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

   1 /* Copyright (C) 1992,1995-1999,2000-2002 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
  23 #include <errno.h>
  24 #if !_LIBC
  25 # if !defined errno && !defined HAVE_ERRNO_DECL
  26 extern int errno;
  27 # endif
  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 # define __environ      environ
  39 # ifndef HAVE_ENVIRON_DECL
  40 extern char **environ;
  41 # endif
  42 #endif
  43
  44 #if _LIBC
  45 /* This lock protects against simultaneous modifications of `environ'.  */
  46 # include <bits/libc-lock.h>
  47 __libc_lock_define_initialized (static, envlock)
  48 # define LOCK   __libc_lock_lock (envlock)
  49 # define UNLOCK __libc_lock_unlock (envlock)
  50 #else
  51 # define LOCK
  52 # define UNLOCK
  53 #endif
  54
  55 /* In the GNU C library we must keep the namespace clean.  */
  56 #ifdef _LIBC
  57 # define unsetenv __unsetenv
  58 #endif
  59
  60
  61 int
  62 unsetenv (const char *name)
  63 {
  64   size_t len;
  65   char **ep;
  66
  67   if (name == NULL || *name == '\0' || strchr (name, '=') != NULL)
  68     {
  69       __set_errno (EINVAL);
  70       return -1;
  71     }
  72
  73   len = strlen (name);
  74
  75   LOCK;
  76
  77   ep = __environ;
  78   while (*ep != NULL)
  79     if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
  80       {
  81         /* Found it.  Remove this pointer by moving later ones back.  */
  82         char **dp = ep;
  83
  84         do
  85           dp[0] = dp[1];
  86         while (*dp++);
  87         /* Continue the loop in case NAME appears again.  */
  88       }
  89     else
  90       ++ep;
  91
  92   UNLOCK;
  93
  94   return 0;
  95 }
  96
  97 #ifdef _LIBC
  98 # undef unsetenv
  99 weak_alias (__unsetenv, unsetenv)
 100 #endif