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 // We rely on a std::string implementation for which repeated calls to
148 // 'c_str()' don't allocate memory. We pre-call 'c_str()' on all of these
149 // strings to try to ensure this is safe.
150 const char *path = FilesToRemoveRef[i].c_str();
152 // Get the status so we can determine if it's a file or directory. If we
153 // can't stat the file, ignore it.
155 if (stat(path, &buf) != 0)
158 // If this is not a regular file, ignore it. We want to prevent removal of
159 // special files like /dev/null, even if the compiler is being run with the
160 // super-user permissions.
161 if (!S_ISREG(buf.st_mode))
164 // Otherwise, remove the file. We ignore any errors here as there is nothing
170 // SignalHandler - The signal handler that runs.
171 static RETSIGTYPE SignalHandler(int Sig) {
172 // Restore the signal behavior to default, so that the program actually
173 // crashes when we return and the signal reissues. This also ensures that if
174 // we crash in our signal handler that the program will terminate immediately
175 // instead of recursing in the signal handler.
176 UnregisterHandlers();
178 // Unmask all potentially blocked kill signals.
180 sigfillset(&SigMask);
181 sigprocmask(SIG_UNBLOCK, &SigMask, nullptr);
184 unique_lock<SmartMutex<true>> Guard(*SignalsMutex);
185 RemoveFilesToRemove();
187 if (std::find(std::begin(IntSigs), std::end(IntSigs), Sig)
188 != std::end(IntSigs)) {
189 if (InterruptFunction) {
190 void (*IF)() = InterruptFunction;
192 InterruptFunction = nullptr;
193 IF(); // run the interrupt function.
198 raise(Sig); // Execute the default handler.
203 // Otherwise if it is a fault (like SEGV) run any handler.
204 llvm::sys::RunSignalHandlers();
207 // On S/390, certain signals are delivered with PSW Address pointing to
208 // *after* the faulting instruction. Simply returning from the signal
209 // handler would continue execution after that point, instead of
210 // re-raising the signal. Raise the signal manually in those cases.
211 if (Sig == SIGILL || Sig == SIGFPE || Sig == SIGTRAP)
216 void llvm::sys::RunInterruptHandlers() {
217 sys::SmartScopedLock<true> Guard(*SignalsMutex);
218 RemoveFilesToRemove();
221 void llvm::sys::SetInterruptFunction(void (*IF)()) {
223 sys::SmartScopedLock<true> Guard(*SignalsMutex);
224 InterruptFunction = IF;
229 // RemoveFileOnSignal - The public API
230 bool llvm::sys::RemoveFileOnSignal(StringRef Filename,
231 std::string* ErrMsg) {
233 sys::SmartScopedLock<true> Guard(*SignalsMutex);
234 std::vector<std::string>& FilesToRemoveRef = *FilesToRemove;
235 std::string *OldPtr =
236 FilesToRemoveRef.empty() ? nullptr : &FilesToRemoveRef[0];
237 FilesToRemoveRef.push_back(Filename);
239 // We want to call 'c_str()' on every std::string in this vector so that if
240 // the underlying implementation requires a re-allocation, it happens here
241 // rather than inside of the signal handler. If we see the vector grow, we
242 // have to call it on every entry. If it remains in place, we only need to
243 // call it on the latest one.
244 if (OldPtr == &FilesToRemoveRef[0])
245 FilesToRemoveRef.back().c_str();
247 for (unsigned i = 0, e = FilesToRemoveRef.size(); i != e; ++i)
248 FilesToRemoveRef[i].c_str();
255 // DontRemoveFileOnSignal - The public API
256 void llvm::sys::DontRemoveFileOnSignal(StringRef Filename) {
257 sys::SmartScopedLock<true> Guard(*SignalsMutex);
258 std::vector<std::string>::reverse_iterator RI =
259 std::find(FilesToRemove->rbegin(), FilesToRemove->rend(), Filename);
260 std::vector<std::string>::iterator I = FilesToRemove->end();
261 if (RI != FilesToRemove->rend())
262 I = FilesToRemove->erase(RI.base()-1);
265 /// AddSignalHandler - Add a function to be called when a signal is delivered
266 /// to the process. The handler can have a cookie passed to it to identify
267 /// what instance of the handler it is.
