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/* go-panic.c -- support for the go panic function.

   Copyright 2009 The Go Authors. All rights reserved.

   Use of this source code is governed by a BSD-style

   license that can be found in the LICENSE file.  */

#include <stdio.h>

#include <stdlib.h>

#include "runtime.h"

#include "arch.h"

#include "malloc.h"

#include "go-alloc.h"

#include "go-defer.h"

#include "go-panic.h"

#include "go-string.h"

#include "interface.h"

/* Print the panic stack.  This is used when there is no recover.  */

static void

__printpanics (struct __go_panic_stack *p)

{

  if (p->__next != NULL)

    {

      __printpanics (p->__next);

      fprintf (stderr, "\t");

    }

  fprintf (stderr, "panic: ");

  printany (p->__arg);

  if (p->__was_recovered)

    fprintf (stderr, " [recovered]");

  fputc ('\n', stderr);

}

/* This implements __go_panic which is used for the panic

   function.  */

void

__go_panic (struct __go_empty_interface arg)

{

  G *g;

  struct __go_panic_stack *n;

  g = runtime_g ();

  n = (struct __go_panic_stack *) __go_alloc (sizeof (struct __go_panic_stack));

  n->__arg = arg;

  n->__next = g->panic;

  g->panic = n;

  /* Run all the defer functions.  */

  while (1)

    {

      struct __go_defer_stack *d;

      void (*pfn) (void *);

      d = g->defer;

      if (d == NULL)

        break;

      pfn = d->__pfn;

      d->__pfn = NULL;

      if (pfn != NULL)

        {

          (*pfn) (d->__arg);

          if (n->__was_recovered)

            {

              /* Some defer function called recover.  That means that

                 we should stop running this panic.  */

              g->panic = n->__next;

              __go_free (n);

              /* Now unwind the stack by throwing an exception.  The

                 compiler has arranged to create exception handlers in

                 each function which uses a defer statement.  These

                 exception handlers will check whether the entry on

                 the top of the defer stack is from the current

                 function.  If it is, we have unwound the stack far

                 enough.  */

              __go_unwind_stack ();

              /* __go_unwind_stack should not return.  */

              abort ();

            }

          /* Because we executed that defer function by a panic, and

             it did not call recover, we know that we are not

             returning from the calling function--we are panicing

             through it.  */

          *d->__frame = 0;

        }

      g->defer = d->__next;

      __go_free (d);

    }

  /* The panic was not recovered.  */

  runtime_startpanic ();

  __printpanics (g->panic);

  runtime_dopanic (0);

}