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// Copyright (c) 2010 Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef CLIENT_LINUX_HANDLER_EXCEPTION_HANDLER_H_
#define CLIENT_LINUX_HANDLER_EXCEPTION_HANDLER_H_
#include <signal.h>
#include <stdint.h>
#include <stdio.h>
#include <sys/ucontext.h>
#include <string>
#include "client/linux/crash_generation/crash_generation_client.h"
#include "client/linux/handler/minidump_descriptor.h"
#include "client/linux/minidump_writer/minidump_writer.h"
#include "common/scoped_ptr.h"
#include "common/using_std_string.h"
#include "google_breakpad/common/minidump_format.h"
namespace google_breakpad {
// ExceptionHandler
//
// ExceptionHandler can write a minidump file when an exception occurs,
// or when WriteMinidump() is called explicitly by your program.
//
// To have the exception handler write minidumps when an uncaught exception
// (crash) occurs, you should create an instance early in the execution
// of your program, and keep it around for the entire time you want to
// have crash handling active (typically, until shutdown).
// (NOTE): There should be only be one this kind of exception handler
// object per process.
//
// If you want to write minidumps without installing the exception handler,
// you can create an ExceptionHandler with install_handler set to false,
// then call WriteMinidump. You can also use this technique if you want to
// use different minidump callbacks for different call sites.
//
// In either case, a callback function is called when a minidump is written,
// which receives the full path or file descriptor of the minidump. The
// caller can collect and write additional application state to that minidump,
// and launch an external crash-reporting application.
//
// Caller should try to make the callbacks as crash-friendly as possible,
// it should avoid use heap memory allocation as much as possible.
class ExceptionHandler {
public:
// A callback function to run before Breakpad performs any substantial
// processing of an exception. A FilterCallback is called before writing
// a minidump. |context| is the parameter supplied by the user as
// callback_context when the handler was created.
//
// If a FilterCallback returns true, Breakpad will continue processing,
// attempting to write a minidump. If a FilterCallback returns false,
// Breakpad will immediately report the exception as unhandled without
// writing a minidump, allowing another handler the opportunity to handle it.
typedef bool (*FilterCallback)(void *context);
// A callback function to run after the minidump has been written.
// |descriptor| contains the file descriptor or file path containing the
// minidump. |context| is the parameter supplied by the user as
// callback_context when the handler was created. |succeeded| indicates
// whether a minidump file was successfully written.
//
// If an exception occurred and the callback returns true, Breakpad will
// treat the exception as fully-handled, suppressing any other handlers from
// being notified of the exception. If the callback returns false, Breakpad
// will treat the exception as unhandled, and allow another handler to handle
// it. If there are no other handlers, Breakpad will report the exception to
// the system as unhandled, allowing a debugger or native crash dialog the
// opportunity to handle the exception. Most callback implementations
// should normally return the value of |succeeded|, or when they wish to
// not report an exception of handled, false. Callbacks will rarely want to
// return true directly (unless |succeeded| is true).
typedef bool (*MinidumpCallback)(const MinidumpDescriptor& descriptor,
void* context,
bool succeeded);
// In certain cases, a user may wish to handle the generation of the minidump
// themselves. In this case, they can install a handler callback which is
// called when a crash has occurred. If this function returns true, no other
// processing of occurs and the process will shortly be crashed. If this
// returns false, the normal processing continues.
typedef bool (*HandlerCallback)(const void* crash_context,
size_t crash_context_size,
void* context);
// Creates a new ExceptionHandler instance to handle writing minidumps.
// Before writing a minidump, the optional |filter| callback will be called.
// Its return value determines whether or not Breakpad should write a
// minidump. The minidump content will be written to the file path or file
// descriptor from |descriptor|, and the optional |callback| is called after
// writing the dump file, as described above.
// If install_handler is true, then a minidump will be written whenever
// an unhandled exception occurs. If it is false, minidumps will only
// be written when WriteMinidump is called.
// If |server_fd| is valid, the minidump is generated out-of-process. If it
// is -1, in-process generation will always be used.
ExceptionHandler(const MinidumpDescriptor& descriptor,
FilterCallback filter,
MinidumpCallback callback,
void* callback_context,
bool install_handler,
const int server_fd);
~ExceptionHandler();
const MinidumpDescriptor& minidump_descriptor() const {
return minidump_descriptor_;
}
void set_minidump_descriptor(const MinidumpDescriptor& descriptor) {
minidump_descriptor_ = descriptor;
}
void set_crash_handler(HandlerCallback callback) {
crash_handler_ = callback;
}
void set_crash_generation_client(CrashGenerationClient* client) {
crash_generation_client_.reset(client);
}
// Writes a minidump immediately. This can be used to capture the execution
// state independently of a crash.
// Returns true on success.
