PostgreSQL的 initdb 源代码分析之一

开始第一段：

int
main(int argc, char *argv[])
{
/*
     * options with no short version return a low integer, the rest return
     * their short version value
     */
    static struct option long_options[] = {
        {"pgdata", required_argument, NULL, 'D'},
        {"encoding", required_argument, NULL, 'E'},
        {"locale", required_argument, NULL, 1},
        {"lc-collate", required_argument, NULL, 2},
        {"lc-ctype", required_argument, NULL, 3},
        {"lc-monetary", required_argument, NULL, 4},
        {"lc-numeric", required_argument, NULL, 5},
        {"lc-time", required_argument, NULL, 6},
        {"lc-messages", required_argument, NULL, 7},
        {"no-locale", no_argument, NULL, 8},
        {"text-search-config", required_argument, NULL, 'T'},
        {"auth", required_argument, NULL, 'A'},
        {"pwprompt", no_argument, NULL, 'W'},
        {"pwfile", required_argument, NULL, 9},
        {"username", required_argument, NULL, 'U'},
        {"help", no_argument, NULL, '?'},
        {"version", no_argument, NULL, 'V'},
        {"debug", no_argument, NULL, 'd'},
        {"show", no_argument, NULL, 's'},
        {"noclean", no_argument, NULL, 'n'},
        {"xlogdir", required_argument, NULL, 'X'},
        {NULL, 0, NULL, 0}
    };

    int            c,i,ret;
    int            option_index;
    char       *effective_user;
    char       *pgdenv;            /* PGDATA value gotten from and sent to
                                 * environment */
    char        bin_dir[MAXPGPATH];
    char       *pg_data_native;
    int            user_enc;

#ifdef WIN32
    char       *restrict_env;
#endif
    static const char *subdirs[] = {
        "global",
        "pg_xlog",
        "pg_xlog/archive_status",
        "pg_clog",
        "pg_notify",
        "pg_serial",
        "pg_subtrans",
        "pg_twophase",
        "pg_multixact/members",
        "pg_multixact/offsets",
        "base",
        "base/1",
        "pg_tblspc",
        "pg_stat_tmp"
    };

    progname = get_progname(argv[0]);

    set_pglocale_pgservice(argv[0], PG_TEXTDOMAIN("initdb"));
    ......
}

上述程序部分运行后，get_progname的返回值是：

progname ----------initdb
而我传递给 get_progname的参数 argv[0] 是 : /home/pgsql/project/bin/initdb 

再来看 set_pglocale_pgservice函数：

此时传递的第一个参数是：  /home/pgsql/project/bin/initdb  传递的第二个参数是：initdb-9.1 

由于  set_pglocale_pgservice 也会被postgres进程所调用，所以需要第二个参数来明确调用者。

/*
 *    set_pglocale_pgservice
 *
 *    Set application-specific locale and service directory
 *
 *    This function takes the value of argv[0] rather than a full path.
 *
 * (You may be wondering why this is in exec.c.  It requires this module's
 * services and doesn't introduce any new dependencies, so this seems as
 * good as anyplace.)
 */
void
set_pglocale_pgservice(const char *argv0, const char *app)
{
 char        path[MAXPGPATH];
    char        my_exec_path[MAXPGPATH];
    char        env_path[MAXPGPATH + sizeof("PGSYSCONFDIR=")];    /* longer than
                                                                 * PGLOCALEDIR */
/* don't set LC_ALL in the backend */
    if (strcmp(app, PG_TEXTDOMAIN("postgres")) != 0)
        setlocale(LC_ALL, "");

if (find_my_exec(argv0, my_exec_path) < 0)
        return;
#ifdef ENABLE_NLS
    get_locale_path(my_exec_path, path);
    bindtextdomain(app, path);
    textdomain(app);

    if (getenv("PGLOCALEDIR") == NULL)
    {
        /* set for libpq to use */
        snprintf(env_path, sizeof(env_path), "PGLOCALEDIR=%s", path);
        canonicalize_path(env_path + 12);
        putenv(strdup(env_path));
    }
#endif

    if (getenv("PGSYSCONFDIR") == NULL)
    {

        get_etc_path(my_exec_path, path);

        /* set for libpq to use */
        snprintf(env_path, sizeof(env_path), "PGSYSCONFDIR=%s", path);
        canonicalize_path(env_path + 13);
        putenv(strdup(env_path));

    }
}

实际上，运行时，得到的 

my_exec_path :          /home/pgsql/project/bin/initdb
env_path :                  PGSYSCONFDIR=/home/pgsql/project/etc