc->attrs[i]->atttypid))
        {
            SV         *sv = plperl_hash_from_datum(attr);

            hv_store_string(hv, attname, sv);
        }
        else
        {
            SV         *sv;

            if (OidIsValid(get_base_element_type(tupdesc->attrs[i]->atttypid)))
                sv = plperl_ref_from_pg_array(attr, tupdesc->attrs[i]->atttypid);
            else
            {
                char       *outputstr;

                /* XXX should have a way to cache these lookups */
                getTypeOutputInfo(tupdesc->attrs[i]->atttypid,
                                  &typoutput, &typisvarlena);

                outputstr = OidOutputFunctionCall(typoutput, attr);
                sv = cstr2sv(outputstr);
                pfree(outputstr);
            }

            hv_store_string(hv, attname, sv);
        }
    }
    return newRV_noinc((SV *) hv);
}


static void
check_spi_usage_allowed()
{
    /* see comment in plperl_fini() */
    if (plperl_ending)
    {
        /* simple croak as we don't want to involve PostgreSQL code */
        croak("SPI functions can not be used in END blocks");
    }
}


HV *
plperl_spi_exec(char *query, int limit)
{
    HV         *ret_hv;

    /*
     * Execute the query inside a sub-transaction, so we can cope with errors
     * sanely
     */
    MemoryContext oldcontext = CurrentMemoryContext;
    ResourceOwner oldowner = CurrentResourceOwner;

    check_spi_usage_allowed();

    BeginInternalSubTransaction(NULL);
    /* Want to run inside function's memory context */
    MemoryContextSwitchTo(oldcontext);

    PG_TRY();
    {
        int         spi_rv;

        pg_verifymbstr(query, strlen(query), false);

        spi_rv = SPI_execute(query, current_call_data->prodesc->fn_readonly,
                             limit);
        ret_hv = plperl_spi_execute_fetch_result(SPI_tuptable, SPI_processed,
                                                 spi_rv);

        /* Commit the inner transaction, return to outer xact context */
        ReleaseCurrentSubTransaction();
        MemoryContextSwitchTo(oldcontext);
        CurrentResourceOwner = oldowner;

        /*
         * AtEOSubXact_SPI() should not have popped any SPI context, but just
         * in case it did, make sure we remain connected.
         */
        SPI_restore_connection();
    }
    PG_CATCH();
    {
        ErrorData  *edata;

        /* Save error info */
        MemoryContextSwitchTo(oldcontext);
        edata = CopyErrorData();
        FlushErrorState();

        /* Abort the inner transaction */
        RollbackAndReleaseCurrentSubTransaction();
        MemoryContextSwitchTo(oldcontext);
        CurrentResourceOwner = oldowner;

        /*
         * If AtEOSubXact_SPI() popped any SPI context of the subxact, it will
         * have left us in a disconnected state.  We need this hack to return
         * to connected state.
         */
        SPI_restore_connection();

        /* Punt the error to Perl */
        croak("%s", edata->message);

        /* Can't get here, but keep compiler quiet */
        return NULL;
    }
    PG_END_TRY();

    return ret_hv;
}


static HV  *
plperl_spi_execute_fetch_result(SPITupleTable *tuptable, int processed,
                                int status)
{
    HV         *result;

    check_spi_usage_allowed();

    result = newHV();

    hv_store_string(result, "status",
                    cstr2sv(SPI_result_code_string(status)));
    hv_store_string(result, "processed",
                    newSViv(processed));

    if (status > 0 && tuptable)
    {
        AV         *rows;
        SV         *row;
        int         i;

        rows = newAV();
        av_extend(rows, processed);
        for (i = 0; i < processed; i++)
        {
            row = plperl_hash_from_tuple(tuptable->vals[i], tuptable->tupdesc);
            av_push(rows, row);
        }
        hv_store_string(result, "rows",
                        newRV_noinc((SV *) rows));
    }

