1  /* Copyright (C) 1991-2023 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, see
      16     <https://www.gnu.org/licenses/>.  */
      17  
      18  #if defined _AIX && !defined __GNUC__
      19   #pragma alloca
      20  #endif
      21  
      22  #if HAVE_CONFIG_H
      23  # include <config.h>
      24  #endif
      25  
      26  #if _LIBC || HAVE_STDLIB_H
      27  # include <stdlib.h>
      28  #endif
      29  #if _LIBC || HAVE_STRING_H
      30  # include <string.h>
      31  #endif
      32  
      33  #if !__GNU_LIBRARY__ && !HAVE_STRCHR
      34  # define strchr index
      35  #endif
      36  
      37  #ifndef _LIBC
      38  # ifdef HAVE_ALLOCA_H
      39  #  include <alloca.h>
      40  # else
      41  #  ifdef __GNUC__
      42  #   define alloca __builtin_alloca
      43  #  else
      44  extern char *alloca ();
      45  #  endif /* __GNUC__ */
      46  # endif /* HAVE_ALLOCA_H */
      47  #endif /* _LIBC */
      48  
      49  
      50  /* Put STRING, which is of the form "NAME=VALUE", in the environment.  */
      51  int
      52  putenv (char *string)
      53  {
      54    const char *const name_end = strchr (string, '=');
      55  
      56    if (name_end != NULL)
      57      {
      58        char *name;
      59  #ifdef _LIBC
      60        int use_malloc = !__libc_use_alloca (name_end - string + 1);
      61        if (__builtin_expect (use_malloc, 0))
      62  	{
      63  	  name = __strndup (string, name_end - string);
      64  	  if (name == NULL)
      65  	    return -1;
      66  	}
      67        else
      68  	name = strndupa (string, name_end - string);
      69  #else
      70  # define use_malloc 1
      71        name = malloc (name_end - string + 1);
      72        if (name == NULL)
      73  	return -1;
      74        memcpy (name, string, name_end - string);
      75        name[name_end - string] = '\0';
      76  #endif
      77        int result = __add_to_environ (name, NULL, string, 1);
      78  
      79        if (__glibc_unlikely (use_malloc))
      80  	free (name);
      81  
      82        return result;
      83      }
      84  
      85    __unsetenv (string);
      86    return 0;
      87  }