1 | /* Copyright (C) 1991-2022 Free Software Foundation, Inc. |
2 | This file is part of the GNU C Library. |
3 | |
4 | The GNU C Library is free software; you can redistribute it and/or |
5 | modify it under the terms of the GNU Lesser General Public |
6 | License as published by the Free Software Foundation; either |
7 | version 2.1 of the License, or (at your option) any later version. |
8 | |
9 | The GNU C Library is distributed in the hope that it will be useful, |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
12 | Lesser General Public License for more details. |
13 | |
14 | You should have received a copy of the GNU Lesser General Public |
15 | License along with the GNU C Library; see the file COPYING.LIB. If |
16 | not, see <https://www.gnu.org/licenses/>. */ |
17 | |
18 | #include <unistd.h> |
19 | #include <hurd.h> |
20 | #include <hurd/paths.h> |
21 | #include <hurd/fd.h> |
22 | #include <fcntl.h> |
23 | #include <string.h> |
24 | |
25 | /* Read the contents of the symbolic link FILE_NAME relative to FD into no more |
26 | than LEN bytes of BUF. The contents are not null-terminated. |
27 | Returns the number of characters read, or -1 for errors. */ |
28 | ssize_t |
29 | readlinkat (int fd, const char *file_name, char *buf, size_t len) |
30 | { |
31 | error_t err; |
32 | file_t file; |
33 | struct stat64 st; |
34 | |
35 | file = __file_name_lookup_at (fd, 0, file_name, O_READ | O_NOLINK, 0); |
36 | if (file == MACH_PORT_NULL) |
37 | return -1; |
38 | |
39 | err = __io_stat (file, &st); |
40 | if (! err) |
41 | if (S_ISLNK (st.st_mode)) |
42 | { |
43 | char *rbuf = buf; |
44 | |
45 | err = __io_read (file, &rbuf, &len, 0, len); |
46 | if (!err && rbuf != buf) |
47 | { |
48 | memcpy (buf, rbuf, len); |
49 | __vm_deallocate (__mach_task_self (), (vm_address_t)rbuf, len); |
50 | } |
51 | } |
52 | else |
53 | err = EINVAL; |
54 | |
55 | __mach_port_deallocate (__mach_task_self (), file); |
56 | |
57 | return err ? __hurd_fail (err) : len; |
58 | } |
59 | libc_hidden_def (readlinkat) |
60 | |