1 files changed, 376 insertions, 0 deletions
diff --git a/HandleCrash.cpp b/HandleCrash.cpp
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+/* Copyright 2014 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// This is the Unix implementation of MultiMC's crash handling system.
+#include <stdio.h>
+#include <iostream>
+#include <signal.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <time.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <sys/stat.h>
+
+#include <MultiMC.h>
+
+#if defined Q_OS_UNIX
+#include <sys/utsname.h>
+#include <execinfo.h>
+#elif defined Q_OS_WIN32
+#include <windows.h>
+#include <dbghelp.h>
+#include <WinBacktrace.h>
+#endif
+
+#include "BuildConfig.h"
+
+#include "HandleCrash.h"
+
+// The maximum number of frames to include in the backtrace.
+#define BT_SIZE 20
+
+
+#define DUMPF_NAME_FMT "mmc-crash-%X.bm" // Black magic? Bowel movement? Dump?
+//                      1234567890  1234
+// The maximum number of digits in a unix timestamp when encoded in hexadecimal is about 17.
+// Our format string is ~14 characters long.
+// The maximum length of the dump file's filename should be well over both of these. 42 is a good number.
+#define DUMPF_NAME_LEN 42
+
+// {{{ Platform hackery
+
+#if defined Q_OS_UNIX
+
+struct CrashData
+{
+	int signal = 0;
+};
+
+// This has to be declared here, after the CrashData struct, but before the function that uses it.
+void handleCrash(CrashData);
+
+void handler(int sig)
+{
+	CrashData cData;
+	cData.signal = sig;
+	handleCrash(cData);
+}
+
+#elif defined Q_OS_WIN32
+
+// Struct for storing platform specific crash information.
+// This gets passed into the generic handler, which will use
+// it to access platform specific information.
+struct CrashData
+{
+	EXCEPTION_RECORD* exceptionInfo;
+	CONTEXT* context;
+};
+
+void handleCrash(CrashData);
+
+LONG WINAPI ExceptionFilter(EXCEPTION_POINTERS* eInfo)
+{
+	CrashData cData;
+	cData.exceptionInfo = eInfo->ExceptionRecord;
+	cData.context = eInfo->ContextRecord;
+	handleCrash(cData);
+	return EXCEPTION_EXECUTE_HANDLER;
+}
+
+#endif
+
+// }}}
+
+// {{{ Handling
+
+#ifdef Q_OS_WIN32
+// #ThanksMicrosoft
+// Blame Microsoft for this atrocity.
+void dprintf(int fd, const char* fmt...)
+{
+	va_list args;
+	va_start(args, fmt);
+	char buffer[10240];
+	// Just sprintf to a really long string and hope it works...
+	// This is a hack, but I can't think of a better way to do it easily.
+	int len = vsnprintf(buffer, 10240, fmt, args);
+	printf(buffer, fmt, args);
+	write(fd, buffer, len);
+	va_end(args);
+}
+#endif
+
+void getVsnType(char* out);
+void readFromTo(int from, int to);
+
+void dumpErrorInfo(int dumpFile, CrashData crash)
+{
+#ifdef Q_OS_UNIX
+	// TODO: Moar unix
+	dprintf(dumpFile, "Signal: %d\n", crash.signal);
+#elif defined Q_OS_WIN32
+	EXCEPTION_RECORD* excInfo = crash.exceptionInfo;
+
+	dprintf(dumpFile, "Exception Code: %d\n", excInfo->ExceptionCode);
+	dprintf(dumpFile, "Exception Address: 0x%0X\n", excInfo->ExceptionAddress);
+#endif
+}
+
+void dumpMiscInfo(int dumpFile)
+{
+	char vsnType[42]; // The version type. If it's more than 42 chars, the universe might implode...
+
+	// Get MMC info.
+	getVsnType(vsnType);
+
+	// Get MMC info.
