1  /* backtrace.c -- Entry point for stack backtrace library.
       2     Copyright (C) 2012-2023 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  }