contrib/bmake/realpath.c

   1 /* $Id: realpath.c,v 1.3 2013/01/25 17:06:09 sjg Exp $ */
   2 /* from: $NetBSD: getcwd.c,v 1.53 2012/06/21 23:29:23 enami Exp $       */
   3
   4 /*
   5  * Copyright (c) 1989, 1991, 1993, 1995
   6  *      The Regents of the University of California.  All rights reserved.
   7  *
   8  * This code is derived from software contributed to Berkeley by
   9  * Jan-Simon Pendry.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in the
  18  *    documentation and/or other materials provided with the distribution.
  19  * 3. 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 #ifdef HAVE_CONFIG_H
  36 # include <config.h>
  37 #endif
  38 #ifndef HAVE_REALPATH
  39
  40 #include <sys/cdefs.h>
  41 #include <sys/param.h>
  42 #include <sys/stat.h>
  43
  44 #include <errno.h>
  45 #ifdef HAVE_STDLIB_H
  46 # include <stdlib.h>
  47 #endif
  48 #ifdef HAVE_STRING_H
  49 # include <string.h>
  50 #endif
  51 #ifdef HAVE_UNISTD_H
  52 # include <unistd.h>
  53 #endif
  54
  55 #ifndef __restrict
  56 # define __restrict /* restrict */
  57 #endif
  58
  59 /*
  60  * char *realpath(const char *path, char *resolved);
  61  *
  62  * Find the real name of path, by removing all ".", ".." and symlink
  63  * components.  Returns (resolved) on success, or (NULL) on failure,
  64  * in which case the path which caused trouble is left in (resolved).
  65  */
  66 char *
  67 realpath(const char * __restrict path, char * __restrict resolved)
  68 {
  69         struct stat sb;
  70         int idx = 0, nlnk = 0;
  71         const char *q;
  72         char *p, wbuf[2][MAXPATHLEN], *fres;
  73         size_t len;
  74         ssize_t n;
  75
  76         /* POSIX sez we must test for this */
  77         if (path == NULL) {
  78                 errno = EINVAL;
  79                 return NULL;
  80         }
  81
  82         if (resolved == NULL) {
  83                 fres = resolved = malloc(MAXPATHLEN);
  84                 if (resolved == NULL)
  85                         return NULL;
  86         } else
  87                 fres = NULL;
  88
  89
  90         /*
  91          * Build real path one by one with paying an attention to .,
  92          * .. and symbolic link.
  93          */
  94
  95         /*
  96          * `p' is where we'll put a new component with prepending
  97          * a delimiter.
  98          */
  99         p = resolved;
 100
 101         if (*path == '\0') {
 102                 *p = '\0';
 103                 errno = ENOENT;
 104                 goto out;
 105         }
 106
 107         /* If relative path, start from current working directory. */
 108         if (*path != '/') {
 109                 /* check for resolved pointer to appease coverity */
 110                 if (resolved && getcwd(resolved, MAXPATHLEN) == NULL) {
 111                         p[0] = '.';
 112                         p[1] = '\0';
 113                         goto out;
 114                 }
 115                 len = strlen(resolved);
 116                 if (len > 1)
 117                         p += len;
 118         }
 119
 120 loop:
 121         /* Skip any slash. */
 122         while (*path == '/')
 123                 path++;
 124
 125         if (*path == '\0') {
 126                 if (p == resolved)
 127                         *p++ = '/';
 128                 *p = '\0';
 129                 return resolved;
 130         }
 131
 132         /* Find the end of this component. */
 133         q = path;
 134         do
 135                 q++;
 136         while (*q != '/' && *q != '\0');
 137
 138         /* Test . or .. */
 139         if (path[0] == '.') {
 140                 if (q - path == 1) {
 141                         path = q;
 142                         goto loop;
 143                 }
 144                 if (path[1] == '.' && q - path == 2) {
 145                         /* Trim the last component. */
 146                         if (p != resolved)
 147                                 while (*--p != '/')
 148                                         continue;
 149                         path = q;
 150                         goto loop;
 151                 }
 152         }
 153
 154         /* Append this component. */
 155         if (p - resolved + 1 + q - path + 1 > MAXPATHLEN) {
 156                 errno = ENAMETOOLONG;
 157                 if (p == resolved)
 158                         *p++ = '/';
 159                 *p = '\0';
 160                 goto out;
 161         }
 162         p[0] = '/';
 163         memcpy(&p[1], path,
 164             /* LINTED We know q > path. */
 165             q - path);
 166         p[1 + q - path] = '\0';
 167
 168         /*
 169          * If this component is a symlink, toss it and prepend link
 170          * target to unresolved path.
 171          */
 172         if (lstat(resolved, &sb) == -1)
 173                 goto out;
 174
 175         if (S_ISLNK(sb.st_mode)) {
 176                 if (nlnk++ >= MAXSYMLINKS) {
 177                         errno = ELOOP;
 178                         goto out;
 179                 }
 180                 n = readlink(resolved, wbuf[idx], sizeof(wbuf[0]) - 1);
 181                 if (n < 0)
 182                         goto out;
 183                 if (n == 0) {
 184                         errno = ENOENT;
 185                         goto out;
 186                 }
 187
 188                 /* Append unresolved path to link target and switch to it. */
 189                 if (n + (len = strlen(q)) + 1 > sizeof(wbuf[0])) {
 190                         errno = ENAMETOOLONG;
 191                         goto out;
 192                 }
 193                 memcpy(&wbuf[idx][n], q, len + 1);
 194                 path = wbuf[idx];
 195                 idx ^= 1;
 196
 197                 /* If absolute symlink, start from root. */
 198                 if (*path == '/')
 199                         p = resolved;
 200                 goto loop;
 201         }
 202         if (*q == '/' && !S_ISDIR(sb.st_mode)) {
 203                 errno = ENOTDIR;
 204                 goto out;
 205         }
 206
 207         /* Advance both resolved and unresolved path. */
 208         p += 1 + q - path;
 209         path = q;
 210         goto loop;
 211 out:
 212         free(fres);
 213         return NULL;
 214 }
 215 #endif