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 int symlinks = 0; 66 67 /* Save the starting point. */ 68 if ((fd = open(".", O_RDONLY)) < 0) { 69 (void)strcpy(resolved, "."); 70 return (NULL); 71 } 72 73 /* 74 * Find the dirname and basename from the path to be resolved. 75 * Change directory to the dirname component. 76 * lstat the basename part. 77 * if it is a symlink, read in the value and loop. 78 * if it is a directory, then change to that directory. 79 * get the current directory name and append the basename. 80 */ 81 (void)strncpy(resolved, path, MAXPATHLEN - 1); 82 resolved[MAXPATHLEN - 1] = '\0'; 83 loop: 84 q = strrchr(resolved, '/'); 85 if (q != NULL) { 86 p = q + 1; 87 if (q == resolved) 88 q = "/"; 89 else { 90 do { 91 --q; 92 } while (q > resolved && *q == '/'); 93 q[1] = '\0'; 94 q = resolved; 95 } 96 if (chdir(q) < 0) 97 goto err1; 98 } else 99 p = resolved; 100 101 /* Deal with the last component. */ 102 if (*p != '\0' && lstat(p, &sb) == 0) { 103 if (S_ISLNK(sb.st_mode)) { 104 if (++symlinks > MAXSYMLINKS) { 105 errno = ELOOP; 106 goto err1; 107 } 108 n = readlink(p, resolved, MAXPATHLEN - 1); 109 if (n < 0) 110 goto err1; 111 resolved[n] = '\0'; 112 goto loop; 113 } 114 if (S_ISDIR(sb.st_mode)) { 115 if (chdir(p) < 0) 116 goto err1; 117 p = ""; 118 } 119 } 120 121 /* 122 * Save the last component name and get the full pathname of 123 * the current directory. 124 */ 125 (void)strcpy(wbuf, p); 126 if (getcwd(resolved, MAXPATHLEN) == 0) 127 goto err1; 128 129 /* 130 * Join the two strings together, ensuring that the right thing 131 * happens if the last component is empty, or the dirname is root. 132 */ 133 if (resolved[0] == '/' && resolved[1] == '\0') 134 rootd = 1; 135 else 136 rootd = 0; 137 138 if (*wbuf) { 139 if (strlen(resolved) + strlen(wbuf) + rootd + 1 > MAXPATHLEN) { 140 errno = ENAMETOOLONG; 141 goto err1; 142 } 143 if (rootd == 0) 144 (void)strcat(resolved, "/"); 145 (void)strcat(resolved, wbuf); 146 } 147 148 /* Go back to where we came from. */ 149 if (fchdir(fd) < 0) { 150 serrno = errno; 151 goto err2; 152 } 153 154 /* It's okay if the close fails, what's an fd more or less? */ 155 (void)close(fd); 156 return (resolved); 157 158 err1: serrno = errno; 159 (void)fchdir(fd); 160 err2: (void)close(fd); 161 errno = serrno; 162 return (NULL); 163 } 164