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1 | /* Copyright (C) 2005 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; if not, write to the Free | |
16 | Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA | |
17 | 02111-1307 USA. */ | |
18 | ||
19 | #include <errno.h> | |
20 | #include <fcntl.h> | |
21 | #include <stddef.h> | |
22 | #include <stdio.h> | |
23 | #include <stdlib.h> | |
24 | #include <string.h> | |
25 | #include <sysdep.h> | |
26 | #include <unistd.h> | |
27 | ||
28 | ||
29 | /* Make a symbolic link to FROM named TO relative to TOFD. */ | |
30 | int | |
31 | symlinkat (from, tofd, to) | |
32 | const char *from; | |
33 | int tofd; | |
34 | const char *to; | |
35 | { | |
36 | char *buf = NULL; | |
37 | ||
38 | if (tofd != AT_FDCWD && to[0] != '/') | |
39 | { | |
40 | size_t tolen = strlen (to); | |
41 | static const char procfd[] = "/proc/self/fd/%d/%s"; | |
42 | /* Buffer for the path name we are going to use. It consists of | |
43 | - the string /proc/self/fd/ | |
44 | - the file descriptor number | |
45 | - the file name provided. | |
46 | The final NUL is included in the sizeof. A bit of overhead | |
47 | due to the format elements compensates for possible negative | |
48 | numbers. */ | |
49 | size_t buflen = sizeof (procfd) + sizeof (int) * 3 + tolen; | |
50 | buf = __alloca (buflen); | |
51 | ||
52 | __snprintf (buf, buflen, procfd, tofd, to); | |
53 | to = buf; | |
54 | } | |
55 | ||
56 | INTERNAL_SYSCALL_DECL (err); | |
57 | ||
58 | int result = INTERNAL_SYSCALL (symlink, err, 2, from, to); | |
59 | ||
60 | if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 0)) | |
61 | { | |
62 | __atfct_seterrno (INTERNAL_SYSCALL_ERRNO (result, err), tofd, buf); | |
63 | result = -1; | |
64 | } | |
65 | ||
66 | return result; | |
67 | } |