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. */
28ssize_t
29readlinkat (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}
59libc_hidden_def (readlinkat)
60

source code of glibc/sysdeps/mach/hurd/readlinkat.c