117 lines
3.6 KiB
C
117 lines
3.6 KiB
C
/* This function serves as replacement for a missing fchownat function,
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as well as a work around for the fchownat bug in glibc-2.4:
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<https://lists.ubuntu.com/archives/ubuntu-users/2006-September/093218.html>
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when the buggy fchownat-with-AT_SYMLINK_NOFOLLOW operates on a symlink, it
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mistakenly affects the symlink referent, rather than the symlink itself.
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Copyright (C) 2006-2007, 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 Jim Meyering */
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#include <config.h>
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/* Specification. */
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#include <unistd.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <string.h>
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#include "openat.h"
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#if !HAVE_FCHOWNAT
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/* Replacement for Solaris' function by the same name.
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Invoke chown or lchown on file, FILE, using OWNER and GROUP, in the
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directory open on descriptor FD. If FLAG is AT_SYMLINK_NOFOLLOW, then
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use lchown, otherwise, use chown. If possible, do it without changing
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the working directory. Otherwise, resort to using save_cwd/fchdir,
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then (chown|lchown)/restore_cwd. If either the save_cwd or the
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restore_cwd fails, then give a diagnostic and exit nonzero. */
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# define AT_FUNC_NAME fchownat
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# define AT_FUNC_F1 lchown
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# define AT_FUNC_F2 chown
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# define AT_FUNC_USE_F1_COND AT_SYMLINK_NOFOLLOW
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# define AT_FUNC_POST_FILE_PARAM_DECLS , uid_t owner, gid_t group, int flag
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# define AT_FUNC_POST_FILE_ARGS , owner, group
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# include "at-func.c"
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# undef AT_FUNC_NAME
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# undef AT_FUNC_F1
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# undef AT_FUNC_F2
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# undef AT_FUNC_USE_F1_COND
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# undef AT_FUNC_POST_FILE_PARAM_DECLS
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# undef AT_FUNC_POST_FILE_ARGS
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#else /* HAVE_FCHOWNAT */
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# undef fchownat
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# if FCHOWNAT_NOFOLLOW_BUG
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/* Failure to handle AT_SYMLINK_NOFOLLOW requires the /proc/self/fd or
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fchdir workaround to call lchown for lchownat, but there is no need
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to penalize chownat. */
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static int
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local_lchownat (int fd, char const *file, uid_t owner, gid_t group);
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# define AT_FUNC_NAME local_lchownat
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# define AT_FUNC_F1 lchown
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# define AT_FUNC_POST_FILE_PARAM_DECLS , uid_t owner, gid_t group
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# define AT_FUNC_POST_FILE_ARGS , owner, group
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# include "at-func.c"
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# undef AT_FUNC_NAME
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# undef AT_FUNC_F1
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# undef AT_FUNC_POST_FILE_PARAM_DECLS
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# undef AT_FUNC_POST_FILE_ARGS
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# endif
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/* Work around bugs with trailing slash, using the same workarounds as
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chown and lchown. */
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int
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rpl_fchownat (int fd, char const *file, uid_t owner, gid_t group, int flag)
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{
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# if FCHOWNAT_NOFOLLOW_BUG
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if (flag == AT_SYMLINK_NOFOLLOW)
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return local_lchownat (fd, file, owner, group);
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# endif
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# if FCHOWNAT_EMPTY_FILENAME_BUG
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if (file[0] == '\0')
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{
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errno = ENOENT;
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return -1;
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}
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# endif
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# if CHOWN_TRAILING_SLASH_BUG
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{
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size_t len = strlen (file);
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struct stat st;
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if (len && file[len - 1] == '/')
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{
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if (statat (fd, file, &st))
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return -1;
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if (flag == AT_SYMLINK_NOFOLLOW)
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return fchownat (fd, file, owner, group, 0);
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}
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}
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# endif
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return fchownat (fd, file, owner, group, flag);
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}
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#endif /* HAVE_FCHOWNAT */
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