exec.c File Reference

#include "postgres.h"
#include <signal.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>

Include dependency graph for exec.c:

Go to the source code of this file.

Macros
#define	_DARWIN_BETTER_REALPATH
#define	log_error(errcodefn, ...)    ereport(LOG, (errcodefn, errmsg_internal(__VA_ARGS__)))

Functions
static int	normalize_exec_path (char *path)
static char *	pg_realpath (const char *fname)
int	validate_exec (const char *path)
int	find_my_exec (const char *argv0, char *retpath)
int	find_other_exec (const char *argv0, const char *target, const char *versionstr, char *retpath)
char *	pipe_read_line (char *cmd, char *line, int maxsize)
int	pclose_check (FILE *stream)
void	set_pglocale_pgservice (const char *argv0, const char *app)

Macro Definition Documentation

_DARWIN_BETTER_REALPATH

#define _DARWIN_BETTER_REALPATH

Definition at line 24 of file exec.c.

log_error

#define log_error	(		errcodefn,
			...
	)		ereport(LOG, (errcodefn, errmsg_internal(__VA_ARGS__)))

Definition at line 63 of file exec.c.

Function Documentation

find_my_exec()

int find_my_exec	(	const char *	argv0,
		char *	retpath
	)

Definition at line 158 of file exec.c.

{
    char       *path;
 
    /*
     * If argv0 contains a separator, then PATH wasn't used.
     */
    strlcpy(retpath, argv0, MAXPGPATH);
    if (first_dir_separator(retpath) != NULL)
    {
        if (validate_exec(retpath) == 0)
            return normalize_exec_path(retpath);
 
        log_error(errcode(ERRCODE_WRONG_OBJECT_TYPE),
                  _("invalid binary \"%s\": %m"), retpath);
        return -1;
    }
 
#ifdef WIN32
    /* Win32 checks the current directory first for names without slashes */
    if (validate_exec(retpath) == 0)
        return normalize_exec_path(retpath);
#endif
 
    /*
     * Since no explicit path was supplied, the user must have been relying on
     * PATH.  We'll search the same PATH.
     */
    if ((path = getenv("PATH")) && *path)
    {
        char       *startp = NULL,
                   *endp = NULL;
 
        do
        {
            if (!startp)
                startp = path;
            else
                startp = endp + 1;
 
            endp = first_path_var_separator(startp);
            if (!endp)
                endp = startp + strlen(startp); /* point to end */
 
            strlcpy(retpath, startp, Min(endp - startp + 1, MAXPGPATH));
 
            join_path_components(retpath, retpath, argv0);
            canonicalize_path(retpath);
 
            switch (validate_exec(retpath))
            {
                case 0:         /* found ok */
                    return normalize_exec_path(retpath);
                case -1:        /* wasn't even a candidate, keep looking */
                    break;
                case -2:        /* found but disqualified */
                    log_error(errcode(ERRCODE_WRONG_OBJECT_TYPE),
                              _("could not read binary \"%s\": %m"),
                              retpath);
                    break;
            }
        } while (*endp);
    }
 
    log_error(errcode(ERRCODE_UNDEFINED_FILE),
              _("could not find a \"%s\" to execute"), argv0);
    return -1;
}

References _, argv0, canonicalize_path(), errcode(), first_dir_separator(), first_path_var_separator(), join_path_components(), log_error, MAXPGPATH, Min, normalize_exec_path(), strlcpy(), and validate_exec().

Referenced by ensureCleanShutdown(), find_other_exec(), find_other_exec_or_die(), getInstallationPaths(), getRestoreCommand(), InitStandaloneProcess(), main(), process_psqlrc(), set_pglocale_pgservice(), setup(), and setup_bin_paths().

find_other_exec()

int find_other_exec	(	const char *	argv0,
		const char *	target,
		const char *	versionstr,
		char *	retpath
	)

Definition at line 327 of file exec.c.

