The Tor Browser: comparison toolkit/crashreporter/google-breakpad/src/client/linux/handler/exception

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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 <string>
+#include <vector>
+#include <pthread.h>
+#include <signal.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <sys/ucontext.h>
+#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;
+}
+// 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.
+struct ucontext context;
+#if !defined(__ARM_EABI__)
+// #ifdef this out because FP state is not part of user ABI for Linux ARM.
+struct _libc_fpstate 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_;
+HandlerCallback crash_handler_;
+// The global exception handler stack. This is need becuase there may exist
+// multiple ExceptionHandler instances in a process. Each will have itself
+// registered in this stack.
+static std::vector<ExceptionHandler*> *handler_stack_;
+static pthread_mutex_t handler_stack_mutex_;
+// 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];
+// 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_;
+};
+}  // namespace google_breakpad
+#endif  // CLIENT_LINUX_HANDLER_EXCEPTION_HANDLER_H_

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