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().
37 #include <mach/mach.h>
42 static RETSIGTYPE SignalHandler(int Sig); // defined below.
44 static SmartMutex<true> SignalsMutex;
46 /// InterruptFunction - The function to call if ctrl-c is pressed.
47 static void (*InterruptFunction)() = 0;
49 static std::vector<std::string> FilesToRemove;
50 static std::vector<std::pair<void(*)(void*), void*> > CallBacksToRun;
52 // IntSigs - Signals that represent requested termination. There's no bug
53 // or failure, or if there is, it's not our direct responsibility. For whatever
54 // reason, our continued execution is no longer desirable.
55 static const int IntSigs[] = {
56 SIGHUP, SIGINT, SIGPIPE, SIGTERM, SIGUSR1, SIGUSR2
58 static const int *const IntSigsEnd =
59 IntSigs + sizeof(IntSigs) / sizeof(IntSigs[0]);
61 // KillSigs - Signals that represent that we have a bug, and our prompt
62 // termination has been ordered.
63 static const int KillSigs[] = {
64 SIGILL, SIGTRAP, SIGABRT, SIGFPE, SIGBUS, SIGSEGV, SIGQUIT
78 static const int *const KillSigsEnd =
79 KillSigs + sizeof(KillSigs) / sizeof(KillSigs[0]);
81 static unsigned NumRegisteredSignals = 0;
85 } RegisteredSignalInfo[(sizeof(IntSigs)+sizeof(KillSigs))/sizeof(KillSigs[0])];
88 static void RegisterHandler(int Signal) {
89 assert(NumRegisteredSignals <
90 sizeof(RegisteredSignalInfo)/sizeof(RegisteredSignalInfo[0]) &&
91 "Out of space for signal handlers!");
93 struct sigaction NewHandler;
95 NewHandler.sa_handler = SignalHandler;
96 NewHandler.sa_flags = SA_NODEFER|SA_RESETHAND;
97 sigemptyset(&NewHandler.sa_mask);
99 // Install the new handler, save the old one in RegisteredSignalInfo.
100 sigaction(Signal, &NewHandler,
101 &RegisteredSignalInfo[NumRegisteredSignals].SA);
102 RegisteredSignalInfo[NumRegisteredSignals].SigNo = Signal;
103 ++NumRegisteredSignals;
106 static void RegisterHandlers() {
107 // If the handlers are already registered, we're done.
108 if (NumRegisteredSignals != 0) return;
110 std::for_each(IntSigs, IntSigsEnd, RegisterHandler);
111 std::for_each(KillSigs, KillSigsEnd, RegisterHandler);
114 static void UnregisterHandlers() {
115 // Restore all of the signal handlers to how they were before we showed up.
116 for (unsigned i = 0, e = NumRegisteredSignals; i != e; ++i)
117 sigaction(RegisteredSignalInfo[i].SigNo,
118 &RegisteredSignalInfo[i].SA, 0);
119 NumRegisteredSignals = 0;
123 /// RemoveFilesToRemove - Process the FilesToRemove list. This function
124 /// should be called with the SignalsMutex lock held.
125 /// NB: This must be an async signal safe function. It cannot allocate or free
126 /// memory, even in debug builds.
127 static void RemoveFilesToRemove() {
128 // We avoid iterators in case of debug iterators that allocate or release
130 for (unsigned i = 0, e = FilesToRemove.size(); i != e; ++i) {
131 // We rely on a std::string implementation for which repeated calls to
132 // 'c_str()' don't allocate memory. We pre-call 'c_str()' on all of these
133 // strings to try to ensure this is safe.
134 const char *path = FilesToRemove[i].c_str();
136 // Get the status so we can determine if it's a file or directory. If we
137 // can't stat the file, ignore it.
139 if (stat(path, &buf) != 0)
142 // If this is not a regular file, ignore it. We want to prevent removal of
143 // special files like /dev/null, even if the compiler is being run with the
144 // super-user permissions.
