pollymc/HandleCrash.cpp

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/* Copyright 2013-2014 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?
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// 1234567890 1234
// The maximum number of digits in a unix timestamp when encoded in hexadecimal is about 17.
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// 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);
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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
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
}
// }}}