    SPI_freetuptable(tuptable);

    return result;
}


/*
 * Note: plperl_return_next is called both in Postgres and Perl contexts.
 * We report any errors in Postgres fashion (via ereport).  If called in
 * Perl context, it is SPI.xs's responsibility to catch the error and
 * convert to a Perl error.  We assume (perhaps without adequate justification)
 * that we need not abort the current transaction if the Perl code traps the
 * error.
 */
void
plperl_return_next(SV *sv)
{
    plperl_proc_desc *prodesc;
    FunctionCallInfo fcinfo;
    ReturnSetInfo *rsi;
    MemoryContext old_cxt;

    if (!sv)
        return;

    prodesc = current_call_data->prodesc;
    fcinfo = current_call_data->fcinfo;
    rsi = (ReturnSetInfo *) fcinfo->resultinfo;

    if (!prodesc->fn_retisset)
        ereport(ERROR,
                (errcode(ERRCODE_SYNTAX_ERROR),
                 errmsg("cannot use return_next in a non-SETOF function")));

    if (!current_call_data->ret_tdesc)
    {
        TupleDesc   tupdesc;

        Assert(!current_call_data->tuple_store);

        /*
         * This is the first call to return_next in the current PL/Perl
         * function call, so memoize some lookups
         */
        if (prodesc->fn_retistuple)
            (void) get_call_result_type(fcinfo, NULL, &tupdesc);
        else
            tupdesc = rsi->expectedDesc;

        /*
         * Make sure the tuple_store and ret_tdesc are sufficiently
         * long-lived.
         */
        old_cxt = MemoryContextSwitchTo(rsi->econtext->ecxt_per_query_memory);

        current_call_data->ret_tdesc = CreateTupleDescCopy(tupdesc);
        current_call_data->tuple_store =
            tuplestore_begin_heap(rsi->allowedModes & SFRM_Materialize_Random,
                                  false, work_mem);

        MemoryContextSwitchTo(old_cxt);
    }

    /*
     * Producing the tuple we want to return requires making plenty of
     * palloc() allocations that are not cleaned up. Since this function can
     * be called many times before the current memory context is reset, we
     * need to do those allocations in a temporary context.
     */
    if (!current_call_data->tmp_cxt)
    {
        current_call_data->tmp_cxt =
            AllocSetContextCreate(CurrentMemoryContext,
                                  "PL/Perl return_next temporary cxt",
                                  ALLOCSET_DEFAULT_MINSIZE,
                                  ALLOCSET_DEFAULT_INITSIZE,
                                  ALLOCSET_DEFAULT_MAXSIZE);
    }

    old_cxt = MemoryContextSwitchTo(current_call_data->tmp_cxt);

    if (prodesc->fn_retistuple)
    {
        HeapTuple   tuple;

        if (!(SvOK(sv) && SvROK(sv) && SvTYPE(SvRV(sv)) == SVt_PVHV))
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("SETOF-composite-returning PL/Perl function "
                            "must call return_next with reference to hash")));

        tuple = plperl_build_tuple_result((HV *) SvRV(sv),
                                          current_call_data->ret_tdesc);
        tuplestore_puttuple(current_call_data->tuple_store, tuple);
    }
    else
    {
        Datum       ret;
        bool        isNull;

        ret = plperl_sv_to_datum(sv,
                                 prodesc->result_oid,
                                 -1,
                                 fcinfo,
                                 &prodesc->result_in_func,
                                 prodesc->result_typioparam,
                                 &isNull);

        tuplestore_putvalues(current_call_data->tuple_store,
                             current_call_data->ret_tdesc,
                             &ret, &isNull);
    }

    MemoryContextSwitchTo(old_cxt);
    MemoryContextReset(current_call_data->tmp_cxt);
}


SV *
plperl_spi_query(char *query)
{
    SV         *cursor;

    /*
     * Execute the query inside a sub-transaction, so we can cope with errors
     * sanely
     */
    MemoryContext oldcontext = CurrentMemoryContext;
    ResourceOwner oldowner = CurrentResourceOwner;

    check_spi_usage_allowed();

    BeginInternalSubTransaction(NULL);
    /* Want to run inside function's memory context */
    MemoryContextSwitchTo(oldcontext);

    PG_TRY();
    {
        SPIPlanPtr  plan;
        Portal      portal;

        /* Make sure the query is validly encoded */
        pg_verifymbstr(query, strlen(query), false);

        /* Create a cursor for the query */
        plan = SPI_prepare(query, 0, NULL);
        if (plan == NULL)
            elog(ERROR, "SPI_prepare() failed:%s",
                 SPI_result_code_string(SPI_result));

        portal = SPI_cursor_open(NULL, plan, NULL, NULL, false);
        SPI_freeplan(plan);
        if (portal == NULL)
            elog(ERROR, "SPI_cursor_open() failed:%s",
                 SPI_result_code_string(SPI_result));
        cursor = cstr2sv(portal->name);

