1 /* Copyright (C) 1992,1995-1999,2000-2003 Free Software Foundation, Inc. 2 This file is part of the GNU C Library. 3 4 This program is free software; you can redistribute it and/or modify 5 it under the terms of the GNU General Public License as published by 6 the Free Software Foundation; either version 2, or (at your option) 7 any later version. 8 9 This program is distributed in the hope that it will be useful, 10 but WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 GNU General Public License for more details. 13 14 You should have received a copy of the GNU General Public License along 15 with this program; if not, write to the Free Software Foundation, 16 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ 17 #include <sys/cdefs.h> 18 __RCSID("$NetBSD: setenv.c,v 1.2 2016/05/17 14:00:09 christos Exp $"); 19 20 21 #if HAVE_CONFIG_H 22 # include <config.h> 23 #endif 24 #include <alloca.h> 25 26 #include <errno.h> 27 #ifndef __set_errno 28 # define __set_errno(ev) ((errno) = (ev)) 29 #endif 30 31 #include <stdlib.h> 32 #include <string.h> 33 #if _LIBC || HAVE_UNISTD_H 34 # include <unistd.h> 35 #endif 36 37 #if !_LIBC 38 # include "allocsa.h" 39 #endif 40 41 #if !_LIBC 42 # define __environ environ 43 # ifndef HAVE_ENVIRON_DECL 44 extern char **environ; 45 # endif 46 #endif 47 48 #if _LIBC 49 /* This lock protects against simultaneous modifications of `environ'. */ 50 # include <bits/libc-lock.h> 51 __libc_lock_define_initialized (static, envlock) 52 # define LOCK __libc_lock_lock (envlock) 53 # define UNLOCK __libc_lock_unlock (envlock) 54 #else 55 # define LOCK 56 # define UNLOCK 57 #endif 58 59 /* In the GNU C library we must keep the namespace clean. */ 60 #ifdef _LIBC 61 # define setenv __setenv 62 # define clearenv __clearenv 63 # define tfind __tfind 64 # define tsearch __tsearch 65 #endif 66 67 /* In the GNU C library implementation we try to be more clever and 68 allow arbitrarily many changes of the environment given that the used 69 values are from a small set. Outside glibc this will eat up all 70 memory after a while. */ 71 #if defined _LIBC || (defined HAVE_SEARCH_H && defined HAVE_TSEARCH \ 72 && defined __GNUC__) 73 # define USE_TSEARCH 1 74 # include <search.h> 75 typedef int (*compar_fn_t) (const void *, const void *); 76 77 /* This is a pointer to the root of the search tree with the known 78 values. */ 79 static void *known_values; 80 81 # define KNOWN_VALUE(Str) \ 82 ({ \ 83 void *value = tfind (Str, &known_values, (compar_fn_t) strcmp); \ 84 value != NULL ? *(char **) value : NULL; \ 85 }) 86 # define STORE_VALUE(Str) \ 87 tsearch (Str, &known_values, (compar_fn_t) strcmp) 88 89 #else 90 # undef USE_TSEARCH 91 92 # define KNOWN_VALUE(Str) NULL 93 # define STORE_VALUE(Str) do { } while (0) 94 95 #endif 96 97 98 /* If this variable is not a null pointer we allocated the current 99 environment. */ 100 static char **last_environ; 101 102 103 /* This function is used by `setenv' and `putenv'. The difference between 104 the two functions is that for the former must create a new string which 105 is then placed in the environment, while the argument of `putenv' 106 must be used directly. This is all complicated by the fact that we try 107 to reuse values once generated for a `setenv' call since we can never 108 free the strings. */ 109 int 110 __add_to_environ (const char *name, const char *value, const char *combined, 111 int replace) 112 { 113 register char **ep; 114 register size_t size; 115 const size_t namelen = strlen (name); 116 const size_t vallen = value != NULL ? strlen (value) + 1 : 0; 117 118 LOCK; 119 120 /* We have to get the pointer now that we have the lock and not earlier 121 since another thread might have created a new environment. */ 122 ep = __environ; 123 124 size = 0; 125 if (ep != NULL) 126 { 127 for (; *ep != NULL; ++ep) 128 if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=') 129 break; 130 else 131 ++size; 132 } 133 134 if (ep == NULL || *ep == NULL) 135 { 136 char **new_environ; 137 #ifdef USE_TSEARCH 138 char *new_value; 139 #endif 140 141 /* We allocated this space; we can extend it. */ 142 new_environ = 143 (char **) (last_environ == NULL 144 ? malloc ((size + 2) * sizeof (char *)) 145 : realloc (last_environ, (size + 2) * sizeof (char *))); 146 if (new_environ == NULL) 147 { 148 UNLOCK; 149 