config.c

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/*
 * config.c
 *
 * Helper functions for parsing config items.
 * Originally copied from GIT source.
 *
 * Copyright (C) Linus Torvalds, 2005
 * Copyright (C) Johannes Schindelin, 2005
 *
 */
#include "util.h"
#include "cache.h"
#include "exec_cmd.h"

#define MAXNAME (256)

#define DEBUG_CACHE_DIR ".debug"


char buildid_dir[MAXPATHLEN]; /* root dir for buildid, binary cache */

static FILE *config_file;
static const char *config_file_name;
static int config_linenr;
static int config_file_eof;

static const char *config_exclusive_filename;

static int get_next_char(void)
{
    int c;
    FILE *f;

    c = '\n';
    if ((f = config_file) != NULL) {
        c = fgetc(f);
        if (c == '\r') {
            /* DOS like systems */
            c = fgetc(f);
            if (c != '\n') {
                ungetc(c, f);
                c = '\r';
            }
        }
        if (c == '\n')
            config_linenr++;
        if (c == EOF) {
            config_file_eof = 1;
            c = '\n';
        }
    }
    return c;
}

static char *parse_value(void)
{
    static char value[1024];
    int quote = 0, comment = 0, space = 0;
    size_t len = 0;

    for (;;) {
        int c = get_next_char();

        if (len >= sizeof(value) - 1)
            return NULL;
        if (c == '\n') {
            if (quote)
                return NULL;
            value[len] = 0;
            return value;
        }
        if (comment)
            continue;
        if (isspace(c) && !quote) {
            space = 1;
            continue;
        }
        if (!quote) {
            if (c == ';' || c == '#') {
                comment = 1;
                continue;
            }
        }
        if (space) {
            if (len)
                value[len++] = ' ';
            space = 0;
        }
        if (c == '\\') {
            c = get_next_char();
            switch (c) {
            case '\n':
                continue;
            case 't':
                c = '\t';
                break;
            case 'b':
                c = '\b';
                break;
            case 'n':
                c = '\n';
                break;
            /* Some characters escape as themselves */
            case '\\': case '"':
                break;
            /* Reject unknown escape sequences */
            default:
                return NULL;
            }
            value[len++] = c;
            continue;
        }
        if (c == '"') {
            quote = 1-quote;
            continue;
        }
        value[len++] = c;
    }
}

static inline int iskeychar(int c)
{
    return isalnum(c) || c == '-' || c == '_';
}

static int get_value(config_fn_t fn, void *data, char *name, unsigned int len)
{
    int c;
    char *value;

    /* Get the full name */
    for (;;) {
        c = get_next_char();
        if (config_file_eof)
            break;
        if (!iskeychar(c))
            break;
        name[len++] = c;
        if (len >= MAXNAME)
            return -1;
    }
    name[len] = 0;
    while (c == ' ' || c == '\t')
        c = get_next_char();

    value = NULL;
    if (c != '\n') {
        if (c != '=')
            return -1;
        value = parse_value();
        if (!value)
            return -1;
    }
    return fn(name, value, data);
}

static int get_extended_base_var(char *name, int baselen, int c)
{
    do {
        if (c == '\n')
            return -1;
        c = get_next_char();
    } while (isspace(c));

    /* We require the format to be '[base "extension"]' */
    if (c != '"')
        return -1;
    name[baselen++] = '.';

    for (;;) {
        int ch = get_next_char();

        if (ch == '\n')
            return -1;
        if (ch == '"')
            break;
        if (ch == '\\') {
            ch = get_next_char();
            if (ch == '\n')
                return -1;
        }
        name[baselen++] = ch;
        if (baselen > MAXNAME / 2)
            return -1;
    }

