Line data Source code
1 : // Copyright (c) 2010 Google Inc.
2 : // All rights reserved.
3 : //
4 : // Redistribution and use in source and binary forms, with or without
5 : // modification, are permitted provided that the following conditions are
6 : // met:
7 : //
8 : // * Redistributions of source code must retain the above copyright
9 : // notice, this list of conditions and the following disclaimer.
10 : // * Redistributions in binary form must reproduce the above
11 : // copyright notice, this list of conditions and the following disclaimer
12 : // in the documentation and/or other materials provided with the
13 : // distribution.
14 : // * Neither the name of Google Inc. nor the names of its
15 : // contributors may be used to endorse or promote products derived from
16 : // this software without specific prior written permission.
17 : //
18 : // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 : // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 : // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 : // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 : // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 : // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 : // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 : // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 : // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 : // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 : // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 :
30 : #ifndef CLIENT_LINUX_HANDLER_EXCEPTION_HANDLER_H_
31 : #define CLIENT_LINUX_HANDLER_EXCEPTION_HANDLER_H_
32 :
33 : #include <signal.h>
34 : #include <stdint.h>
35 : #include <stdio.h>
36 : #include <sys/ucontext.h>
37 :
38 : #include <string>
39 :
40 : #include "linux/crash_generation/crash_generation_client.h"
41 : #include "linux/handler/minidump_descriptor.h"
42 : #include "linux/minidump_writer/minidump_writer.h"
43 : #include "common/scoped_ptr.h"
44 : #include "common/using_std_string.h"
45 : #include "google_breakpad/common/minidump_format.h"
46 :
47 : namespace google_breakpad {
48 :
49 : // ExceptionHandler
50 : //
51 : // ExceptionHandler can write a minidump file when an exception occurs,
52 : // or when WriteMinidump() is called explicitly by your program.
53 : //
54 : // To have the exception handler write minidumps when an uncaught exception
55 : // (crash) occurs, you should create an instance early in the execution
56 : // of your program, and keep it around for the entire time you want to
57 : // have crash handling active (typically, until shutdown).
58 : // (NOTE): There should be only be one this kind of exception handler
59 : // object per process.
60 : //
61 : // If you want to write minidumps without installing the exception handler,
62 : // you can create an ExceptionHandler with install_handler set to false,
63 : // then call WriteMinidump. You can also use this technique if you want to
64 : // use different minidump callbacks for different call sites.
65 : //
66 : // In either case, a callback function is called when a minidump is written,
67 : // which receives the full path or file descriptor of the minidump. The
68 : // caller can collect and write additional application state to that minidump,
69 : // and launch an external crash-reporting application.
70 : //
71 : // Caller should try to make the callbacks as crash-friendly as possible,
72 : // it should avoid use heap memory allocation as much as possible.
73 :
74 : class ExceptionHandler {
75 : public:
76 : // A callback function to run before Breakpad performs any substantial
77 : // processing of an exception. A FilterCallback is called before writing
78 : // a minidump. |context| is the parameter supplied by the user as
79 : // callback_context when the handler was created.
80 : //
81 : // If a FilterCallback returns true, Breakpad will continue processing,
82 : // attempting to write a minidump. If a FilterCallback returns false,
83 : // Breakpad will immediately report the exception as unhandled without
84 : // writing a minidump, allowing another handler the opportunity to handle it.
85 : typedef bool (*FilterCallback)(void *context);
86 :
87 : // A callback function to run after the minidump has been written.
88 : // |descriptor| contains the file descriptor or file path containing the
89 : // minidump. |context| is the parameter supplied by the user as
90 : // callback_context when the handler was created. |succeeded| indicates
91 : // whether a minidump file was successfully written.
