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