        /* Commit the inner transaction, return to outer xact context */
        ReleaseCurrentSubTransaction();
        MemoryContextSwitchTo(oldcontext);
        CurrentResourceOwner = oldowner;

        /*
         * AtEOSubXact_SPI() should not have popped any SPI context, but just
         * in case it did, make sure we remain connected.
         */
        SPI_restore_connection();
    }
    PG_CATCH();
    {
        ErrorData  *edata;

        /* Save error info */
        MemoryContextSwitchTo(oldcontext);
        edata = CopyErrorData();
        FlushErrorState();

        /* Abort the inner transaction */
        RollbackAndReleaseCurrentSubTransaction();
        MemoryContextSwitchTo(oldcontext);
        CurrentResourceOwner = oldowner;

        /*
         * If AtEOSubXact_SPI() popped any SPI context of the subxact, it will
         * have left us in a disconnected state.  We need this hack to return
         * to connected state.
         */
        SPI_restore_connection();

        /* Punt the error to Perl */
        croak("%s", edata->message);

        /* Can't get here, but keep compiler quiet */
        return NULL;
    }
    PG_END_TRY();

    return cursor;
}


SV *
plperl_spi_fetchrow(char *cursor)
{
    SV         *row;

    /*
     * Execute the FETCH inside a sub-transaction, so we can cope with errors
     * sanely
     */
    MemoryContext oldcontext = CurrentMemoryContext;
    ResourceOwner oldowner = CurrentResourceOwner;

    check_spi_usage_allowed();

    BeginInternalSubTransaction(NULL);
    /* Want to run inside function's memory context */
    MemoryContextSwitchTo(oldcontext);

    PG_TRY();
    {
        Portal      p = SPI_cursor_find(cursor);

        if (!p)
        {
            row = &PL_sv_undef;
        }
        else
        {
            SPI_cursor_fetch(p, true, 1);
            if (SPI_processed == 0)
            {
                SPI_cursor_close(p);
                row = &PL_sv_undef;
            }
            else
            {
                row = plperl_hash_from_tuple(SPI_tuptable->vals[0],
                                             SPI_tuptable->tupdesc);
            }
            SPI_freetuptable(SPI_tuptable);
        }

        /* Commit the inner transaction, return to outer xact context */
        ReleaseCurrentSubTransaction();
        MemoryContextSwitchTo(oldcontext);
        CurrentResourceOwner = oldowner;

        /*
         * AtEOSubXact_SPI() should not have popped any SPI context, but just
         * in case it did, make sure we remain connected.
         */
        SPI_restore_connection();
    }
    PG_CATCH();
    {
        ErrorData  *edata;

        /* Save error info */
        MemoryContextSwitchTo(oldcontext);
        edata = CopyErrorData();
        FlushErrorState();

        /* Abort the inner transaction */
        RollbackAndReleaseCurrentSubTransaction();
        MemoryContextSwitchTo(oldcontext);
        CurrentResourceOwner = oldowner;

        /*
         * If AtEOSubXact_SPI() popped any SPI context of the subxact, it will
         * have left us in a disconnected state.  We need this hack to return
         * to connected state.
         */
        SPI_restore_connection();

        /* Punt the error to Perl */
        croak("%s", edata->message);

        /* Can't get here, but keep compiler quiet */
        return NULL;
    }
    PG_END_TRY();

    return row;
}

void
plperl_spi_cursor_close(char *cursor)
{
    Portal      p;

    check_spi_usage_allowed();

    p = SPI_cursor_find(cursor);

    if (p)
        SPI_cursor_close(p);
}

SV *
plperl_spi_prepare(char *query, int argc, SV **argv)
{
    volatile SPIPlanPtr plan = NULL;
    volatile MemoryContext plan_cxt = NULL;
    plperl_query_desc *volatile qdesc = NULL;
    plperl_query_entry *volatile hash_entry = NULL;
    MemoryContext oldcontext = CurrentMemoryContext;
    ResourceOwner oldowner = CurrentResourceOwner;
    MemoryContext work_cxt;
    bool        found;
    int         i;

    check_spi_usage_allowed();

    BeginInternalSubTransaction(NULL);
    MemoryContextSwitchTo(oldcontext);

    PG_TRY();
    {
        CHECK_FOR_INTERRUPTS();