    /* Final ']' */
    if (get_next_char() != ']')
        return -1;
    return baselen;
}

static int get_base_var(char *name)
{
    int baselen = 0;

    for (;;) {
        int c = get_next_char();
        if (config_file_eof)
            return -1;
        if (c == ']')
            return baselen;
        if (isspace(c))
            return get_extended_base_var(name, baselen, c);
        if (!iskeychar(c) && c != '.')
            return -1;
        if (baselen > MAXNAME / 2)
            return -1;
        name[baselen++] = tolower(c);
    }
}

static int perf_parse_file(config_fn_t fn, void *data)
{
    int comment = 0;
    int baselen = 0;
    static char var[MAXNAME];

    /* U+FEFF Byte Order Mark in UTF8 */
    static const unsigned char *utf8_bom = (unsigned char *) "\xef\xbb\xbf";
    const unsigned char *bomptr = utf8_bom;

    for (;;) {
        int c = get_next_char();
        if (bomptr && *bomptr) {
            /* We are at the file beginning; skip UTF8-encoded BOM
             * if present. Sane editors won't put this in on their
             * own, but e.g. Windows Notepad will do it happily. */
            if ((unsigned char) c == *bomptr) {
                bomptr++;
                continue;
            } else {
                /* Do not tolerate partial BOM. */
                if (bomptr != utf8_bom)
                    break;
                /* No BOM at file beginning. Cool. */
                bomptr = NULL;
            }
        }
        if (c == '\n') {
            if (config_file_eof)
                return 0;
            comment = 0;
            continue;
        }
        if (comment || isspace(c))
            continue;
        if (c == '#' || c == ';') {
            comment = 1;
            continue;
        }
        if (c == '[') {
            baselen = get_base_var(var);
            if (baselen <= 0)
                break;
            var[baselen++] = '.';
            var[baselen] = 0;
            continue;
        }
        if (!isalpha(c))
            break;
        var[baselen] = tolower(c);
        if (get_value(fn, data, var, baselen+1) < 0)
            break;
    }
    die("bad config file line %d in %s", config_linenr, config_file_name);
}

static int parse_unit_factor(const char *end, unsigned long *val)
{
    if (!*end)
        return 1;
    else if (!strcasecmp(end, "k")) {
        *val *= 1024;
        return 1;
    }
    else if (!strcasecmp(end, "m")) {
        *val *= 1024 * 1024;
        return 1;
    }
    else if (!strcasecmp(end, "g")) {
        *val *= 1024 * 1024 * 1024;
        return 1;
    }
    return 0;
}

static int perf_parse_long(const char *value, long *ret)
{
    if (value && *value) {
        char *end;
        long val = strtol(value, &end, 0);
        unsigned long factor = 1;
        if (!parse_unit_factor(end, &factor))
            return 0;
        *ret = val * factor;
        return 1;
    }
    return 0;
}

static void die_bad_config(const char *name)
{
    if (config_file_name)
        die("bad config value for '%s' in %s", name, config_file_name);
    die("bad config value for '%s'", name);
}

int perf_config_int(const char *name, const char *value)
{
    long ret = 0;
    if (!perf_parse_long(value, &ret))
        die_bad_config(name);
    return ret;
}

static int perf_config_bool_or_int(const char *name, const char *value, int *is_bool)
{
    *is_bool = 1;
    if (!value)
        return 1;
    if (!*value)
        return 0;
    if (!strcasecmp(value, "true") || !strcasecmp(value, "yes") || !strcasecmp(value, "on"))
        return 1;
    if (!strcasecmp(value, "false") || !strcasecmp(value, "no") || !strcasecmp(value, "off"))
        return 0;
    *is_bool = 0;
    return perf_config_int(name, value);
}

int perf_config_bool(const char *name, const char *value)
{
    int discard;
    return !!perf_config_bool_or_int(name, value, &discard);
}

const char *perf_config_dirname(const char *name, const char *value)
{
    if (!name)
        return NULL;
    return value;
}

static int perf_default_core_config(const char *var __maybe_unused,
                    const char *value __maybe_unused)
{
    /* Add other config variables here. */
    return 0;
}

int perf_default_config(const char *var, const char *value,
            void *dummy __maybe_unused)
{
    if (!prefixcmp(var, "core."))
        return perf_default_core_config(var, value);

