assuan/setenv.c

   1 /* Copyright (C) 1992,1995-2001,2004 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 Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the 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    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not,
  16    see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #if HAVE_CONFIG_H
  20 # include <config.h>
  21 #endif
  22
  23 #include "assuan-defs.h"
  24
  25 #define __builtin_expect(cond,val) (cond)
  26
  27 #include <errno.h>
  28 #if !_LIBC
  29 # if !defined errno && !defined HAVE_ERRNO_DECL
  30 extern int errno;
  31 # endif
  32 # define __set_errno(ev) ((errno) = (ev))
  33 #endif
  34
  35 #if _LIBC || HAVE_STDLIB_H
  36 # include <stdlib.h>
  37 #endif
  38 #if _LIBC || HAVE_STRING_H
  39 # include <string.h>
  40 #endif
  41 #if _LIBC || HAVE_UNISTD_H
  42 # include <unistd.h>
  43 #endif
  44
  45 #if !_LIBC
  46 # define __environ      environ
  47 # ifndef HAVE_ENVIRON_DECL
  48 extern char **environ;
  49 # endif
  50 #endif
  51
  52 #if _LIBC
  53 /* This lock protects against simultaneous modifications of `environ'.  */
  54 # include <bits/libc-lock.h>
  55 __libc_lock_define_initialized (static, envlock)
  56 # define LOCK   __libc_lock_lock (envlock)
  57 # define UNLOCK __libc_lock_unlock (envlock)
  58 #else
  59 # define LOCK
  60 # define UNLOCK
  61 #endif
  62
  63 /* In the GNU C library we must keep the namespace clean.  */
  64 #ifdef _LIBC
  65 # define setenv __setenv
  66 # define unsetenv __unsetenv
  67 # define clearenv __clearenv
  68 # define tfind __tfind
  69 # define tsearch __tsearch
  70 #endif
  71
  72 /* In the GNU C library implementation we try to be more clever and
  73    allow arbitrarily many changes of the environment given that the used
  74    values are from a small set.  Outside glibc this will eat up all
  75    memory after a while.  */
  76 #if defined _LIBC || (defined HAVE_SEARCH_H && defined HAVE_TSEARCH \
  77                       && defined __GNUC__)
  78 # define USE_TSEARCH    1
  79 # include <search.h>
  80
  81 /* This is a pointer to the root of the search tree with the known
  82    values.  */
  83 static void *known_values;
  84
  85 # define KNOWN_VALUE(Str) \
  86   ({                                                                          \
  87     void *value = tfind (Str, &known_values, (__compar_fn_t) strcmp);         \
  88     value != NULL ? *(char **) value : NULL;                                  \
  89   })
  90 # define STORE_VALUE(Str) \
  91   tsearch (Str, &known_values, (__compar_fn_t) strcmp)
  92
  93 #else
  94 # undef USE_TSEARCH
  95
  96 # define KNOWN_VALUE(Str) NULL
  97 # define STORE_VALUE(Str) do { } while (0)
  98
  99 #endif
 100
 101
 102 /* If this variable is not a null pointer we allocated the current
 103    environment.  */
 104 static char **last_environ;
 105
 106
 107 /* This function is used by `setenv' and `putenv'.  The difference between
 108    the two functions is that for the former must create a new string which
 109    is then placed in the environment, while the argument of `putenv'
 110    must be used directly.  This is all complicated by the fact that we try
 111    to reuse values once generated for a `setenv' call since we can never
 112    free the strings.  */
 113 static int
 114 __add_to_environ (const char *name, const char *value, const char *combined,
 115                   int replace)
 116 {
 117   register char **ep;
 118   register size_t size;
 119   const size_t namelen = strlen (name);
 120   const size_t vallen = value != NULL ? strlen (value) + 1 : 0;
 121
 122   LOCK;
 123
 124   /* We have to get the pointer now that we have the lock and not earlier
 125      since another thread might have created a new environment.  */
 126   ep = __environ;
 127
 128   size = 0;
 129   if (ep != NULL)
 130     {
 131       for (; *ep != NULL; ++ep)
 132         if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
 133           break;
 134         else
 135           ++size;
 136     }
 137
 138   if (ep == NULL || __builtin_expect (*ep == NULL, 1))
 139     {
 140       char **new_environ;
 141
 142       /* We allocated this space; we can extend it.  */
 143       new_environ = (char **) realloc (last_environ,
 144                                        (size + 2) * sizeof (char *));
 145       if (new_environ == NULL)
 146         {
 147           UNLOCK;
 148           return -1;
 149         }
 150
 151       /* If the whole entry is given add it.  */
 152       if (combined != NULL)
 153         /* We must not add the string to the search tree since it belongs
 154            to the user.  */
 155         new_environ[size] = (char *) combined;
 156       else
 157         {
 158           /* See whether the value is already known.  */
 159 #ifdef USE_TSEARCH
 160 # ifdef __GNUC__
 161           char new_value[namelen + 1 + vallen];
 162 # else
 163           char *new_value = (char *) alloca (namelen + 1 + vallen);
 164 # endif
 165 # ifdef _LIBC
 166           __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
 167                      value, vallen);
 168 # else