268 void llvm::sys::AddSignalHandler(void (*FnPtr)(void *), void *Cookie) {
269 CallBacksToRun->push_back(std::make_pair(FnPtr, Cookie));
273 #if defined(HAVE_BACKTRACE) && defined(ENABLE_BACKTRACES)
275 #if HAVE_LINK_H && (defined(__linux__) || defined(__FreeBSD__) || \
276 defined(__FreeBSD_kernel__) || defined(__NetBSD__))
277 struct DlIteratePhdrData {
281 const char **modules;
283 const char *main_exec_name;
286 static int dl_iterate_phdr_cb(dl_phdr_info *info, size_t size, void *arg) {
287 DlIteratePhdrData *data = (DlIteratePhdrData*)arg;
288 const char *name = data->first ? data->main_exec_name : info->dlpi_name;
290 for (int i = 0; i < info->dlpi_phnum; i++) {
291 const auto *phdr = &info->dlpi_phdr[i];
292 if (phdr->p_type != PT_LOAD)
294 intptr_t beg = info->dlpi_addr + phdr->p_vaddr;
295 intptr_t end = beg + phdr->p_memsz;
296 for (int j = 0; j < data->depth; j++) {
297 if (data->modules[j])
299 intptr_t addr = (intptr_t)data->StackTrace[j];
300 if (beg <= addr && addr < end) {
301 data->modules[j] = name;
302 data->offsets[j] = addr - info->dlpi_addr;
309 static bool findModulesAndOffsets(void **StackTrace, int Depth,
310 const char **Modules, intptr_t *Offsets,
311 const char *MainExecutableName) {
312 DlIteratePhdrData data = {StackTrace, Depth, true,
313 Modules, Offsets, MainExecutableName};
314 dl_iterate_phdr(dl_iterate_phdr_cb, &data);
318 static bool findModulesAndOffsets(void **StackTrace, int Depth,
319 const char **Modules, intptr_t *Offsets,
320 const char *MainExecutableName) {
325 static bool printSymbolizedStackTrace(void **StackTrace, int Depth,
326 llvm::raw_ostream &OS) {
327 // FIXME: Subtract necessary number from StackTrace entries to turn return addresses
328 // into actual instruction addresses.
329 // Use llvm-symbolizer tool to symbolize the stack traces.
330 ErrorOr<std::string> LLVMSymbolizerPathOrErr =
331 sys::findProgramByName("llvm-symbolizer");
332 if (!LLVMSymbolizerPathOrErr)
334 const std::string &LLVMSymbolizerPath = *LLVMSymbolizerPathOrErr;
335 // We don't know argv0 or the address of main() at this point, but try
336 // to guess it anyway (it's possible on some platforms).
337 std::string MainExecutableName = sys::fs::getMainExecutable(nullptr, nullptr);
338 if (MainExecutableName.empty() ||
339 MainExecutableName.find("llvm-symbolizer") != std::string::npos)
342 std::vector<const char *> Modules(Depth, nullptr);
343 std::vector<intptr_t> Offsets(Depth, 0);
344 if (!findModulesAndOffsets(StackTrace, Depth, Modules.data(), Offsets.data(),
345 MainExecutableName.c_str()))
348 SmallString<32> InputFile, OutputFile;
349 sys::fs::createTemporaryFile("symbolizer-input", "", InputFD, InputFile);
350 sys::fs::createTemporaryFile("symbolizer-output", "", OutputFile);
351 FileRemover InputRemover(InputFile.c_str());
352 FileRemover OutputRemover(OutputFile.c_str());
355 raw_fd_ostream Input(InputFD, true);
356 for (int i = 0; i < Depth; i++) {
358 Input << Modules[i] << " " << (void*)Offsets[i] << "\n";
362 StringRef InputFileStr(InputFile);
363 StringRef OutputFileStr(OutputFile);
364 StringRef StderrFileStr;
365 const StringRef *Redirects[] = {&InputFileStr, &OutputFileStr,
367 const char *Args[] = {"llvm-symbolizer", "--functions=linkage", "--inlining",
368 "--demangle", nullptr};
370 sys::ExecuteAndWait(LLVMSymbolizerPath, Args, nullptr, Redirects);
374 auto OutputBuf = MemoryBuffer::getFile(OutputFile.c_str());
377 StringRef Output = OutputBuf.get()->getBuffer();
378 SmallVector<StringRef, 32> Lines;
379 Output.split(Lines, "\n");
380 auto CurLine = Lines.begin();
382 for (int i = 0; i < Depth; i++) {
384 OS << format("#%d %p\n", frame_no++, StackTrace[i]);
387 // Read pairs of lines (function name and file/line info) until we
388 // encounter empty line.
390 if (CurLine == Lines.end())
392 StringRef FunctionName = *CurLine++;
393 if (FunctionName.empty())
395 OS << format("#%d %p ", frame_no++, StackTrace[i]);
396 if (!FunctionName.startswith("??"))
