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Add code to find_my_exec() to resolve a symbolic link down to the

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actual executable location.  This allows people to continue to use
setups where, eg, postmaster is symlinked from a convenient place.
Per gripe from Josh Berkus.
REL8_0_STABLE
Tom Lane 21 years ago
parent bffe45a72c
commit 336969e490
4 changed files with 173 additions and 61 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 3
      configure
  2. 4
      configure.in
  3. 3
      src/include/pg_config.h.in
  4. 224
      src/port/exec.c

3
configure vendored
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@ -11295,7 +11295,8 @@ test $ac_cv_func_memcmp_working = no && LIBOBJS="$LIBOBJS memcmp.$ac_objext"
for ac_func in cbrt dlopen fcvt fdatasync getpeereid memmove poll pstat setproctitle setsid sigprocmask symlink sysconf towlower utime utimes waitpid wcstombs
for ac_func in cbrt dlopen fcvt fdatasync getpeereid memmove poll pstat readlink setproctitle setsid sigprocmask symlink sysconf towlower utime utimes waitpid wcstombs
do
as_ac_var=`echo "ac_cv_func_$ac_func" | $as_tr_sh`
echo "$as_me:$LINENO: checking for $ac_func" >&5

4
configure.in
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@ -1,5 +1,5 @@
dnl Process this file with autoconf to produce a configure script.
dnl $PostgreSQL: pgsql/configure.in,v 1.384 2004/11/02 05:44:45 momjian Exp $
dnl $PostgreSQL: pgsql/configure.in,v 1.385 2004/11/06 23:06:15 tgl Exp $
dnl
dnl Developers, please strive to achieve this order:
dnl
@ -826,7 +826,7 @@ PGAC_FUNC_GETTIMEOFDAY_1ARG
# SunOS doesn't handle negative byte comparisons properly with +/- return
AC_FUNC_MEMCMP
AC_CHECK_FUNCS([cbrt dlopen fcvt fdatasync getpeereid memmove poll pstat setproctitle setsid sigprocmask symlink sysconf towlower utime utimes waitpid wcstombs])
AC_CHECK_FUNCS([cbrt dlopen fcvt fdatasync getpeereid memmove poll pstat readlink setproctitle setsid sigprocmask symlink sysconf towlower utime utimes waitpid wcstombs])
AC_CHECK_DECLS(fdatasync, [], [], [#include <unistd.h>])

3
src/include/pg_config.h.in
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@ -345,6 +345,9 @@
/* Define to 1 if you have the <readline/readline.h> header file. */
#undef HAVE_READLINE_READLINE_H
/* Define to 1 if you have the `readlink' function. */
#undef HAVE_READLINK
/* Define to 1 if you have the `replace_history_entry' function. */
#undef HAVE_REPLACE_HISTORY_ENTRY

