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30891f35fa
We stopped adding "Contributed by" or similar lines in sources in 2012 in favour of git logs and keeping the Contributors section of the glibc manual up to date. Removing these lines makes the license header a bit more consistent across files and also removes the possibility of error in attribution when license blocks or files are copied across since the contributed-by lines don't actually reflect reality in those cases. Move all "Contributed by" and similar lines (Written by, Test by, etc.) into a new file CONTRIBUTED-BY to retain record of these contributions. These contributors are also mentioned in manual/contrib.texi, so we just maintain this additional record as a courtesy to the earlier developers. The following scripts were used to filter a list of files to edit in place and to clean up the CONTRIBUTED-BY file respectively. These were not added to the glibc sources because they're not expected to be of any use in future given that this is a one time task: https://gist.github.com/siddhesh/b5ecac94eabfd72ed2916d6d8157e7dc https://gist.github.com/siddhesh/15ea1f5e435ace9774f485030695ee02 Reviewed-by: Carlos O'Donell <carlos@redhat.com>
117 lines
3.2 KiB
C
117 lines
3.2 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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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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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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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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#include <execinfo.h>
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#include <stdlib.h>
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#include <unwind-link.h>
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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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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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/* 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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/* %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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/* 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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/* 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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%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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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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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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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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if (size <= 0 || arg.unwind_link == NULL)
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return 0;
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UNWIND_LINK_PTR (arg.unwind_link, _Unwind_Backtrace)
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(backtrace_helper, &arg);
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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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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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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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