1 /* 2 * $OpenBSD: readlink.c,v 1.28 2019/06/28 13:35:03 deraadt Exp $ 3 * 4 * Copyright (c) 1997 5 * Kenneth Stailey (hereinafter referred to as the author) 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. The name of the author may not be used to endorse or promote products 16 * derived from this software without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 */ 29 30 #include <err.h> 31 #include <errno.h> 32 #include <limits.h> 33 #include <stdio.h> 34 #include <stdlib.h> 35 #include <string.h> 36 #include <unistd.h> 37 38 static void usage(void); 39 40 int 41 main(int argc, char *argv[]) 42 { 43 char buf[PATH_MAX]; 44 int n, ch, nflag = 0, fflag = 0; 45 extern int optind; 46 47 if (pledge("stdio rpath", NULL) == -1) 48 err(1, "pledge"); 49 50 while ((ch = getopt(argc, argv, "fn")) != -1) 51 switch (ch) { 52 case 'f': 53 fflag = 1; 54 break; 55 case 'n': 56 nflag = 1; 57 break; 58 default: 59 usage(); 60 } 61 argc -= optind; 62 argv += optind; 63 64 if (argc != 1) 65 usage(); 66 67 n = strlen(argv[0]); 68 if (n > PATH_MAX - 1) { 69 fprintf(stderr, 70 "readlink: filename longer than PATH_MAX-1 (%d)\n", 71 PATH_MAX - 1); 72 exit(1); 73 } 74 75 if (fflag) { 76 if (realpath(argv[0], buf) == NULL) 77 err(1, "%s", argv[0]); 78 } else { 79 if ((n = readlink(argv[0], buf, sizeof buf-1)) == -1) 80 exit(1); 81 buf[n] = '\0'; 82 } 83 84 printf("%s", buf); 85 if (!nflag) 86 putchar('\n'); 87 exit(0); 88 } 89 90 static void 91 usage(void) 92 { 93 (void)fprintf(stderr, "usage: readlink [-fn] file\n"); 94 exit(1); 95 } 96