    /* Add other config variables here. */
    return 0;
}

static int perf_config_from_file(config_fn_t fn, const char *filename, void *data)
{
    int ret;
    FILE *f = fopen(filename, "r");

    ret = -1;
    if (f) {
        config_file = f;
        config_file_name = filename;
        config_linenr = 1;
        config_file_eof = 0;
        ret = perf_parse_file(fn, data);
        fclose(f);
        config_file_name = NULL;
    }
    return ret;
}

static const char *perf_etc_perfconfig(void)
{
    static const char *system_wide;
    if (!system_wide)
        system_wide = system_path(ETC_PERFCONFIG);
    return system_wide;
}

static int perf_env_bool(const char *k, int def)
{
    const char *v = getenv(k);
    return v ? perf_config_bool(k, v) : def;
}

static int perf_config_system(void)
{
    return !perf_env_bool("PERF_CONFIG_NOSYSTEM", 0);
}

static int perf_config_global(void)
{
    return !perf_env_bool("PERF_CONFIG_NOGLOBAL", 0);
}

int perf_config(config_fn_t fn, void *data)
{
    int ret = 0, found = 0;
    const char *home = NULL;

    /* Setting $PERF_CONFIG makes perf read _only_ the given config file. */
    if (config_exclusive_filename)
        return perf_config_from_file(fn, config_exclusive_filename, data);
    if (perf_config_system() && !access(perf_etc_perfconfig(), R_OK)) {
        ret += perf_config_from_file(fn, perf_etc_perfconfig(),
                        data);
        found += 1;
    }

    home = getenv("HOME");
    if (perf_config_global() && home) {
        char *user_config = strdup(mkpath("%s/.perfconfig", home));
        struct stat st;

        if (user_config == NULL) {
            warning("Not enough memory to process %s/.perfconfig, "
                "ignoring it.", home);
            goto out;
        }

        if (stat(user_config, &st) < 0)
            goto out_free;

        if (st.st_uid && (st.st_uid != geteuid())) {
            warning("File %s not owned by current user or root, "
                "ignoring it.", user_config);
            goto out_free;
        }

        if (!st.st_size)
            goto out_free;

        ret += perf_config_from_file(fn, user_config, data);
        found += 1;
out_free:
        free(user_config);
    }
out:
    if (found == 0)
        return -1;
    return ret;
}

/*
 * Call this to report error for your variable that should not
 * get a boolean value (i.e. "[my] var" means "true").
 */
int config_error_nonbool(const char *var)
{
    return error("Missing value for '%s'", var);
}

struct buildid_dir_config {
    char *dir;
};

static int buildid_dir_command_config(const char *var, const char *value,
                      void *data)
{
    struct buildid_dir_config *c = data;
    const char *v;

    /* same dir for all commands */
    if (!prefixcmp(var, "buildid.") && !strcmp(var + 8, "dir")) {
        v = perf_config_dirname(var, value);
        if (!v)
            return -1;
        strncpy(c->dir, v, MAXPATHLEN-1);
        c->dir[MAXPATHLEN-1] = '\0';
    }
    return 0;
}

static void check_buildid_dir_config(void)
{
    struct buildid_dir_config c;
    c.dir = buildid_dir;
    perf_config(buildid_dir_command_config, &c);
}

void set_buildid_dir(void)
{
    buildid_dir[0] = '\0';

    /* try config file */
    check_buildid_dir_config();

    /* default to $HOME/.debug */
    if (buildid_dir[0] == '\0') {
        char *v = getenv("HOME");
        if (v) {
            snprintf(buildid_dir, MAXPATHLEN-1, "%s/%s",
                 v, DEBUG_CACHE_DIR);
        } else {
            strncpy(buildid_dir, DEBUG_CACHE_DIR, MAXPATHLEN-1);
        }
        buildid_dir[MAXPATHLEN-1] = '\0';
    }
    /* for communicating with external commands */
    setenv("PERF_BUILDID_DIR", buildid_dir, 1);
}