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/FileSystem.h"
18 #include "llvm/Support/FileUtilities.h"
19 #include "llvm/Support/ManagedStatic.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"
29 # include <execinfo.h> // For backtrace().
44 #include <mach/mach.h>
52 static RETSIGTYPE SignalHandler(int Sig); // defined below.
54 static ManagedStatic<SmartMutex<true> > SignalsMutex;
56 /// InterruptFunction - The function to call if ctrl-c is pressed.
57 static void (*InterruptFunction)() = nullptr;
59 static ManagedStatic<std::vector<std::string>> FilesToRemove;
60 static ManagedStatic<std::vector<std::pair<void (*)(void *), void *>>>
63 // IntSigs - Signals that represent requested termination. There's no bug
64 // or failure, or if there is, it's not our direct responsibility. For whatever
65 // reason, our continued execution is no longer desirable.
66 static const int IntSigs[] = {
67 SIGHUP, SIGINT, SIGPIPE, SIGTERM, SIGUSR1, SIGUSR2
70 // KillSigs - Signals that represent that we have a bug, and our prompt
71 // termination has been ordered.
72 static const int KillSigs[] = {
73 SIGILL, SIGTRAP, SIGABRT, SIGFPE, SIGBUS, SIGSEGV, SIGQUIT
88 static unsigned NumRegisteredSignals = 0;
92 } RegisteredSignalInfo[(sizeof(IntSigs)+sizeof(KillSigs))/sizeof(KillSigs[0])];
95 static void RegisterHandler(int Signal) {
96 assert(NumRegisteredSignals <
97 sizeof(RegisteredSignalInfo)/sizeof(RegisteredSignalInfo[0]) &&
98 "Out of space for signal handlers!");
100 struct sigaction NewHandler;
102 NewHandler.sa_handler = SignalHandler;
103 NewHandler.sa_flags = SA_NODEFER|SA_RESETHAND;
104 sigemptyset(&NewHandler.sa_mask);
106 // Install the new handler, save the old one in RegisteredSignalInfo.
107 sigaction(Signal, &NewHandler,
108 &RegisteredSignalInfo[NumRegisteredSignals].SA);
109 RegisteredSignalInfo[NumRegisteredSignals].SigNo = Signal;
110 ++NumRegisteredSignals;
113 static void RegisterHandlers() {
114 // If the handlers are already registered, we're done.
115 if (NumRegisteredSignals != 0) return;
117 for (auto S : IntSigs) RegisterHandler(S);
118 for (auto S : KillSigs) RegisterHandler(S);
121 static void UnregisterHandlers() {
122 // Restore all of the signal handlers to how they were before we showed up.
123 for (unsigned i = 0, e = NumRegisteredSignals; i != e; ++i)
124 sigaction(RegisteredSignalInfo[i].SigNo,
125 &RegisteredSignalInfo[i].SA, nullptr);
126 NumRegisteredSignals = 0;
130 /// RemoveFilesToRemove - Process the FilesToRemove list. This function
131 /// should be called with the SignalsMutex lock held.
132 /// NB: This must be an async signal safe function. It cannot allocate or free
133 /// memory, even in debug builds.
134 static void RemoveFilesToRemove() {
135 // We avoid iterators in case of debug iterators that allocate or release
137 std::vector<std::string>& FilesToRemoveRef = *FilesToRemove;
138 for (unsigned i = 0, e = FilesToRemoveRef.size(); i != e; ++i) {
139 // We rely on a std::string implementation for which repeated calls to
140 // 'c_str()' don't allocate memory. We pre-call 'c_str()' on all of these
141 // strings to try to ensure this is safe.
142 const char *path = FilesToRemoveRef[i].c_str();
144 // Get the status so we can determine if it's a file or directory. If we
145 // can't stat the file, ignore it.
147 if (stat(path, &buf) != 0)
150 // If this is not a regular file, ignore it. We want to prevent removal of
151 // special files like /dev/null, even if the compiler is being run with the
152 // super-user permissions.
153 if (!S_ISREG(buf.st_mode))
156 // Otherwise, remove the file. We ignore any errors here as there is nothing
162 // SignalHandler - The signal handler that runs.
163 static RETSIGTYPE SignalHandler(int Sig) {
164 // Restore the signal behavior to default, so that the program actually
165 // crashes when we return and the signal reissues. This also ensures that if
166 // we crash in our signal handler that the program will terminate immediately
167 // instead of recursing in the signal handler.
168 UnregisterHandlers();
170 // Unmask all potentially blocked kill signals.
172 sigfillset(&SigMask);
173 sigprocmask(SIG_UNBLOCK, &SigMask, nullptr);
176 unique_lock<SmartMutex<true>> Guard(*SignalsMutex);
177 RemoveFilesToRemove();
179 if (std::find(std::begin(IntSigs), std::end(IntSigs), Sig)
180 != std::end(IntSigs)) {
181 if (InterruptFunction) {
182 void (*IF)() = InterruptFunction;
184 InterruptFunction = nullptr;
185 IF(); // run the interrupt function.
190 raise(Sig); // Execute the default handler.
195 // Otherwise if it is a fault (like SEGV) run any handler.