92 : //
93 : // If an exception occurred and the callback returns true, Breakpad will
94 : // treat the exception as fully-handled, suppressing any other handlers from
95 : // being notified of the exception. If the callback returns false, Breakpad
96 : // will treat the exception as unhandled, and allow another handler to handle
97 : // it. If there are no other handlers, Breakpad will report the exception to
98 : // the system as unhandled, allowing a debugger or native crash dialog the
99 : // opportunity to handle the exception. Most callback implementations
100 : // should normally return the value of |succeeded|, or when they wish to
101 : // not report an exception of handled, false. Callbacks will rarely want to
102 : // return true directly (unless |succeeded| is true).
103 : typedef bool (*MinidumpCallback)(const MinidumpDescriptor& descriptor,
104 : void* context,
105 : bool succeeded);
106 :
107 : // In certain cases, a user may wish to handle the generation of the minidump
108 : // themselves. In this case, they can install a handler callback which is
109 : // called when a crash has occurred. If this function returns true, no other
110 : // processing of occurs and the process will shortly be crashed. If this
111 : // returns false, the normal processing continues.
112 : typedef bool (*HandlerCallback)(const void* crash_context,
113 : size_t crash_context_size,
114 : void* context);
115 :
116 : // Creates a new ExceptionHandler instance to handle writing minidumps.
117 : // Before writing a minidump, the optional |filter| callback will be called.
118 : // Its return value determines whether or not Breakpad should write a
119 : // minidump. The minidump content will be written to the file path or file
120 : // descriptor from |descriptor|, and the optional |callback| is called after
121 : // writing the dump file, as described above.
122 : // If install_handler is true, then a minidump will be written whenever
123 : // an unhandled exception occurs. If it is false, minidumps will only
124 : // be written when WriteMinidump is called.
125 : // If |server_fd| is valid, the minidump is generated out-of-process. If it
126 : // is -1, in-process generation will always be used.
127 : ExceptionHandler(const MinidumpDescriptor& descriptor,
128 : FilterCallback filter,
129 : MinidumpCallback callback,
130 : void* callback_context,
131 : bool install_handler,
132 : const int server_fd);
133 : ~ExceptionHandler();
134 :
135 0 : const MinidumpDescriptor& minidump_descriptor() const {
136 0 : return minidump_descriptor_;
137 : }
138 :
139 0 : void set_minidump_descriptor(const MinidumpDescriptor& descriptor) {
140 0 : minidump_descriptor_ = descriptor;
141 0 : }
142 :
143 : void set_crash_handler(HandlerCallback callback) {
144 : crash_handler_ = callback;
145 : }
146 :
147 : void set_crash_generation_client(CrashGenerationClient* client) {
148 : crash_generation_client_.reset(client);
149 : }
150 :
151 : // Writes a minidump immediately. This can be used to capture the execution
152 : // state independently of a crash.
153 : // Returns true on success.
154 : // If the ExceptionHandler has been created with a path, a new file is
155 : // generated for each minidump. The file path can be retrieved in the
156 : // MinidumpDescriptor passed to the MinidumpCallback or by accessing the
157 : // MinidumpDescriptor directly from the ExceptionHandler (with
158 : // minidump_descriptor()).
159 : // If the ExceptionHandler has been created with a file descriptor, the file
160 : // descriptor is repositioned to its beginning and the previous generated
161 : // minidump is overwritten.
162 : // Note that this method is not supposed to be called from a compromised
163 : // context as it uses the heap.
164 : bool WriteMinidump();
165 :
166 : // Convenience form of WriteMinidump which does not require an
167 : // ExceptionHandler instance.
168 : static bool WriteMinidump(const string& dump_path,
169 : MinidumpCallback callback,
170 : void* callback_context);
171 :
172 : // Write a minidump of |child| immediately. This can be used to
173 : // capture the execution state of |child| independently of a crash.
174 : // Pass a meaningful |child_blamed_thread| to make that thread in
175 : // the child process the one from which a crash signature is
176 : // extracted.
177 : //
178 : // WARNING: the return of this function *must* happen before
179 : // the code that will eventually reap |child| executes.
180 : // Otherwise there's a pernicious race condition in which |child|
181 : // exits, is reaped, another process created with its pid, then that
182 : // new process dumped.
