Emscripten experimentation

CMakeLists.txt

@@ -66,7 +66,40 @@ else()
 endif()
 
 # ========================================== Platform Support and Auto-config ==========================================
-include(cmake/Autoconfig.cmake)
+if(NOT EMSCRIPTEN)
+  include(cmake/Autoconfig.cmake)
+else()
+  if(
+    CPPTRACE_UNWIND_WITH_UNWIND OR
+    CPPTRACE_UNWIND_WITH_LIBUNWIND OR
+    CPPTRACE_UNWIND_WITH_EXECINFO OR
+    CPPTRACE_UNWIND_WITH_WINAPI OR
+    CPPTRACE_UNWIND_WITH_DBGHELP OR
+    CPPTRACE_UNWIND_WITH_NOTHING
+  )
+    message(FATAL_ERROR "Cpptrace config error: Unwinding back-end may not be specified under emscripten.")
+  endif()
+  if(
+    CPPTRACE_GET_SYMBOLS_WITH_LIBBACKTRACE OR
+    CPPTRACE_GET_SYMBOLS_WITH_LIBDL OR
+    CPPTRACE_GET_SYMBOLS_WITH_ADDR2LINE OR
+    CPPTRACE_GET_SYMBOLS_WITH_LIBDWARF OR
+    CPPTRACE_GET_SYMBOLS_WITH_DBGHELP OR
+    CPPTRACE_GET_SYMBOLS_WITH_NOTHING
+  )
+    message(FATAL_ERROR "Cpptrace config error: Symbol back-end may not be specified under emscripten.")
+  endif()
+  if(
+    CPPTRACE_DEMANGLE_WITH_CXXABI OR
+    CPPTRACE_DEMANGLE_WITH_WINAPI OR
+    CPPTRACE_DEMANGLE_WITH_NOTHING
+  )
+    message(FATAL_ERROR "Cpptrace config error: Demangling back-end may not be specified under emscripten.")
+  endif()
+  set(CPPTRACE_UNWIND_WITH_NOTHING On)
+  set(CPPTRACE_GET_SYMBOLS_WITH_NOTHING On)
+  set(CPPTRACE_DEMANGLE_WITH_NOTHING On)
+endif()
 
 # =================================================== Library Setup ====================================================
 
@@ -469,6 +502,13 @@ if(CPPTRACE_DEMANGLE_WITH_NOTHING)
   target_compile_definitions(${target_name} PUBLIC CPPTRACE_DEMANGLE_WITH_NOTHING)
 endif()
 
+# Emscripten
+if(EMSCRIPTEN)
+  target_compile_definitions(${target_name} PUBLIC CPPTRACE_EMSCRIPTEN)
+endif()
+
+# Other options
+
 if(NOT "${CPPTRACE_BACKTRACE_PATH}" STREQUAL "")
   target_compile_definitions(${target_name} PUBLIC CPPTRACE_BACKTRACE_PATH=${CPPTRACE_BACKTRACE_PATH})
 endif()

src/binary/module_base.cpp

@@ -68,7 +68,7 @@ namespace detail {
             return it->second;
         }
     }
-    #else // Windows
+    #elif IS_WINDOWS
     Result<std::uintptr_t, internal_error> get_module_image_base(const std::string& object_path) {
         static std::mutex mutex;
         std::lock_guard<std::mutex> lock(mutex);

src/binary/object.cpp

@@ -107,7 +107,7 @@ namespace detail {
         return frame;
     }
     #endif
-    #else
+    #elif IS_WINDOWS
     std::string get_module_name(HMODULE handle) {
         static std::mutex mutex;
         std::lock_guard<std::mutex> lock(mutex);
@@ -153,6 +153,10 @@ namespace detail {
         }
         return frame;
     }
+    #elif IS_EMSCRIPTEN
+    object_frame get_frame_object_info(frame_ptr) {
+        return {};
+    }
     #endif
 
     std::vector<object_frame> get_frames_object_info(const std::vector<frame_ptr>& addresses) {

src/binary/object.hpp

@@ -7,7 +7,6 @@
 #include <cstdint>
 
 namespace cpptrace {
-
 namespace detail {
     object_frame get_frame_object_info(frame_ptr address);
 

src/cpptrace.cpp

@@ -18,6 +18,7 @@
 #include "binary/object.hpp"
 #include "binary/safe_dl.hpp"
 #include "snippets/snippet.hpp"
+#include "platform/emscripten.hpp"
 
 namespace cpptrace {
     CPPTRACE_FORCE_NO_INLINE
@@ -396,12 +397,16 @@ namespace cpptrace {
     CPPTRACE_FORCE_NO_INLINE
     stacktrace generate_trace(std::size_t skip, std::size_t max_depth) {
         try {
+            #if IS_EMSCRIPTEN
+            return detail::generate_emscripten_trace(skip + 1, max_depth);
+            #else
             std::vector<frame_ptr> frames = detail::capture_frames(skip + 1, max_depth);
             std::vector<stacktrace_frame> trace = detail::resolve_frames(frames);
             for(auto& frame : trace) {
                 frame.symbol = detail::demangle(frame.symbol);
             }
             return {std::move(trace)};
+            #endif
         } catch(...) { // NOSONAR
             if(!detail::should_absorb_trace_exceptions()) {
                 throw;