{
    char        cmd[MAXPGPATH];
    char        line[MAXPGPATH];
 
    if (find_my_exec(argv0, retpath) < 0)
        return -1;
 
    /* Trim off program name and keep just directory */
    *last_dir_separator(retpath) = '\0';
    canonicalize_path(retpath);
 
    /* Now append the other program's name */
    snprintf(retpath + strlen(retpath), MAXPGPATH - strlen(retpath),
             "/%s%s", target, EXE);
 
    if (validate_exec(retpath) != 0)
        return -1;
 
    snprintf(cmd, sizeof(cmd), "\"%s\" -V", retpath);
 
    if (!pipe_read_line(cmd, line, sizeof(line)))
        return -1;
 
    if (strcmp(line, versionstr) != 0)
        return -2;
 
    return 0;
}

References argv0, canonicalize_path(), EXE, find_my_exec(), last_dir_separator(), MAXPGPATH, pipe_read_line(), snprintf, and validate_exec().

Referenced by ensureCleanShutdown(), find_other_exec_or_die(), getInstallationPaths(), getRestoreCommand(), isolation_start_test(), main(), and setup_bin_paths().

normalize_exec_path()

static int normalize_exec_path ( char *  path )

static

Definition at line 239 of file exec.c.

{
    /*
     * We used to do a lot of work ourselves here, but now we just let
     * realpath(3) do all the heavy lifting.
     */
    char       *abspath = pg_realpath(path);
 
    if (abspath == NULL)
    {
        log_error(errcode_for_file_access(),
                  _("could not resolve path \"%s\" to absolute form: %m"),
                  path);
        return -1;
    }
    strlcpy(path, abspath, MAXPGPATH);
    free(abspath);
 
#ifdef WIN32
    /* On Windows, be sure to convert '\' to '/' */
    canonicalize_path(path);
#endif
 
    return 0;
}

References _, canonicalize_path(), errcode_for_file_access(), free, log_error, MAXPGPATH, pg_realpath(), and strlcpy().

Referenced by find_my_exec().

pclose_check()

int pclose_check

(

FILE *

stream

)

Definition at line 398 of file exec.c.

{
    int         exitstatus;
    char       *reason;
 
    exitstatus = pclose(stream);
 
    if (exitstatus == 0)
        return 0;               /* all is well */
 
    if (exitstatus == -1)
    {
        /* pclose() itself failed, and hopefully set errno */
        log_error(errcode(ERRCODE_SYSTEM_ERROR),
                  _("%s() failed: %m"), "pclose");
    }
    else
    {
        reason = wait_result_to_str(exitstatus);
        log_error(errcode(ERRCODE_SYSTEM_ERROR),
                  "%s", reason);
        pfree(reason);
    }
    return exitstatus;
}

References _, errcode(), log_error, pfree(), and wait_result_to_str().

Referenced by pipe_read_line().

pg_realpath()

static char * pg_realpath ( const char *  fname )

static

Definition at line 280 of file exec.c.

{
    char       *path;
 
#ifndef WIN32
    path = realpath(fname, NULL);
    if (path == NULL && errno == EINVAL)
    {
        /*
         * Cope with old-POSIX systems that require a user-provided buffer.
         * Assume MAXPGPATH is enough room on all such systems.
         */
        char       *buf = malloc(MAXPGPATH);
 
        if (buf == NULL)
            return NULL;        /* assume errno is set */
        path = realpath(fname, buf);
        if (path == NULL)       /* don't leak memory */
        {
            int         save_errno = errno;
 
            free(buf);
            errno = save_errno;
        }
    }
#else                           /* WIN32 */
 
    /*
     * Microsoft is resolutely non-POSIX, but _fullpath() does the same thing.
     * The documentation claims it reports errors by setting errno, which is a
     * bit surprising for Microsoft, but we'll believe that until it's proven
     * wrong.  Clear errno first, though, so we can at least tell if a failure
     * occurs and doesn't set it.
     */
    errno = 0;
    path = _fullpath(NULL, fname, 0);
#endif
 
    return path;
}

References buf, free, malloc, and MAXPGPATH.

Referenced by normalize_exec_path().

pipe_read_line()

char* pipe_read_line	(	char *	cmd,
		char *	line,
		int	maxsize
	)

Definition at line 363 of file exec.c.