145 if (!S_ISREG(buf.st_mode))
148 // Otherwise, remove the file. We ignore any errors here as there is nothing
154 // SignalHandler - The signal handler that runs.
155 static RETSIGTYPE SignalHandler(int Sig) {
156 // Restore the signal behavior to default, so that the program actually
157 // crashes when we return and the signal reissues. This also ensures that if
158 // we crash in our signal handler that the program will terminate immediately
159 // instead of recursing in the signal handler.
160 UnregisterHandlers();
162 // Unmask all potentially blocked kill signals.
164 sigfillset(&SigMask);
165 sigprocmask(SIG_UNBLOCK, &SigMask, 0);
167 SignalsMutex.acquire();
168 RemoveFilesToRemove();
170 if (std::find(IntSigs, IntSigsEnd, Sig) != IntSigsEnd) {
171 if (InterruptFunction) {
172 void (*IF)() = InterruptFunction;
173 SignalsMutex.release();
174 InterruptFunction = 0;
175 IF(); // run the interrupt function.
179 SignalsMutex.release();
180 raise(Sig); // Execute the default handler.
184 SignalsMutex.release();
186 // Otherwise if it is a fault (like SEGV) run any handler.
187 for (unsigned i = 0, e = CallBacksToRun.size(); i != e; ++i)
188 CallBacksToRun[i].first(CallBacksToRun[i].second);
191 // On S/390, certain signals are delivered with PSW Address pointing to
192 // *after* the faulting instruction. Simply returning from the signal
193 // handler would continue execution after that point, instead of
194 // re-raising the signal. Raise the signal manually in those cases.
195 if (Sig == SIGILL || Sig == SIGFPE || Sig == SIGTRAP)
200 void llvm::sys::RunInterruptHandlers() {
201 SignalsMutex.acquire();
202 RemoveFilesToRemove();
203 SignalsMutex.release();
206 void llvm::sys::SetInterruptFunction(void (*IF)()) {
207 SignalsMutex.acquire();
208 InterruptFunction = IF;
209 SignalsMutex.release();
213 // RemoveFileOnSignal - The public API
214 bool llvm::sys::RemoveFileOnSignal(StringRef Filename,
215 std::string* ErrMsg) {
216 SignalsMutex.acquire();
217 std::string *OldPtr = FilesToRemove.empty() ? 0 : &FilesToRemove[0];
218 FilesToRemove.push_back(Filename);
220 // We want to call 'c_str()' on every std::string in this vector so that if
221 // the underlying implementation requires a re-allocation, it happens here
222 // rather than inside of the signal handler. If we see the vector grow, we
223 // have to call it on every entry. If it remains in place, we only need to
224 // call it on the latest one.
225 if (OldPtr == &FilesToRemove[0])
226 FilesToRemove.back().c_str();
228 for (unsigned i = 0, e = FilesToRemove.size(); i != e; ++i)
229 FilesToRemove[i].c_str();
231 SignalsMutex.release();
237 // DontRemoveFileOnSignal - The public API
238 void llvm::sys::DontRemoveFileOnSignal(StringRef Filename) {
239 SignalsMutex.acquire();
240 std::vector<std::string>::reverse_iterator RI =
241 std::find(FilesToRemove.rbegin(), FilesToRemove.rend(), Filename);
242 std::vector<std::string>::iterator I = FilesToRemove.end();
243 if (RI != FilesToRemove.rend())
244 I = FilesToRemove.erase(RI.base()-1);
246 // We need to call c_str() on every element which would have been moved by
247 // the erase. These elements, in a C++98 implementation where c_str()
248 // requires a reallocation on the first call may have had the call to c_str()
249 // made on insertion become invalid by being copied down an element.
250 for (std::vector<std::string>::iterator E = FilesToRemove.end(); I != E; ++I)
253 SignalsMutex.release();
256 /// AddSignalHandler - Add a function to be called when a signal is delivered
257 /// to the process. The handler can have a cookie passed to it to identify
258 /// what instance of the handler it is.
