NULL environ?

[Simon Josefsson]

Does POSIX permit a NULL 'environ' variable?  I'd say no given what
http://www.opengroup.org/onlinepubs/9699919799/functions/environ.html
has to say:

   In addition, the following variable:

   extern char **environ;

   is initialized as a pointer to an array of character pointers to the
   environment strings. The argv and environ arrays are each terminated
   by a null pointer.

Strictly speaking, I don't think NULL is a valid array of character
pointers terminated with a null pointer.

I've noticed that Wine uses one:

address@hidden:~$ cat environ-wine.c
#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>

int main (void)
{
  if (environ == NULL)
    puts("NULL");
  else
    puts("non-NULL");
  return 0;
}
address@hidden:~$ i686-w64-mingw32-gcc -o environ-wine.exe environ-wine.c
address@hidden:~$ ./environ-wine.exe
NULL
address@hidden:~$

The same EXE file prints non-NULL on real Windows.

This crashes the test-environ.c and test-unsetenv.c self tests.

/Simon