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1 // Copyright (c) 2007, 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 // Author: Alfred Peng
31 
32 #ifndef CLIENT_SOLARIS_HANDLER_EXCEPTION_HANDLER_H__
33 #define CLIENT_SOLARIS_HANDLER_EXCEPTION_HANDLER_H__
34 
35 #include <map>
36 #include <string>
37 #include <vector>
38 
39 #include "client/solaris/handler/minidump_generator.h"
40 
41 namespace google_breakpad {
42 
43 using std::string;
44 
45 //
46 // ExceptionHandler
47 //
48 // ExceptionHandler can write a minidump file when an exception occurs,
49 // or when WriteMinidump() is called explicitly by your program.
50 //
51 // To have the exception handler write minidumps when an uncaught exception
52 // (crash) occurs, you should create an instance early in the execution
53 // of your program, and keep it around for the entire time you want to
54 // have crash handling active (typically, until shutdown).
55 // (NOTE): There should be only one this kind of exception handler
56 // object per process.
57 //
58 // If you want to write minidumps without installing the exception handler,
59 // you can create an ExceptionHandler with install_handler set to false,
60 // then call WriteMinidump.  You can also use this technique if you want to
61 // use different minidump callbacks for different call sites.
62 //
63 // In either case, a callback function is called when a minidump is written,
64 // which receives the unqiue id of the minidump.  The caller can use this
65 // id to collect and write additional application state, and to launch an
66 // external crash-reporting application.
67 //
68 // Caller should try to make the callbacks as crash-friendly as possible,
69 // it should avoid use heap memory allocation as much as possible.
70 //
71 class ExceptionHandler {
72  public:
73   // A callback function to run before Breakpad performs any substantial
74   // processing of an exception.  A FilterCallback is called before writing
75   // a minidump.  context is the parameter supplied by the user as
76   // callback_context when the handler was created.
77   //
78   // If a FilterCallback returns true, Breakpad will continue processing,
79   // attempting to write a minidump.  If a FilterCallback returns false,
80   // Breakpad  will immediately report the exception as unhandled without
81   // writing a minidump, allowing another handler the opportunity to handle it.
82   typedef bool (*FilterCallback)(void *context);
83 
84   // A callback function to run after the minidump has been written.
85   // minidump_id is a unique id for the dump, so the minidump
86   // file is <dump_path>/<minidump_id>.dmp.  context is the parameter supplied
87   // by the user as callback_context when the handler was created.  succeeded
88   // indicates whether a minidump file was successfully written.
89   //
90   // If an exception occurred and the callback returns true, Breakpad will
91   // treat the exception as fully-handled, suppressing any other handlers from
92   // being notified of the exception.  If the callback returns false, Breakpad
93   // will treat the exception as unhandled, and allow another handler to handle
94   // it. If there are no other handlers, Breakpad will report the exception to
95   // the system as unhandled, allowing a debugger or native crash dialog the
96   // opportunity to handle the exception.  Most callback implementations
97   // should normally return the value of |succeeded|, or when they wish to
98   // not report an exception of handled, false.  Callbacks will rarely want to
99   // return true directly (unless |succeeded| is true).
100   typedef bool (*MinidumpCallback)(const char *dump_path,
101                                    const char *minidump_id,
102                                    void *context,
103                                    bool succeeded);
104 
105   // Creates a new ExceptionHandler instance to handle writing minidumps.
106   // Before writing a minidump, the optional filter callback will be called.
107   // Its return value determines whether or not Breakpad should write a
108   // minidump.  Minidump files will be written to dump_path, and the optional
109   // callback is called after writing the dump file, as described above.
110   // If install_handler is true, then a minidump will be written whenever
111   // an unhandled exception occurs.  If it is false, minidumps will only
112   // be written when WriteMinidump is called.
113   ExceptionHandler(const string &dump_path,
114                    FilterCallback filter, MinidumpCallback callback,
115                    void *callback_context,
116                    bool install_handler);
117   ~ExceptionHandler();
118 
119   // Get and Set the minidump path.
dump_path()120   string dump_path() const { return dump_path_; }
set_dump_path(const string & dump_path)121   void set_dump_path(const string &dump_path) {
122     dump_path_ = dump_path;
123     dump_path_c_ = dump_path_.c_str();
124   }
125 
126   // Writes a minidump immediately.  This can be used to capture the
127   // execution state independently of a crash.  Returns true on success.
128   bool WriteMinidump();
129 
130   // Convenience form of WriteMinidump which does not require an
131   // ExceptionHandler instance.
132   static bool WriteMinidump(const string &dump_path,
133                             MinidumpCallback callback,
134                             void *callback_context);
135 
136  private:
137   // Setup crash handler.
138   void SetupHandler();
139   // Setup signal handler for a signal.
140   void SetupHandler(int signo);
141   // Teardown the handler for a signal.
142   void TeardownHandler(int signo);
143   // Teardown all handlers.
144   void TeardownAllHandlers();
145 
146   // Runs the main loop for the exception handler thread.
147   static void* ExceptionHandlerThreadMain(void *lpParameter);
148 
149   // Signal handler.
150   static void HandleException(int signo);
151 
152   // Write all the information to the dump file.
153   // If called from a signal handler, sighandler_ebp is the ebp of
154   // that signal handler's frame, and sig_ctx is an out parameter
155   // that will be set to point at the ucontext_t that was placed
156   // on the stack by the kernel.  You can pass zero and NULL
157   // for the second and third parameters if you are not calling
158   // this from a signal handler.
159   bool InternalWriteMinidump(int signo, uintptr_t sighandler_ebp,
160                              ucontext_t **sig_ctx);
161 
162  private:
163   // The callbacks before and after writing the dump file.
164   FilterCallback filter_;
165   MinidumpCallback callback_;
166   void *callback_context_;
167 
168   // The directory in which a minidump will be written, set by the dump_path
169   // argument to the constructor, or set_dump_path.
170   string dump_path_;
171   // C style dump path. Keep this when setting dump path, since calling
172   // c_str() of std::string when crashing may not be safe.
173   const char *dump_path_c_;
174 
175   // True if the ExceptionHandler installed an unhandled exception filter
176   // when created (with an install_handler parameter set to true).
177   bool installed_handler_;
178 
179   // Keep the previous handlers for the signal.
180   typedef void (*sighandler_t)(int);
181   std::map<int, sighandler_t> old_handlers_;
182 
183   // The global exception handler stack. This is need becuase there may exist
184   // multiple ExceptionHandler instances in a process. Each will have itself
185   // registered in this stack.
186   static std::vector<ExceptionHandler *> *handler_stack_;
187   // The index of the handler that should handle the next exception.
188   static int handler_stack_index_;
189   static pthread_mutex_t handler_stack_mutex_;
190 
191   // The minidump generator.
192   MinidumpGenerator minidump_generator_;
193 
194   // disallow copy ctor and operator=
195   explicit ExceptionHandler(const ExceptionHandler &);
196   void operator=(const ExceptionHandler &);
197 };
198 
199 }  // namespace google_breakpad
200 
201 #endif  // CLIENT_SOLARIS_HANDLER_EXCEPTION_HANDLER_H__
202