1 //===- Signals.cpp - Generic Unix Signals Implementation -----*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines some helpful functions for dealing with the possibility of
11 // Unix signals occurring while your program is running.
13 //===----------------------------------------------------------------------===//
16 #include "llvm/ADT/STLExtras.h"
17 #include "llvm/Support/Mutex.h"
22 # include <execinfo.h> // For backtrace().
30 #if HAVE_DLFCN_H && __GNUG__
35 #include <mach/mach.h>
40 static RETSIGTYPE SignalHandler(int Sig); // defined below.
42 static SmartMutex<true> SignalsMutex;
44 /// InterruptFunction - The function to call if ctrl-c is pressed.
45 static void (*InterruptFunction)() = 0;
47 static std::vector<std::string> FilesToRemove;
48 static std::vector<std::pair<void(*)(void*), void*> > CallBacksToRun;
50 // IntSigs - Signals that may interrupt the program at any time.
51 static const int IntSigs[] = {
52 SIGHUP, SIGINT, SIGQUIT, SIGPIPE, SIGTERM, SIGUSR1, SIGUSR2
54 static const int *const IntSigsEnd =
55 IntSigs + sizeof(IntSigs) / sizeof(IntSigs[0]);
57 // KillSigs - Signals that are synchronous with the program that will cause it
59 static const int KillSigs[] = {
60 SIGILL, SIGTRAP, SIGABRT, SIGFPE, SIGBUS, SIGSEGV
74 static const int *const KillSigsEnd =
75 KillSigs + sizeof(KillSigs) / sizeof(KillSigs[0]);
77 static unsigned NumRegisteredSignals = 0;
81 } RegisteredSignalInfo[(sizeof(IntSigs)+sizeof(KillSigs))/sizeof(KillSigs[0])];
84 static void RegisterHandler(int Signal) {
85 assert(NumRegisteredSignals <
86 sizeof(RegisteredSignalInfo)/sizeof(RegisteredSignalInfo[0]) &&
87 "Out of space for signal handlers!");
89 struct sigaction NewHandler;
91 NewHandler.sa_handler = SignalHandler;
92 NewHandler.sa_flags = SA_NODEFER|SA_RESETHAND;
93 sigemptyset(&NewHandler.sa_mask);
95 // Install the new handler, save the old one in RegisteredSignalInfo.
96 sigaction(Signal, &NewHandler,
97 &RegisteredSignalInfo[NumRegisteredSignals].SA);
98 RegisteredSignalInfo[NumRegisteredSignals].SigNo = Signal;
99 ++NumRegisteredSignals;
102 static void RegisterHandlers() {
103 // If the handlers are already registered, we're done.
104 if (NumRegisteredSignals != 0) return;
106 std::for_each(IntSigs, IntSigsEnd, RegisterHandler);
107 std::for_each(KillSigs, KillSigsEnd, RegisterHandler);
110 static void UnregisterHandlers() {
111 // Restore all of the signal handlers to how they were before we showed up.
112 for (unsigned i = 0, e = NumRegisteredSignals; i != e; ++i)
113 sigaction(RegisteredSignalInfo[i].SigNo,
114 &RegisteredSignalInfo[i].SA, 0);
115 NumRegisteredSignals = 0;
119 /// RemoveFilesToRemove - Process the FilesToRemove list. This function
120 /// should be called with the SignalsMutex lock held.
121 /// NB: This must be an async signal safe function. It cannot allocate or free
122 /// memory, even in debug builds.
123 static void RemoveFilesToRemove() {
124 // Note: avoid iterators in case of debug iterators that allocate or release
126 for (unsigned i = 0, e = FilesToRemove.size(); i != e; ++i) {
127 // Note that we don't want to use any external code here, and we don't care
128 // about errors. We're going to try as hard as we can as often as we need
129 // to to make these files go away. If these aren't files, too bad.
131 // We do however rely on a std::string implementation for which repeated
132 // calls to 'c_str()' don't allocate memory. We pre-call 'c_str()' on all
133 // of these strings to try to ensure this is safe.
134 unlink(FilesToRemove[i].c_str());
138 // SignalHandler - The signal handler that runs.
139 static RETSIGTYPE SignalHandler(int Sig) {
140 // Restore the signal behavior to default, so that the program actually
141 // crashes when we return and the signal reissues. This also ensures that if
142 // we crash in our signal handler that the program will terminate immediately
143 // instead of recursing in the signal handler.
144 UnregisterHandlers();
146 // Unmask all potentially blocked kill signals.
148 sigfillset(&SigMask);
149 sigprocmask(SIG_UNBLOCK, &SigMask, 0);
151 SignalsMutex.acquire();
152 RemoveFilesToRemove();
154 if (std::find(IntSigs, IntSigsEnd, Sig) != IntSigsEnd) {
155 if (InterruptFunction) {
156 void (*IF)() = InterruptFunction;
157 SignalsMutex.release();
158 InterruptFunction = 0;
159 IF(); // run the interrupt function.
163 SignalsMutex.release();
164 raise(Sig); // Execute the default handler.
168 SignalsMutex.release();
170 // Otherwise if it is a fault (like SEGV) run any handler.
