1 /***********************************************************************
2 * *
3 * This software is part of the ast package *
4 * Copyright (c) 1982-2007 AT&T Intellectual Property *
5 * and is licensed under the *
6 * Common Public License, Version 1.0 *
7 * by AT&T Intellectual Property *
8 * *
9 * A copy of the License is available at *
10 * http://www.opensource.org/licenses/cpl1.0.txt *
11 * (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) *
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 * *
20 ***********************************************************************/
21 #pragma prototyped
22
23 static const char usage[] =
24 "[-?\n@(#)$Id: readlink (AT&T Research) 2008-06-08 $\n]"
25 USAGE_LICENSE
26 "[+NAME?readlink - read the contents of a symbolic link]"
27 "[+DESCRIPTION?\breadlink\b returns the contents of the symbolic "
28 "link referred to by the path argument. Unless the \b-f\b "
29 "option is specified an error will be returned when the path "
30 "is not a symbolic link.]"
31 "[f:canonicalize?The returned value will be an absolute pathname that names "
32 "the same file, whose resolution does not involve \".\", \"..\", or "
33 "symbolic links, otherwise only the exact (relative) value will be returned.]"
34 "[n:no-newline?Supress newline at the end.]"
35 "[v:verbose?Verbose - print errors.]"
36 "[+SEE ALSO?\bbasename\b(1),\bdirname\b(2),\breadlink\b(2),\breadpath\n(2)]"
37 ;
38
39 #include <cmd.h>
40
41 int
b_readlink(int argc,char ** argv,void * context)42 b_readlink(int argc, char** argv, void* context)
43 {
44 register char* s;
45 register int i;
46 register char* m;
47 register char* x;
48 int canonicalize = 0,
49 nonewline = 0,
50 verbose = 0;
51 char buf[PATH_MAX+2];
52 int len = 0;
53 char *filename,
54 *resolvedname = NULL;
55
56 cmdinit(argc, argv, context, ERROR_CATALOG, 0);
57 for (;;)
58 {
59 switch (optget(argv, usage))
60 {
61 case 'f':
62 canonicalize = opt_info.num;
63 continue;
64 case 'n':
65 nonewline = opt_info.num;
66 continue;
67 case 'v':
68 verbose = opt_info.num;
69 continue;
70 case '?':
71 error(ERROR_usage(2), "%s", opt_info.arg);
72 continue;
73 case ':':
74 error(2, "%s", opt_info.arg);
75 continue;
76 }
77 break;
78 }
79 argv += opt_info.index;
80 argc -= opt_info.index;
81 if(error_info.errors || argc != 1)
82 error(ERROR_usage(2),"%s", optusage(NiL));
83 filename = argv[0];
84
85 if (canonicalize)
86 {
87 len = resolvepath(filename, buf, sizeof(buf)-2);
88 }
89 else
90 {
91 len = readlink(filename, buf, sizeof(buf)-2);
92 }
93
94 if (len != -1)
95 resolvedname = buf;
96
97 if (!resolvedname)
98 {
99 if (verbose)
100 error(ERROR_system(1),"%s: readlink failed", filename);
101 else
102 return 1;
103 }
104
105 if (!nonewline)
106 resolvedname[len++] = '\n';
107
108 sfwrite(sfstdout, resolvedname, len);
109
110 return 0;
111 }
112