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Commit336969e

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Add code to find_my_exec() to resolve a symbolic link down to the
actual executable location. This allows people to continue to usesetups where, eg, postmaster is symlinked from a convenient place.Per gripe from Josh Berkus.
1 parentbffe45a commit336969e

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4 files changed

+173
-61
lines changed

4 files changed

+173
-61
lines changed

‎configure

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -11295,7 +11295,8 @@ test $ac_cv_func_memcmp_working = no && LIBOBJS="$LIBOBJS memcmp.$ac_objext"
1129511295

1129611296

1129711297

11298-
for ac_func in cbrt dlopen fcvt fdatasync getpeereid memmove poll pstat setproctitle setsid sigprocmask symlink sysconf towlower utime utimes waitpid wcstombs
11298+
11299+
for ac_func in cbrt dlopen fcvt fdatasync getpeereid memmove poll pstat readlink setproctitle setsid sigprocmask symlink sysconf towlower utime utimes waitpid wcstombs
1129911300
do
1130011301
as_ac_var=`echo "ac_cv_func_$ac_func" | $as_tr_sh`
1130111302
echo "$as_me:$LINENO: checking for $ac_func" >&5

‎configure.in

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
dnl Process this file with autoconf to produce a configure script.
2-
dnl $PostgreSQL: pgsql/configure.in,v 1.384 2004/11/02 05:44:45 momjian Exp $
2+
dnl $PostgreSQL: pgsql/configure.in,v 1.385 2004/11/06 23:06:15 tgl Exp $
33
dnl
44
dnl Developers, please strive to achieve this order:
55
dnl
@@ -826,7 +826,7 @@ PGAC_FUNC_GETTIMEOFDAY_1ARG
826826
# SunOS doesn't handle negative byte comparisons properly with +/- return
827827
AC_FUNC_MEMCMP
828828

829-
AC_CHECK_FUNCS([cbrt dlopen fcvt fdatasync getpeereid memmove poll pstat setproctitle setsid sigprocmask symlink sysconf towlower utime utimes waitpid wcstombs])
829+
AC_CHECK_FUNCS([cbrt dlopen fcvt fdatasync getpeereid memmove poll pstatreadlinksetproctitle setsid sigprocmask symlink sysconf towlower utime utimes waitpid wcstombs])
830830

831831
AC_CHECK_DECLS(fdatasync, [], [], [#include <unistd.h>])
832832

‎src/include/pg_config.h.in

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -345,6 +345,9 @@
345345
/* Define to 1 if you have the <readline/readline.h> header file. */
346346
#undef HAVE_READLINE_READLINE_H
347347

348+
/* Define to 1 if you have the `readlink' function. */
349+
#undef HAVE_READLINK
350+
348351
/* Define to 1 if you have the `replace_history_entry' function. */
349352
#undef HAVE_REPLACE_HISTORY_ENTRY
350353

‎src/port/exec.c

Lines changed: 166 additions & 58 deletions
Original file line numberDiff line numberDiff line change
@@ -1,13 +1,15 @@
11
/*-------------------------------------------------------------------------
22
*
33
* exec.c
4+
*Functions for finding and validating executable files
5+
*
46
*
57
* Portions Copyright (c) 1996-2004, PostgreSQL Global Development Group
68
* Portions Copyright (c) 1994, Regents of the University of California
79
*
810
*
911
* IDENTIFICATION
10-
* $PostgreSQL: pgsql/src/port/exec.c,v 1.31 2004/11/0601:16:22 tgl Exp $
12+
* $PostgreSQL: pgsql/src/port/exec.c,v 1.32 2004/11/0623:06:29 tgl Exp $
1113
*
1214
*-------------------------------------------------------------------------
1315
*/
@@ -47,6 +49,14 @@
4749
#definelog_error(str,param)(fprintf(stderr, str, param), fputc('\n', stderr))
4850
#endif
4951

52+
#ifdefWIN32_CLIENT_ONLY
53+
#definegetcwd(cwd,len) GetCurrentDirectory(len, cwd)
54+
#endif
55+
56+
staticintvalidate_exec(constchar*path);
57+
staticintresolve_symlinks(char*path);
58+
staticchar*pipe_read_line(char*cmd,char*line,intmaxsize);
59+
5060

5161
/*
5262
* validate_exec -- validate "path" as an executable file
@@ -154,13 +164,20 @@ validate_exec(const char *path)
154164
#endif
155165
}
156166