 169           memcpy (new_value, name, namelen);
 170           new_value[namelen] = '=';
 171           memcpy (&new_value[namelen + 1], value, vallen);
 172 # endif
 173
 174           new_environ[size] = KNOWN_VALUE (new_value);
 175           if (__builtin_expect (new_environ[size] == NULL, 1))
 176 #endif
 177             {
 178               new_environ[size] = (char *) malloc (namelen + 1 + vallen);
 179               if (__builtin_expect (new_environ[size] == NULL, 0))
 180                 {
 181                   __set_errno (ENOMEM);
 182                   UNLOCK;
 183                   return -1;
 184                 }
 185
 186 #ifdef USE_TSEARCH
 187               memcpy (new_environ[size], new_value, namelen + 1 + vallen);
 188 #else
 189               memcpy (new_environ[size], name, namelen);
 190               new_environ[size][namelen] = '=';
 191               memcpy (&new_environ[size][namelen + 1], value, vallen);
 192 #endif
 193               /* And save the value now.  We cannot do this when we remove
 194                  the string since then we cannot decide whether it is a
 195                  user string or not.  */
 196               STORE_VALUE (new_environ[size]);
 197             }
 198         }
 199
 200       if (__environ != last_environ)
 201         memcpy ((char *) new_environ, (char *) __environ,
 202                 size * sizeof (char *));
 203
 204       new_environ[size + 1] = NULL;
 205
 206       last_environ = __environ = new_environ;
 207     }
 208   else if (replace)
 209     {
 210       char *np;
 211
 212       /* Use the user string if given.  */
 213       if (combined != NULL)
 214         np = (char *) combined;
 215       else
 216         {
 217 #ifdef USE_TSEARCH
 218 # ifdef __GNUC__
 219           char new_value[namelen + 1 + vallen];
 220 # else
 221           char *new_value = (char *) alloca (namelen + 1 + vallen);
 222 # endif
 223 # ifdef _LIBC
 224           __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
 225                      value, vallen);
 226 # else
 227           memcpy (new_value, name, namelen);
 228           new_value[namelen] = '=';
 229           memcpy (&new_value[namelen + 1], value, vallen);
 230 # endif
 231
 232           np = KNOWN_VALUE (new_value);
 233           if (__builtin_expect (np == NULL, 1))
 234 #endif
 235             {
 236               np = malloc (namelen + 1 + vallen);
 237               if (__builtin_expect (np == NULL, 0))
 238                 {
 239                   UNLOCK;
 240                   return -1;
 241                 }
 242
 243 #ifdef USE_TSEARCH
 244               memcpy (np, new_value, namelen + 1 + vallen);
 245 #else
 246               memcpy (np, name, namelen);
 247               np[namelen] = '=';
 248               memcpy (&np[namelen + 1], value, vallen);
 249 #endif
 250               /* And remember the value.  */
 251               STORE_VALUE (np);
 252             }
 253         }
 254
 255       *ep = np;
 256     }
 257
 258   UNLOCK;
 259
 260   return 0;
 261 }
 262
 263 int
 264 setenv (const char *name, const char *value, int replace)
 265 {
 266   if (name == NULL || *name == '\0' || strchr (name, '=') != NULL)
 267     {
 268       __set_errno (EINVAL);
 269       return -1;
 270     }
 271
 272   return __add_to_environ (name, value, NULL, replace);
 273 }
 274
 275 int
 276 unsetenv (const char *name)
 277 {
 278   size_t len;
 279   char **ep;
 280
 281   if (name == NULL || *name == '\0' || strchr (name, '=') != NULL)
 282     {
 283       __set_errno (EINVAL);
 284       return -1;
 285     }
 286
 287   len = strlen (name);
 288
 289   LOCK;
 290
 291   ep = __environ;
 292   while (*ep != NULL)
 293     if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
 294       {
 295         /* Found it.  Remove this pointer by moving later ones back.  */
 296         char **dp = ep;
 297
 298         do
 299           dp[0] = dp[1];
 300         while (*dp++);
 301         /* Continue the loop in case NAME appears again.  */
 302       }
 303     else
 304       ++ep;
 305
 306   UNLOCK;
 307
 308   return 0;
 309 }
 310
 311 /* The `clearenv' was planned to be added to POSIX.1 but probably
 312    never made it.  Nevertheless the POSIX.9 standard (POSIX bindings
 313    for Fortran 77) requires this function.  */
 314 int
 315 clearenv (void)
 316 {
 317   LOCK;
 318
 319   if (__environ == last_environ && __environ != NULL)
 320     {
 321       /* We allocated this environment so we can free it.  */
 322       free (__environ);
 323       last_environ = NULL;
 324     }
 325
 326   /* Clear the environment pointer removes the whole environment.  */
 327   __environ = NULL;
 328
 329   UNLOCK;
 330
 331   return 0;
 332 }
 333 #ifdef _LIBC
 334 libc_freeres_fn (free_mem)
 335 {
 336   /* Remove all traces.  */
 337   clearenv ();
 338
 339   /* Now remove the search tree.  */
 340   __tdestroy (known_values, free);
 341   known_values = NULL;
 342 }
 343
 344 # undef setenv
 345 # undef unsetenv
 346 # undef clearenv
 347 weak_alias (__setenv, setenv)
 348 weak_alias (__unsetenv, unsetenv)
 349 weak_alias (__clearenv, clearenv)
 350 #endif
 351
 352