171 for (unsigned i = 0, e = CallBacksToRun.size(); i != e; ++i)
172 CallBacksToRun[i].first(CallBacksToRun[i].second);
175 void llvm::sys::RunInterruptHandlers() {
176 SignalsMutex.acquire();
177 RemoveFilesToRemove();
178 SignalsMutex.release();
181 void llvm::sys::SetInterruptFunction(void (*IF)()) {
182 SignalsMutex.acquire();
183 InterruptFunction = IF;
184 SignalsMutex.release();
188 // RemoveFileOnSignal - The public API
189 bool llvm::sys::RemoveFileOnSignal(const sys::Path &Filename,
190 std::string* ErrMsg) {
191 SignalsMutex.acquire();
192 std::string *OldPtr = FilesToRemove.empty() ? 0 : &FilesToRemove[0];
193 FilesToRemove.push_back(Filename.str());
195 // We want to call 'c_str()' on every std::string in this vector so that if
196 // the underlying implementation requires a re-allocation, it happens here
197 // rather than inside of the signal handler. If we see the vector grow, we
198 // have to call it on every entry. If it remains in place, we only need to
199 // call it on the latest one.
200 if (OldPtr == &FilesToRemove[0])
201 FilesToRemove.back().c_str();
203 for (unsigned i = 0, e = FilesToRemove.size(); i != e; ++i)
204 FilesToRemove[i].c_str();
206 SignalsMutex.release();
212 // DontRemoveFileOnSignal - The public API
213 void llvm::sys::DontRemoveFileOnSignal(const sys::Path &Filename) {
214 SignalsMutex.acquire();
215 std::vector<std::string>::reverse_iterator RI =
216 std::find(FilesToRemove.rbegin(), FilesToRemove.rend(), Filename.str());
217 std::vector<std::string>::iterator I = FilesToRemove.end();
218 if (RI != FilesToRemove.rend())
219 I = FilesToRemove.erase(RI.base()-1);
221 // We need to call c_str() on every element which would have been moved by
222 // the erase. These elements, in a C++98 implementation where c_str()
223 // requires a reallocation on the first call may have had the call to c_str()
224 // made on insertion become invalid by being copied down an element.
225 for (std::vector<std::string>::iterator E = FilesToRemove.end(); I != E; ++I)
228 SignalsMutex.release();
231 /// AddSignalHandler - Add a function to be called when a signal is delivered
232 /// to the process. The handler can have a cookie passed to it to identify
233 /// what instance of the handler it is.
234 void llvm::sys::AddSignalHandler(void (*FnPtr)(void *), void *Cookie) {
235 CallBacksToRun.push_back(std::make_pair(FnPtr, Cookie));
240 // PrintStackTrace - In the case of a program crash or fault, print out a stack
241 // trace so that the user has an indication of why and where we died.
243 // On glibc systems we have the 'backtrace' function, which works nicely, but
244 // doesn't demangle symbols.
245 static void PrintStackTrace(void *) {
246 #if defined(HAVE_BACKTRACE) && defined(ENABLE_BACKTRACES)
247 static void* StackTrace[256];
248 // Use backtrace() to output a backtrace on Linux systems with glibc.
249 int depth = backtrace(StackTrace,
250 static_cast<int>(array_lengthof(StackTrace)));
251 #if HAVE_DLFCN_H && __GNUG__
253 for (int i = 0; i < depth; ++i) {
255 dladdr(StackTrace[i], &dlinfo);
256 const char* name = strrchr(dlinfo.dli_fname, '/');
259 if (name == NULL) nwidth = strlen(dlinfo.dli_fname);
260 else nwidth = strlen(name) - 1;
262 if (nwidth > width) width = nwidth;
265 for (int i = 0; i < depth; ++i) {
267 dladdr(StackTrace[i], &dlinfo);
269 fprintf(stderr, "%-2d", i);
271 const char* name = strrchr(dlinfo.dli_fname, '/');
272 if (name == NULL) fprintf(stderr, " %-*s", width, dlinfo.dli_fname);
273 else fprintf(stderr, " %-*s", width, name+1);
275 fprintf(stderr, " %#0*lx",
276 (int)(sizeof(void*) * 2) + 2, (unsigned long)StackTrace[i]);
278 if (dlinfo.dli_sname != NULL) {
281 char* d = abi::__cxa_demangle(dlinfo.dli_sname, NULL, NULL, &res);
282 if (d == NULL) fputs(dlinfo.dli_sname, stderr);
283 else fputs(d, stderr);
286 fprintf(stderr, " + %tu",(char*)StackTrace[i]-(char*)dlinfo.dli_saddr);
291 backtrace_symbols_fd(StackTrace, depth, STDERR_FILENO);
296 /// PrintStackTraceOnErrorSignal - When an error signal (such as SIGABRT or
297 /// SIGSEGV) is delivered to the process, print a stack trace and then exit.
298 void llvm::sys::PrintStackTraceOnErrorSignal() {
299 AddSignalHandler(PrintStackTrace, 0);
301 #if defined(__APPLE__)
302 // Environment variable to disable any kind of crash dialog.
303 if (getenv("LLVM_DISABLE_CRASH_REPORT")) {
304 mach_port_t self = mach_task_self();
306 exception_mask_t mask = EXC_MASK_CRASH;
308 kern_return_t ret = task_set_exception_ports(self,
311 EXCEPTION_STATE_IDENTITY | MACH_EXCEPTION_CODES,
321 // On Darwin, raise sends a signal to the main thread instead of the current
322 // thread. This has the unfortunate effect that assert() and abort() will end up
323 // bypassing our crash recovery attempts. We work around this for anything in
324 // the same linkage unit by just defining our own versions of the assert handler
333 return pthread_kill(pthread_self(), sig);
336 void __assert_rtn(const char *func,
341 fprintf(stderr, "Assertion failed: (%s), function %s, file %s, line %d.\n",
342 expr, func, file, line);
344 fprintf(stderr, "Assertion failed: (%s), file %s, line %d.\n",