{
    FILE       *pgver;
 
    fflush(NULL);
 
    errno = 0;
    if ((pgver = popen(cmd, "r")) == NULL)
    {
        perror("popen failure");
        return NULL;
    }
 
    errno = 0;
    if (fgets(line, maxsize, pgver) == NULL)
    {
        if (feof(pgver))
            fprintf(stderr, "no data was returned by command \"%s\"\n", cmd);
        else
            perror("fgets failure");
        pclose(pgver);          /* no error checking */
        return NULL;
    }
 
    if (pclose_check(pgver))
        return NULL;
 
    return line;
}

References fflush(), fprintf, and pclose_check().

Referenced by check_exec(), find_other_exec(), and getRestoreCommand().

set_pglocale_pgservice()

void set_pglocale_pgservice	(	const char *	argv0,
		const char *	app
	)

Definition at line 436 of file exec.c.

{
    char        path[MAXPGPATH];
    char        my_exec_path[MAXPGPATH];
 
    /* don't set LC_ALL in the backend */
    if (strcmp(app, PG_TEXTDOMAIN("postgres")) != 0)
    {
        setlocale(LC_ALL, "");
 
        /*
         * One could make a case for reproducing here PostmasterMain()'s test
         * for whether the process is multithreaded.  Unlike the postmaster,
         * no frontend program calls sigprocmask() or otherwise provides for
         * mutual exclusion between signal handlers.  While frontends using
         * fork(), if multithreaded, are formally exposed to undefined
         * behavior, we have not witnessed a concrete bug.  Therefore,
         * complaining about multithreading here may be mere pedantry.
         */
    }
 
    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);
    /* set for libpq to use, but don't override existing setting */
    setenv("PGLOCALEDIR", path, 0);
#endif
 
    if (getenv("PGSYSCONFDIR") == NULL)
    {
        get_etc_path(my_exec_path, path);
        /* set for libpq to use */
        setenv("PGSYSCONFDIR", path, 0);
    }
}

References argv0, find_my_exec(), get_etc_path(), get_locale_path(), MAXPGPATH, my_exec_path, PG_TEXTDOMAIN, setenv, and setlocale.

Referenced by main(), and regression_main().

validate_exec()

int validate_exec

(

const char *

path

)

Definition at line 86 of file exec.c.

{
    struct stat buf;
    int         is_r;
    int         is_x;
 
#ifdef WIN32
    char        path_exe[MAXPGPATH + sizeof(".exe") - 1];
 
    /* Win32 requires a .exe suffix for stat() */
    if (strlen(path) < strlen(".exe") ||
        pg_strcasecmp(path + strlen(path) - strlen(".exe"), ".exe") != 0)
    {
        strlcpy(path_exe, path, sizeof(path_exe) - 4);
        strcat(path_exe, ".exe");
        path = path_exe;
    }
#endif
 
    /*
     * Ensure that the file exists and is a regular file.
     *
     * XXX if you have a broken system where stat() looks at the symlink
     * instead of the underlying file, you lose.
     */
    if (stat(path, &buf) < 0)
        return -1;
 
    if (!S_ISREG(buf.st_mode))
    {
        /*
         * POSIX offers no errno code that's simply "not a regular file".  If
         * it's a directory we can use EISDIR.  Otherwise, it's most likely a
         * device special file, and EPERM (Operation not permitted) isn't too
         * horribly off base.
         */
        errno = S_ISDIR(buf.st_mode) ? EISDIR : EPERM;
        return -1;
    }
 
    /*
     * Ensure that the file is both executable and readable (required for
     * dynamic loading).
     */
#ifndef WIN32
    is_r = (access(path, R_OK) == 0);
    is_x = (access(path, X_OK) == 0);
    /* access() will set errno if it returns -1 */
#else
    is_r = buf.st_mode & S_IRUSR;
    is_x = buf.st_mode & S_IXUSR;
    errno = EACCES;             /* appropriate thing if we return nonzero */
#endif
    return is_x ? (is_r ? 0 : -2) : -1;
}

References buf, MAXPGPATH, pg_strcasecmp(), S_IRUSR, S_ISDIR, S_ISREG, S_IXUSR, stat, and strlcpy().

Referenced by check_exec(), find_my_exec(), and find_other_exec().