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 #include "array.h"
  13
  14 /* Argument passed to callback function.  */
  15
  16 struct callers_data
  17 {
  18   uintptr *pcbuf;
  19   int index;
  20   int max;
  21 };
  22
  23 /* Callback function for backtrace_simple.  Just collect the PC
  24    values.  Return zero to continue, non-zero to stop.  */
  25
  26 static int
  27 callback (void *data, uintptr_t pc)
  28 {
  29   struct callers_data *arg = (struct callers_data *) data;
  30
  31   arg->pcbuf[arg->index] = pc;
  32   ++arg->index;
  33   return arg->index >= arg->max;
  34 }
  35
  36 /* Error callback.  */
  37
  38 static void
  39 error_callback (void *data __attribute__ ((unused)),
  40                 const char *msg, int errnum)
  41 {
  42   if (errnum != 0)
  43     runtime_printf ("%s errno %d\n", msg, errnum);
  44   runtime_throw (msg);
  45 }
  46
  47 /* Gather caller PC's.  */
  48
  49 int32
  50 runtime_callers (int32 skip, uintptr *pcbuf, int32 m)
  51 {
  52   struct callers_data data;
  53
  54   data.pcbuf = pcbuf;
  55   data.index = 0;
  56   data.max = m;
  57   backtrace_simple (__go_get_backtrace_state (), skip + 1, callback,
  58                     error_callback, &data);
  59   return data.index;
  60 }
  61
  62 int Callers (int, struct __go_open_array)
  63   __asm__ ("runtime.Callers");
  64
  65 int
  66 Callers (int skip, struct __go_open_array pc)
  67 {
  68   /* In the Go 1 release runtime.Callers has an off-by-one error,
  69      which we can not correct because it would break backward
  70      compatibility.  Adjust SKIP here to be compatible.  */
  71   return runtime_callers (skip - 1, (uintptr *) pc.__values, pc.__count);
  72 }