        /************************************************************
         * Allocate the new querydesc structure
         *
         * The qdesc struct, as well as all its subsidiary data, lives in its
         * plan_cxt.  But note that the SPIPlan does not.
         ************************************************************/
        plan_cxt = AllocSetContextCreate(TopMemoryContext,
                                         "PL/Perl spi_prepare query",
                                         ALLOCSET_SMALL_MINSIZE,
                                         ALLOCSET_SMALL_INITSIZE,
                                         ALLOCSET_SMALL_MAXSIZE);
        MemoryContextSwitchTo(plan_cxt);
        qdesc = (plperl_query_desc *) palloc0(sizeof(plperl_query_desc));
        snprintf(qdesc->qname, sizeof(qdesc->qname), "%p", qdesc);
        qdesc->plan_cxt = plan_cxt;
        qdesc->nargs = argc;
        qdesc->argtypes = (Oid *) palloc(argc * sizeof(Oid));
        qdesc->arginfuncs = (FmgrInfo *) palloc(argc * sizeof(FmgrInfo));
        qdesc->argtypioparams = (Oid *) palloc(argc * sizeof(Oid));
        MemoryContextSwitchTo(oldcontext);

        /************************************************************
         * Do the following work in a short-lived context so that we don't
         * leak a lot of memory in the PL/Perl function's SPI Proc context.
         ************************************************************/
        work_cxt = AllocSetContextCreate(CurrentMemoryContext,
                                         "PL/Perl spi_prepare workspace",
                                         ALLOCSET_DEFAULT_MINSIZE,
                                         ALLOCSET_DEFAULT_INITSIZE,
                                         ALLOCSET_DEFAULT_MAXSIZE);
        MemoryContextSwitchTo(work_cxt);

        /************************************************************
         * Resolve argument type names and then look them up by oid
         * in the system cache, and remember the required information
         * for input conversion.
         ************************************************************/
        for (i = 0; i < argc; i++)
        {
            Oid         typId,
                        typInput,
                        typIOParam;
            int32       typmod;
            char       *typstr;

            typstr = sv2cstr(argv[i]);
            parseTypeString(typstr, &typId, &typmod);
            pfree(typstr);

            getTypeInputInfo(typId, &typInput, &typIOParam);

            qdesc->argtypes[i] = typId;
            fmgr_info_cxt(typInput, &(qdesc->arginfuncs[i]), plan_cxt);
            qdesc->argtypioparams[i] = typIOParam;
        }

        /* Make sure the query is validly encoded */
        pg_verifymbstr(query, strlen(query), false);

        /************************************************************
         * Prepare the plan and check for errors
         ************************************************************/
        plan = SPI_prepare(query, argc, qdesc->argtypes);

        if (plan == NULL)
            elog(ERROR, "SPI_prepare() failed:%s",
                 SPI_result_code_string(SPI_result));

        /************************************************************
         * Save the plan into permanent memory (right now it's in the
         * SPI procCxt, which will go away at function end).
         ************************************************************/
        if (SPI_keepplan(plan))
            elog(ERROR, "SPI_keepplan() failed");
        qdesc->plan = plan;

        /************************************************************
         * Insert a hashtable entry for the plan.
         ************************************************************/
        hash_entry = hash_search(plperl_active_interp->query_hash,
                                 qdesc->qname,
                                 HASH_ENTER, &found);
        hash_entry->query_data = qdesc;

        /* Get rid of workspace */
        MemoryContextDelete(work_cxt);

        /* Commit the inner transaction, return to outer xact context */
        ReleaseCurrentSubTransaction();
        MemoryContextSwitchTo(oldcontext);
        CurrentResourceOwner = oldowner;

        /*
         * AtEOSubXact_SPI() should not have popped any SPI context, but just
         * in case it did, make sure we remain connected.
         */
        SPI_restore_connection();
    }
    PG_CATCH();
    {
        ErrorData  *edata;

        /* Save error info */
        MemoryContextSwitchTo(oldcontext);
        edata = CopyErrorData();
        FlushErrorState();

        /* Drop anything we managed to allocate */
        if (hash_entry)
            hash_search(plperl_active_interp->query_hash,
                        qdesc->qname,
                        HASH_REMOVE, NULL);
        if (plan_cxt)
            MemoryContextDelete(plan_cxt);
        if (plan)
            SPI_freeplan(plan);

