libbacktrace/backtrace.c

   1 /* backtrace.c -- Entry point for stack backtrace library.
   2    Copyright (C) 2012-2020 Free Software Foundation, Inc.
   3    Written by Ian Lance Taylor, Google.
   4
   5 Redistribution and use in source and binary forms, with or without
   6 modification, are permitted provided that the following conditions are
   7 met:
   8
   9     (1) Redistributions of source code must retain the above copyright
  10     notice, this list of conditions and the following disclaimer.
  11
  12     (2) Redistributions in binary form must reproduce the above copyright
  13     notice, this list of conditions and the following disclaimer in
  14     the documentation and/or other materials provided with the
  15     distribution.
  16
  17     (3) The name of the author may not be used to
  18     endorse or promote products derived from this software without
  19     specific prior written permission.
  20
  21 THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  22 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  23 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  24 DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
  25 INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  26 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  27 SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28 HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  29 STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  30 IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  31 POSSIBILITY OF SUCH DAMAGE.  */
  32
  33 #include "config.h"
  34
  35 #include <sys/types.h>
  36
  37 #include "unwind.h"
  38 #include "backtrace.h"
  39 #include "internal.h"
  40
  41 /* The main backtrace_full routine.  */
  42
  43 /* Data passed through _Unwind_Backtrace.  */
  44
  45 struct backtrace_data
  46 {
  47   /* Number of frames to skip.  */
  48   int skip;
  49   /* Library state.  */
  50   struct backtrace_state *state;
  51   /* Callback routine.  */
  52   backtrace_full_callback callback;
  53   /* Error callback routine.  */
  54   backtrace_error_callback error_callback;
  55   /* Data to pass to callback routines.  */
  56   void *data;
  57   /* Value to return from backtrace_full.  */
  58   int ret;
  59   /* Whether there is any memory available.  */
  60   int can_alloc;
  61 };
  62
  63 /* Unwind library callback routine.  This is passed to
  64    _Unwind_Backtrace.  */
  65
  66 static _Unwind_Reason_Code
  67 unwind (struct _Unwind_Context *context, void *vdata)
  68 {
  69   struct backtrace_data *bdata = (struct backtrace_data *) vdata;
  70   uintptr_t pc;
  71   int ip_before_insn = 0;
  72
  73 #ifdef HAVE_GETIPINFO
  74   pc = _Unwind_GetIPInfo (context, &ip_before_insn);
  75 #else
  76   pc = _Unwind_GetIP (context);
  77 #endif
  78
  79   if (bdata->skip > 0)
  80     {
  81       --bdata->skip;
  82       return _URC_NO_REASON;
  83     }
  84
  85   if (!ip_before_insn)
  86     --pc;
  87
  88   if (!bdata->can_alloc)
  89     bdata->ret = bdata->callback (bdata->data, pc, NULL, 0, NULL);
  90   else
  91     bdata->ret = backtrace_pcinfo (bdata->state, pc, bdata->callback,
  92                                    bdata->error_callback, bdata->data);
  93   if (bdata->ret != 0)
  94     return _URC_END_OF_STACK;
  95
  96   return _URC_NO_REASON;
  97 }
  98
  99 /* Get a stack backtrace.  */
 100
 101 int __attribute__((noinline))
 102 backtrace_full (struct backtrace_state *state, int skip,
 103                 backtrace_full_callback callback,
 104                 backtrace_error_callback error_callback, void *data)
 105 {
 106   struct backtrace_data bdata;
 107   void *p;
 108
 109   bdata.skip = skip + 1;
 110   bdata.state = state;
 111   bdata.callback = callback;
 112   bdata.error_callback = error_callback;
 113   bdata.data = data;
 114   bdata.ret = 0;
 115
 116   /* If we can't allocate any memory at all, don't try to produce
 117      file/line information.  */
 118   p = backtrace_alloc (state, 4096, NULL, NULL);
 119   if (p == NULL)
 120     bdata.can_alloc = 0;
 121   else
 122     {
 123       backtrace_free (state, p, 4096, NULL, NULL);
 124       bdata.can_alloc = 1;
 125     }
 126
 127   _Unwind_Backtrace (unwind, &bdata);
 128   return bdata.ret;
 129 }