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Add customizable printer support to SignalHandling class #361

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Add customizable printer support to SignalHandling class #361

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70 changes: 63 additions & 7 deletions backward.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -92,6 +92,7 @@
#include <vector>
#include <exception>
#include <iterator>
#include <memory>

#if defined(BACKWARD_SYSTEM_LINUX)

Expand Down Expand Up @@ -4164,6 +4165,18 @@ class Printer {

class SignalHandling {
public:
using PrinterPtr = std::shared_ptr<Printer>;

// Replace the default printer with a custom one.
// The supplied printer is stored and used by all signal handling output.
void set_printer(PrinterPtr printer) {
if (printer) {
printer_ = std::move(printer);
}
}

PrinterPtr get_printer() const { return printer_; }

static std::vector<int> make_default_signals() {
const int posix_signals[] = {
// Signals for which the default action is "Core".
Expand All @@ -4188,7 +4201,14 @@ class SignalHandling {
}

SignalHandling(const std::vector<int> &posix_signals = make_default_signals())
: _loaded(false) {
: _loaded(false), printer_(std::make_shared<Printer>()) {
// Default printer configuration (can be overwritten via set_printer()).
printer_->snippet = false;
printer_->address = false;
printer_->object = false;
printer_->inliner_context_size = 0;
printer_->trace_context_size = 0;
instance() = this;
bool success = true;

const size_t stack_size = 1024 * 1024 * 8;
Expand Down Expand Up @@ -4229,6 +4249,12 @@ class SignalHandling {
_loaded = success;
}

~SignalHandling() {
if (instance() == this) {
instance() = nullptr;
}
}

bool loaded() const { return _loaded; }

static void handleSignal(int, siginfo_t *info, void *_ctx) {
Expand Down Expand Up @@ -4272,9 +4298,8 @@ class SignalHandling {
st.load_here(32, reinterpret_cast<void *>(uctx), info->si_addr);
}

Printer printer;
printer.address = true;
printer.print(st, stderr);
// Use the configured printer.
instance()->printer_->print(st, stderr);

#if (defined(_XOPEN_SOURCE) && _XOPEN_SOURCE >= 700) || \
(defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200809L)
Expand All @@ -4285,8 +4310,14 @@ class SignalHandling {
}

private:
static SignalHandling *&instance() {
static SignalHandling *inst = nullptr;
return inst;
}

details::handle<char *> _stack_content;
bool _loaded;
PrinterPtr printer_;

#ifdef __GNUC__
__attribute__((noreturn))
Expand All @@ -4310,8 +4341,18 @@ class SignalHandling {

class SignalHandling {
public:
using PrinterPtr = std::shared_ptr<Printer>;

void set_printer(PrinterPtr printer) {
if (printer) {
printer_ = std::move(printer);
}
}

PrinterPtr get_printer() const { return printer_; }

SignalHandling(const std::vector<int> & = std::vector<int>())
: reporter_thread_([]() {
: printer_(std::make_shared<Printer>()), reporter_thread_([]() {
/* We handle crashes in a utility thread:
backward structures and some Windows functions called here
need stack space, which we do not have when we encounter a
Expand All @@ -4333,6 +4374,9 @@ class SignalHandling {
}
cv().notify_one();
}) {
// Default printer configuration (can be overwritten via set_printer()).
printer_->address = true;
instance() = this;
SetUnhandledExceptionFilter(crash_handler);

signal(SIGABRT, signal_handler);
Expand All @@ -4348,6 +4392,9 @@ class SignalHandling {
bool loaded() const { return true; }

~SignalHandling() {
if (instance() == this) {
instance() = nullptr;
}
{
std::unique_lock<std::mutex> lk(mtx());
crashed() = crash_status::normal_exit;
Expand All @@ -4359,6 +4406,10 @@ class SignalHandling {
}

private:
static SignalHandling *&instance() {
static SignalHandling *inst = nullptr;
return inst;
}
static CONTEXT *ctx() {
static CONTEXT data;
return &data;
Expand Down Expand Up @@ -4465,17 +4516,19 @@ class SignalHandling {
// macros.
// StackTrace also requires that the PDBs are already loaded, which is done
// in the constructor of TraceResolver
Printer printer;
auto *inst = instance();
auto &printer = *inst->printer_;

StackTrace st;
st.set_machine_type(printer.resolver().machine_type());
st.set_thread_handle(thread_handle());
st.load_here(32 + skip_frames, ctx());
st.skip_n_firsts(skip_frames);

printer.address = true;
printer.print(st, std::cerr);
}

PrinterPtr printer_;
};

#endif // BACKWARD_SYSTEM_WINDOWS
Expand All @@ -4485,6 +4538,9 @@ class SignalHandling {
class SignalHandling {
public:
SignalHandling(const std::vector<int> & = std::vector<int>()) {}
using PrinterPtr = std::shared_ptr<Printer>;
void set_printer(PrinterPtr) {}
PrinterPtr get_printer() const { return PrinterPtr{}; }
bool init() { return false; }
bool loaded() { return false; }
};
Expand Down