getcwd.c revision 1.5.4.1
1 /* $NetBSD: getcwd.c,v 1.5.4.1 1996/09/16 18:40:24 jtc Exp $ */ 2 3 /* 4 * Copyright (c) 1989, 1991, 1993 5 * The Regents of the University of California. All rights reserved. 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. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #if defined(LIBC_SCCS) && !defined(lint) 37 #if 0 38 static char sccsid[] = "@(#)getcwd.c 8.1 (Berkeley) 6/4/93"; 39 #else 40 static char rcsid[] = "$NetBSD: getcwd.c,v 1.5.4.1 1996/09/16 18:40:24 jtc Exp $"; 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 44 #include "namespace.h" 45 #include <sys/param.h> 46 #include <sys/stat.h> 47 48 #include <errno.h> 49 #include <dirent.h> 50 #include <stdio.h> 51 #include <stdlib.h> 52 #include <string.h> 53 #include <unistd.h> 54 55 #define ISDOT(dp) \ 56 (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \ 57 dp->d_name[1] == '.' && dp->d_name[2] == '\0')) 58 59 char * 60 getcwd(pt, size) 61 char *pt; 62 size_t size; 63 { 64 register struct dirent *dp; 65 register DIR *dir; 66 register dev_t dev; 67 register ino_t ino; 68 register int first; 69 register char *bpt, *bup; 70 struct stat s; 71 dev_t root_dev; 72 ino_t root_ino; 73 size_t ptsize, upsize; 74 int save_errno; 75 char *ept, *eup, *up; 76 77 /* 78 * If no buffer specified by the user, allocate one as necessary. 79 * If a buffer is specified, the size has to be non-zero. The path 80 * is built from the end of the buffer backwards. 81 */ 82 if (pt) { 83 ptsize = 0; 84 if (!size) { 85 errno = EINVAL; 86 return (NULL); 87 } 88 ept = pt + size; 89 } else { 90 if ((pt = malloc(ptsize = 1024 - 4)) == NULL) 91 return (NULL); 92 ept = pt + ptsize; 93 } 94 bpt = ept - 1; 95 *bpt = '\0'; 96 97 /* 98 * Allocate bytes (1024 - malloc space) for the string of "../"'s. 99 * Should always be enough (it's 340 levels). If it's not, allocate 100 * as necessary. Special * case the first stat, it's ".", not "..". 101 */ 102 if ((up = malloc(upsize = 1024 - 4)) == NULL) 103 goto err; 104 eup = up + MAXPATHLEN; 105 bup = up; 106 up[0] = '.'; 107 up[1] = '\0'; 108 109 /* Save root values, so know when to stop. */ 110 if (stat("/", &s)) 111 goto err; 112 root_dev = s.st_dev; 113 root_ino = s.st_ino; 114 115 errno = 0; /* XXX readdir has no error return. */ 116 117 for (first = 1;; first = 0) { 118 /* Stat the current level. */ 119 if (lstat(up, &s)) 120 goto err; 121 122 /* Save current node values. */ 123 ino = s.st_ino; 124 dev = s.st_dev; 125 126 /* Check for reaching root. */ 127 if (root_dev == dev && root_ino == ino) { 128 *--bpt = '/'; 129 /* 130 * It's unclear that it's a requirement to copy the 131 * path to the beginning of the buffer, but it's always 132 * been that way and stuff would probably break. 133 */ 134 bcopy(bpt, pt, ept - bpt); 135 free(up); 136 return (pt); 137 } 138 139 /* 140 * Build pointer to the parent directory, allocating memory 141 * as necessary. Max length is 3 for "../", the largest 142 * possible component name, plus a trailing NULL. 143 */ 144 if (bup + 3 + MAXNAMLEN + 1 >= eup) { 145 if ((up = realloc(up, upsize *= 2)) == NULL) 146 goto err; 147 bup = up; 148 eup = up + upsize; 149 } 150 *bup++ = '.'; 151 *bup++ = '.'; 152 *bup = '\0'; 153 154 /* Open and stat parent directory. */ 155 if (!(dir = opendir(up)) || fstat(dirfd(dir), &s)) 156 goto err; 157 158 /* Add trailing slash for next directory. */ 159 *bup++ = '/'; 160 161 /* 162 * If it's a mount point, have to stat each element because 163 * the inode number in the directory is for the entry in the 164 * parent directory, not the inode number of the mounted file. 165 */ 166 save_errno = 0; 167 if (s.st_dev == dev) { 168 for (;;) { 169 if (!(dp = readdir(dir))) 170 goto notfound; 171 if (dp->d_fileno == ino) 172 break; 173 } 174 } else 175 for (;;) { 176 if (!(dp = readdir(dir))) 177 goto notfound; 178 if (ISDOT(dp)) 179 continue; 180 bcopy(dp->d_name, bup, dp->d_namlen + 1); 181 182 /* Save the first error for later. */ 183 if (lstat(up, &s)) { 184 if (!save_errno) 185 save_errno = errno; 186 errno = 0; 187 continue; 188 } 189 if (s.st_dev == dev && s.st_ino == ino) 190 break; 191 } 192 193 /* 194 * Check for length of the current name, preceding slash, 195 * leading slash. 196 */ 197 if (bpt - pt <= dp->d_namlen + (first ? 1 : 2)) { 198 size_t len, off; 199 200 if (!ptsize) { 201 errno = ERANGE; 202 goto err; 203 } 204 off = bpt - pt; 205 len = ept - bpt; 206 if ((pt = realloc(pt, ptsize *= 2)) == NULL) 207 goto err; 208 bpt = pt + off; 209 ept = pt + ptsize; 210 bcopy(bpt, ept - len, len); 211 bpt = ept - len; 212 } 213 if (!first) 214 *--bpt = '/'; 215 bpt -= dp->d_namlen; 216 bcopy(dp->d_name, bpt, dp->d_namlen); 217 (void)closedir(dir); 218 219 /* Truncate any file name. */ 220 *bup = '\0'; 221 } 222 223 notfound: 224 /* 225 * If readdir set errno, use it, not any saved error; otherwise, 226 * didn't find the current directory in its parent directory, set 227 * errno to ENOENT. 228 */ 229 if (!errno) 230 errno = save_errno ? save_errno : ENOENT; 231 /* FALLTHROUGH */ 232 err: 233 if (ptsize) 234 free(pt); 235 free(up); 236 return (NULL); 237 } 238
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