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1 // Copyright (c) 2011, 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 //
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9 // notice, this list of conditions and the following disclaimer.
10 //     * Redistributions in binary form must reproduce the above
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13 // distribution.
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16 // this software without specific prior written permission.
17 //
18 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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28 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 
30 // crash_generator.h: Define the google_breakpad::CrashGenerator class,
31 // which is used to generate a crash (and a core dump file) for testing.
32 
33 #ifndef COMMON_LINUX_TESTS_CRASH_GENERATOR_H_
34 #define COMMON_LINUX_TESTS_CRASH_GENERATOR_H_
35 
36 #include <sys/resource.h>
37 
38 #include <string>
39 
40 #include "common/tests/auto_tempdir.h"
41 #include "common/using_std_string.h"
42 
43 namespace google_breakpad {
44 
45 // A utility class for generating a crash (and a core dump file) for
46 // testing. It creates a child process with the specified number of
47 // threads, which is then termainated by the specified signal. A core
48 // dump file is expected to be created upon the termination of the child
49 // process, which can then be used for testing code that processes core
50 // dump files.
51 class CrashGenerator {
52  public:
53   CrashGenerator();
54 
55   ~CrashGenerator();
56 
57   // Returns true if a core dump file named 'core' will be generated in
58   // the current directory for a test that produces a crash by checking
59   // if /proc/sys/kernel/core_pattern has the default value 'core'.
60   bool HasDefaultCorePattern() const;
61 
62   // Returns the expected path of the core dump file.
63   string GetCoreFilePath() const;
64 
65   // Returns the directory of a copy of proc files of the child process.
66   string GetDirectoryOfProcFilesCopy() const;
67 
68   // Creates a crash (and a core dump file) by creating a child process with
69   // |num_threads| threads, and the terminating the child process by sending
70   // a signal with number |crash_signal| to the |crash_thread|-th thread.
71   // Returns true on success.
72   bool CreateChildCrash(unsigned num_threads, unsigned crash_thread,
73                         int crash_signal, pid_t* child_pid);
74 
75   // Returns the thread ID of the |index|-th thread in the child process.
76   // This method does not validate |index|.
77   pid_t GetThreadId(unsigned index) const;
78 
79  private:
80   // Copies the following proc files of the process with |pid| to the directory
81   // at |path|: auxv, cmdline, environ, maps, status
82   // The directory must have been created. Returns true on success.
83   bool CopyProcFiles(pid_t pid, const char* path) const;
84 
85   // Creates |num_threads| threads in the child process.
86   void CreateThreadsInChildProcess(unsigned num_threads);
87 
88   // Sets the maximum size of core dump file (both the soft and hard limit)
89   // to |limit| bytes. Returns true on success.
90   bool SetCoreFileSizeLimit(rlim_t limit) const;
91 
92   // Creates a shared memory of |memory_size| bytes for communicating thread
93   // IDs between the parent and child process. Returns true on success.
94   bool MapSharedMemory(size_t memory_size);
95 
96   // Releases any shared memory created by MapSharedMemory(). Returns true on
97   // success.
98   bool UnmapSharedMemory();
99 
100   // Returns the pointer to the thread ID of the |index|-th thread in the child
101   // process. This method does not validate |index|.
102   pid_t* GetThreadIdPointer(unsigned index);
103 
104   // Temporary directory in which a core file is generated.
105   AutoTempDir temp_dir_;
106 
107   // Shared memory for communicating thread IDs between the parent and
108   // child process.
109   void* shared_memory_;
110 
111   // Number of bytes mapped for |shared_memory_|.
112   size_t shared_memory_size_;
113 };
114 
115 }  // namespace google_breakpad
116 
117 #endif  // COMMON_LINUX_TESTS_CRASH_GENERATOR_H_
118