name.c

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/*-------------------------------------------------------------------------
 *
 * name.c
 *    Functions for the built-in type "name".
 *
 * name replaces char16 and is carefully implemented so that it
 * is a string of physical length NAMEDATALEN.
 * DO NOT use hard-coded constants anywhere
 * always use NAMEDATALEN as the symbolic constant!   - jolly 8/21/95
 *
 *
 * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/utils/adt/name.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "catalog/namespace.h"
#include "catalog/pg_type.h"
#include "libpq/pqformat.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"


/*****************************************************************************
 *   USER I/O ROUTINES (none)                                                *
 *****************************************************************************/


/*
 *      namein  - converts "..." to internal representation
 *
 *      Note:
 *              [Old] Currently if strlen(s) < NAMEDATALEN, the extra chars are nulls
 *              Now, always NULL terminated
 */
Datum
namein(PG_FUNCTION_ARGS)
{
    char       *s = PG_GETARG_CSTRING(0);
    Name        result;
    int         len;

    len = strlen(s);

    /* Truncate oversize input */
    if (len >= NAMEDATALEN)
        len = pg_mbcliplen(s, len, NAMEDATALEN - 1);

    /* We use palloc0 here to ensure result is zero-padded */
    result = (Name) palloc0(NAMEDATALEN);
    memcpy(NameStr(*result), s, len);

    PG_RETURN_NAME(result);
}

/*
 *      nameout - converts internal representation to "..."
 */
Datum
nameout(PG_FUNCTION_ARGS)
{
    Name        s = PG_GETARG_NAME(0);

    PG_RETURN_CSTRING(pstrdup(NameStr(*s)));
}

/*
 *      namerecv            - converts external binary format to name
 */
Datum
namerecv(PG_FUNCTION_ARGS)
{
    StringInfo  buf = (StringInfo) PG_GETARG_POINTER(0);
    Name        result;
    char       *str;
    int         nbytes;

    str = pq_getmsgtext(buf, buf->len - buf->cursor, &nbytes);
    if (nbytes >= NAMEDATALEN)
        ereport(ERROR,
                (errcode(ERRCODE_NAME_TOO_LONG),
                 errmsg("identifier too long"),
                 errdetail("Identifier must be less than %d characters.",
                           NAMEDATALEN)));
    result = (NameData *) palloc0(NAMEDATALEN);
    memcpy(result, str, nbytes);
    pfree(str);
    PG_RETURN_NAME(result);
}

/*
 *      namesend            - converts name to binary format
 */
Datum
namesend(PG_FUNCTION_ARGS)
{
    Name        s = PG_GETARG_NAME(0);
    StringInfoData buf;

    pq_begintypsend(&buf);
    pq_sendtext(&buf, NameStr(*s), strlen(NameStr(*s)));
    PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}


/*****************************************************************************
 *   PUBLIC ROUTINES                                                         *
 *****************************************************************************/

/*
 *      nameeq  - returns 1 iff arguments are equal
 *      namene  - returns 1 iff arguments are not equal
 *
 *      BUGS:
 *              Assumes that "xy\0\0a" should be equal to "xy\0b".
 *              If not, can do the comparison backwards for efficiency.
 *
 *      namelt  - returns 1 iff a < b
 *      namele  - returns 1 iff a <= b
 *      namegt  - returns 1 iff a > b
 *      namege  - returns 1 iff a >= b
 *
 */
Datum
nameeq(PG_FUNCTION_ARGS)
{
    Name        arg1 = PG_GETARG_NAME(0);
    Name        arg2 = PG_GETARG_NAME(1);

    PG_RETURN_BOOL(strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN) == 0);
}

Datum
namene(PG_FUNCTION_ARGS)
{
    Name        arg1 = PG_GETARG_NAME(0);
    Name        arg2 = PG_GETARG_NAME(1);

    PG_RETURN_BOOL(strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN) != 0);
}

Datum
namelt(PG_FUNCTION_ARGS)
{
    Name        arg1 = PG_GETARG_NAME(0);
    Name        arg2 = PG_GETARG_NAME(1);

    PG_RETURN_BOOL(strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN) < 0);
}

Datum
namele(PG_FUNCTION_ARGS)
{
    Name        arg1 = PG_GETARG_NAME(0);
    Name        arg2 = PG_GETARG_NAME(1);

