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 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