mirror of
https://git.savannah.gnu.org/git/emacs.git
synced 2024-11-24 07:20:37 +00:00
95 lines
2.5 KiB
C
95 lines
2.5 KiB
C
/* Implement lchmod on platforms where it does not work correctly.
|
|
|
|
Copyright 2020-2024 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 Paul Eggert */
|
|
|
|
#include <config.h>
|
|
|
|
/* Specification. */
|
|
#include <sys/stat.h>
|
|
|
|
#include <errno.h>
|
|
#include <fcntl.h>
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
#include <unistd.h>
|
|
|
|
#include <intprops.h>
|
|
|
|
/* Work like chmod, except when FILE is a symbolic link.
|
|
In that case, on systems where permissions on symbolic links are unsupported
|
|
(such as Linux), set errno to EOPNOTSUPP and return -1. */
|
|
|
|
int
|
|
lchmod (char const *file, mode_t mode)
|
|
{
|
|
char readlink_buf[1];
|
|
|
|
#ifdef O_PATH
|
|
/* Open a file descriptor with O_NOFOLLOW, to make sure we don't
|
|
follow symbolic links, if /proc is mounted. O_PATH is used to
|
|
avoid a failure if the file is not readable.
|
|
Cf. <https://sourceware.org/bugzilla/show_bug.cgi?id=14578> */
|
|
int fd = open (file, O_PATH | O_NOFOLLOW | O_CLOEXEC);
|
|
if (fd < 0)
|
|
return fd;
|
|
|
|
int err;
|
|
if (0 <= readlinkat (fd, "", readlink_buf, sizeof readlink_buf))
|
|
err = EOPNOTSUPP;
|
|
else if (errno == EINVAL)
|
|
{
|
|
static char const fmt[] = "/proc/self/fd/%d";
|
|
char buf[sizeof fmt - sizeof "%d" + INT_BUFSIZE_BOUND (int)];
|
|
sprintf (buf, fmt, fd);
|
|
err = chmod (buf, mode) == 0 ? 0 : errno == ENOENT ? -1 : errno;
|
|
}
|
|
else
|
|
err = errno == ENOENT ? -1 : errno;
|
|
|
|
close (fd);
|
|
|
|
errno = err;
|
|
if (0 <= err)
|
|
return err == 0 ? 0 : -1;
|
|
#endif
|
|
|
|
size_t len = strlen (file);
|
|
if (len && file[len - 1] == '/')
|
|
{
|
|
struct stat st;
|
|
if (lstat (file, &st) < 0)
|
|
return -1;
|
|
if (!S_ISDIR (st.st_mode))
|
|
{
|
|
errno = ENOTDIR;
|
|
return -1;
|
|
}
|
|
}
|
|
|
|
/* O_PATH + /proc is not supported. */
|
|
|
|
if (0 <= readlink (file, readlink_buf, sizeof readlink_buf))
|
|
{
|
|
errno = EOPNOTSUPP;
|
|
return -1;
|
|
}
|
|
|
|
/* Fall back on chmod, despite a possible race. */
|
|
return chmod (file, mode);
|
|
}
|