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/Format.h"
18 #include "llvm/Support/FileSystem.h"
19 #include "llvm/Support/FileUtilities.h"
20 #include "llvm/Support/MemoryBuffer.h"
21 #include "llvm/Support/Mutex.h"
22 #include "llvm/Support/Program.h"
23 #include "llvm/Support/UniqueLock.h"
24 #include "llvm/Support/raw_ostream.h"
28 # include <execinfo.h> // For backtrace().
43 #include <mach/mach.h>
51 static RETSIGTYPE SignalHandler(int Sig); // defined below.
53 static ManagedStatic<SmartMutex<true> > SignalsMutex;
55 /// InterruptFunction - The function to call if ctrl-c is pressed.
56 static void (*InterruptFunction)() = nullptr;
58 static ManagedStatic<std::vector<std::string>> FilesToRemove;
60 // IntSigs - Signals that represent requested termination. There's no bug
61 // or failure, or if there is, it's not our direct responsibility. For whatever
62 // reason, our continued execution is no longer desirable.
63 static const int IntSigs[] = {
64 SIGHUP, SIGINT, SIGPIPE, SIGTERM, SIGUSR1, SIGUSR2
67 // KillSigs - Signals that represent that we have a bug, and our prompt
68 // termination has been ordered.
69 static const int KillSigs[] = {
70 SIGILL, SIGTRAP, SIGABRT, SIGFPE, SIGBUS, SIGSEGV, SIGQUIT
85 static unsigned NumRegisteredSignals = 0;
89 } RegisteredSignalInfo[(sizeof(IntSigs)+sizeof(KillSigs))/sizeof(KillSigs[0])];
92 static void RegisterHandler(int Signal) {
93 assert(NumRegisteredSignals <
94 sizeof(RegisteredSignalInfo)/sizeof(RegisteredSignalInfo[0]) &&
95 "Out of space for signal handlers!");
97 struct sigaction NewHandler;
99 NewHandler.sa_handler = SignalHandler;
100 NewHandler.sa_flags = SA_NODEFER|SA_RESETHAND;
101 sigemptyset(&NewHandler.sa_mask);
103 // Install the new handler, save the old one in RegisteredSignalInfo.
104 sigaction(Signal, &NewHandler,
105 &RegisteredSignalInfo[NumRegisteredSignals].SA);
106 RegisteredSignalInfo[NumRegisteredSignals].SigNo = Signal;
107 ++NumRegisteredSignals;
110 static void RegisterHandlers() {
111 // We need to dereference the signals mutex during handler registration so
112 // that we force its construction. This is to prevent the first use being
113 // during handling an actual signal because you can't safely call new in a
117 // If the handlers are already registered, we're done.
118 if (NumRegisteredSignals != 0) return;
120 for (auto S : IntSigs) RegisterHandler(S);
121 for (auto S : KillSigs) RegisterHandler(S);
124 static void UnregisterHandlers() {
125 // Restore all of the signal handlers to how they were before we showed up.
126 for (unsigned i = 0, e = NumRegisteredSignals; i != e; ++i)
127 sigaction(RegisteredSignalInfo[i].SigNo,
128 &RegisteredSignalInfo[i].SA, nullptr);
129 NumRegisteredSignals = 0;
133 /// RemoveFilesToRemove - Process the FilesToRemove list. This function
134 /// should be called with the SignalsMutex lock held.
135 /// NB: This must be an async signal safe function. It cannot allocate or free
136 /// memory, even in debug builds.
137 static void RemoveFilesToRemove() {
138 // Avoid constructing ManagedStatic in the signal handler.
139 // If FilesToRemove is not constructed, there are no files to remove.
140 if (!FilesToRemove.isConstructed())
143 // We avoid iterators in case of debug iterators that allocate or release
145 std::vector<std::string>& FilesToRemoveRef = *FilesToRemove;
146 for (unsigned i = 0, e = FilesToRemoveRef.size(); i != e; ++i) {
147 const char *path = FilesToRemoveRef[i].c_str();
149 // Get the status so we can determine if it's a file or directory. If we
150 // can't stat the file, ignore it.
152 if (stat(path, &buf) != 0)
155 // If this is not a regular file, ignore it. We want to prevent removal of
156 // special files like /dev/null, even if the compiler is being run with the
157 // super-user permissions.
158 if (!S_ISREG(buf.st_mode))
161 // Otherwise, remove the file. We ignore any errors here as there is nothing
167 // SignalHandler - The signal handler that runs.
