libgo/runtime/go-callers.c

   1 /* go-callers.c -- get callers for Go.
   2
   3    Copyright 2012 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 "backtrace.h"
  10
  11 #include "runtime.h"
  12
  13 /* Argument passed to callback function.  */
  14
  15 struct callers_data
  16 {
  17   uintptr *pcbuf;
  18   int index;
  19   int max;
  20 };
  21
  22 /* Callback function for backtrace_simple.  Just collect the PC
  23    values.  Return zero to continue, non-zero to stop.  */
  24
  25 static int
  26 callback (void *data, uintptr_t pc)
  27 {
  28   struct callers_data *arg = (struct callers_data *) data;
  29
  30   arg->pcbuf[arg->index] = pc;
  31   ++arg->index;
  32   return arg->index >= arg->max;
  33 }
  34
  35 /* Error callback.  */
  36
  37 static void
  38 error_callback (void *data __attribute__ ((unused)),
  39                 const char *msg, int errnum)
  40 {
  41   if (errnum != 0)
  42     runtime_printf ("%s errno %d\n", msg, errnum);
  43   runtime_throw (msg);
  44 }
  45
  46 /* Gather caller PC's.  */
  47
  48 int32
  49 runtime_callers (int32 skip, uintptr *pcbuf, int32 m)
  50 {
  51   struct callers_data data;
  52
  53   data.pcbuf = pcbuf;
  54   data.index = 0;
  55   data.max = m;
  56   backtrace_simple (__go_get_backtrace_state (), skip + 1, callback,
  57                     error_callback, &data);
  58   return data.index;
  59 }
  60
  61 int Callers (int, struct __go_open_array)
  62   __asm__ ("runtime.Callers");
  63
  64 int
  65 Callers (int skip, struct __go_open_array pc)
  66 {
  67   /* In the Go 1 release runtime.Callers has an off-by-one error,
  68      which we can not correct because it would break backward
  69      compatibility.  Adjust SKIP here to be compatible.  */
  70   return runtime_callers (skip - 1, (uintptr *) pc.__values, pc.__count);
  71 }