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			118 lines
		
	
	
		
			3.3 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			118 lines
		
	
	
		
			3.3 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
| /* Return backtrace of current program state.
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|    Copyright (C) 1998-2021 Free Software Foundation, Inc.
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|    This file is part of the GNU C Library.
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|    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
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| 
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|    The GNU C Library is free software; you can redistribute it and/or
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|    modify it under the terms of the GNU Lesser General Public
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|    License as published by the Free Software Foundation; either
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|    version 2.1 of the License, or (at your option) any later version.
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| 
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|    The GNU C Library is distributed in the hope that it will be useful,
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|    but WITHOUT ANY WARRANTY; without even the implied warranty of
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|    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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|    Lesser General Public License for more details.
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| 
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|    You should have received a copy of the GNU Lesser General Public
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|    License along with the GNU C Library; if not, see
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|    <https://www.gnu.org/licenses/>.  */
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| 
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| #include <execinfo.h>
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| #include <stdlib.h>
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| #include <unwind-link.h>
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| 
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| struct trace_arg
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| {
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|   void **array;
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|   struct unwind_link *unwind_link;
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|   int cnt, size;
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|   void *lastebp, *lastesp;
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| };
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| 
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| static _Unwind_Reason_Code
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| backtrace_helper (struct _Unwind_Context *ctx, void *a)
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| {
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|   struct trace_arg *arg = a;
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| 
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|   /* We are first called with address in the __backtrace function.
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|      Skip it.  */
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|   if (arg->cnt != -1)
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|     arg->array[arg->cnt]
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|       = (void *) UNWIND_LINK_PTR (arg->unwind_link, _Unwind_GetIP) (ctx);
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|   if (++arg->cnt == arg->size)
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|     return _URC_END_OF_STACK;
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| 
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|   /* %ebp is DWARF2 register 5 on IA-32.  */
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|   arg->lastebp
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|     = (void *) UNWIND_LINK_PTR (arg->unwind_link, _Unwind_GetGR) (ctx, 5);
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|   arg->lastesp
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|     = (void *) UNWIND_LINK_PTR (arg->unwind_link, _Unwind_GetCFA) (ctx);
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|   return _URC_NO_REASON;
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| }
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| 
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| 
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| /* This is a global variable set at program start time.  It marks the
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|    highest used stack address.  */
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| extern void *__libc_stack_end;
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| 
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| 
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| /* This is the stack layout we see with every stack frame
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|    if not compiled without frame pointer.
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| 
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|             +-----------------+        +-----------------+
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|     %ebp -> | %ebp last frame--------> | %ebp last frame--->...
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|             |                 |        |                 |
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|             | return address  |        | return address  |
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|             +-----------------+        +-----------------+
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| 
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|    First try as far to get as far as possible using
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|    _Unwind_Backtrace which handles -fomit-frame-pointer
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|    as well, but requires .eh_frame info.  Then fall back to
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|    walking the stack manually.  */
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| 
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| struct layout
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| {
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|   struct layout *ebp;
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|   void *ret;
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| };
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| 
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| 
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| int
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| __backtrace (void **array, int size)
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| {
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|   struct trace_arg arg =
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|     {
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|      .array = array,
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|      .unwind_link = __libc_unwind_link_get (),
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|      .size = size,
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|      .cnt = -1,
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|     };
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| 
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|   if (size <= 0 || arg.unwind_link == NULL)
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|     return 0;
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| 
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|   UNWIND_LINK_PTR (arg.unwind_link, _Unwind_Backtrace)
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|     (backtrace_helper, &arg);
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| 
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|   if (arg.cnt > 1 && arg.array[arg.cnt - 1] == NULL)
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|     --arg.cnt;
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|   else if (arg.cnt < size)
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|     {
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|       struct layout *ebp = (struct layout *) arg.lastebp;
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| 
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|       while (arg.cnt < size)
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| 	{
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| 	  /* Check for out of range.  */
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| 	  if ((void *) ebp < arg.lastesp || (void *) ebp > __libc_stack_end
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| 	      || ((long) ebp & 3))
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| 	    break;
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| 
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| 	  array[arg.cnt++] = ebp->ret;
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| 	  ebp = ebp->ebp;
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| 	}
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|     }
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|   return arg.cnt != -1 ? arg.cnt : 0;
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| }
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| weak_alias (__backtrace, backtrace)
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| libc_hidden_def (__backtrace)
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