| /* Return backtrace of current program state. |
| Copyright (C) 2003-2014 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| Contributed by Jakub Jelinek <jakub@redhat.com>, 2003. |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include <bits/libc-lock.h> |
| #include <dlfcn.h> |
| #include <execinfo.h> |
| #include <stdlib.h> |
| #include <unwind.h> |
| |
| struct trace_arg |
| { |
| void **array; |
| _Unwind_Word cfa; |
| int cnt; |
| int size; |
| }; |
| |
| #ifdef SHARED |
| static _Unwind_Reason_Code (*unwind_backtrace) (_Unwind_Trace_Fn, void *); |
| static _Unwind_Ptr (*unwind_getip) (struct _Unwind_Context *); |
| static _Unwind_Word (*unwind_getcfa) (struct _Unwind_Context *); |
| static void *libgcc_handle; |
| |
| |
| /* Dummy version in case libgcc_s does not contain the real code. */ |
| static _Unwind_Word |
| dummy_getcfa (struct _Unwind_Context *ctx __attribute__ ((unused))) |
| { |
| return 0; |
| } |
| |
| |
| static void |
| init (void) |
| { |
| libgcc_handle = __libc_dlopen ("libgcc_s.so.1"); |
| |
| if (libgcc_handle == NULL) |
| return; |
| |
| unwind_backtrace = __libc_dlsym (libgcc_handle, "_Unwind_Backtrace"); |
| unwind_getip = __libc_dlsym (libgcc_handle, "_Unwind_GetIP"); |
| if (unwind_getip == NULL) |
| unwind_backtrace = NULL; |
| unwind_getcfa = (__libc_dlsym (libgcc_handle, "_Unwind_GetCFA") |
| ?: dummy_getcfa); |
| } |
| #else |
| # define unwind_backtrace _Unwind_Backtrace |
| # define unwind_getip _Unwind_GetIP |
| # define unwind_getcfa _Unwind_GetCFA |
| #endif |
| |
| static _Unwind_Reason_Code |
| backtrace_helper (struct _Unwind_Context *ctx, void *a) |
| { |
| struct trace_arg *arg = a; |
| |
| /* We are first called with address in the __backtrace function. |
| Skip it. */ |
| if (arg->cnt != -1) |
| { |
| arg->array[arg->cnt] = (void *) unwind_getip (ctx); |
| |
| /* Check whether we make any progress. */ |
| _Unwind_Word cfa = unwind_getcfa (ctx); |
| |
| if (arg->cnt > 0 && arg->array[arg->cnt - 1] == arg->array[arg->cnt] |
| && cfa == arg->cfa) |
| return _URC_END_OF_STACK; |
| arg->cfa = cfa; |
| } |
| if (++arg->cnt == arg->size) |
| return _URC_END_OF_STACK; |
| return _URC_NO_REASON; |
| } |
| |
| int |
| __backtrace (array, size) |
| void **array; |
| int size; |
| { |
| struct trace_arg arg = { .array = array, .cfa = 0, .size = size, .cnt = -1 }; |
| #ifdef SHARED |
| __libc_once_define (static, once); |
| |
| __libc_once (once, init); |
| if (unwind_backtrace == NULL) |
| return 0; |
| #endif |
| |
| if (size >= 1) |
| unwind_backtrace (backtrace_helper, &arg); |
| |
| /* _Unwind_Backtrace seems to put NULL address above |
| _start. Fix it up here. */ |
| if (arg.cnt > 1 && arg.array[arg.cnt - 1] == NULL) |
| --arg.cnt; |
| return arg.cnt != -1 ? arg.cnt : 0; |
| } |
| weak_alias (__backtrace, backtrace) |
| libc_hidden_def (__backtrace) |
| |
| |
| #ifdef SHARED |
| /* Free all resources if necessary. */ |
| libc_freeres_fn (free_mem) |
| { |
| unwind_backtrace = NULL; |
| if (libgcc_handle != NULL) |
| { |
| __libc_dlclose (libgcc_handle); |
| libgcc_handle = NULL; |
| } |
| } |
| #endif |
