gnu/dist/gettext/gettext-tools/lib/setenv.c

   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., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #if 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
  42 extern 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>
  73 typedef 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.  */
  77 static 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.  */
  98 static 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.  */
 107 int
 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
 282 int
 283 setenv (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.  */
 291 int
 292 clearenv (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
 312 static void
 313 free_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 }
 322 text_set_element (__libc_subfreeres, free_mem);
 323
 324
 325 # undef setenv
 326 # undef clearenv
 327 weak_alias (__setenv, setenv)
 328 weak_alias (__clearenv, clearenv)
 329 #endif