        /* Abort the inner transaction */
        RollbackAndReleaseCurrentSubTransaction();
        MemoryContextSwitchTo(oldcontext);
        CurrentResourceOwner = oldowner;

        /*
         * If AtEOSubXact_SPI() popped any SPI context of the subxact, it will
         * have left us in a disconnected state.  We need this hack to return
         * to connected state.
         */
        SPI_restore_connection();

        /* Punt the error to Perl */
        croak("%s", edata->message);

        /* Can't get here, but keep compiler quiet */
        return NULL;
    }
    PG_END_TRY();

    /************************************************************
     * Return the query's hash key to the caller.
     ************************************************************/
    return cstr2sv(qdesc->qname);
}

HV *
plperl_spi_exec_prepared(char *query, HV *attr, int argc, SV **argv)
{
    HV         *ret_hv;
    SV        **sv;
    int         i,
                limit,
                spi_rv;
    char       *nulls;
    Datum      *argvalues;
    plperl_query_desc *qdesc;
    plperl_query_entry *hash_entry;

    /*
     * Execute the query inside a sub-transaction, so we can cope with errors
     * sanely
     */
    MemoryContext oldcontext = CurrentMemoryContext;
    ResourceOwner oldowner = CurrentResourceOwner;

    check_spi_usage_allowed();

    BeginInternalSubTransaction(NULL);
    /* Want to run inside function's memory context */
    MemoryContextSwitchTo(oldcontext);

    PG_TRY();
    {
        /************************************************************
         * Fetch the saved plan descriptor, see if it's o.k.
         ************************************************************/
        hash_entry = hash_search(plperl_active_interp->query_hash, query,
                                 HASH_FIND, NULL);
        if (hash_entry == NULL)
            elog(ERROR, "spi_exec_prepared: Invalid prepared query passed");

        qdesc = hash_entry->query_data;
        if (qdesc == NULL)
            elog(ERROR, "spi_exec_prepared: plperl query_hash value vanished");

        if (qdesc->nargs != argc)
            elog(ERROR, "spi_exec_prepared: expected %d argument(s), %d passed",
                 qdesc->nargs, argc);

        /************************************************************
         * Parse eventual attributes
         ************************************************************/
        limit = 0;
        if (attr != NULL)
        {
            sv = hv_fetch_string(attr, "limit");
            if (sv && *sv && SvIOK(*sv))
                limit = SvIV(*sv);
        }
        /************************************************************
         * Set up arguments
         ************************************************************/
        if (argc > 0)
        {
            nulls = (char *) palloc(argc);
            argvalues = (Datum *) palloc(argc * sizeof(Datum));
        }
        else
        {
            nulls = NULL;
            argvalues = NULL;
        }

        for (i = 0; i < argc; i++)
        {
            bool        isnull;

            argvalues[i] = plperl_sv_to_datum(argv[i],
                                              qdesc->argtypes[i],
                                              -1,
                                              NULL,
                                              &qdesc->arginfuncs[i],
                                              qdesc->argtypioparams[i],
                                              &isnull);
            nulls[i] = isnull ? 'n' : ' ';
        }

        /************************************************************
         * go
         ************************************************************/
        spi_rv = SPI_execute_plan(qdesc->plan, argvalues, nulls,
                             current_call_data->prodesc->fn_readonly, limit);
        ret_hv = plperl_spi_execute_fetch_result(SPI_tuptable, SPI_processed,
                                                 spi_rv);
        if (argc > 0)
        {
            pfree(argvalues);
            pfree(nulls);
        }

        /* Commit the inner transaction, return to outer xact context */
        ReleaseCurrentSubTransaction();
        MemoryContextSwitchTo(oldcontext);
        CurrentResourceOwner = oldowner;

        /*
         * AtEOSubXact_SPI() should not have popped any SPI context, but just
         * in case it did, make sure we remain connected.
         */
        SPI_restore_connection();
    }
    PG_CATCH();
    {
        ErrorData  *edata;

        /* Save error info */
        MemoryContextSwitchTo(oldcontext);
        edata = CopyErrorData();
        FlushErrorState();

        /* Abort the inner transaction */
        RollbackAndReleaseCurrentSubTransaction();
        MemoryContextSwitchTo(oldcontext);
        CurrentResourceOwner = oldowner;

        /*
         * If AtEOSubXact_SPI() popped any SPI context of the subxact, it will
         * have left us in a disconnected state.  We need this hack to return
         * to connected state.
         */
        SPI_restore_connection();