    PG_RETURN_BOOL(strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN) <= 0);
}

Datum
namegt(PG_FUNCTION_ARGS)
{
    Name        arg1 = PG_GETARG_NAME(0);
    Name        arg2 = PG_GETARG_NAME(1);

    PG_RETURN_BOOL(strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN) > 0);
}

Datum
namege(PG_FUNCTION_ARGS)
{
    Name        arg1 = PG_GETARG_NAME(0);
    Name        arg2 = PG_GETARG_NAME(1);

    PG_RETURN_BOOL(strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN) >= 0);
}


/* (see char.c for comparison/operation routines) */

int
namecpy(Name n1, Name n2)
{
    if (!n1 || !n2)
        return -1;
    strncpy(NameStr(*n1), NameStr(*n2), NAMEDATALEN);
    return 0;
}

#ifdef NOT_USED
int
namecat(Name n1, Name n2)
{
    return namestrcat(n1, NameStr(*n2));        /* n2 can't be any longer than
                                                 * n1 */
}
#endif

#ifdef NOT_USED
int
namecmp(Name n1, Name n2)
{
    return strncmp(NameStr(*n1), NameStr(*n2), NAMEDATALEN);
}
#endif

int
namestrcpy(Name name, const char *str)
{
    if (!name || !str)
        return -1;
    StrNCpy(NameStr(*name), str, NAMEDATALEN);
    return 0;
}

#ifdef NOT_USED
int
namestrcat(Name name, const char *str)
{
    int         i;
    char       *p,
               *q;

    if (!name || !str)
        return -1;
    for (i = 0, p = NameStr(*name); i < NAMEDATALEN && *p; ++i, ++p)
        ;
    for (q = str; i < NAMEDATALEN; ++i, ++p, ++q)
    {
        *p = *q;
        if (!*q)
            break;
    }
    return 0;
}
#endif

int
namestrcmp(Name name, const char *str)
{
    if (!name && !str)
        return 0;
    if (!name)
        return -1;              /* NULL < anything */
    if (!str)
        return 1;               /* NULL < anything */
    return strncmp(NameStr(*name), str, NAMEDATALEN);
}


/*
 * SQL-functions CURRENT_USER, SESSION_USER
 */
Datum
current_user(PG_FUNCTION_ARGS)
{
    PG_RETURN_DATUM(DirectFunctionCall1(namein, CStringGetDatum(GetUserNameFromId(GetUserId()))));
}

Datum
session_user(PG_FUNCTION_ARGS)
{
    PG_RETURN_DATUM(DirectFunctionCall1(namein, CStringGetDatum(GetUserNameFromId(GetSessionUserId()))));
}


/*
 * SQL-functions CURRENT_SCHEMA, CURRENT_SCHEMAS
 */
Datum
current_schema(PG_FUNCTION_ARGS)
{
    List       *search_path = fetch_search_path(false);
    char       *nspname;

    if (search_path == NIL)
        PG_RETURN_NULL();
    nspname = get_namespace_name(linitial_oid(search_path));
    list_free(search_path);
    if (!nspname)
        PG_RETURN_NULL();       /* recently-deleted namespace? */
    PG_RETURN_DATUM(DirectFunctionCall1(namein, CStringGetDatum(nspname)));
}

Datum
current_schemas(PG_FUNCTION_ARGS)
{
    List       *search_path = fetch_search_path(PG_GETARG_BOOL(0));
    ListCell   *l;
    Datum      *names;
    int         i;
    ArrayType  *array;

    names = (Datum *) palloc(list_length(search_path) * sizeof(Datum));
    i = 0;
    foreach(l, search_path)
    {
        char       *nspname;

        nspname = get_namespace_name(lfirst_oid(l));
        if (nspname)            /* watch out for deleted namespace */
        {
            names[i] = DirectFunctionCall1(namein, CStringGetDatum(nspname));
            i++;
        }
    }
    list_free(search_path);

    array = construct_array(names, i,
                            NAMEOID,
                            NAMEDATALEN,        /* sizeof(Name) */
                            false,      /* Name is not by-val */
                            'c');       /* alignment of Name */

    PG_RETURN_POINTER(array);
}