1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "base/debug/debugger.h" 6 #include "build/build_config.h" 7 8 #include <errno.h> 9 #include <execinfo.h> 10 #include <fcntl.h> 11 #include <stdio.h> 12 #include <stdlib.h> 13 #include <sys/param.h> 14 #include <sys/stat.h> 15 #if !defined(OS_NACL) 16 #include <sys/sysctl.h> 17 #endif 18 #include <sys/types.h> 19 #include <unistd.h> 20 21 #include <string> 22 #include <vector> 23 24 #if defined(__GLIBCXX__) 25 #include <cxxabi.h> 26 #endif 27 28 #if defined(OS_MACOSX) 29 #include <AvailabilityMacros.h> 30 #endif 31 32 #include <iostream> 33 34 #include "base/basictypes.h" 35 #include "base/eintr_wrapper.h" 36 #include "base/logging.h" 37 #include "base/memory/scoped_ptr.h" 38 #include "base/safe_strerror_posix.h" 39 #include "base/string_piece.h" 40 #include "base/stringprintf.h" 41 42 #if defined(USE_SYMBOLIZE) 43 #include "base/third_party/symbolize/symbolize.h" 44 #endif 45 46 namespace base { 47 namespace debug { 48 49 bool SpawnDebuggerOnProcess(unsigned /* process_id */) { 50 NOTIMPLEMENTED(); 51 return false; 52 } 53 54 #if defined(OS_MACOSX) 55 56 // Based on Apple's recommended method as described in 57 // http://developer.apple.com/qa/qa2004/qa1361.html 58 bool BeingDebugged() { 59 // If the process is sandboxed then we can't use the sysctl, so cache the 60 // value. 61 static bool is_set = false; 62 static bool being_debugged = false; 63 64 if (is_set) { 65 return being_debugged; 66 } 67 68 // Initialize mib, which tells sysctl what info we want. In this case, 69 // we're looking for information about a specific process ID. 70 int mib[] = { 71 CTL_KERN, 72 KERN_PROC, 73 KERN_PROC_PID, 74 getpid() 75 }; 76 77 // Caution: struct kinfo_proc is marked __APPLE_API_UNSTABLE. The source and 78 // binary interfaces may change. 79 struct kinfo_proc info; 80 size_t info_size = sizeof(info); 81 82 int sysctl_result = sysctl(mib, arraysize(mib), &info, &info_size, NULL, 0); 83 DCHECK_EQ(sysctl_result, 0); 84 if (sysctl_result != 0) { 85 is_set = true; 86 being_debugged = false; 87 return being_debugged; 88 } 89 90 // This process is being debugged if the P_TRACED flag is set. 91 is_set = true; 92 being_debugged = (info.kp_proc.p_flag & P_TRACED) != 0; 93 return being_debugged; 94 } 95 96 #elif defined(OS_LINUX) 97 98 // We can look in /proc/self/status for TracerPid. We are likely used in crash 99 // handling, so we are careful not to use the heap or have side effects. 100 // Another option that is common is to try to ptrace yourself, but then we 101 // can't detach without forking(), and that's not so great. 102 // static 103 bool BeingDebugged() { 104 int status_fd = open("/proc/self/status", O_RDONLY); 105 if (status_fd == -1) 106 return false; 107 108 // We assume our line will be in the first 1024 characters and that we can 109 // read this much all at once. In practice this will generally be true. 110 // This simplifies and speeds up things considerably. 111 char buf[1024]; 112 113 ssize_t num_read = HANDLE_EINTR(read(status_fd, buf, sizeof(buf))); 114 if (HANDLE_EINTR(close(status_fd)) < 0) 115 return false; 116 117 if (num_read <= 0) 118 return false; 119 120 StringPiece status(buf, num_read); 121 StringPiece tracer("TracerPid:\t"); 122 123 StringPiece::size_type pid_index = status.find(tracer); 124 if (pid_index == StringPiece::npos) 125 return false; 126 127 // Our pid is 0 without a debugger, assume this for any pid starting with 0. 128 pid_index += tracer.size(); 129 return pid_index < status.size() && status[pid_index] != '0'; 130 } 131 132 #elif defined(OS_NACL) 133 134 bool BeingDebugged() { 135 NOTIMPLEMENTED(); 136 return false; 137 } 138 139 #elif defined(OS_FREEBSD) 140 141 bool BeingDebugged() { 142 // TODO(benl): can we determine this under FreeBSD? 143 NOTIMPLEMENTED(); 144 return false; 145 } 146 147 #endif // defined(OS_FREEBSD) 148 149 // We want to break into the debugger in Debug mode, and cause a crash dump in 150 // Release mode. Breakpad behaves as follows: 151 // 152 // +-------+-----------------+-----------------+ 153 // | OS | Dump on SIGTRAP | Dump on SIGABRT | 154 // +-------+-----------------+-----------------+ 155 // | Linux | N | Y | 156 // | Mac | Y | N | 157 // +-------+-----------------+-----------------+ 158 // 159 // Thus we do the following: 160 // Linux: Debug mode, send SIGTRAP; Release mode, send SIGABRT. 161 // Mac: Always send SIGTRAP. 162 163 #if defined(NDEBUG) && !defined(OS_MACOSX) 164 #define DEBUG_BREAK() abort() 165 #elif defined(OS_NACL) 166 // The NaCl verifier doesn't let use use int3. For now, we call abort(). We 167 // should ask for advice from some NaCl experts about the optimum thing here. 168 // http://code.google.com/p/nativeclient/issues/detail?id=645 169 #define DEBUG_BREAK() abort() 170 #elif defined(ARCH_CPU_ARM_FAMILY) 171 #define DEBUG_BREAK() asm("bkpt 0") 172 #elif defined(ARCH_CPU_MIPS_FAMILY) 173 #define DEBUG_BREAK() asm("break 2") 174 #else 175 #define DEBUG_BREAK() asm("int3") 176 #endif 177 178 void BreakDebugger() { 179 DEBUG_BREAK(); 180 #if defined(NDEBUG) 181 _exit(1); 182 #endif 183 } 184 185 } // namespace debug 186 } // namespace base 187