return -1; 150 } 151 152 /* If the whole entry is given add it. */ 153 if (combined != NULL) 154 /* We must not add the string to the search tree since it belongs 155 to the user. */ 156 new_environ[size] = (char *) combined; 157 else 158 { 159 /* See whether the value is already known. */ 160 #ifdef USE_TSEARCH 161 # ifdef _LIBC 162 new_value = (char *) alloca (namelen + 1 + vallen); 163 __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1), 164 value, vallen); 165 # else 166 new_value = (char *) allocsa (namelen + 1 + vallen); 167 if (new_value == NULL) 168 { 169 __set_errno (ENOMEM); 170 UNLOCK; 171 return -1; 172 } 173 memcpy (new_value, name, namelen); 174 new_value[namelen] = '='; 175 memcpy (&new_value[namelen + 1], value, vallen); 176 # endif 177 178 new_environ[size] = KNOWN_VALUE (new_value); 179 if (new_environ[size] == NULL) 180 #endif 181 { 182 new_environ[size] = (char *) malloc (namelen + 1 + vallen); 183 if (new_environ[size] == NULL) 184 { 185 #if defined USE_TSEARCH && !defined _LIBC 186 freesa (new_value); 187 #endif 188 __set_errno (ENOMEM); 189 UNLOCK; 190 return -1; 191 } 192 193 #ifdef USE_TSEARCH 194 memcpy (new_environ[size], new_value, namelen + 1 + vallen); 195 #else 196 memcpy (new_environ[size], name, namelen); 197 new_environ[size][namelen] = '='; 198 memcpy (&new_environ[size][namelen + 1], value, vallen); 199 #endif 200 /* And save the value now. We cannot do this when we remove 201 the string since then we cannot decide whether it is a 202 user string or not. */ 203 STORE_VALUE (new_environ[size]); 204 } 205 #if defined USE_TSEARCH && !defined _LIBC 206 freesa (new_value); 207 #endif 208 } 209 210 if (__environ != last_environ) 211 memcpy ((char *) new_environ, (char *) __environ, 212 size * sizeof (char *)); 213 214 new_environ[size + 1] = NULL; 215 216 last_environ = __environ = new_environ; 217 } 218 else if (replace) 219 { 220 char *np; 221 222 /* Use the user string if given. */ 223 if (combined != NULL) 224 np = (char *) combined; 225 else 226 { 227 #ifdef USE_TSEARCH 228 char *new_value; 229 # ifdef _LIBC 230 new_value = alloca (namelen + 1 + vallen); 231 __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1), 232 value, vallen); 233 # else 234 new_value = allocsa (namelen + 1 + vallen); 235 if (new_value == NULL) 236 { 237 __set_errno (ENOMEM); 238 UNLOCK; 239 return -1; 240 } 241 memcpy (new_value, name, namelen); 242 new_value[namelen] = '='; 243 memcpy (&new_value[namelen + 1], value, vallen); 244 # endif 245 246 np = KNOWN_VALUE (new_value); 247 if (np == NULL) 248 #endif 249 { 250 np = malloc (namelen + 1 + vallen); 251 if (np == NULL) 252 { 253 #if defined USE_TSEARCH && !defined _LIBC 254 freesa (new_value); 255 #endif 256 __set_errno (ENOMEM); 257 UNLOCK; 258 return -1; 259 } 260 261 #ifdef USE_TSEARCH 262 memcpy (np, new_value, namelen + 1 + vallen); 263 #else 264 memcpy (np, name, namelen); 265 np[namelen] = '='; 266 memcpy (&np[namelen + 1], value, vallen); 267 #endif 268 /* And remember the value. */ 269 STORE_VALUE (np); 270 } 271 #if defined USE_TSEARCH && !defined _LIBC 272 freesa (new_value); 273 #endif 274 } 275 276 *ep = np; 277 } 278 279 UNLOCK; 280 281 return 0; 282 } 283 284 int 285 setenv (const char *name, const char *value, int replace) 286 { 287 return __add_to_environ (name, value, NULL, replace); 288 } 289 290 /* The `clearenv' was planned to be added to POSIX.1 but probably 291 never made it. Nevertheless the POSIX.9 standard (POSIX bindings 292 for Fortran 77) requires this function. */ 293 int 294 clearenv (void) 295 { 296 LOCK; 297 298 if (__environ == last_environ && __environ != NULL) 299 { 300 /* We allocated this environment so we can free it. */ 301 free (__environ); 302 last_environ = NULL; 303 } 304 305 /* Clear the environment pointer removes the whole environment. */ 306 __environ = NULL; 307 308 UNLOCK; 309 310 return 0; 311 } 312 313 #ifdef _LIBC 314 static void 315 free_mem (void) 316 { 317 /* Remove all traces. */ 318 clearenv (); 319 320 /* Now remove the search tree. */ 321 __tdestroy (known_values, free); 322 known_values = NULL; 323 } 324 text_set_element (__libc_subfreeres, free_mem); 325 326 327 # undef setenv 328 # undef clearenv 329 weak_alias (__setenv, setenv) 330 weak_alias (__clearenv, clearenv) 331 #endif 332
Indexes created Tue Feb 24 08:35:24 UTC 2026