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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 "linux/crash_generation/crash_generation_client.h"
+#include "linux/handler/minidump_descriptor.h"
+#include "linux/minidump_writer/minidump_writer.h"
+#include "common/scoped_ptr.h"
+#include "common/using_std_string.h"
+#include "google_breakpad/common/minidump_format.h"
+
+#ifdef MOZ_PHC
+#include "PHC.h"
+#else
+namespace mozilla { namespace phc { class AddrInfo {}; } }
+#endif
+
+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,
+ const mozilla::phc::AddrInfo* addr_info,
+ 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 wasteful_vector<uint8_t>& identifier,
+ 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,
+ const mozilla::phc::AddrInfo* addr_info);
+ 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);
+
+} // namespace google_breakpad
+
+#endif // CLIENT_LINUX_HANDLER_EXCEPTION_HANDLER_H_