259 void llvm::sys::AddSignalHandler(void (*FnPtr)(void *), void *Cookie) {
260 CallBacksToRun.push_back(std::make_pair(FnPtr, Cookie));
265 // PrintStackTrace - In the case of a program crash or fault, print out a stack
266 // trace so that the user has an indication of why and where we died.
268 // On glibc systems we have the 'backtrace' function, which works nicely, but
269 // doesn't demangle symbols.
270 void llvm::sys::PrintStackTrace(FILE *FD) {
271 #if defined(HAVE_BACKTRACE) && defined(ENABLE_BACKTRACES)
272 static void* StackTrace[256];
273 // Use backtrace() to output a backtrace on Linux systems with glibc.
274 int depth = backtrace(StackTrace,
275 static_cast<int>(array_lengthof(StackTrace)));
276 #if HAVE_DLFCN_H && __GNUG__
278 for (int i = 0; i < depth; ++i) {
280 dladdr(StackTrace[i], &dlinfo);
281 const char* name = strrchr(dlinfo.dli_fname, '/');
284 if (name == NULL) nwidth = strlen(dlinfo.dli_fname);
285 else nwidth = strlen(name) - 1;
287 if (nwidth > width) width = nwidth;
290 for (int i = 0; i < depth; ++i) {
292 dladdr(StackTrace[i], &dlinfo);
294 fprintf(FD, "%-2d", i);
296 const char* name = strrchr(dlinfo.dli_fname, '/');
297 if (name == NULL) fprintf(FD, " %-*s", width, dlinfo.dli_fname);
298 else fprintf(FD, " %-*s", width, name+1);
300 fprintf(FD, " %#0*lx",
301 (int)(sizeof(void*) * 2) + 2, (unsigned long)StackTrace[i]);
303 if (dlinfo.dli_sname != NULL) {
307 char* d = abi::__cxa_demangle(dlinfo.dli_sname, NULL, NULL, &res);
311 if (d == NULL) fputs(dlinfo.dli_sname, FD);
315 // FIXME: When we move to C++11, use %t length modifier. It's not in
316 // C++03 and causes gcc to issue warnings. Losing the upper 32 bits of
317 // the stack offset for a stack dump isn't likely to cause any problems.
318 fprintf(FD, " + %u",(unsigned)((char*)StackTrace[i]-
319 (char*)dlinfo.dli_saddr));
324 backtrace_symbols_fd(StackTrace, depth, STDERR_FILENO);
329 static void PrintStackTraceSignalHandler(void *) {
330 PrintStackTrace(stderr);
333 /// PrintStackTraceOnErrorSignal - When an error signal (such as SIGABRT or
334 /// SIGSEGV) is delivered to the process, print a stack trace and then exit.
335 void llvm::sys::PrintStackTraceOnErrorSignal() {
336 AddSignalHandler(PrintStackTraceSignalHandler, 0);
338 #if defined(__APPLE__)
339 // Environment variable to disable any kind of crash dialog.
340 if (getenv("LLVM_DISABLE_CRASH_REPORT")) {
341 mach_port_t self = mach_task_self();
343 exception_mask_t mask = EXC_MASK_CRASH;
345 kern_return_t ret = task_set_exception_ports(self,
348 EXCEPTION_STATE_IDENTITY | MACH_EXCEPTION_CODES,
358 // On Darwin, raise sends a signal to the main thread instead of the current
359 // thread. This has the unfortunate effect that assert() and abort() will end up
360 // bypassing our crash recovery attempts. We work around this for anything in
361 // the same linkage unit by just defining our own versions of the assert handler
370 return pthread_kill(pthread_self(), sig);
373 void __assert_rtn(const char *func,
378 fprintf(stderr, "Assertion failed: (%s), function %s, file %s, line %d.\n",
379 expr, func, file, line);
381 fprintf(stderr, "Assertion failed: (%s), file %s, line %d.\n",