77 lines
2.2 KiB
C
77 lines
2.2 KiB
C
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/* Invoke opendir, but avoid some glitches.
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Copyright (C) 2009-2020 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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/* Written by Eric Blake. */
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#include <config.h>
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#include "dirent-safer.h"
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#include <errno.h>
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#include <fcntl.h>
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#include <unistd.h>
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/* Like opendir, but do not clobber stdin, stdout, or stderr. */
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DIR *
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opendir_safer (char const *name)
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{
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DIR *dp = opendir (name);
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if (dp)
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{
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int fd = dirfd (dp);
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if (0 <= fd && fd <= STDERR_FILENO)
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{
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/* If fdopendir is native (as on Linux), then it is safe to
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assume dirfd(fdopendir(n))==n. If we are using the
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gnulib module fdopendir, then this guarantee is not met,
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but fdopendir recursively calls opendir_safer up to 3
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times to at least get a safe fd. If fdopendir is not
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present but dirfd is accurate (as on cygwin 1.5.x), then
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we recurse up to 3 times ourselves. Finally, if dirfd
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always fails (as on mingw), then we are already safe. */
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DIR *newdp;
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int e;
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#if HAVE_FDOPENDIR || GNULIB_FDOPENDIR
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int f = fcntl (fd, F_DUPFD_CLOEXEC, STDERR_FILENO + 1);
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if (f < 0)
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{
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e = errno;
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newdp = NULL;
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}
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else
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{
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newdp = fdopendir (f);
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e = errno;
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if (! newdp)
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close (f);
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}
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#else /* !FDOPENDIR */
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newdp = opendir_safer (name);
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e = errno;
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#endif
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closedir (dp);
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errno = e;
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dp = newdp;
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}
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}
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return dp;
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}
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