167+
157168
/*
158169
* find_my_exec -- find an absolute path to a valid executable
159170
*
171+
*argv0 is the name passed on the command line
172+
*retpath is the output area (must be of size MAXPGPATH)
173+
*Returns 0 if OK, -1 if error.
174+
*
160175
* The reason we have to work so hard to find an absolute path is that
161176
* on some platforms we can't do dynamic loading unless we know the
162177
* executable's location. Also, we need a full path not a relative
163-
* path because we will later change working directory.
178+
* path because we will later change working directory. Finally, we want
179+
* a true path not a symlink location, so that we can locate other files
180+
* that are part of our installation relative to the executable.
164181
*
165182
* This function is not thread-safe because it calls validate_exec(),
166183
* which calls getgrgid().This function should be used only in
@@ -173,13 +190,12 @@ find_my_exec(const char *argv0, char *retpath)
173190
test_path[MAXPGPATH];
174191
char*path;
175192

176-
#ifndefWIN32_CLIENT_ONLY
177193
if (!getcwd(cwd,MAXPGPATH))
178-
strcpy(cwd,".");/* cheesy, but better than nothing */
179-
#else
180-
if (!GetCurrentDirectory(MAXPGPATH,cwd))
181-
strcpy(cwd,".");/* cheesy, but better than nothing */
182-
#endif
194+
{
195+
log_error(_("could not identify current directory: %s"),
196+
strerror(errno));
197+
return-1;
198+
}
183199

184200
/*
185201
* If argv0 contains a separator, then PATH wasn't used.
@@ -193,7 +209,7 @@ find_my_exec(const char *argv0, char *retpath)
193209
canonicalize_path(retpath);
194210

195211
if (validate_exec(retpath)==0)
196-
return0;
212+
returnresolve_symlinks(retpath);
197213

198214
log_error("invalid binary \"%s\"",retpath);
199215
return-1;
@@ -203,7 +219,7 @@ find_my_exec(const char *argv0, char *retpath)
203219
/* Win32 checks the current directory first for names without slashes */
204220
join_path_components(retpath,cwd,argv0);
205221
if (validate_exec(retpath)==0)
206-
return0;
222+
returnresolve_symlinks(retpath);
207223
#endif
208224

209225
/*
@@ -240,7 +256,7 @@ find_my_exec(const char *argv0, char *retpath)
240256
switch (validate_exec(retpath))
241257
{
242258
case0:/* found ok */
243-
return0;
259+
returnresolve_symlinks(retpath);
244260
case-1:/* wasn't even a candidate, keep looking */
245261
break;
246262
case-2:/* found but disqualified */
@@ -254,6 +270,141 @@ find_my_exec(const char *argv0, char *retpath)
254270
return-1;
255271
}
256272

