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/*
* Perform stack unwinding by using the _Unwind_Backtrace.
*
* User application that wants to use backtrace needs to be
* compiled with -fasynchronous-unwind-tables option and -rdynamic to get full
* symbols printed.
*
* Copyright (C) 2009, 2010 STMicroelectronics Ltd.
*
* Author(s): Giuseppe Cavallaro <peppe.cavallaro@st.com>
* - Initial implementation for glibc
*
* Author(s): Carmelo Amoroso <carmelo.amoroso@st.com>
* - Reworked for uClibc
* - use dlsym/dlopen from libdl
* - rewrite initialisation to not use libc_once
* - make it available in static link too
*
* Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
*
*/
#include <libgcc_s.h>
#include <execinfo.h>
#include <dlfcn.h>
#include <stdlib.h>
#include <unwind.h>
#include <assert.h>
#include <stdio.h>
struct trace_arg
{
void **array;
int cnt, size;
};
#ifdef SHARED
static _Unwind_Reason_Code (*unwind_backtrace) (_Unwind_Trace_Fn, void *);
static _Unwind_Ptr (*unwind_getip) (struct _Unwind_Context *);
static void backtrace_init (void)
{
void *handle = dlopen (LIBGCC_S_SO, RTLD_LAZY);
if (handle == NULL
|| ((unwind_backtrace = dlsym (handle, "_Unwind_Backtrace")) == NULL)
|| ((unwind_getip = dlsym (handle, "_Unwind_GetIP")) == NULL)) {
printf(LIBGCC_S_SO " must be installed for backtrace to work\n");
abort();
}
}
#else
# define unwind_backtrace _Unwind_Backtrace
# define unwind_getip _Unwind_GetIP
#endif
static _Unwind_Reason_Code
backtrace_helper (struct _Unwind_Context *ctx, void *a)
{
struct trace_arg *arg = a;
assert (unwind_getip != NULL);
/* We are first called with address in the __backtrace function. Skip it. */
if (arg->cnt != -1)
arg->array[arg->cnt] = (void *) unwind_getip (ctx);
if (++arg->cnt == arg->size)
return _URC_END_OF_STACK;
return _URC_NO_REASON;
}
/*
* Perform stack unwinding by using the _Unwind_Backtrace.
*
*/
int backtrace (void **array, int size)
{
struct trace_arg arg = { .array = array, .size = size, .cnt = -1 };
#ifdef SHARED
if (unwind_backtrace == NULL)
backtrace_init();
#endif
if (size >= 1)
unwind_backtrace (backtrace_helper, &arg);
return arg.cnt != -1 ? arg.cnt : 0;
}
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