224
src/port/exec.c
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@ -1,13 +1,15 @@
/*-------------------------------------------------------------------------
*
* exec.c
* Functions for finding and validating executable files
*
*
* Portions Copyright (c) 1996-2004, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/port/exec.c,v 1.31 2004/11/06 01:16:22 tgl Exp $
* $PostgreSQL: pgsql/src/port/exec.c,v 1.32 2004/11/06 23:06:29 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -47,6 +49,14 @@
#define log_error(str, param) (fprintf(stderr, str, param), fputc('\n', stderr))
#endif
#ifdef WIN32_CLIENT_ONLY
#define getcwd(cwd,len) GetCurrentDirectory(len, cwd)
#endif
static int validate_exec(const char *path);
static int resolve_symlinks(char *path);
static char *pipe_read_line(char *cmd, char *line, int maxsize);
/*
* validate_exec -- validate "path" as an executable file
@ -154,13 +164,20 @@ validate_exec(const char *path)
#endif
}
/*
* find_my_exec -- find an absolute path to a valid executable
*
* argv0 is the name passed on the command line
* retpath is the output area (must be of size MAXPGPATH)
* Returns 0 if OK, -1 if error.
*
* The reason we have to work so hard to find an absolute path is that
* on some platforms we can't do dynamic loading unless we know the
* executable's location. Also, we need a full path not a relative
* path because we will later change working directory.
* path because we will later change working directory. Finally, we want
* a true path not a symlink location, so that we can locate other files
* that are part of our installation relative to the executable.
*
* This function is not thread-safe because it calls validate_exec(),
* which calls getgrgid(). This function should be used only in
@ -173,13 +190,12 @@ find_my_exec(const char *argv0, char *retpath)
test_path[MAXPGPATH];
char *path;
#ifndef WIN32_CLIENT_ONLY
if (!getcwd(cwd, MAXPGPATH))
strcpy(cwd, "."); /* cheesy, but better than nothing */
#else
if (!GetCurrentDirectory(MAXPGPATH, cwd))
strcpy(cwd, "."); /* cheesy, but better than nothing */
#endif
{
log_error(_("could not identify current directory: %s"),
strerror(errno));
return -1;
}
/*
* If argv0 contains a separator, then PATH wasn't used.
@ -193,7 +209,7 @@ find_my_exec(const char *argv0, char *retpath)
canonicalize_path(retpath);
if (validate_exec(retpath) == 0)
return 0;
return resolve_symlinks(retpath);
log_error("invalid binary \"%s\"", retpath);
return -1;
@ -203,7 +219,7 @@ find_my_exec(const char *argv0, char *retpath)
/* Win32 checks the current directory first for names without slashes */
join_path_components(retpath, cwd, argv0);
if (validate_exec(retpath) == 0)
return 0;
return resolve_symlinks(retpath);
#endif
/*
@ -240,7 +256,7 @@ find_my_exec(const char *argv0, char *retpath)
switch (validate_exec(retpath))
{
case 0: /* found ok */
return 0;
return resolve_symlinks(retpath);
case -1: /* wasn't even a candidate, keep looking */
break;
case -2: /* found but disqualified */
@ -254,6 +270,141 @@ find_my_exec(const char *argv0, char *retpath)
return -1;
}
/*
* resolve_symlinks - resolve symlinks to the underlying file
*
* If path does not point to a symlink, leave it alone. If it does,
* replace it by the absolute path to the referenced file.
*
* Returns 0 if OK, -1 if error.
*
* Note: we are not particularly tense about producing nice error messages
* because we are not really expecting error here; we just determined that
* the symlink does point to a valid executable.
*/
static int
resolve_symlinks(char *path)
{
#ifdef HAVE_READLINK
struct stat buf;
char orig_wd[MAXPGPATH],
link_buf[MAXPGPATH];
char *fname;
/* Quick out if it's not a symlink */
if (lstat(path, &buf) < 0 ||
(buf.st_mode & S_IFMT) != S_IFLNK)
return 0;
/*
* To resolve a symlink properly, we have to chdir into its directory
* and then chdir to where the symlink points; otherwise we may fail to
* resolve relative links correctly (consider cases involving mount
* points, for example). After following the final symlink, we use
* getcwd() to figure out where the heck we're at.
*/
if (!getcwd(orig_wd, MAXPGPATH))
{
log_error(_("could not identify current directory: %s"),
strerror(errno));
return -1;
}
for (;;)
{
char *lsep;
int rllen;
lsep = last_dir_separator(path);
if (lsep)
{
*lsep = '\0';
if (chdir(path) == -1)
{
log_error(_("could not change directory to \"%s\""), path);
return -1;
}
fname = lsep + 1;
}
else
fname = path;
if (lstat(fname, &buf) < 0 ||
(buf.st_mode & S_IFMT) != S_IFLNK)
break;
rllen = readlink(fname, link_buf, sizeof(link_buf));
if (rllen < 0 || rllen >= sizeof(link_buf))
{
log_error(_("could not read symbolic link \"%s\""), fname);
return -1;
}
link_buf[rllen] = '\0';
strcpy(path, link_buf);
}
/* must copy final component out of 'path' temporarily */
strcpy(link_buf, fname);
if (!getcwd(path, MAXPGPATH))
{
log_error(_("could not identify current directory: %s"),
strerror(errno));
return -1;
}
join_path_components(path, path, link_buf);
canonicalize_path(path);
if (chdir(orig_wd) == -1)
{
log_error(_("could not change directory to \"%s\""), orig_wd);
return -1;
}
#endif /* HAVE_READLINK */
return 0;
}
/*
* Find another program in our binary's directory,
* then make sure it is the proper version.
*/
int
find_other_exec(const char *argv0, const char *target,
const char *versionstr, char *retpath)
{
char cmd[MAXPGPATH];
char line[100];
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 2>%s", retpath, DEVNULL);
if (!pipe_read_line(cmd, line, sizeof(line)))
return -1;
if (strcmp(line, versionstr) != 0)
return -2;
return 0;
}
/*
* The runtime library's popen() on win32 does not work when being
* called from a service when running on windows <= 2000, because
@ -262,7 +413,6 @@ find_my_exec(const char *argv0, char *retpath)
* Executing a command in a pipe and reading the first line from it
* is all we need.
*/
static char *
pipe_read_line(char *cmd, char *line, int maxsize)
{
@ -286,8 +436,9 @@ pipe_read_line(char *cmd, char *line, int maxsize)
return NULL;
return line;
#else
/* Win32 */
#else /* WIN32 */
SECURITY_ATTRIBUTES sattr;
HANDLE childstdoutrd,
childstdoutwr,
@ -392,44 +543,7 @@ pipe_read_line(char *cmd, char *line, int maxsize)
CloseHandle(childstdoutrddup);
return retval;
#endif
}
/*
* Find another program in our binary's directory,
* then make sure it is the proper version.
*/
int
find_other_exec(const char *argv0, const char *target,
const char *versionstr, char *retpath)
{
char cmd[MAXPGPATH];
char line[100];
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))
return -1;
snprintf(cmd, sizeof(cmd), "\"%s\" -V 2>%s", retpath, DEVNULL);
if (!pipe_read_line(cmd, line, sizeof(line)))
return -1;
if (strcmp(line, versionstr) != 0)
return -2;
return 0;
#endif /* WIN32 */
}
@ -454,20 +568,14 @@ pclose_check(FILE *stream)
perror("pclose failed");
}
else if (WIFEXITED(exitstatus))
{
log_error(_("child process exited with exit code %d"),
WEXITSTATUS(exitstatus));
}
else if (WIFSIGNALED(exitstatus))
{
log_error(_("child process was terminated by signal %d"),
WTERMSIG(exitstatus));
}
else
{
log_error(_("child process exited with unrecognized status %d"),
exitstatus);
}
return -1;
}

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