1/* Copyright (C) 1992,1995-1999,2000-2003,2005 Free Software Foundation, Inc. 2 This file is part of the GNU C Library. 3 4 The GNU C Library is free software; you can redistribute it and/or 5 modify it under the terms of the GNU Library General Public License as 6 published by the Free Software Foundation; either version 2 of the 7 License, or (at your option) any later version. 8 9 The GNU C Library 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 GNU 12 Library General Public License for more details. 13 14 You should have received a copy of the GNU Library General Public 15 License along with the GNU C Library; see the file COPYING.LIB. If not, 16 write to the Free Software Foundation, Inc., 51 Franklin Street, 17 Fifth Floor, Boston, MA 02110-1301, USA. */ 18 19#ifdef HAVE_CONFIG_H 20# include <config.h> 21#endif 22#include <alloca.h> 23 24#include <errno.h> 25#ifndef __set_errno 26# define __set_errno(ev) ((errno) = (ev)) 27#endif 28 29#include <stdlib.h> 30#include <string.h> 31#if _LIBC || HAVE_UNISTD_H 32# include <unistd.h> 33#endif 34 35#if !_LIBC 36# include "allocsa.h" 37#endif 38 39#if !_LIBC 40# define __environ environ 41# ifndef HAVE_ENVIRON_DECL 42extern char **environ; 43# endif 44#endif 45 46#if _LIBC 47/* This lock protects against simultaneous modifications of `environ'. */ 48# include <bits/libc-lock.h> 49__libc_lock_define_initialized (static, envlock) 50# define LOCK __libc_lock_lock (envlock) 51# define UNLOCK __libc_lock_unlock (envlock) 52#else 53# define LOCK 54# define UNLOCK 55#endif 56 57/* In the GNU C library we must keep the namespace clean. */ 58#ifdef _LIBC 59# define setenv __setenv 60# define clearenv __clearenv 61# define tfind __tfind 62# define tsearch __tsearch 63#endif 64 65/* In the GNU C library implementation we try to be more clever and 66 allow arbitrarily many changes of the environment given that the used 67 values are from a small set. Outside glibc this will eat up all 68 memory after a while. */ 69#if defined _LIBC || (defined HAVE_SEARCH_H && defined HAVE_TSEARCH \ 70 && defined __GNUC__) 71# define USE_TSEARCH 1 72# include <search.h> 73typedef int (*compar_fn_t) (const void *, const void *); 74 75/* This is a pointer to the root of the search tree with the known 76 values. */ 77static void *known_values; 78 79# define KNOWN_VALUE(Str) \ 80 ({ \ 81 void *value = tfind (Str, &known_values, (compar_fn_t) strcmp); \ 82 value != NULL ? *(char **) value : NULL; \ 83 }) 84# define STORE_VALUE(Str) \ 85 tsearch (Str, &known_values, (compar_fn_t) strcmp) 86 87#else 88# undef USE_TSEARCH 89 90# define KNOWN_VALUE(Str) NULL 91# define STORE_VALUE(Str) do { } while (0) 92 93#endif 94 95 96/* If this variable is not a null pointer we allocated the current 97 environment. */ 98static char **last_environ; 99 100 101/* This function is used by `setenv' and `putenv'. The difference between 102 the two functions is that for the former must create a new string which 103 is then placed in the environment, while the argument of `putenv' 104 must be used directly. This is all complicated by the fact that we try 105 to reuse values once generated for a `setenv' call since we can never 106 free the strings. */ 107int 108__add_to_environ (const char *name, const char *value, const char *combined, 109 int replace) 110{ 111 register char **ep; 112 register size_t size; 113 const size_t namelen = strlen (name); 114 const size_t vallen = value != NULL ? strlen (value) + 1 : 0; 115 116 LOCK; 117 118 /* We have to get the pointer now that we have the lock and not earlier 119 since another thread might have created a new environment. */ 120 ep = __environ; 121 122 size = 0; 123 if (ep != NULL) 124 { 125 for (; *ep != NULL; ++ep) 126 if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=') 127 break; 128 else 129 ++size; 130 } 131 132 if (ep == NULL || *ep == NULL) 133 { 134 char **new_environ; 135#ifdef USE_TSEARCH 136 char *new_value; 137#endif 138 139 /* We allocated this space; we can extend it. */ 140 new_environ = 141 (char **) (last_environ == NULL 142 ? malloc ((size + 2) * sizeof (char *)) 143 : realloc (last_environ, (size + 2) * sizeof (char *))); 144 if (new_environ == NULL) 145 { 146 UNLOCK; 147 return -1; 148 } 149 150 /* If the whole entry is given add it. */ 151 if (combined != NULL) 152 /* We must not add the string to the search tree since it belongs 153 to the user. */ 154 new_environ[size] = (char *) combined; 155 else 156 { 157 /* See whether the value is already known. */ 158#ifdef USE_TSEARCH 159# ifdef _LIBC 160 new_value = (char *) alloca (namelen + 1 + vallen); 161 __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1), 162 value, vallen); 163# else 164 new_value = (char *) allocsa (namelen + 1 + vallen); 165 if (new_value == NULL) 166 { 167 __set_errno (ENOMEM); 168 UNLOCK; 169 return -1; 170 } 171 memcpy (new_value, name, namelen); 172 new_value[namelen] = '='; 173 memcpy (&new_value[namelen + 1], value, vallen); 174# endif 175 176 new_environ[size] = KNOWN_VALUE (new_value); 177 if (new_environ[size] == NULL) 178#endif 179 { 180 new_environ[size] = (char *) malloc (namelen + 1 + vallen); 181 if (new_environ[size] == NULL) 182 { 183#if defined USE_TSEARCH && !defined _LIBC 184 freesa (new_value); 185#endif 186 __set_errno (ENOMEM); 187 UNLOCK; 188 return -1; 189 } 190 191#ifdef USE_TSEARCH 192 memcpy (new_environ[size], new_value, namelen + 1 + vallen); 193#else 194 memcpy (new_environ[size], name, namelen); 195 new_environ[size][namelen] = '='; 196 memcpy (&new_environ[size][namelen + 1], value, vallen); 197#endif 198 /* And save the value now. We cannot do this when we remove 199 the string since then we cannot decide whether it is a 200 user string or not. */ 201 STORE_VALUE (new_environ[size]); 202 } 203#if defined USE_TSEARCH && !defined _LIBC 204 freesa (new_value); 205#endif 206 } 207 208 if (__environ != last_environ) 209 memcpy ((char *) new_environ, (char *) __environ, 210 size * sizeof (char *)); 211 212 new_environ[size + 1] = NULL; 213 214 last_environ = __environ = new_environ; 215 } 216 else if (replace) 217 { 218 char *np; 219 220 /* Use the user string if given. */ 221 if (combined != NULL) 222 np = (char *) combined; 223 else 224 { 225#ifdef USE_TSEARCH 226 char *new_value; 227# ifdef _LIBC 228 new_value = alloca (namelen + 1 + vallen); 229 __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1), 230 value, vallen); 231# else 232 new_value = allocsa (namelen + 1 + vallen); 233 if (new_value == NULL) 234 { 235 __set_errno (ENOMEM); 236 UNLOCK; 237 return -1; 238 } 239 memcpy (new_value, name, namelen); 240 new_value[namelen] = '='; 241 memcpy (&new_value[namelen + 1], value, vallen); 242# endif 243 244 np = KNOWN_VALUE (new_value); 245 if (np == NULL) 246#endif 247 { 248 np = malloc (namelen + 1 + vallen); 249 if (np == NULL) 250 { 251#if defined USE_TSEARCH && !defined _LIBC 252 freesa (new_value); 253#endif 254 __set_errno (ENOMEM); 255 UNLOCK; 256 return -1; 257 } 258 259#ifdef USE_TSEARCH 260 memcpy (np, new_value, namelen + 1 + vallen); 261#else 262 memcpy (np, name, namelen); 263 np[namelen] = '='; 264 memcpy (&np[namelen + 1], value, vallen); 265#endif 266 /* And remember the value. */ 267 STORE_VALUE (np); 268 } 269#if defined USE_TSEARCH && !defined _LIBC 270 freesa (new_value); 271#endif 272 } 273 274 *ep = np; 275 } 276 277 UNLOCK; 278 279 return 0; 280} 281 282int 283setenv (const char *name, const char *value, int replace) 284{ 285 return __add_to_environ (name, value, NULL, replace); 286} 287 288/* The `clearenv' was planned to be added to POSIX.1 but probably 289 never made it. Nevertheless the POSIX.9 standard (POSIX bindings 290 for Fortran 77) requires this function. */ 291int 292clearenv (void) 293{ 294 LOCK; 295 296 if (__environ == last_environ && __environ != NULL) 297 { 298 /* We allocated this environment so we can free it. */ 299 free (__environ); 300 last_environ = NULL; 301 } 302 303 /* Clear the environment pointer removes the whole environment. */ 304 __environ = NULL; 305 306 UNLOCK; 307 308 return 0; 309} 310 311#ifdef _LIBC 312static void 313free_mem (void) 314{ 315 /* Remove all traces. */ 316 clearenv (); 317 318 /* Now remove the search tree. */ 319 __tdestroy (known_values, free); 320 known_values = NULL; 321} 322text_set_element (__libc_subfreeres, free_mem); 323 324 325# undef setenv 326# undef clearenv 327weak_alias (__setenv, setenv) 328weak_alias (__clearenv, clearenv) 329#endif 330