1 /***********************************************************************
2 *                                                                      *
3 *               This software is part of the ast package               *
4 *          Copyright (c) 1985-2012 AT&T Intellectual Property          *
5 *                      and is licensed under the                       *
6 *                 Eclipse Public License, Version 1.0                  *
7 *                    by AT&T Intellectual Property                     *
8 *                                                                      *
9 *                A copy of the License is available at                 *
10 *          http://www.eclipse.org/org/documents/epl-v10.html           *
11 *         (with md5 checksum b35adb5213ca9657e911e9befb180842)         *
12 *                                                                      *
13 *              Information and Software Systems Research               *
14 *                            AT&T Research                             *
15 *                           Florham Park NJ                            *
16 *                                                                      *
17 *                 Glenn Fowler <gsf@research.att.com>                  *
18 *                  David Korn <dgk@research.att.com>                   *
19 *                   Phong Vo <kpv@research.att.com>                    *
20 *                                                                      *
21 ***********************************************************************/
22 #pragma prototyped
23 
24 #include <ast.h>
25 
26 #if _lib_readlink
27 
28 NoN(readlink)
29 
30 #else
31 
32 #include "fakelink.h"
33 
34 #include <error.h>
35 
36 #ifndef ENOSYS
37 #define ENOSYS	EINVAL
38 #endif
39 
40 int
41 readlink(const char* path, char* buf, int siz)
42 {
43 	int	fd;
44 	int	n;
45 
46 	if (siz > sizeof(FAKELINK_MAGIC))
47 	{
48 		if ((fd = open(path, O_RDONLY|O_cloexec)) < 0)
49 			return -1;
50 		if (read(fd, buf, sizeof(FAKELINK_MAGIC)) == sizeof(FAKELINK_MAGIC) && !strcmp(buf, FAKELINK_MAGIC) && (n = read(fd, buf, siz)) > 0 && !buf[n - 1])
51 		{
52 			close(fd);
53 			return n;
54 		}
55 		close(fd);
56 	}
57 	errno = ENOSYS;
58 	return -1;
59 }
60 
61 #endif
62