libgo/runtime/go-unsetenv.c

   1 /* go-unsetenv.c -- unset an environment variable from Go.
   2
   3    Copyright 2015 The Go Authors. All rights reserved.
   4    Use of this source code is governed by a BSD-style
   5    license that can be found in the LICENSE file.  */
   6
   7 #include "config.h"
   8
   9 #include <stddef.h>
  10 #include <stdlib.h>
  11
  12 #include "go-alloc.h"
  13 #include "runtime.h"
  14 #include "arch.h"
  15 #include "malloc.h"
  16
  17 /* Unset an environment variable from Go.  This is called by
  18    syscall.Unsetenv.  */
  19
  20 void unsetenv_c (String) __asm__ (GOSYM_PREFIX "syscall.unsetenv_c");
  21
  22 void
  23 unsetenv_c (String k)
  24 {
  25   const byte *ks;
  26   unsigned char *kn;
  27   intgo len;
  28
  29   ks = k.str;
  30   if (ks == NULL)
  31     ks = (const byte *) "";
  32   kn = NULL;
  33
  34 #ifdef HAVE_UNSETENV
  35
  36   if (ks != NULL && ks[k.len] != 0)
  37     {
  38       // Objects that are explicitly freed must be at least 16 bytes in size,
  39       // so that they are not allocated using tiny alloc.
  40       len = k.len + 1;
  41       if (len < TinySize)
  42         len = TinySize;
  43       kn = __go_alloc (len);
  44       __builtin_memcpy (kn, ks, k.len);
  45       ks = kn;
  46     }
  47
  48   unsetenv ((const char *) ks);
  49
  50 #endif /* !defined(HAVE_UNSETENV) */
  51
  52   if (kn != NULL)
  53     __go_free (kn);
  54 }