168 static RETSIGTYPE SignalHandler(int Sig) {
169 // Restore the signal behavior to default, so that the program actually
170 // crashes when we return and the signal reissues. This also ensures that if
171 // we crash in our signal handler that the program will terminate immediately
172 // instead of recursing in the signal handler.
173 UnregisterHandlers();
175 // Unmask all potentially blocked kill signals.
177 sigfillset(&SigMask);
178 sigprocmask(SIG_UNBLOCK, &SigMask, nullptr);
181 unique_lock<SmartMutex<true>> Guard(*SignalsMutex);
182 RemoveFilesToRemove();
184 if (std::find(std::begin(IntSigs), std::end(IntSigs), Sig)
185 != std::end(IntSigs)) {
186 if (InterruptFunction) {
187 void (*IF)() = InterruptFunction;
189 InterruptFunction = nullptr;
190 IF(); // run the interrupt function.
195 raise(Sig); // Execute the default handler.
200 // Otherwise if it is a fault (like SEGV) run any handler.
201 llvm::sys::RunSignalHandlers();
204 // On S/390, certain signals are delivered with PSW Address pointing to
205 // *after* the faulting instruction. Simply returning from the signal
206 // handler would continue execution after that point, instead of
207 // re-raising the signal. Raise the signal manually in those cases.
208 if (Sig == SIGILL || Sig == SIGFPE || Sig == SIGTRAP)
213 void llvm::sys::RunInterruptHandlers() {
214 sys::SmartScopedLock<true> Guard(*SignalsMutex);
215 RemoveFilesToRemove();
218 void llvm::sys::SetInterruptFunction(void (*IF)()) {
220 sys::SmartScopedLock<true> Guard(*SignalsMutex);
221 InterruptFunction = IF;
226 // RemoveFileOnSignal - The public API
227 bool llvm::sys::RemoveFileOnSignal(StringRef Filename,
228 std::string* ErrMsg) {
230 sys::SmartScopedLock<true> Guard(*SignalsMutex);
231 FilesToRemove->push_back(Filename);
238 // DontRemoveFileOnSignal - The public API
239 void llvm::sys::DontRemoveFileOnSignal(StringRef Filename) {
240 sys::SmartScopedLock<true> Guard(*SignalsMutex);
241 std::vector<std::string>::reverse_iterator RI =
242 std::find(FilesToRemove->rbegin(), FilesToRemove->rend(), Filename);
243 std::vector<std::string>::iterator I = FilesToRemove->end();
244 if (RI != FilesToRemove->rend())
245 I = FilesToRemove->erase(RI.base()-1);
248 /// AddSignalHandler - Add a function to be called when a signal is delivered
249 /// to the process. The handler can have a cookie passed to it to identify
250 /// what instance of the handler it is.
251 void llvm::sys::AddSignalHandler(void (*FnPtr)(void *), void *Cookie) {
252 CallBacksToRun->push_back(std::make_pair(FnPtr, Cookie));
256 #if defined(HAVE_BACKTRACE) && defined(ENABLE_BACKTRACES)
258 #if HAVE_LINK_H && (defined(__linux__) || defined(__FreeBSD__) || \
259 defined(__FreeBSD_kernel__) || defined(__NetBSD__))
260 struct DlIteratePhdrData {
264 const char **modules;
266 const char *main_exec_name;
269 static int dl_iterate_phdr_cb(dl_phdr_info *info, size_t size, void *arg) {
270 DlIteratePhdrData *data = (DlIteratePhdrData*)arg;
271 const char *name = data->first ? data->main_exec_name : info->dlpi_name;
273 for (int i = 0; i < info->dlpi_phnum; i++) {
274 const auto *phdr = &info->dlpi_phdr[i];
275 if (phdr->p_type != PT_LOAD)
277 intptr_t beg = info->dlpi_addr + phdr->p_vaddr;
278 intptr_t end = beg + phdr->p_memsz;
279 for (int j = 0; j < data->depth; j++) {
280 if (data->modules[j])
282 intptr_t addr = (intptr_t)data->StackTrace[j];
283 if (beg <= addr && addr < end) {
284 data->modules[j] = name;
285 data->offsets[j] = addr - info->dlpi_addr;
292 static bool findModulesAndOffsets(void **StackTrace, int Depth,
293 const char **Modules, intptr_t *Offsets,
294 const char *MainExecutableName,
295 StringSaver &StrPool) {
296 DlIteratePhdrData data = {StackTrace, Depth, true,
297 Modules, Offsets, MainExecutableName};
298 dl_iterate_phdr(dl_iterate_phdr_cb, &data);
302 static bool findModulesAndOffsets(void **StackTrace, int Depth,
303 const char **Modules, intptr_t *Offsets,
304 const char *MainExecutableName) {
308 #endif // defined(HAVE_BACKTRACE) && defined(ENABLE_BACKTRACES)
310 // PrintStackTrace - In the case of a program crash or fault, print out a stack
311 // trace so that the user has an indication of why and where we died.
