Mercurial > gnulib
annotate lib/freopen-safer.c @ 17363:5a51fb7777a9
sys_select, sys_time: port 2013-01-30 Solaris 2.6 fix to Cygwin
Problem reported by Marco Atzeri in
<http://lists.gnu.org/archive/html/bug-gnulib/2013-03/msg00000.html>.
* lib/sys_select.in.h [HAVE_SYS_SELECT_H && _CYGWIN_SYS_TIME_H]:
Simply delegate to the system <sys/select.h> in this case too.
Also, pay attention to _GL_SYS_SELECT_H_REDIRECT_FROM_SYS_TIME_H only
if OSF/1, since otherwise Cygwin breaks, and it doesn't seem to
be needed on Solaris either.
* lib/sys_time.in.h [_CYGWIN_SYS_TIME_H]:
Simply delgate to the system <sys/time.h> in this case.
| author | Paul Eggert <eggert@cs.ucla.edu> |
|---|---|
| date | Tue, 19 Mar 2013 09:08:47 -0700 |
| parents | e542fd46ad6f |
| children | 344018b6e5d7 |
| rev | line source |
|---|---|
| 12246 | 1 /* Invoke freopen, but avoid some glitches. |
| 2 | |
|
17249
e542fd46ad6f
maint: update all copyright year number ranges
Eric Blake <eblake@redhat.com>
parents:
16201
diff
changeset
|
3 Copyright (C) 2009-2013 Free Software Foundation, Inc. |
| 12246 | 4 |
| 5 This program is free software: you can redistribute it and/or modify | |
| 6 it under the terms of the GNU General Public License as published by | |
| 7 the Free Software Foundation; either version 3 of the License, or | |
| 8 (at your option) any later version. | |
| 9 | |
| 10 This program is distributed in the hope that it will be useful, | |
| 11 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 13 GNU General Public License for more details. | |
| 14 | |
| 15 You should have received a copy of the GNU General Public License | |
| 16 along with this program. If not, see <http://www.gnu.org/licenses/>. */ | |
| 17 | |
| 18 /* Written by Eric Blake. */ | |
| 19 | |
| 20 #include <config.h> | |
| 21 | |
| 22 #include "stdio-safer.h" | |
| 23 | |
| 24 #include <errno.h> | |
| 25 #include <fcntl.h> | |
| 26 #include <stdbool.h> | |
| 27 #include <unistd.h> | |
| 28 | |
| 29 /* Guarantee that FD is open; all smaller FDs must already be open. | |
| 30 Return true if successful. */ | |
| 31 static bool | |
| 32 protect_fd (int fd) | |
| 33 { | |
| 34 int value = open ("/dev/null", O_RDONLY); | |
| 35 if (value != fd) | |
| 36 { | |
| 37 if (0 <= value) | |
| 38 { | |
| 39 close (value); | |
| 40 errno = EBADF; /* Unexpected; this is as good as anything else. */ | |
| 41 } | |
| 42 return false; | |
| 43 } | |
| 44 return true; | |
| 45 } | |
| 46 | |
| 47 /* Like freopen, but guarantee that reopening stdin, stdout, or stderr | |
| 48 preserves the invariant that STDxxx_FILENO==fileno(stdxxx), and | |
| 49 that no other stream will interfere with the standard streams. | |
| 50 This is necessary because most freopen implementations will change | |
| 51 the associated fd of a stream to the lowest available slot. */ | |
| 52 | |
| 53 FILE * | |
| 54 freopen_safer (char const *name, char const *mode, FILE *f) | |
| 55 { | |
| 56 /* Unfortunately, we cannot use the fopen_safer approach of using | |
| 57 fdopen (dup_safer (fileno (freopen (cmd, mode, f)))), because we | |
| 58 need to return f itself. The implementation of freopen(NULL,m,f) | |
| 59 is system-dependent, so the best we can do is guarantee that all | |
| 60 lower-valued standard fds are open prior to the freopen call, | |
| 61 even though this puts more pressure on open fds. */ | |
| 62 bool protect_in = false; | |
| 63 bool protect_out = false; | |
| 64 bool protect_err = false; | |
| 65 int saved_errno; | |
| 66 | |
| 67 switch (fileno (f)) | |
| 68 { | |
| 69 default: /* -1 or not a standard stream. */ | |
| 70 if (dup2 (STDERR_FILENO, STDERR_FILENO) != STDERR_FILENO) | |
| 71 protect_err = true; | |
| 72 /* fall through */ | |
| 73 case STDERR_FILENO: | |
| 74 if (dup2 (STDOUT_FILENO, STDOUT_FILENO) != STDOUT_FILENO) | |
| 75 protect_out = true; | |
| 76 /* fall through */ | |
| 77 case STDOUT_FILENO: | |
| 78 if (dup2 (STDIN_FILENO, STDIN_FILENO) != STDIN_FILENO) | |
| 79 protect_in = true; | |
| 80 /* fall through */ | |
| 81 case STDIN_FILENO: | |
| 82 /* Nothing left to protect. */ | |
| 83 break; | |
| 84 } | |
| 85 if (protect_in && !protect_fd (STDIN_FILENO)) | |
| 86 f = NULL; | |
| 87 else if (protect_out && !protect_fd (STDOUT_FILENO)) | |
| 88 f = NULL; | |
| 89 else if (protect_err && !protect_fd (STDERR_FILENO)) | |
| 90 f = NULL; | |
| 91 else | |
| 92 f = freopen (name, mode, f); | |
| 93 saved_errno = errno; | |
| 94 if (protect_err) | |
| 95 close (STDERR_FILENO); | |
| 96 if (protect_out) | |
| 97 close (STDOUT_FILENO); | |
| 98 if (protect_in) | |
| 99 close (STDIN_FILENO); | |
| 100 if (!f) | |
| 101 errno = saved_errno; | |
| 102 return f; | |
| 103 } |