        /* Punt the error to Perl */
        croak("%s", edata->message);

        /* Can't get here, but keep compiler quiet */
        return NULL;
    }
    PG_END_TRY();

    return ret_hv;
}

SV *
plperl_spi_query_prepared(char *query, int argc, SV **argv)
{
    int         i;
    char       *nulls;
    Datum      *argvalues;
    plperl_query_desc *qdesc;
    plperl_query_entry *hash_entry;
    SV         *cursor;
    Portal      portal = NULL;

    /*
     * Execute the query inside a sub-transaction, so we can cope with errors
     * sanely
     */
    MemoryContext oldcontext = CurrentMemoryContext;
    ResourceOwner oldowner = CurrentResourceOwner;

    check_spi_usage_allowed();

    BeginInternalSubTransaction(NULL);
    /* Want to run inside function's memory context */
    MemoryContextSwitchTo(oldcontext);

    PG_TRY();
    {
        /************************************************************
         * Fetch the saved plan descriptor, see if it's o.k.
         ************************************************************/
        hash_entry = hash_search(plperl_active_interp->query_hash, query,
                                 HASH_FIND, NULL);
        if (hash_entry == NULL)
            elog(ERROR, "spi_query_prepared: Invalid prepared query passed");

        qdesc = hash_entry->query_data;
        if (qdesc == NULL)
            elog(ERROR, "spi_query_prepared: plperl query_hash value vanished");

        if (qdesc->nargs != argc)
            elog(ERROR, "spi_query_prepared: expected %d argument(s), %d passed",
                 qdesc->nargs, argc);

        /************************************************************
         * Set up arguments
         ************************************************************/
        if (argc > 0)
        {
            nulls = (char *) palloc(argc);
            argvalues = (Datum *) palloc(argc * sizeof(Datum));
        }
        else
        {
            nulls = NULL;
            argvalues = NULL;
        }

        for (i = 0; i < argc; i++)
        {
            bool        isnull;

            argvalues[i] = plperl_sv_to_datum(argv[i],
                                              qdesc->argtypes[i],
                                              -1,
                                              NULL,
                                              &qdesc->arginfuncs[i],
                                              qdesc->argtypioparams[i],
                                              &isnull);
            nulls[i] = isnull ? 'n' : ' ';
        }

        /************************************************************
         * go
         ************************************************************/
        portal = SPI_cursor_open(NULL, qdesc->plan, argvalues, nulls,
                                 current_call_data->prodesc->fn_readonly);
        if (argc > 0)
        {
            pfree(argvalues);
            pfree(nulls);
        }
        if (portal == NULL)
            elog(ERROR, "SPI_cursor_open() failed:%s",
                 SPI_result_code_string(SPI_result));

        cursor = cstr2sv(portal->name);

        /* Commit the inner transaction, return to outer xact context */
        ReleaseCurrentSubTransaction();
        MemoryContextSwitchTo(oldcontext);
        CurrentResourceOwner = oldowner;

        /*
         * AtEOSubXact_SPI() should not have popped any SPI context, but just
         * in case it did, make sure we remain connected.
         */
        SPI_restore_connection();
    }
    PG_CATCH();
    {
        ErrorData  *edata;

        /* Save error info */
        MemoryContextSwitchTo(oldcontext);
        edata = CopyErrorData();
        FlushErrorState();

        /* Abort the inner transaction */
        RollbackAndReleaseCurrentSubTransaction();
        MemoryContextSwitchTo(oldcontext);
        CurrentResourceOwner = oldowner;

        /*
         * If AtEOSubXact_SPI() popped any SPI context of the subxact, it will
         * have left us in a disconnected state.  We need this hack to return
         * to connected state.
         */
        SPI_restore_connection();

        /* Punt the error to Perl */
        croak("%s", edata->message);

        /* Can't get here, but keep compiler quiet */
        return NULL;
    }
    PG_END_TRY();

    return cursor;
}

void
plperl_spi_freeplan(char *query)
{
    SPIPlanPtr  plan;
    plperl_query_desc *qdesc;
    plperl_query_entry *hash_entry;

    check_spi_usage_allowed();

    hash_entry = hash_search(plperl_active_interp->query_hash, query,
                             HASH_FIND, NULL);
    if (hash_entry == NULL)
        elog(ERROR, "spi_freeplan: Invalid prepared query passed");

    qdesc = hash_entry->query_data;
    if (qdesc == NULL)
        elog(ERROR, "spi_freeplan: plperl query_hash value vanished");
    plan = qdesc->plan;

