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
37static int skip_newline, quiet_errors, canonicalize;
38
39static void usage(char* name) {
40    fprintf(stderr, "Usage: %s [OPTION]... FILE\n", name);
41}
42
43int 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