397 OS << format("%s ", FunctionName.str().c_str());
398 if (CurLine == Lines.end())
400 StringRef FileLineInfo = *CurLine++;
401 if (!FileLineInfo.startswith("??"))
402 OS << format("%s", FileLineInfo.str().c_str());
404 OS << format("(%s+%p)", Modules[i], (void *)Offsets[i]);
410 #endif // defined(HAVE_BACKTRACE) && defined(ENABLE_BACKTRACES)
412 // PrintStackTrace - In the case of a program crash or fault, print out a stack
413 // trace so that the user has an indication of why and where we died.
415 // On glibc systems we have the 'backtrace' function, which works nicely, but
416 // doesn't demangle symbols.
417 void llvm::sys::PrintStackTrace(raw_ostream &OS) {
418 #if defined(HAVE_BACKTRACE) && defined(ENABLE_BACKTRACES)
419 static void* StackTrace[256];
420 // Use backtrace() to output a backtrace on Linux systems with glibc.
421 int depth = backtrace(StackTrace,
422 static_cast<int>(array_lengthof(StackTrace)));
423 if (printSymbolizedStackTrace(StackTrace, depth, OS))
425 #if HAVE_DLFCN_H && __GNUG__
427 for (int i = 0; i < depth; ++i) {
429 dladdr(StackTrace[i], &dlinfo);
430 const char* name = strrchr(dlinfo.dli_fname, '/');
433 if (!name) nwidth = strlen(dlinfo.dli_fname);
434 else nwidth = strlen(name) - 1;
436 if (nwidth > width) width = nwidth;
439 for (int i = 0; i < depth; ++i) {
441 dladdr(StackTrace[i], &dlinfo);
443 OS << format("%-2d", i);
445 const char* name = strrchr(dlinfo.dli_fname, '/');
446 if (!name) OS << format(" %-*s", width, dlinfo.dli_fname);
447 else OS << format(" %-*s", width, name+1);
449 OS << format(" %#0*lx", (int)(sizeof(void*) * 2) + 2,
450 (unsigned long)StackTrace[i]);
452 if (dlinfo.dli_sname != nullptr) {
456 char* d = abi::__cxa_demangle(dlinfo.dli_sname, nullptr, nullptr, &res);
460 if (!d) OS << dlinfo.dli_sname;
464 // FIXME: When we move to C++11, use %t length modifier. It's not in
465 // C++03 and causes gcc to issue warnings. Losing the upper 32 bits of
466 // the stack offset for a stack dump isn't likely to cause any problems.
467 OS << format(" + %u",(unsigned)((char*)StackTrace[i]-
468 (char*)dlinfo.dli_saddr));
473 backtrace_symbols_fd(StackTrace, depth, STDERR_FILENO);
478 static void PrintStackTraceSignalHandler(void *) {
479 PrintStackTrace(llvm::errs());
482 void llvm::sys::DisableSystemDialogsOnCrash() {}
484 /// PrintStackTraceOnErrorSignal - When an error signal (such as SIGABRT or
485 /// SIGSEGV) is delivered to the process, print a stack trace and then exit.
486 void llvm::sys::PrintStackTraceOnErrorSignal(bool DisableCrashReporting) {
487 AddSignalHandler(PrintStackTraceSignalHandler, nullptr);
489 #if defined(__APPLE__) && defined(ENABLE_CRASH_OVERRIDES)
490 // Environment variable to disable any kind of crash dialog.
491 if (DisableCrashReporting || getenv("LLVM_DISABLE_CRASH_REPORT")) {
492 mach_port_t self = mach_task_self();
494 exception_mask_t mask = EXC_MASK_CRASH;
496 kern_return_t ret = task_set_exception_ports(self,
499 EXCEPTION_STATE_IDENTITY | MACH_EXCEPTION_CODES,
509 // On Darwin, raise sends a signal to the main thread instead of the current
510 // thread. This has the unfortunate effect that assert() and abort() will end up
511 // bypassing our crash recovery attempts. We work around this for anything in
512 // the same linkage unit by just defining our own versions of the assert handler
515 #if defined(__APPLE__) && defined(ENABLE_CRASH_OVERRIDES)
521 return pthread_kill(pthread_self(), sig);
524 void __assert_rtn(const char *func,
529 fprintf(stderr, "Assertion failed: (%s), function %s, file %s, line %d.\n",
530 expr, func, file, line);
532 fprintf(stderr, "Assertion failed: (%s), file %s, line %d.\n",