unsetenv.c raw

   1  #include <stdlib.h>
   2  #include <string.h>
   3  #include <errno.h>
   4  #include <unistd.h>
   5  
   6  static void dummy(char *old, char *new) {}
   7  weak_alias(dummy, __env_rm_add);
   8  
   9  int unsetenv(const char *name)
  10  {
  11  	size_t l = __strchrnul(name, '=') - name;
  12  	if (!l || name[l]) {
  13  		errno = EINVAL;
  14  		return -1;
  15  	}
  16  	if (__environ) {
  17  		char **e = __environ, **eo = e;
  18  		for (; *e; e++)
  19  			if (!strncmp(name, *e, l) && l[*e] == '=')
  20  				__env_rm_add(*e, 0);
  21  			else if (eo != e)
  22  				*eo++ = *e;
  23  			else
  24  				eo++;
  25  		if (eo != e) *eo = 0;
  26  	}
  27  	return 0;
  28  }
  29