313 // On glibc systems we have the 'backtrace' function, which works nicely, but
314 // doesn't demangle symbols.
315 void llvm::sys::PrintStackTrace(raw_ostream &OS) {
316 #if defined(HAVE_BACKTRACE) && defined(ENABLE_BACKTRACES)
317 static void* StackTrace[256];
318 // Use backtrace() to output a backtrace on Linux systems with glibc.
319 int depth = backtrace(StackTrace,
320 static_cast<int>(array_lengthof(StackTrace)));
321 if (printSymbolizedStackTrace(StackTrace, depth, OS))
323 #if HAVE_DLFCN_H && __GNUG__
325 for (int i = 0; i < depth; ++i) {
327 dladdr(StackTrace[i], &dlinfo);
328 const char* name = strrchr(dlinfo.dli_fname, '/');
331 if (!name) nwidth = strlen(dlinfo.dli_fname);
332 else nwidth = strlen(name) - 1;
334 if (nwidth > width) width = nwidth;
337 for (int i = 0; i < depth; ++i) {
339 dladdr(StackTrace[i], &dlinfo);
341 OS << format("%-2d", i);
343 const char* name = strrchr(dlinfo.dli_fname, '/');
344 if (!name) OS << format(" %-*s", width, dlinfo.dli_fname);
345 else OS << format(" %-*s", width, name+1);
347 OS << format(" %#0*lx", (int)(sizeof(void*) * 2) + 2,
348 (unsigned long)StackTrace[i]);
350 if (dlinfo.dli_sname != nullptr) {
354 char* d = abi::__cxa_demangle(dlinfo.dli_sname, nullptr, nullptr, &res);
358 if (!d) OS << dlinfo.dli_sname;
362 // FIXME: When we move to C++11, use %t length modifier. It's not in
363 // C++03 and causes gcc to issue warnings. Losing the upper 32 bits of
364 // the stack offset for a stack dump isn't likely to cause any problems.
365 OS << format(" + %u",(unsigned)((char*)StackTrace[i]-
366 (char*)dlinfo.dli_saddr));
371 backtrace_symbols_fd(StackTrace, depth, STDERR_FILENO);
376 static void PrintStackTraceSignalHandler(void *) {
377 PrintStackTrace(llvm::errs());
380 void llvm::sys::DisableSystemDialogsOnCrash() {}
382 /// PrintStackTraceOnErrorSignal - When an error signal (such as SIGABRT or
383 /// SIGSEGV) is delivered to the process, print a stack trace and then exit.
384 void llvm::sys::PrintStackTraceOnErrorSignal(bool DisableCrashReporting) {
385 AddSignalHandler(PrintStackTraceSignalHandler, nullptr);
387 #if defined(__APPLE__) && defined(ENABLE_CRASH_OVERRIDES)
388 // Environment variable to disable any kind of crash dialog.
389 if (DisableCrashReporting || getenv("LLVM_DISABLE_CRASH_REPORT")) {
390 mach_port_t self = mach_task_self();
392 exception_mask_t mask = EXC_MASK_CRASH;
394 kern_return_t ret = task_set_exception_ports(self,
397 EXCEPTION_STATE_IDENTITY | MACH_EXCEPTION_CODES,
407 // On Darwin, raise sends a signal to the main thread instead of the current
408 // thread. This has the unfortunate effect that assert() and abort() will end up
409 // bypassing our crash recovery attempts. We work around this for anything in
410 // the same linkage unit by just defining our own versions of the assert handler
413 #if defined(__APPLE__) && defined(ENABLE_CRASH_OVERRIDES)
419 return pthread_kill(pthread_self(), sig);
422 void __assert_rtn(const char *func,
427 fprintf(stderr, "Assertion failed: (%s), function %s, file %s, line %d.\n",
428 expr, func, file, line);
430 fprintf(stderr, "Assertion failed: (%s), file %s, line %d.\n",