1 | /* |
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2 | * Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru> |
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3 | * |
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4 | * Redistribution and use in source and binary forms, with or without |
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5 | * modification, are permitted provided that the following conditions |
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6 | * are met: |
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7 | * 1. Redistributions of source code must retain the above copyright |
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8 | * notice, this list of conditions and the following disclaimer. |
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9 | * 2. Redistributions in binary form must reproduce the above copyright |
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10 | * notice, this list of conditions and the following disclaimer in the |
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11 | * documentation and/or other materials provided with the distribution. |
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12 | * 3. The names of the authors may not be used to endorse or promote |
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13 | * products derived from this software without specific prior written |
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14 | * permission. |
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15 | * |
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16 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
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17 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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18 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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19 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
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20 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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21 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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22 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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23 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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24 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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25 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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26 | * SUCH DAMAGE. |
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27 | */ |
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28 | |
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29 | #if defined(LIBC_SCCS) && !defined(lint) |
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30 | static char sccsid[] = "@(#)realpath.c 8.1 (Berkeley) 2/16/94"; |
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31 | #endif /* LIBC_SCCS and not lint */ |
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32 | #include <sys/cdefs.h> |
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33 | __FBSDID("$FreeBSD: release/9.1.0/lib/libc/stdlib/realpath.c 240647 2012-09-18 13:03:00Z emaste $"); |
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34 | |
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35 | #if !defined(__rtems__) |
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36 | #include "namespace.h" |
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37 | #endif |
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38 | #include <sys/param.h> |
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39 | #include <sys/stat.h> |
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40 | |
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41 | #include <errno.h> |
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42 | #include <stdlib.h> |
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43 | #include <string.h> |
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44 | #include <unistd.h> |
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45 | #if !defined(__rtems__) |
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46 | #include "un-namespace.h" |
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47 | #endif |
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48 | |
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49 | /* |
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50 | * Find the real name of path, by removing all ".", ".." and symlink |
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51 | * components. Returns (resolved) on success, or (NULL) on failure, |
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52 | * in which case the path which caused trouble is left in (resolved). |
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53 | */ |
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54 | char * |
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55 | realpath(const char * __restrict path, char * __restrict resolved) |
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56 | { |
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57 | struct stat sb; |
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58 | char *p, *q, *s; |
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59 | size_t left_len, resolved_len; |
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60 | unsigned symlinks; |
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61 | int m, slen; |
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62 | char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX]; |
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63 | |
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64 | if (path == NULL) { |
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65 | errno = EINVAL; |
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66 | return (NULL); |
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67 | } |
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68 | if (path[0] == '\0') { |
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69 | errno = ENOENT; |
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70 | return (NULL); |
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71 | } |
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72 | if (resolved == NULL) { |
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73 | resolved = malloc(PATH_MAX); |
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74 | if (resolved == NULL) |
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75 | return (NULL); |
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76 | m = 1; |
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77 | } else |
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78 | m = 0; |
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79 | symlinks = 0; |
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80 | if (path[0] == '/') { |
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81 | resolved[0] = '/'; |
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82 | resolved[1] = '\0'; |
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83 | if (path[1] == '\0') |
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84 | return (resolved); |
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85 | resolved_len = 1; |
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86 | left_len = strlcpy(left, path + 1, sizeof(left)); |
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87 | } else { |
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88 | if (getcwd(resolved, PATH_MAX) == NULL) { |
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89 | if (m) |
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90 | free(resolved); |
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91 | else { |
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92 | resolved[0] = '.'; |
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93 | resolved[1] = '\0'; |
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94 | } |
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95 | return (NULL); |
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96 | } |
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97 | resolved_len = strlen(resolved); |
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98 | left_len = strlcpy(left, path, sizeof(left)); |
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99 | } |
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100 | if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) { |
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101 | if (m) |
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102 | free(resolved); |
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103 | errno = ENAMETOOLONG; |
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104 | return (NULL); |
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105 | } |
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106 | |
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107 | /* |
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108 | * Iterate over path components in `left'. |
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109 | */ |
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110 | while (left_len != 0) { |
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111 | /* |
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112 | * Extract the next path component and adjust `left' |
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113 | * and its length. |
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114 | */ |
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115 | p = strchr(left, '/'); |
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116 | s = p ? p : left + left_len; |
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117 | if (s - left >= sizeof(next_token)) { |
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118 | if (m) |
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119 | free(resolved); |
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120 | errno = ENAMETOOLONG; |
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121 | return (NULL); |
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122 | } |
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123 | memcpy(next_token, left, s - left); |
