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1 /*
2  * Copyright (c) 2013, The Android Open Source Project
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  *  * Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  *  * Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in
12  *    the documentation and/or other materials provided with the
13  *    distribution.
14  *  * Neither the name of Google, Inc. nor the names of its contributors
15  *    may be used to endorse or promote products derived from this
16  *    software without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
21  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
22  * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
24  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
25  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
26  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
27  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
28  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #include <limits.h>
33 #include <stdio.h>
34 #include <stdlib.h>
35 #include <unistd.h>
36 
37 static int skip_newline, quiet_errors, canonicalize;
38 
usage(char * name)39 static void usage(char* name) {
40     fprintf(stderr, "Usage: %s [OPTION]... FILE\n", name);
41 }
42 
readlink_main(int argc,char * argv[])43 int readlink_main(int argc, char* argv[]) {
44     int c;
45     while ((c = getopt(argc, argv, "nfqs")) != -1) {
46         switch (c) {
47         case 'n':
48             skip_newline = 1;
49             break;
50         case 'f':
51             canonicalize = 1;
52             break;
53         case 'q':
54         case 's':
55             quiet_errors = 1;
56             break;
57         case '?':
58         default:
59             usage(argv[0]);
60             return EXIT_FAILURE;
61         }
62     }
63     int index = optind;
64     if (argc - index != 1) {
65         usage(argv[0]);
66         return EXIT_FAILURE;
67     }
68 
69     char name[PATH_MAX+1];
70     if (canonicalize) {
71         if(!realpath(argv[optind], name)) {
72             if (!quiet_errors) {
73                 perror("readlink");
74             }
75             return EXIT_FAILURE;
76         }
77     } else {
78         ssize_t len = readlink(argv[1], name, PATH_MAX);
79 
80         if (len < 0) {
81             if (!quiet_errors) {
82                 perror("readlink");
83             }
84             return EXIT_FAILURE;
85         }
86         name[len] = '\0';
87     }
88 
89     fputs(name, stdout);
90     if (!skip_newline) {
91         fputs("\n", stdout);
92     }
93 
94     return EXIT_SUCCESS;
95 }
96