libgo/runtime/go-defer.c

   1 /* go-defer.c -- manage the defer stack.
   2
   3    Copyright 2009 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 <stddef.h>
   8
   9 #include "go-alloc.h"
  10 #include "go-panic.h"
  11 #include "go-defer.h"
  12
  13 /* This function is called each time we need to defer a call.  */
  14
  15 void
  16 __go_defer (void *frame, void (*pfn) (void *), void *arg)
  17 {
  18   struct __go_defer_stack *n;
  19
  20   if (__go_panic_defer == NULL)
  21     __go_panic_defer = ((struct __go_panic_defer_struct *)
  22                         __go_alloc (sizeof (struct __go_panic_defer_struct)));
  23
  24   n = (struct __go_defer_stack *) __go_alloc (sizeof (struct __go_defer_stack));
  25   n->__next = __go_panic_defer->__defer;
  26   n->__frame = frame;
  27   n->__panic = __go_panic_defer->__panic;
  28   n->__pfn = pfn;
  29   n->__arg = arg;
  30   n->__retaddr = NULL;
  31   __go_panic_defer->__defer = n;
  32 }
  33
  34 /* This function is called when we want to undefer the stack.  */
  35
  36 void
  37 __go_undefer (void *frame)
  38 {
  39   if (__go_panic_defer == NULL)
  40     return;
  41   while (__go_panic_defer->__defer != NULL
  42          && __go_panic_defer->__defer->__frame == frame)
  43     {
  44       struct __go_defer_stack *d;
  45       void (*pfn) (void *);
  46
  47       d = __go_panic_defer->__defer;
  48       pfn = d->__pfn;
  49       d->__pfn = NULL;
  50
  51       if (pfn != NULL)
  52         (*pfn) (d->__arg);
  53
  54       __go_panic_defer->__defer = d->__next;
  55       __go_free (d);
  56     }
  57 }
  58
  59 /* This function is called to record the address to which the deferred
  60    function returns.  This may in turn be checked by __go_can_recover.
  61    The frontend relies on this function returning false.  */
  62
  63 _Bool
  64 __go_set_defer_retaddr (void *retaddr)
  65 {
  66   if (__go_panic_defer != NULL && __go_panic_defer->__defer != NULL)
  67     __go_panic_defer->__defer->__retaddr = retaddr;
  68   return 0;
  69 }