183 : static bool WriteMinidumpForChild(pid_t child,
184 : pid_t child_blamed_thread,
185 : const string& dump_path,
186 : MinidumpCallback callback,
187 : void* callback_context);
188 :
189 : // This structure is passed to minidump_writer.h:WriteMinidump via an opaque
190 : // blob. It shouldn't be needed in any user code.
191 : struct CrashContext {
192 : siginfo_t siginfo;
193 : pid_t tid; // the crashing thread.
194 : struct ucontext context;
195 : #if !defined(__ARM_EABI__) && !defined(__mips__)
196 : // #ifdef this out because FP state is not part of user ABI for Linux ARM.
197 : // In case of MIPS Linux FP state is already part of struct
198 : // ucontext so 'float_state' is not required.
199 : fpstate_t float_state;
200 : #endif
201 : };
202 :
203 : // Returns whether out-of-process dump generation is used or not.
204 0 : bool IsOutOfProcess() const {
205 0 : return crash_generation_client_.get() != NULL;
206 : }
207 :
208 : // Add information about a memory mapping. This can be used if
209 : // a custom library loader is used that maps things in a way
210 : // that the linux dumper can't handle by reading the maps file.
211 : void AddMappingInfo(const string& name,
212 : const uint8_t identifier[sizeof(MDGUID)],
213 : uintptr_t start_address,
214 : size_t mapping_size,
215 : size_t file_offset);
216 :
217 : // Register a block of memory of length bytes starting at address ptr
218 : // to be copied to the minidump when a crash happens.
219 : void RegisterAppMemory(void* ptr, size_t length);
220 :
221 : // Unregister a block of memory that was registered with RegisterAppMemory.
222 : void UnregisterAppMemory(void* ptr);
223 :
224 : // Force signal handling for the specified signal.
225 : bool SimulateSignalDelivery(int sig);
226 :
227 : // Report a crash signal from an SA_SIGINFO signal handler.
228 : bool HandleSignal(int sig, siginfo_t* info, void* uc);
229 :
230 : private:
231 : // Save the old signal handlers and install new ones.
232 : static bool InstallHandlersLocked();
233 : // Restore the old signal handlers.
234 : static void RestoreHandlersLocked();
235 :
236 : void PreresolveSymbols();
237 : bool GenerateDump(CrashContext *context);
238 : void SendContinueSignalToChild();
239 : void WaitForContinueSignal();
240 :
241 : static void SignalHandler(int sig, siginfo_t* info, void* uc);
242 : static int ThreadEntry(void* arg);
243 : bool DoDump(pid_t crashing_process, const void* context,
244 : size_t context_size);
245 :
246 : const FilterCallback filter_;
247 : const MinidumpCallback callback_;
248 : void* const callback_context_;
249 :
250 : scoped_ptr<CrashGenerationClient> crash_generation_client_;
251 :
252 : MinidumpDescriptor minidump_descriptor_;
253 :
254 : // Must be volatile. The compiler is unaware of the code which runs in
255 : // the signal handler which reads this variable. Without volatile the
256 : // compiler is free to optimise away writes to this variable which it
257 : // believes are never read.
258 : volatile HandlerCallback crash_handler_;
259 :
260 : // We need to explicitly enable ptrace of parent processes on some
261 : // kernels, but we need to know the PID of the cloned process before we
262 : // can do this. We create a pipe which we can use to block the
263 : // cloned process after creating it, until we have explicitly enabled
264 : // ptrace. This is used to store the file descriptors for the pipe
265 : int fdes[2];
266 :
267 : // Callers can add extra info about mappings for cases where the
268 : // dumper code cannot extract enough information from /proc/<pid>/maps.
269 : MappingList mapping_list_;
270 :
271 : // Callers can request additional memory regions to be included in
272 : // the dump.
273 : AppMemoryList app_memory_list_;
274 : };
275 :
276 : } // namespace google_breakpad
277 :
278 : #endif // CLIENT_LINUX_HANDLER_EXCEPTION_HANDLER_H_
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