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#include <library/cpp/yt/backtrace/backtrace.h>
#include <library/cpp/yt/string/raw_formatter.h>
#include <util/system/compiler.h>
#include <dlfcn.h>
#include <cxxabi.h>
namespace NYT::NBacktrace {
////////////////////////////////////////////////////////////////////////////////
namespace {
int GetSymbolInfo(const void* pc, char* buffer, int length)
{
TBaseFormatter formatter(buffer, length);
// See http://www.codesourcery.com/cxx-abi/abi.html#mangling
// And, yes, dladdr() is not async signal safe. We can substitute it
// with hand-written symbolization code from google-glog in case of any trouble.
Dl_info info;
if (!dladdr(pc, &info)) {
return 0;
}
/*
* typedef struct {
* const char *dli_fname; // Pathname of shared object that
* // contains address
* void *dli_fbase; // Address at which shared object
* // is loaded
* const char *dli_sname; // Name of nearest symbol with address
* // lower than addr
* void *dli_saddr; // Exact address of symbol named
* // in dli_sname
* } Dl_info;
*
* If no symbol matching addr could be found, then dli_sname and dli_saddr are set to NULL.
*/
if (info.dli_sname && info.dli_saddr) {
formatter.AppendString("<");
int demangleStatus = 0;
if (info.dli_sname[0] == '_' && info.dli_sname[1] == 'Z') {
// This is also not async signal safe.
// But (ta-dah!) we can replace it with symbolization code from google-glob.
char* demangledName = abi::__cxa_demangle(info.dli_sname, 0, 0, &demangleStatus);
if (demangleStatus == 0) {
formatter.AppendString(demangledName);
} else {
formatter.AppendString(info.dli_sname);
}
free(demangledName);
} else {
formatter.AppendString(info.dli_sname);
}
formatter.AppendString("+");
formatter.AppendNumber((char*)pc - (char*)info.dli_saddr);
formatter.AppendString(">");
formatter.AppendString(" ");
}
if (info.dli_fname && info.dli_fbase) {
formatter.AppendString("(");
formatter.AppendString(info.dli_fname);
formatter.AppendString("+");
formatter.AppendNumber((char*)pc - (char*)info.dli_fbase);
formatter.AppendString(")");
}
return formatter.GetBytesWritten();
}
void DumpStackFrameInfo(TBaseFormatter* formatter, const void* pc)
{
formatter->AppendString("@ ");
const int width = (sizeof(void*) == 8 ? 12 : 8) + 2;
// +2 for "0x"; 12 for x86_64 because higher bits are always zeroed.
formatter->AppendNumberAsHexWithPadding(reinterpret_cast<uintptr_t>(pc), width);
formatter->AppendString(" ");
// Get the symbol from the previous address of PC,
// because PC may be in the next function.
formatter->Advance(GetSymbolInfo(
reinterpret_cast<const char*>(pc) - 1,
formatter->GetCursor(),
formatter->GetBytesRemaining()));
if (formatter->GetBytesRemaining() == 0) {
formatter->Revert(1);
}
formatter->AppendString("\n");
}
} // namespace
Y_WEAK void SymbolizeBacktrace(
TBacktrace backtrace,
const std::function<void(TStringBuf)>& frameCallback)
{
for (int i = 0; i < std::ssize(backtrace); ++i) {
TRawFormatter<1024> formatter;
formatter.Reset();
formatter.AppendNumber(i + 1, 10, 2);
formatter.AppendString(". ");
DumpStackFrameInfo(&formatter, backtrace[i]);
frameCallback(formatter.GetBuffer());
}
}
////////////////////////////////////////////////////////////////////////////////
} // namespace NYT::NBacktrace
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