273+
274+
/*
275+
* resolve_symlinks - resolve symlinks to the underlying file
276+
*
277+
* If path does not point to a symlink, leave it alone. If it does,
278+
* replace it by the absolute path to the referenced file.
279+
*
280+
* Returns 0 if OK, -1 if error.
281+
*
282+
* Note: we are not particularly tense about producing nice error messages
283+
* because we are not really expecting error here; we just determined that
284+
* the symlink does point to a valid executable.
285+
*/
286+
staticint
287+
resolve_symlinks(char*path)
288+
{
289+
#ifdefHAVE_READLINK
290+
structstatbuf;
291+
charorig_wd[MAXPGPATH],
292+
link_buf[MAXPGPATH];
293+
char*fname;
294+
295+
/* Quick out if it's not a symlink */
296+
if (lstat(path,&buf)<0||
297+
(buf.st_mode&S_IFMT)!=S_IFLNK)
298+
return0;
299+
300+
/*
301+
* To resolve a symlink properly, we have to chdir into its directory
302+
* and then chdir to where the symlink points; otherwise we may fail to
303+
* resolve relative links correctly (consider cases involving mount
304+
* points, for example). After following the final symlink, we use
305+
* getcwd() to figure out where the heck we're at.
306+
*/
307+
if (!getcwd(orig_wd,MAXPGPATH))
308+
{
309+
log_error(_("could not identify current directory: %s"),
310+
strerror(errno));
311+
return-1;
312+
}
313+
314+
for (;;)
315+
{
316+
char*lsep;
317+
intrllen;
318+
319+
lsep=last_dir_separator(path);
320+
if (lsep)
321+
{
322+
*lsep='\0';
323+
if (chdir(path)==-1)
324+
{
325+
log_error(_("could not change directory to \"%s\""),path);
326+
return-1;
327+
}
328+
fname=lsep+1;
329+
}
330+
else
331+
fname=path;
332+
333+
if (lstat(fname,&buf)<0||
334+
(buf.st_mode&S_IFMT)!=S_IFLNK)
335+
break;
336+
337+
rllen=readlink(fname,link_buf,sizeof(link_buf));
338+
if (rllen<0||rllen >=sizeof(link_buf))
339+
{
340+
log_error(_("could not read symbolic link \"%s\""),fname);
341+
return-1;
342+
}
343+
link_buf[rllen]='\0';
344+
strcpy(path,link_buf);
345+
}
346+
347+
/* must copy final component out of 'path' temporarily */
348+
strcpy(link_buf,fname);
349+
350+
if (!getcwd(path,MAXPGPATH))
351+
{
352+
log_error(_("could not identify current directory: %s"),
353+
strerror(errno));
354+
return-1;
355+
}
356+
join_path_components(path,path,link_buf);
357+
canonicalize_path(path);
358+
359+
if (chdir(orig_wd)==-1)
360+
{
361+
log_error(_("could not change directory to \"%s\""),orig_wd);
362+
return-1;
363+
}
364+
365+
#endif/* HAVE_READLINK */
366+
367+
return0;
368+
}
369+
370+
371+
/*
372+
* Find another program in our binary's directory,
373+
* then make sure it is the proper version.
374+
*/
375+
int
376+
find_other_exec(constchar*argv0,constchar*target,
377+
constchar*versionstr,char*retpath)
378+
{
379+
charcmd[MAXPGPATH];
380+
charline[100];
381+
382+
if (find_my_exec(argv0,retpath)<0)
383+
return-1;
384+
385+
/* Trim off program name and keep just directory */
386+
*last_dir_separator(retpath)='\0';
387+
canonicalize_path(retpath);
388+
389+
/* Now append the other program's name */
390+
snprintf(retpath+strlen(retpath),MAXPGPATH-strlen(retpath),
391+
"/%s%s",target,EXE);
392+
393+
if (validate_exec(retpath)!=0)
394+
return-1;
395+
396+
snprintf(cmd,sizeof(cmd),"\"%s\" -V 2>%s",retpath,DEVNULL);
397+
398+
if (!pipe_read_line(cmd,line,sizeof(line)))
399+
return-1;
400+
401+
if (strcmp(line,versionstr)!=0)
402+
return-2;
403+
404+
return0;
405+
}
406+
407+
257408
/*
258409
* The runtime library's popen() on win32 does not work when being
259410
* called from a service when running on windows <= 2000, because
@@ -262,7 +413,6 @@ find_my_exec(const char *argv0, char *retpath)
262413
* Executing a command in a pipe and reading the first line from it
263414
* is all we need.
264415
*/
265-
266416
staticchar*
267417
pipe_read_line(char*cmd,char*line,intmaxsize)
268418
{
@@ -286,8 +436,9 @@ pipe_read_line(char *cmd, char *line, int maxsize)
286436
returnNULL;
287437

288438
returnline;
289-
#else
290-
/* Win32 */
439+
440+
#else/* WIN32 */
441+
291442
SECURITY_ATTRIBUTESsattr;
292443
HANDLEchildstdoutrd,
293444
childstdoutwr,
@@ -392,44 +543,7 @@ pipe_read_line(char *cmd, char *line, int maxsize)
392543
CloseHandle(childstdoutrddup);
393544

394545
returnretval;
395-
#endif
396-
}
397-
398-
399-
/*
400-
* Find another program in our binary's directory,
401-
* then make sure it is the proper version.
402-
*/
403-
int
404-
find_other_exec(constchar*argv0,constchar*target,
405-
constchar*versionstr,char*retpath)
406-
{
407-
charcmd[MAXPGPATH];
408-
charline[100];
409-
410-
if (find_my_exec(argv0,retpath)<0)
411-
return-1;
412-
413-
/* Trim off program name and keep just directory */
414-
*last_dir_separator(retpath)='\0';
415-
canonicalize_path(retpath);
416-
417-
/* Now append the other program's name */
418-
snprintf(retpath+strlen(retpath),MAXPGPATH-strlen(retpath),
419-
"/%s%s",target,EXE);
420-
421-
if (validate_exec(retpath))
422-
return-1;
423-
424-
snprintf(cmd,sizeof(cmd),"\"%s\" -V 2>%s",retpath,DEVNULL);
425-
426-
if (!pipe_read_line(cmd,line,sizeof(line)))
427-
return-1;
428-
429-
if (strcmp(line,versionstr)!=0)
430-
return-2;
431-
432-
return0;
546+
#endif/* WIN32 */
433547
}
434548

435549

@@ -454,20 +568,14 @@ pclose_check(FILE *stream)
454568
perror("pclose failed");
455569
}
456570
elseif (WIFEXITED(exitstatus))
457-
{
458571
log_error(_("child process exited with exit code %d"),
459572
WEXITSTATUS(exitstatus));
460-
}
461573
elseif (WIFSIGNALED(exitstatus))
462-
{
463574
log_error(_("child process was terminated by signal %d"),
464575
WTERMSIG(exitstatus));
465-
}
466576
else
467-
{
468577
log_error(_("child process exited with unrecognized status %d"),
469578
exitstatus);
470-
}
471579

472580
return-1;
473581
}

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