1 /* 2 * Copyright (c) 1994 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Jan-Simon Pendry. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #if defined(LIBC_SCCS) && !defined(lint) 38 static char sccsid[] = "@(#)realpath.c 8.1 (Berkeley) 2/16/94"; 39 #endif /* LIBC_SCCS and not lint */ 40 41 #include <sys/param.h> 42 #include <sys/stat.h> 43 44 #include <errno.h> 45 #include <fcntl.h> 46 #include <stdlib.h> 47 #include <string.h> 48 #include <unistd.h> 49 50 /* 51 * char *realpath(const char *path, char resolved_path[MAXPATHLEN]); 52 * 53 * Find the real name of path, by removing all ".", ".." and symlink 54 * components. Returns (resolved) on success, or (NULL) on failure, 55 * in which case the path which caused trouble is left in (resolved). 56 */ 57 char * 58 realpath(path, resolved) 59 const char *path; 60 char *resolved; 61 { 62 struct stat sb; 63 int fd, n, rootd, serrno; 64 char *p, *q, wbuf[MAXPATHLEN]; 65 66 /* Save the starting point. */ 67 if ((fd = open(".", O_RDONLY)) < 0) { 68 (void)strcpy(resolved, "."); 69 return (NULL); 70 } 71 72 /* 73 * Find the dirname and basename from the path to be resolved. 74 * Change directory to the dirname component. 75 * lstat the basename part. 76 * if it is a symlink, read in the value and loop. 77 * if it is a directory, then change to that directory. 78 * get the current directory name and append the basename. 79 */ 80 (void)strncpy(resolved, path, MAXPATHLEN - 1); 81 resolved[MAXPATHLEN - 1] = '\0'; 82 loop: 83 q = strrchr(resolved, '/'); 84 if (q != NULL) { 85 p = q + 1; 86 if (q == resolved) 87 q = "/"; 88 else { 89 do { 90 --q; 91 } while (q > resolved && *q == '/'); 92 q[1] = '\0'; 93 q = resolved; 94 } 95 if (chdir(q) < 0) 96 goto err1; 97 } else 98 p = resolved; 99 100 /* Deal with the last component. */ 101 if (lstat(p, &sb) == 0) { 102 if (S_ISLNK(sb.st_mode)) { 103 n = readlink(p, resolved, MAXPATHLEN); 104 if (n < 0) 105 goto err1; 106 resolved[n] = '\0'; 107 goto loop; 108 } 109 if (S_ISDIR(sb.st_mode)) { 110 if (chdir(p) < 0) 111 goto err1; 112 p = ""; 113 } 114 } 115 116 /* 117 * Save the last component name and get the full pathname of 118 * the current directory. 119 */ 120 (void)strcpy(wbuf, p); 121 if (getcwd(resolved, MAXPATHLEN) == 0) 122 goto err1; 123 124 /* 125 * Join the two strings together, ensuring that the right thing 126 * happens if the last component is empty, or the dirname is root. 127 */ 128 if (resolved[0] == '/' && resolved[1] == '\0') 129 rootd = 1; 130 else 131 rootd = 0; 132 133 if (*wbuf) { 134 if (strlen(resolved) + strlen(wbuf) + rootd + 1 > MAXPATHLEN) { 135 errno = ENAMETOOLONG; 136 goto err1; 137 } 138 if (rootd == 0) 139 (void)strcat(resolved, "/"); 140 (void)strcat(resolved, wbuf); 141 } 142 143 /* Go back to where we came from. */ 144 if (fchdir(fd) < 0) { 145 serrno = errno; 146 goto err2; 147 } 148 149 /* It's okay if the close fails, what's an fd more or less? */ 150 (void)close(fd); 151 return (resolved); 152 153 err1: serrno = errno; 154 (void)fchdir(fd); 155 err2: (void)close(fd); 156 errno = serrno; 157 return (NULL); 158 } 159