libbacktrace/backtrace.c

   1 /* backtrace.c -- Entry point for stack backtrace library.
   2    Copyright (C) 2012-2018 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 <unistd.h>
  36 #include <sys/types.h>
  37
  38 #if !BACKTRACE_USES_MALLOC
  39 #include <sys/mman.h>
  40 #endif
  41
  42 #include "unwind.h"
  43 #include "backtrace.h"
  44 #include "backtrace-supported.h"
  45 #include "internal.h"
  46
  47 #ifndef MAP_ANONYMOUS
  48 #define MAP_ANONYMOUS MAP_ANON
  49 #endif
  50
  51 #ifndef MAP_FAILED
  52 #define MAP_FAILED ((void *)-1)
  53 #endif
  54
  55 /* The main backtrace_full routine.  */
  56
  57 /* Data passed through _Unwind_Backtrace.  */
  58
  59 struct backtrace_data
  60 {
  61   /* Number of frames to skip.  */
  62   int skip;
  63   /* Library state.  */
  64   struct backtrace_state *state;
  65   /* Callback routine.  */
  66   backtrace_full_callback callback;
  67   /* Error callback routine.  */
  68   backtrace_error_callback error_callback;
  69   /* Data to pass to callback routines.  */
  70   void *data;
  71   /* Value to return from backtrace_full.  */
  72   int ret;
  73   /* Whether there is any memory available.  */
  74   int can_alloc;
  75 };
  76
  77 /* Unwind library callback routine.  This is passed to
  78    _Unwind_Backtrace.  */
  79
  80 static _Unwind_Reason_Code
  81 unwind (struct _Unwind_Context *context, void *vdata)
  82 {
  83   struct backtrace_data *bdata = (struct backtrace_data *) vdata;
  84   uintptr_t pc;
  85   int ip_before_insn = 0;
  86
  87 #ifdef HAVE_GETIPINFO
  88   pc = _Unwind_GetIPInfo (context, &ip_before_insn);
  89 #else
  90   pc = _Unwind_GetIP (context);
  91 #endif
  92
  93   if (bdata->skip > 0)
  94     {
  95       --bdata->skip;
  96       return _URC_NO_REASON;
  97     }
  98
  99   if (!ip_before_insn)
 100     --pc;
 101
 102   if (!bdata->can_alloc)
 103     bdata->ret = bdata->callback (bdata->data, pc, NULL, 0, NULL);
 104   else
 105     bdata->ret = backtrace_pcinfo (bdata->state, pc, bdata->callback,
 106                                    bdata->error_callback, bdata->data);
 107   if (bdata->ret != 0)
 108     return _URC_END_OF_STACK;
 109
 110   return _URC_NO_REASON;
 111 }
 112
 113 /* Get a stack backtrace.  */
 114
 115 int
 116 backtrace_full (struct backtrace_state *state, int skip,
 117                 backtrace_full_callback callback,
 118                 backtrace_error_callback error_callback, void *data)
 119 {
 120   struct backtrace_data bdata;
 121
 122   bdata.skip = skip + 1;
 123   bdata.state = state;
 124   bdata.callback = callback;
 125   bdata.error_callback = error_callback;
 126   bdata.data = data;
 127   bdata.ret = 0;
 128
 129 #if !BACKTRACE_USES_MALLOC
 130   {
 131     size_t pagesize;
 132     void *page;
 133
 134     /* If we can't allocate any memory at all, don't try to produce
 135        file/line information.  */
 136     pagesize = getpagesize ();
 137     page = mmap (NULL, pagesize, PROT_READ | PROT_WRITE,
 138                  MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 139     if (page == MAP_FAILED)
 140       bdata.can_alloc = 0;
 141     else
 142       {
 143         munmap (page, pagesize);
 144         bdata.can_alloc = 1;
 145       }
 146   }
 147 #endif
 148
 149   _Unwind_Backtrace (unwind, &bdata);
 150   return bdata.ret;
 151 }