// Copyright (c) 2005 - 2007, Google Inc.
// All rights reserved.
//
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//
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// notice, this list of conditions and the following disclaimer.
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Author: Arun Sharma
//
// Produce stack trace using libunwind
#include "utilities.h"
extern "C" {
#define UNW_LOCAL_ONLY
#include <libunwind.h>
}
#include "glog/raw_logging.h"
#include "stacktrace.h"
_START_GOOGLE_NAMESPACE_
// Sometimes, we can try to get a stack trace from within a stack
// trace, because libunwind can call mmap (maybe indirectly via an
// internal mmap based memory allocator), and that mmap gets trapped
// and causes a stack-trace request. If were to try to honor that
// recursive request, we'd end up with infinite recursion or deadlock.
// Luckily, it's safe to ignore those subsequent traces. In such
// cases, we return 0 to indicate the situation.
// We can use the GCC __thread syntax here since libunwind is not supported on
// Windows.
static __thread bool g_tl_entered; // Initialized to false.
// If you change this function, also change GetStackFrames below.
int GetStackTrace(void** result, int max_depth, int skip_count) {
void *ip;
int n = 0;
unw_cursor_t cursor;
unw_context_t uc;
if (g_tl_entered) {
return 0;
}
g_tl_entered = true;
unw_getcontext(&uc);
RAW_CHECK(unw_init_local(&cursor, &uc) >= 0, "unw_init_local failed");
skip_count++; // Do not include the "GetStackTrace" frame
while (n < max_depth) {
int ret = unw_get_reg(&cursor, UNW_REG_IP, (unw_word_t *) &ip);
if (ret < 0)
break;
if (skip_count > 0) {
skip_count--;
} else {
result[n++] = ip;
}
ret = unw_step(&cursor);
if (ret <= 0)
break;
}
g_tl_entered = false;
return n;
}
_END_GOOGLE_NAMESPACE_
