support backtraces on windows

Jamfile

@@ -64,6 +64,14 @@ rule linking ( properties * )
 
 	}
 
+	if <target-os>windows in $(properties)
+		&& ( <asserts>on in $(properties)
+			|| <variant>debug in $(properties)
+			|| <asio-debugging>on in $(properties) )
+	{
+		result += <library>dbghelp ;
+	}
+
 	# gcrypt libraries, if enabled
 	if <encryption>gcrypt in $(properties) || <encryption>openssl in $(properties)
 	{
@@ -187,10 +195,8 @@ rule building ( properties * )
 {
 	local result ;
 
-	if ( <target-os>linux in $(properties)
-		|| <target-os>darwin in $(properties) )
-		&& ( <toolset>gcc in $(properties)
-		|| <toolset>darwin in $(properties) )
+	if ( <variant>debug in $(properties)
+		|| <asserts>on in $(properties) )
 	{
 		result += <source>src/assert.cpp ;
 	}
@@ -345,6 +351,7 @@ lib advapi32 : : <name>Advapi32 ;
 lib user32 : : <name>User32 ;
 lib shell32 : : <name>shell32 ;
 lib gdi32 : : <name>gdi32 ;
+lib dbghelp : : <name>dbghelp ;
 
 # required for networking on beos
 lib netkit : : <name>net <search>/boot/system/lib <link>shared ;

include/libtorrent/assert.hpp

@@ -46,9 +46,8 @@ extern char const* libtorrent_assert_log;
 
 #include <string>
 
-#ifdef __GNUC__
 std::string demangle(char const* name);
-#endif
+void print_backtrace(char* out, int len);
 
 #if (defined __linux__ || defined __MACH__) && defined __GNUC__ && !TORRENT_USE_SYSTEM_ASSERT
 

include/libtorrent/debug.hpp

@@ -38,7 +38,6 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "libtorrent/assert.hpp"
 #include "libtorrent/thread.hpp"
 
-#include <execinfo.h>
 #include <map>
 
 std::string demangle(char const* name);
@@ -62,18 +61,9 @@ namespace libtorrent
 		async_t& a = _async_ops[name];
 		if (a.stack.empty())
 		{
-			void* stack[50];
-			int size = backtrace(stack, 50);
-			char** symbols = backtrace_symbols(stack, size);
-
-			for (int i = 1; i < size; ++i)
-			{
-				char str[200];
-				snprintf(str, sizeof(str), "%d: %s\n", i, demangle(symbols[i]).c_str());
-				a.stack += str;
-			}
-
-			free(symbols);
+			char stack_text[10000];
+			print_backtrace(stack_text, sizeof(stack_text));
+			a.stack = stack_text;
 		}
 		++a.refs;
 	}

src/assert.cpp

@@ -85,6 +85,21 @@ std::string demangle(char const* name)
 	free(unmangled);
 	return ret;
 }
+#elif defined WIN32
+
+#undef _WIN32_WINNT
+#define _WIN32_WINNT 0x0501 // XP
+
+#include "windows.h"
+#include "dbghelp.h"
+
+std::string demangle(char const* name) 
+{ 
+	char demangled_name[256];
+	if (UnDecorateSymbolName(name, demangled_name, sizeof(demangled_name), UNDNAME_NO_THROW_SIGNATURES) == 0)
+		demangled_name[0] = 0;
+	return demangled_name;
+}
 
 #else
 std::string demangle(char const* name) { return name; }
@@ -114,6 +129,69 @@ void print_backtrace(char* out, int len)
 
 	free(symbols);
 }
+
+#elif defined WIN32
+
+#undef _WIN32_WINNT
+#define _WIN32_WINNT 0x0501 // XP
+
+#include "windows.h"
+#include "libtorrent/utf8.hpp"
+
+#include "winbase.h"
+#include "dbghelp.h"
+
+void print_backtrace(char* out, int len)
+{
+	typedef USHORT (*RtlCaptureStackBackTrace_t)(
+		__in ULONG FramesToSkip,
+		__in ULONG FramesToCapture,
+		__out PVOID *BackTrace,
+		__out_opt PULONG BackTraceHash);
+
+	static RtlCaptureStackBackTrace_t RtlCaptureStackBackTrace = 0;
+
+	if (RtlCaptureStackBackTrace == 0)
+	{
+		// we don't actually have to free this library, everyone has it loaded
+		HMODULE lib = LoadLibrary(TEXT("kernel32.dll"));
+		RtlCaptureStackBackTrace = (RtlCaptureStackBackTrace_t)GetProcAddress(lib, "RtlCaptureStackBackTrace");
+		if (RtlCaptureStackBackTrace == 0)
+		{
+			out[0] = 0;
+			return;
+		}
+	}
+
+	int i;
+	void* stack[50];
+	int size = CaptureStackBackTrace(0, 50, stack, 0);
+
+	SYMBOL_INFO* symbol = (SYMBOL_INFO*)calloc(sizeof(SYMBOL_INFO) + MAX_SYM_NAME * sizeof(TCHAR), 1);
+	symbol->MaxNameLen = MAX_SYM_NAME;
+	symbol->SizeOfStruct = sizeof(SYMBOL_INFO);
+
+	HANDLE p = GetCurrentProcess();
+	static bool sym_initialized = false;
+	if (!sym_initialized)
+	{
+		sym_initialized = true;
+		SymInitialize(p, NULL, true);
+	}
+	for (i = 0; i < size && len > 0; ++i)
+	{
+		int ret;
+		if (SymFromAddr(p, uintptr_t(stack[i]), 0, symbol))
+			ret = snprintf(out, len, "%d: %s\n", i, symbol->Name);
+		else
+			ret = snprintf(out, len, "%d: <unknown>\n", i);
+
+		out += ret;
+		len -= ret;
+	}
+	free(symbol);
+}
+
 #else
 
 void print_backtrace(char* out, int len) {}