1/* Copyright (C) 1991-2024 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
29__readlinkat (int fd, const char *file_name, char *buf, size_t len)
30{
31 error_t err;
32 file_t file_stat;
33 struct stat64 st;
34 enum retry_type doretry;
35 char retryname[1024];
36 file_t file;
37 char *rbuf = buf;
38 mach_msg_type_number_t nread = len;
39
40 file_stat = __file_name_lookup_at (fd, 0, file_name, O_NOLINK, 0);
41 if (file_stat == MACH_PORT_NULL)
42 return -1;
43
44 err = __io_stat (file_stat, &st);
45 if (err)
46 goto out;
47 if (!S_ISLNK (st.st_mode))
48 {
49 err = EINVAL;
50 goto out;
51 }
52
53 err = __dir_lookup (file_stat, "", O_READ | O_NOLINK,
54 0, &doretry, retryname, &file);
55 if (err)
56 goto out;
57 if (doretry != FS_RETRY_NORMAL || retryname[0] != '\0')
58 {
59 err = EGRATUITOUS;
60 goto out;
61 }
62
63 err = __io_read (file, &rbuf, &nread, 0, len);
64 __mach_port_deallocate (__mach_task_self (), file);
65 if (err)
66 goto out;
67
68 len = nread;
69 if (rbuf != buf)
70 {
71 memcpy (buf, rbuf, len);
72 __vm_deallocate (__mach_task_self (), (vm_address_t) rbuf, nread);
73 }
74
75
76 out:
77 __mach_port_deallocate (__mach_task_self (), file_stat);
78
79 return err ? __hurd_fail (err) : len;
80}
81weak_alias (__readlinkat, readlinkat)
82libc_hidden_def (readlinkat)
83

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