1  /* Environment handling for dynamic loader.
       2     Copyright (C) 1995-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <string.h>
      20  #include <stdlib.h>
      21  #include <unistd.h>
      22  #include <ldsodefs.h>
      23  
      24  /* Walk through the environment of the process and return all entries
      25     starting with `LD_'.  */
      26  char *
      27  _dl_next_ld_env_entry (char ***position)
      28  {
      29    char **current = *position;
      30    char *result = NULL;
      31  
      32    while (*current != NULL)
      33      {
      34        if (__builtin_expect ((*current)[0] == 'L', 0)
      35  	  && (*current)[1] == 'D' && (*current)[2] == '_')
      36  	{
      37  	  result = &(*current)[3];
      38  
      39  	  /* Save current position for next visit.  */
      40  	  *position = ++current;
      41  
      42  	  break;
      43  	}
      44  
      45        ++current;
      46      }
      47  
      48    return result;
      49  }
      50  
      51  
      52  /* In ld.so __environ is not exported.  */
      53  extern char **__environ attribute_hidden;
      54  
      55  int
      56  unsetenv (const char *name)
      57  {
      58    char **ep;
      59  
      60    ep = __environ;
      61    while (*ep != NULL)
      62      {
      63        size_t cnt = 0;
      64  
      65        while ((*ep)[cnt] == name[cnt] && name[cnt] != '\0')
      66  	++cnt;
      67  
      68        if (name[cnt] == '\0' && (*ep)[cnt] == '=')
      69  	{
      70  	  /* Found it.  Remove this pointer by moving later ones to
      71  	     the front.  */
      72  	  char **dp = ep;
      73  
      74  	  do
      75  	    dp[0] = dp[1];
      76  	  while (*dp++);
      77  	  /* Continue the loop in case NAME appears again.  */
      78  	}
      79        else
      80  	++ep;
      81      }
      82  
      83    return 0;
      84  }