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124 | next_token[s - left] = '\0'; |
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125 | left_len -= s - left; |
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126 | if (p != NULL) |
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127 | memmove(left, s + 1, left_len + 1); |
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128 | if (resolved[resolved_len - 1] != '/') { |
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129 | if (resolved_len + 1 >= PATH_MAX) { |
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130 | if (m) |
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131 | free(resolved); |
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132 | errno = ENAMETOOLONG; |
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133 | return (NULL); |
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134 | } |
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135 | resolved[resolved_len++] = '/'; |
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136 | resolved[resolved_len] = '\0'; |
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137 | } |
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138 | if (next_token[0] == '\0') { |
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139 | /* |
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140 | * Handle consequential slashes. The path |
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141 | * before slash shall point to a directory. |
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142 | * |
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143 | * Only the trailing slashes are not covered |
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144 | * by other checks in the loop, but we verify |
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145 | * the prefix for any (rare) "//" or "/\0" |
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146 | * occurence to not implement lookahead. |
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147 | */ |
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148 | if (lstat(resolved, &sb) != 0) { |
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149 | if (m) |
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150 | free(resolved); |
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151 | return (NULL); |
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152 | } |
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153 | if (!S_ISDIR(sb.st_mode)) { |
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154 | if (m) |
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155 | free(resolved); |
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156 | errno = ENOTDIR; |
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157 | return (NULL); |
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158 | } |
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159 | continue; |
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160 | } |
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161 | else if (strcmp(next_token, ".") == 0) |
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162 | continue; |
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163 | else if (strcmp(next_token, "..") == 0) { |
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164 | /* |
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165 | * Strip the last path component except when we have |
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166 | * single "/" |
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167 | */ |
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168 | if (resolved_len > 1) { |
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169 | resolved[resolved_len - 1] = '\0'; |
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170 | q = strrchr(resolved, '/') + 1; |
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171 | *q = '\0'; |
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172 | resolved_len = q - resolved; |
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173 | } |
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174 | continue; |
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175 | } |
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176 | |
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177 | /* |
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178 | * Append the next path component and lstat() it. |
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179 | */ |
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180 | resolved_len = strlcat(resolved, next_token, PATH_MAX); |
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181 | if (resolved_len >= PATH_MAX) { |
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182 | if (m) |
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183 | free(resolved); |
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184 | errno = ENAMETOOLONG; |
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185 | return (NULL); |
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186 | } |
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187 | if (lstat(resolved, &sb) != 0) { |
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188 | if (m) |
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189 | free(resolved); |
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190 | return (NULL); |
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191 | } |
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192 | if (S_ISLNK(sb.st_mode)) { |
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193 | if (symlinks++ > MAXSYMLINKS) { |
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194 | if (m) |
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195 | free(resolved); |
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196 | errno = ELOOP; |
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197 | return (NULL); |
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198 | } |
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199 | slen = readlink(resolved, symlink, sizeof(symlink) - 1); |
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200 | if (slen < 0) { |
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201 | if (m) |
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202 | free(resolved); |
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203 | return (NULL); |
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204 | } |
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205 | symlink[slen] = '\0'; |
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206 | if (symlink[0] == '/') { |
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207 | resolved[1] = 0; |
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208 | resolved_len = 1; |
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209 | } else if (resolved_len > 1) { |
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210 | /* Strip the last path component. */ |
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211 | resolved[resolved_len - 1] = '\0'; |
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212 | q = strrchr(resolved, '/') + 1; |
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213 | *q = '\0'; |
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214 | resolved_len = q - resolved; |
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215 | } |
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216 | |
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217 | /* |
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218 | * If there are any path components left, then |
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219 | * append them to symlink. The result is placed |
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220 | * in `left'. |
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221 | */ |
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222 | if (p != NULL) { |
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223 | if (symlink[slen - 1] != '/') { |
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224 | if (slen + 1 >= sizeof(symlink)) { |
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225 | if (m) |
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226 | free(resolved); |
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227 | errno = ENAMETOOLONG; |
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228 | return (NULL); |
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229 | } |
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230 | symlink[slen] = '/'; |
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231 | symlink[slen + 1] = 0; |
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232 | } |
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233 | left_len = strlcat(symlink, left, |
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234 | sizeof(symlink)); |
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235 | if (left_len >= sizeof(left)) { |
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236 | if (m) |
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237 | free(resolved); |
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238 | errno = ENAMETOOLONG; |
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239 | return (NULL); |
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240 | } |
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241 | } |
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242 | left_len = strlcpy(left, symlink, sizeof(left)); |
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243 | } |
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244 | } |
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245 | |
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246 | /* |
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247 | * Remove trailing slash except when the resolved pathname |
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248 | * is a single "/". |
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249 | */ |
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250 | if (resolved_len > 1 && resolved[resolved_len - 1] == '/') |
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251 | resolved[resolved_len - 1] = '\0'; |
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252 | return (resolved); |
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253 | } |
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