// If the ExceptionHandler has been created with a path, a new file is
// generated for each minidump. The file path can be retrieved in the
// MinidumpDescriptor passed to the MinidumpCallback or by accessing the
// MinidumpDescriptor directly from the ExceptionHandler (with
// minidump_descriptor()).
// If the ExceptionHandler has been created with a file descriptor, the file
// descriptor is repositioned to its beginning and the previous generated
// minidump is overwritten.
// Note that this method is not supposed to be called from a compromised
// context as it uses the heap.
bool WriteMinidump();
// Convenience form of WriteMinidump which does not require an
// ExceptionHandler instance.
static bool WriteMinidump(const string& dump_path,
MinidumpCallback callback,
void* callback_context);
// Write a minidump of |child| immediately. This can be used to
// capture the execution state of |child| independently of a crash.
// Pass a meaningful |child_blamed_thread| to make that thread in
// the child process the one from which a crash signature is
// extracted.
//
// WARNING: the return of this function *must* happen before
// the code that will eventually reap |child| executes.
// Otherwise there's a pernicious race condition in which |child|
// exits, is reaped, another process created with its pid, then that
// new process dumped.
static bool WriteMinidumpForChild(pid_t child,
pid_t child_blamed_thread,
const string& dump_path,
MinidumpCallback callback,
void* callback_context);
// This structure is passed to minidump_writer.h:WriteMinidump via an opaque
// blob. It shouldn't be needed in any user code.
struct CrashContext {
siginfo_t siginfo;
pid_t tid; // the crashing thread.
ucontext_t context;
#if !defined(__ARM_EABI__) && !defined(__mips__)
// #ifdef this out because FP state is not part of user ABI for Linux ARM.
// In case of MIPS Linux FP state is already part of ucontext_t so
// 'float_state' is not required.
fpstate_t float_state;
#endif
};
// Returns whether out-of-process dump generation is used or not.
bool IsOutOfProcess() const {
return crash_generation_client_.get() != NULL;
}
// Add information about a memory mapping. This can be used if
// a custom library loader is used that maps things in a way
// that the linux dumper can't handle by reading the maps file.
void AddMappingInfo(const string& name,
const uint8_t identifier[sizeof(MDGUID)],
uintptr_t start_address,
size_t mapping_size,
size_t file_offset);
// Register a block of memory of length bytes starting at address ptr
// to be copied to the minidump when a crash happens.
void RegisterAppMemory(void* ptr, size_t length);
// Unregister a block of memory that was registered with RegisterAppMemory.
void UnregisterAppMemory(void* ptr);
// Force signal handling for the specified signal.
bool SimulateSignalDelivery(int sig);
// Report a crash signal from an SA_SIGINFO signal handler.
bool HandleSignal(int sig, siginfo_t* info, void* uc);
private:
// Save the old signal handlers and install new ones.
static bool InstallHandlersLocked();
// Restore the old signal handlers.
static void RestoreHandlersLocked();
void PreresolveSymbols();
bool GenerateDump(CrashContext *context);
void SendContinueSignalToChild();
void WaitForContinueSignal();
static void SignalHandler(int sig, siginfo_t* info, void* uc);
static int ThreadEntry(void* arg);
bool DoDump(pid_t crashing_process, const void* context,
size_t context_size);
const FilterCallback filter_;
const MinidumpCallback callback_;
void* const callback_context_;
scoped_ptr<CrashGenerationClient> crash_generation_client_;
MinidumpDescriptor minidump_descriptor_;
// Must be volatile. The compiler is unaware of the code which runs in
// the signal handler which reads this variable. Without volatile the
// compiler is free to optimise away writes to this variable which it
// believes are never read.
volatile HandlerCallback crash_handler_;
// We need to explicitly enable ptrace of parent processes on some
// kernels, but we need to know the PID of the cloned process before we
// can do this. We create a pipe which we can use to block the
// cloned process after creating it, until we have explicitly enabled
// ptrace. This is used to store the file descriptors for the pipe
int fdes[2] = {-1, -1};
// Callers can add extra info about mappings for cases where the
// dumper code cannot extract enough information from /proc/<pid>/maps.
MappingList mapping_list_;
// Callers can request additional memory regions to be included in
// the dump.
AppMemoryList app_memory_list_;
};
typedef bool (*FirstChanceHandler)(int, siginfo_t*, void*);
void SetFirstChanceExceptionHandler(FirstChanceHandler callback);
typedef bool (*FirstChanceHandlerDeprecated)(int, void*, void*);
// Deprecated. Use SetFirstChanceExceptionHandler(FirstChanceHandler callback)
// instead.
void SetFirstChanceExceptionHandler(FirstChanceHandlerDeprecated callback);
} // namespace google_breakpad
#endif // CLIENT_LINUX_HANDLER_EXCEPTION_HANDLER_H_