src/platform/emscripten.hpp

@@ -0,0 +1,33 @@
+#ifndef EMSCRIPTEN_HPP
+#define EMSCRIPTEN_HPP
+
+#include "platform/platform.hpp"
+
+#if IS_EMSCRIPTEN
+
+#include <emscripten.h>
+#include <memory>
+#include "utils/microfmt.hpp"
+
+namespace cpptrace {
+namespace detail {
+    CPPTRACE_FORCE_NO_INLINE
+    stacktrace generate_emscripten_trace(std::size_t skip, std::size_t max_depth) {
+        int estimated_size = emscripten_get_callstack(0, nullptr, 0);
+        VERIFY(estimated_size >= 0);
+        // "Note that this might be fully accurate since subsequent calls will carry different line numbers, so it is
+        // best to allocate a few bytes extra to be safe."
+        // Thanks, emscripten
+        const auto max_size = estimated_size + 1000;
+        // actually do the trace now
+        std::unique_ptr<char[]> buffer(new char[max_size]);
+        emscripten_get_callstack(0, buffer.get(), max_size);
+        microfmt::print("{}\n", buffer.get());
+        return {};
+    }
+}
+}
+
+#endif
+
+#endif

src/platform/platform.hpp

@@ -14,6 +14,9 @@
 #elif defined(__APPLE__)
  #undef IS_APPLE
  #define IS_APPLE 1
+#elif defined(__EMSCRIPTEN__)
+ #undef IS_EMSCRIPTEN
+ #define IS_EMSCRIPTEN 1
 #else
  #error "Unexpected platform"
 #endif
@@ -32,7 +35,7 @@
  #undef IS_MSVC
  #define IS_MSVC 1
 #else
- #error "Unsupported compiler"
+//  #error "Unsupported compiler"
 #endif
 
 #define IS_LIBSTDCXX 0

src/symbols/symbols_core.cpp

@@ -84,7 +84,9 @@ namespace detail {
     }
 
     std::vector<stacktrace_frame> resolve_frames(const std::vector<object_frame>& frames) {
-        #if defined(CPPTRACE_GET_SYMBOLS_WITH_LIBDWARF) && defined(CPPTRACE_GET_SYMBOLS_WITH_DBGHELP)
+        #if IS_EMSCRIPTEN
+         return {}; // TODO
+        #elif defined(CPPTRACE_GET_SYMBOLS_WITH_LIBDWARF) && defined(CPPTRACE_GET_SYMBOLS_WITH_DBGHELP)
          std::vector<stacktrace_frame> trace = libdwarf::resolve_frames(frames);
          fill_blanks(trace, dbghelp::resolve_frames);
          return trace;
@@ -120,7 +122,9 @@ namespace detail {
     }
 
     std::vector<stacktrace_frame> resolve_frames(const std::vector<frame_ptr>& frames) {
-        #if defined(CPPTRACE_GET_SYMBOLS_WITH_LIBDWARF) \
+        #if IS_EMSCRIPTEN
+         return {}; // TODO
+        #elif defined(CPPTRACE_GET_SYMBOLS_WITH_LIBDWARF) \
             || defined(CPPTRACE_GET_SYMBOLS_WITH_ADDR2LINE)
          auto dlframes = get_frames_object_info(frames);
         #endif

test/demo.cpp

@@ -8,7 +8,7 @@
 void trace() {
     cpptrace::generate_trace().print();
     cpptrace::generate_trace().print_with_snippets();
-    throw cpptrace::logic_error("foobar");
+    // throw cpptrace::logic_error("foobar");
 }
 
 void foo(int n) {

test/unit/raw_trace.cpp

@@ -25,7 +25,7 @@ CPPTRACE_FORCE_NO_INLINE static void raw_trace_basic() {
     EXPECT_LE(raw_trace.frames[0], reinterpret_cast<uintptr_t>(raw_trace_basic) + 90);
 }
 
-#ifndef _MSC_VER
+#if !defined(_MSC_VER) && !defined(__EMSCRIPTEN__)
 CPPTRACE_FORCE_NO_INLINE void raw_trace_basic_precise() {
     a:
     auto raw_trace = cpptrace::generate_raw_trace();
@@ -46,7 +46,7 @@ CPPTRACE_FORCE_NO_INLINE void raw_trace_basic_precise() {
 
 TEST(RawTrace, Basic) {
     raw_trace_basic();
-    #ifndef _MSC_VER
+    #if !defined(_MSC_VER) && !defined(__EMSCRIPTEN__)
     raw_trace_basic_precise();
     #endif
     [[maybe_unused]] volatile int x = 0; // prevent raw_trace_basic_precise() above being a jmp
@@ -80,7 +80,7 @@ CPPTRACE_FORCE_NO_INLINE void record_parent(uintptr_t low_bound, uintptr_t high_
     parents.insert(parents.begin(), {low_bound, high_bound});
 }
 
-#ifndef _MSC_VER
+#if !defined(_MSC_VER) && !defined(__EMSCRIPTEN__)
 CPPTRACE_FORCE_NO_INLINE void raw_trace_multi_precise_3() {
     a:
     auto raw_trace = cpptrace::generate_raw_trace();
@@ -161,7 +161,7 @@ CPPTRACE_FORCE_NO_INLINE void raw_trace_multi_precise_1() {
 TEST(RawTrace, MultipleCalls) {
     parents.clear();
     raw_trace_multi_1();
-    #ifndef _MSC_VER
+    #if !defined(_MSC_VER) && !defined(__EMSCRIPTEN__)
     raw_trace_multi_precise_1();
     #endif
 }