+	getVsnType(vsnType);
+
+	dprintf(dumpFile, "MultiMC Version: %s\n", BuildConfig.VERSION_CSTR);
+	dprintf(dumpFile, "MultiMC Version Type: %s\n", vsnType);
+}
+
+void dumpBacktrace(int dumpFile, CrashData crash)
+{
+#ifdef Q_OS_UNIX
+	// Variables for storing crash info.
+	void* trace[BT_SIZE]; 	// Backtrace frames
+	size_t size; 			// The backtrace size
+
+	// Get the backtrace.
+	size = backtrace(trace, BT_SIZE);
+
+	// Dump the backtrace
+	dprintf(dumpFile, "---- BEGIN BACKTRACE ----\n");
+	backtrace_symbols_fd(trace, size, dumpFile);
+	dprintf(dumpFile, "---- END BACKTRACE ----\n");
+#elif defined Q_OS_WIN32
+	dprintf(dumpFile, "---- BEGIN BACKTRACE ----\n");
+
+	StackFrame stack[BT_SIZE];
+	size_t size;
+
+	SYMBOL_INFO *symbol;
+	HANDLE process;
+
+	size = getBacktrace(stack, BT_SIZE, *crash.context);
+
+	// FIXME: Accessing heap memory is supposedly "dangerous",
+	// but I can't find another way of doing this.
+
+	// Initialize
+	process = GetCurrentProcess();
+	if (!SymInitialize(process, NULL, true))
+	{
+		dprintf(dumpFile, "Failed to initialize symbol handler. Can't print stack trace.\n");
+		dprintf(dumpFile, "Here's a list of addresses in the call stack instead:\n");
+		for(int i = 0; i < size; i++)
+		{
+			dprintf(dumpFile, "0x%0X\n", (DWORD64)stack[i].address);
+		}
+	} else {
+		// Allocate memory... ._.
+		symbol = (SYMBOL_INFO *) calloc(sizeof(SYMBOL_INFO) + 256 * sizeof(char), 1);
+		symbol->MaxNameLen = 255;
+		symbol->SizeOfStruct = sizeof(SYMBOL_INFO);
+
+		// Dump stacktrace
+		for(int i = 0; i < size; i++)
+		{
+			DWORD64 addr = (DWORD64)stack[i].address;
+			if (!SymFromAddr(process, (DWORD64)(addr), 0, symbol))
+				dprintf(dumpFile, "?? - 0x%0X\n", addr);
+			else
+				dprintf(dumpFile, "%s - 0x%0X\n", symbol->Name, symbol->Address);
+		}
+
+		free(symbol);
+	}
+
+	dprintf(dumpFile, "---- END BACKTRACE ----\n");
+#endif
+}
+
+void dumpSysInfo(int dumpFile)
+{
+#ifdef Q_OS_UNIX
+	bool gotSysInfo = false;	// True if system info check succeeded
+	utsname sysinfo;			// System information
+
+	// Dump system info
+	if (uname(&sysinfo) >= 0)
+	{
+		dprintf(dumpFile, "OS System: %s\n", sysinfo.sysname);
+		dprintf(dumpFile, "OS Machine: %s\n", sysinfo.machine);
+		dprintf(dumpFile, "OS Release: %s\n", sysinfo.release);
+		dprintf(dumpFile, "OS Version: %s\n", sysinfo.version);
+	} else {
+		dprintf(dumpFile, "OS System: Unknown Unix");
+	}
+#else
+	// TODO: Get more information here.
+	dprintf(dumpFile, "OS System: Windows");
+#endif
+}
+
+void dumpLogs(int dumpFile)
+{
+	int otherFile;
+
+	// Attempt to attach the log file if the logger was initialized.
+	dprintf(dumpFile, "---- BEGIN LOGS ----\n");
+	if (loggerInitialized)
+	{
+		otherFile = open("MultiMC-0.log", O_RDONLY);
+		readFromTo(otherFile, dumpFile);
+	} else {
+		dprintf(dumpFile, "Logger not initialized.\n");
+	}
+	dprintf(dumpFile, "---- END LOGS ----\n");
+}
+
+// The signal handler. If this function is called, it means shit has probably collided with some sort of device one might use to keep oneself cool.