    /*
     * free all memory before SPI_freeplan, so if it dies, nothing will be
     * left over
     */
    hash_search(plperl_active_interp->query_hash, query,
                HASH_REMOVE, NULL);

    MemoryContextDelete(qdesc->plan_cxt);

    SPI_freeplan(plan);
}

/*
 * Store an SV into a hash table under a key that is a string assumed to be
 * in the current database's encoding.
 */
static SV **
hv_store_string(HV *hv, const char *key, SV *val)
{
    int32       hlen;
    char       *hkey;
    SV        **ret;

    hkey = (char *)
        pg_do_encoding_conversion((unsigned char *) key, strlen(key),
                                  GetDatabaseEncoding(), PG_UTF8);

    /*
     * This seems nowhere documented, but under Perl 5.8.0 and up, hv_store()
     * recognizes a negative klen parameter as meaning a UTF-8 encoded key. It
     * does not appear that hashes track UTF-8-ness of keys at all in Perl
     * 5.6.
     */
    hlen = -(int) strlen(hkey);
    ret = hv_store(hv, hkey, hlen, val, 0);

    if (hkey != key)
        pfree(hkey);

    return ret;
}

/*
 * Fetch an SV from a hash table under a key that is a string assumed to be
 * in the current database's encoding.
 */
static SV **
hv_fetch_string(HV *hv, const char *key)
{
    int32       hlen;
    char       *hkey;
    SV        **ret;

    hkey = (char *)
        pg_do_encoding_conversion((unsigned char *) key, strlen(key),
                                  GetDatabaseEncoding(), PG_UTF8);

    /* See notes in hv_store_string */
    hlen = -(int) strlen(hkey);
    ret = hv_fetch(hv, hkey, hlen, 0);

    if (hkey != key)
        pfree(hkey);

    return ret;
}

/*
 * Provide function name for PL/Perl execution errors
 */
static void
plperl_exec_callback(void *arg)
{
    char       *procname = (char *) arg;

    if (procname)
        errcontext("PL/Perl function \"%s\"", procname);
}

/*
 * Provide function name for PL/Perl compilation errors
 */
static void
plperl_compile_callback(void *arg)
{
    char       *procname = (char *) arg;

    if (procname)
        errcontext("compilation of PL/Perl function \"%s\"", procname);
}

/*
 * Provide error context for the inline handler
 */
static void
plperl_inline_callback(void *arg)
{
    errcontext("PL/Perl anonymous code block");
}


/*
 * Perl's own setlocal() copied from POSIX.xs
 * (needed because of the calls to new_*())
 */
#ifdef WIN32
static char *
setlocale_perl(int category, char *locale)
{
    char       *RETVAL = setlocale(category, locale);

    if (RETVAL)
    {
#ifdef USE_LOCALE_CTYPE
        if (category == LC_CTYPE
#ifdef LC_ALL
            || category == LC_ALL
#endif
            )
        {
            char       *newctype;

#ifdef LC_ALL
            if (category == LC_ALL)
                newctype = setlocale(LC_CTYPE, NULL);
            else
#endif
                newctype = RETVAL;
            new_ctype(newctype);
        }
#endif   /* USE_LOCALE_CTYPE */
#ifdef USE_LOCALE_COLLATE
        if (category == LC_COLLATE
#ifdef LC_ALL
            || category == LC_ALL
#endif
            )
        {
            char       *newcoll;

#ifdef LC_ALL
            if (category == LC_ALL)
                newcoll = setlocale(LC_COLLATE, NULL);
            else
#endif
                newcoll = RETVAL;
            new_collate(newcoll);
        }
#endif   /* USE_LOCALE_COLLATE */

#ifdef USE_LOCALE_NUMERIC
        if (category == LC_NUMERIC
#ifdef LC_ALL
            || category == LC_ALL
#endif
            )
        {
            char       *newnum;

#ifdef LC_ALL
            if (category == LC_ALL)
                newnum = setlocale(LC_NUMERIC, NULL);
            else
#endif
                newnum = RETVAL;
            new_numeric(newnum);
        }
#endif   /* USE_LOCALE_NUMERIC */
    }

    return RETVAL;
}

#endif