1/* Copyright (C) 1992,1995-1999,2000-2003 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#if HAVE_CONFIG_H 20# include <config.h> 21#endif 22#include <alloca.h> 23 24#include <errno.h> 25#if !_LIBC 26# if !defined errno && !defined HAVE_ERRNO_DECL 27extern int errno; 28# endif 29# define __set_errno(ev) ((errno) = (ev)) 30#endif 31 32#include <stdlib.h> 33#include <string.h> 34#if _LIBC || HAVE_UNISTD_H 35# include <unistd.h> 36#endif 37 38#if !_LIBC 39# include "allocsa.h" 40#endif 41 42#if !_LIBC 43# define __environ environ 44# ifndef HAVE_ENVIRON_DECL 45extern char **environ; 46# endif 47#endif 48 49#if _LIBC 50/* This lock protects against simultaneous modifications of `environ'. */ 51# include <bits/libc-lock.h> 52__libc_lock_define_initialized (static, envlock) 53# define LOCK __libc_lock_lock (envlock) 54# define UNLOCK __libc_lock_unlock (envlock) 55#else 56# define LOCK 57# define UNLOCK 58#endif 59 60/* In the GNU C library we must keep the namespace clean. */ 61#ifdef _LIBC 62# define setenv __setenv 63# define clearenv __clearenv 64# define tfind __tfind 65# define tsearch __tsearch 66#endif 67 68/* In the GNU C library implementation we try to be more clever and 69 allow arbitrarily many changes of the environment given that the used 70 values are from a small set. Outside glibc this will eat up all 71 memory after a while. */ 72#if defined _LIBC || (defined HAVE_SEARCH_H && defined HAVE_TSEARCH \ 73 && defined __GNUC__) 74# define USE_TSEARCH 1 75# include <search.h> 76typedef int (*compar_fn_t) (const void *, const void *); 77 78/* This is a pointer to the root of the search tree with the known 79 values. */ 80static void *known_values; 81 82# define KNOWN_VALUE(Str) \ 83 ({ \ 84 void *value = tfind (Str, &known_values, (compar_fn_t) strcmp); \ 85 value != NULL ? *(char **) value : NULL; \ 86 }) 87# define STORE_VALUE(Str) \ 88 tsearch (Str, &known_values, (compar_fn_t) strcmp) 89 90#else 91# undef USE_TSEARCH 92 93# define KNOWN_VALUE(Str) NULL 94# define STORE_VALUE(Str) do { } while (0) 95 96#endif 97 98 99/* If this variable is not a null pointer we allocated the current 100 environment. */ 101static char **last_environ; 102 103 104/* This function is used by `setenv' and `putenv'. The difference between 105 the two functions is that for the former must create a new string which 106 is then placed in the environment, while the argument of `putenv' 107 must be used directly. This is all complicated by the fact that we try 108 to reuse values once generated for a `setenv' call since we can never 109 free the strings. */ 110int 111__add_to_environ (const char *name, const char *value, const char *combined, 112 int replace) 113{ 114 register char **ep; 115 register size_t size; 116 const size_t namelen = strlen (name); 117 const size_t vallen = value != NULL ? strlen (value) + 1 : 0; 118 119 LOCK; 120 121 /* We have to get the pointer now that we have the lock and not earlier 122 since another thread might have created a new environment. */ 123 ep = __environ; 124 125 size = 0; 126 if (ep != NULL) 127 { 128 for (; *ep != NULL; ++ep) 129 if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=') 130 break; 131 else 132 ++size; 133 } 134 135 if (ep == NULL || *ep == NULL) 136 { 137 char **new_environ; 138#ifdef USE_TSEARCH 139 char *new_value; 140#endif 141 142 /* We allocated this space; we can extend it. */ 143 new_environ = 144 (char **) (last_environ == NULL 145 ? malloc ((size + 2) * sizeof (char *)) 146 : realloc (last_environ, (size + 2) * sizeof (char *))); 147 if (new_environ == NULL) 148 { 149 UNLOCK; 150 return -1; 151 } 152 153 /* If the whole entry is given add it. */ 154 if (combined != NULL) 155 /* We must not add the string to the search tree since it belongs 156 to the user. */ 157 new_environ[size] = (char *) combined; 158 else 159 { 160 /* See whether the value is already known. */ 161#ifdef USE_TSEARCH 162# ifdef _LIBC 163 new_value = (char *) alloca (namelen + 1 + vallen); 164 __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1), 165 value, vallen); 166# else 167 new_value = (char *) allocsa (namelen + 1 + vallen); 168 if (new_value == NULL) 169 { 170 __set_errno (ENOMEM); 171 UNLOCK; 172 return -1; 173 } 174 memcpy (new_value, name, namelen); 175 new_value[namelen] = '='; 176 memcpy (&new_value[namelen + 1], value, vallen); 177# endif 178 179 new_environ[size] = KNOWN_VALUE (new_value); 180 if (new_environ[size] == NULL) 181#endif 182 { 183 new_environ[size] = (char *) malloc (namelen + 1 + vallen); 184 if (new_environ[size] == NULL) 185 { 186#if defined USE_TSEARCH && !defined _LIBC 187 freesa (new_value); 188#endif 189 __set_errno (ENOMEM); 190 UNLOCK; 191 return -1; 192 } 193 194#ifdef USE_TSEARCH 195 memcpy (new_environ[size], new_value, namelen + 1 + vallen); 196#else 197 memcpy (new_environ[size], name, namelen); 198 new_environ[size][namelen] = '='; 199 memcpy (&new_environ[size][namelen + 1], value, vallen); 200#endif 201 /* And save the value now. We cannot do this when we remove 202 the string since then we cannot decide whether it is a 203 user string or not. */ 204 STORE_VALUE (new_environ[size]); 205 } 206#if defined USE_TSEARCH && !defined _LIBC 207 freesa (new_value); 208#endif 209 } 210 211 if (__environ != last_environ) 212 memcpy ((char *) new_environ, (char *) __environ, 213 size * sizeof (char *)); 214 215 new_environ[size + 1] = NULL; 216 217 last_environ = __environ = new_environ; 218 } 219 else if (replace) 220 { 221 char *np; 222 223 /* Use the user string if given. */ 224 if (combined != NULL) 225 np = (char *) combined; 226 else 227 { 228#ifdef USE_TSEARCH 229 char *new_value; 230# ifdef _LIBC 231 new_value = alloca (namelen + 1 + vallen); 232 __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1), 233 value, vallen); 234# else 235 new_value = allocsa (namelen + 1 + vallen); 236 if (new_value == NULL) 237 { 238 __set_errno (ENOMEM); 239 UNLOCK; 240 return -1; 241 } 242 memcpy (new_value, name, namelen); 243 new_value[namelen] = '='; 244 memcpy (&new_value[namelen + 1], value, vallen); 245# endif 246 247 np = KNOWN_VALUE (new_value); 248 if (np == NULL) 249#endif 250 { 251 np = malloc (namelen + 1 + vallen); 252 if (np == NULL) 253 { 254#if defined USE_TSEARCH && !defined _LIBC 255 freesa (new_value); 256#endif 257 __set_errno (ENOMEM); 258 UNLOCK; 259 return -1; 260 } 261 262#ifdef USE_TSEARCH 263 memcpy (np, new_value, namelen + 1 + vallen); 264#else 265 memcpy (np, name, namelen); 266 np[namelen] = '='; 267 memcpy (&np[namelen + 1], value, vallen); 268#endif 269 /* And remember the value. */ 270 STORE_VALUE (np); 271 } 272#if defined USE_TSEARCH && !defined _LIBC 273 freesa (new_value); 274#endif 275 } 276 277 *ep = np; 278 } 279 280 UNLOCK; 281 282 return 0; 283} 284 285int 286setenv (const char *name, const char *value, int replace) 287{ 288 return __add_to_environ (name, value, NULL, replace); 289} 290 291/* The `clearenv' was planned to be added to POSIX.1 but probably 292 never made it. Nevertheless the POSIX.9 standard (POSIX bindings 293 for Fortran 77) requires this function. */ 294int 295clearenv (void) 296{ 297 LOCK; 298 299 if (__environ == last_environ && __environ != NULL) 300 { 301 /* We allocated this environment so we can free it. */ 302 free (__environ); 303 last_environ = NULL; 304 } 305 306 /* Clear the environment pointer removes the whole environment. */ 307 __environ = NULL; 308 309 UNLOCK; 310 311 return 0; 312} 313 314#ifdef _LIBC 315static void 316free_mem (void) 317{ 318 /* Remove all traces. */ 319 clearenv (); 320 321 /* Now remove the search tree. */ 322 __tdestroy (known_values, free); 323 known_values = NULL; 324} 325text_set_element (__libc_subfreeres, free_mem); 326 327 328# undef setenv 329# undef clearenv 330weak_alias (__setenv, setenv) 331weak_alias (__clearenv, clearenv) 332#endif 333