77 lines
2.2 KiB
C
77 lines
2.2 KiB
C
/* Invoke opendir, but avoid some glitches.
|
|
|
|
Copyright (C) 2009-2022 Free Software Foundation, Inc.
|
|
|
|
This program is free software: you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation, either version 3 of the License, or
|
|
(at your option) any later version.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program. If not, see <https://www.gnu.org/licenses/>. */
|
|
|
|
/* Written by Eric Blake. */
|
|
|
|
#include <config.h>
|
|
|
|
#include "dirent-safer.h"
|
|
|
|
#include <errno.h>
|
|
#include <fcntl.h>
|
|
#include <unistd.h>
|
|
|
|
/* Like opendir, but do not clobber stdin, stdout, or stderr. */
|
|
|
|
DIR *
|
|
opendir_safer (char const *name)
|
|
{
|
|
DIR *dp = opendir (name);
|
|
|
|
if (dp)
|
|
{
|
|
int fd = dirfd (dp);
|
|
|
|
if (0 <= fd && fd <= STDERR_FILENO)
|
|
{
|
|
/* If fdopendir is native (as on Linux), then it is safe to
|
|
assume dirfd(fdopendir(n))==n. If we are using the
|
|
gnulib module fdopendir, then this guarantee is not met,
|
|
but fdopendir recursively calls opendir_safer up to 3
|
|
times to at least get a safe fd. If fdopendir is not
|
|
present but dirfd is accurate (as on cygwin 1.5.x), then
|
|
we recurse up to 3 times ourselves. Finally, if dirfd
|
|
always fails (as on mingw), then we are already safe. */
|
|
DIR *newdp;
|
|
int e;
|
|
#if HAVE_FDOPENDIR || GNULIB_FDOPENDIR
|
|
int f = fcntl (fd, F_DUPFD_CLOEXEC, STDERR_FILENO + 1);
|
|
if (f < 0)
|
|
{
|
|
e = errno;
|
|
newdp = NULL;
|
|
}
|
|
else
|
|
{
|
|
newdp = fdopendir (f);
|
|
e = errno;
|
|
if (! newdp)
|
|
close (f);
|
|
}
|
|
#else /* !FDOPENDIR */
|
|
newdp = opendir_safer (name);
|
|
e = errno;
|
|
#endif
|
|
closedir (dp);
|
|
errno = e;
|
|
dp = newdp;
|
|
}
|
|
}
|
|
|
|
return dp;
|
|
}
|