+// This is the generic part of the code that will be called after platform specific handling is finished.
+void handleCrash(CrashData crash)
+{
+#ifdef Q_OS_UNIX
+	fprintf(stderr, "Fatal error! Received signal %d\n", crash.signal);
+#endif
+
+	time_t unixTime = 0;		// Unix timestamp. Used to give our crash dumps "unique" names.
+
+	char dumpFileName[DUMPF_NAME_LEN]; // The name of the file we're dumping to.
+	int dumpFile; // File descriptor for our dump file.
+
+	// Determine what our dump file should be called.
+	// We'll just call it "mmc-crash-<unixtime>.dump"
+	// First, check the time.
+	time(&unixTime);
+
+	// Now we get to do some !!FUN!! hackery to ensure we don't use the stack when we convert
+	// the timestamp from an int to a string. To do this, we just allocate a fixed size array
+	// of chars on the stack, and sprintf into it. We know the timestamp won't ever be longer
+	// than a certain number of digits, so this should work just fine.
+	// sprintf doesn't support writing signed values as hex, so this breaks on negative timestamps.
+	// It really shouldn't matter, though...
+	sprintf(dumpFileName, DUMPF_NAME_FMT, unixTime);
+
+	// Now, we need to open the file.
+	// Fail if it already exists. This should never happen.
+	dumpFile = open(dumpFileName, O_WRONLY | O_CREAT | O_TRUNC, 0644);
+
+
+	if (dumpFile >= 0)
+	{
+		// If we opened the dump file successfully.
+		// Dump everything we can and GTFO.
+		fprintf(stderr, "Dumping crash report to %s\n", dumpFileName);
+
+		// Dump misc info
+		dprintf(dumpFile, "Unix Time: %d\n", unixTime);
+		dumpErrorInfo(dumpFile, crash);
+		dumpMiscInfo(dumpFile);
+
+		dprintf(dumpFile, "\n");
+
+		dumpSysInfo(dumpFile);
+
+		dprintf(dumpFile, "\n");
+
+		dumpBacktrace(dumpFile, crash);
+
+		dprintf(dumpFile, "\n");
+
+		// DIE DIE DIE!
+		exit(1);
+	}
+	else
+	{
+		fprintf(stderr, "Failed to open dump file %s to write crash info (ERRNO: %d)\n", dumpFileName, errno);
+		exit(2);
+	}
+}
+
+
+// Reads data from the file descriptor on the first argument into the second argument.
+void readFromTo(int from, int to)
+{
+	char buffer[1024];
+	size_t lastread = 1;
+	while (lastread > 0)
+	{
+		lastread = read(from, buffer, 1024);
+		if (lastread > 0) write(to, buffer, lastread);
+	}
+}
+
+// Writes the current version type to the given char buffer.
+void getVsnType(char* out)
+{
+	switch (BuildConfig.versionTypeEnum)
+	{
+		case Config::Release:
+			sprintf(out, "Release");
+			break;
+		case Config::ReleaseCandidate:
+			sprintf(out, "ReleaseCandidate");
+			break;
+		case Config::Development:
+			sprintf(out, "Development");
+			break;
+		default:
+			sprintf(out, "Unknown");
+			break;
+	}
+}
+
+// }}}
+
+// {{{ Misc
+
+#if defined TEST_SEGV
+// Causes a crash. For testing.
+void testCrash()
+{
+	char* lol = (char*)MMC->settings().get();
+	lol -= 8;
+
+	// Throw shit at the fan.
+	for (int i = 0; i < 8; i++)
+		lol[i] = 'f';
+}
+#endif
+
+// Initializes the Unix crash handler.
+void initBlackMagic()
+{
+#ifdef Q_OS_UNIX
+	// Register the handler.
+	signal(SIGSEGV, handler);
+	signal(SIGABRT, handler);
+#elif defined Q_OS_WIN32
+	// I hate Windows
+	SetUnhandledExceptionFilter(ExceptionFilter);
+#endif
+
+#ifdef TEST_SEGV
+	testCrash();
+#endif
+}
+
+// }}}
+