196 std::vector<std::pair<void (*)(void *), void *>>& CallBacksToRunRef =
198 for (unsigned i = 0, e = CallBacksToRun->size(); i != e; ++i)
199 CallBacksToRunRef[i].first(CallBacksToRunRef[i].second);
202 // On S/390, certain signals are delivered with PSW Address pointing to
203 // *after* the faulting instruction. Simply returning from the signal
204 // handler would continue execution after that point, instead of
205 // re-raising the signal. Raise the signal manually in those cases.
206 if (Sig == SIGILL || Sig == SIGFPE || Sig == SIGTRAP)
211 void llvm::sys::RunInterruptHandlers() {
212 sys::SmartScopedLock<true> Guard(*SignalsMutex);
213 RemoveFilesToRemove();
216 void llvm::sys::SetInterruptFunction(void (*IF)()) {
218 sys::SmartScopedLock<true> Guard(*SignalsMutex);
219 InterruptFunction = IF;
224 // RemoveFileOnSignal - The public API
225 bool llvm::sys::RemoveFileOnSignal(StringRef Filename,
226 std::string* ErrMsg) {
228 sys::SmartScopedLock<true> Guard(*SignalsMutex);
229 std::vector<std::string>& FilesToRemoveRef = *FilesToRemove;
230 std::string *OldPtr =
231 FilesToRemoveRef.empty() ? nullptr : &FilesToRemoveRef[0];
232 FilesToRemoveRef.push_back(Filename);
234 // We want to call 'c_str()' on every std::string in this vector so that if
235 // the underlying implementation requires a re-allocation, it happens here
236 // rather than inside of the signal handler. If we see the vector grow, we
237 // have to call it on every entry. If it remains in place, we only need to
238 // call it on the latest one.
239 if (OldPtr == &FilesToRemoveRef[0])
240 FilesToRemoveRef.back().c_str();
242 for (unsigned i = 0, e = FilesToRemoveRef.size(); i != e; ++i)
243 FilesToRemoveRef[i].c_str();
250 // DontRemoveFileOnSignal - The public API
251 void llvm::sys::DontRemoveFileOnSignal(StringRef Filename) {
252 sys::SmartScopedLock<true> Guard(*SignalsMutex);
253 std::vector<std::string>::reverse_iterator RI =
254 std::find(FilesToRemove->rbegin(), FilesToRemove->rend(), Filename);
255 std::vector<std::string>::iterator I = FilesToRemove->end();
256 if (RI != FilesToRemove->rend())
257 I = FilesToRemove->erase(RI.base()-1);
259 // We need to call c_str() on every element which would have been moved by
260 // the erase. These elements, in a C++98 implementation where c_str()
261 // requires a reallocation on the first call may have had the call to c_str()
262 // made on insertion become invalid by being copied down an element.
263 for (std::vector<std::string>::iterator E = FilesToRemove->end(); I != E; ++I)
267 /// AddSignalHandler - Add a function to be called when a signal is delivered
268 /// to the process. The handler can have a cookie passed to it to identify
269 /// what instance of the handler it is.
270 void llvm::sys::AddSignalHandler(void (*FnPtr)(void *), void *Cookie) {
271 CallBacksToRun->push_back(std::make_pair(FnPtr, Cookie));
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, FILE *FD) {
326 // FIXME: Subtract necessary number from StackTrace entries to turn return addresses
327 // into actual instruction addresses.
328 // Use llvm-symbolizer tool to symbolize the stack traces.
329 std::string LLVMSymbolizerPath = sys::FindProgramByName("llvm-symbolizer");
330 if (LLVMSymbolizerPath.empty())
332 // We don't know argv0 or the address of main() at this point, but try
333 // to guess it anyway (it's possible on some platforms).
334 std::string MainExecutableName = sys::fs::getMainExecutable(nullptr, nullptr);
335 if (MainExecutableName.empty() ||
336 MainExecutableName.find("llvm-symbolizer") != std::string::npos)
339 std::vector<const char *> Modules(Depth, nullptr);
340 std::vector<intptr_t> Offsets(Depth, 0);
341 if (!findModulesAndOffsets(StackTrace, Depth, Modules.data(), Offsets.data(),
342 MainExecutableName.c_str()))
345 SmallString<32> InputFile, OutputFile;
346 sys::fs::createTemporaryFile("symbolizer-input", "", InputFD, InputFile);
347 sys::fs::createTemporaryFile("symbolizer-output", "", OutputFile);
348 FileRemover InputRemover(InputFile.c_str());
349 FileRemover OutputRemover(OutputFile.c_str());
350 std::vector<const StringRef *> Redirects(3, nullptr);
351 StringRef InputFileStr(InputFile);
352 StringRef OutputFileStr(OutputFile);
353 StringRef StderrFileStr;
354 Redirects[0] = &InputFileStr;
355 Redirects[1] = &OutputFileStr;
356 Redirects[2] = &StderrFileStr;
359 raw_fd_ostream Input(InputFD, true);
360 for (int i = 0; i < Depth; i++) {
362 Input << Modules[i] << " " << (void*)Offsets[i] << "\n";
366 const char *Args[] = {"llvm-symbolizer", "--functions=linkage", "--inlining",
367 "--demangle", nullptr};
369 sys::ExecuteAndWait(LLVMSymbolizerPath, Args, nullptr, Redirects.data());
373 auto OutputBuf = MemoryBuffer::getFile(OutputFile.c_str());
376 StringRef Output = OutputBuf.get()->getBuffer();
377 SmallVector<StringRef, 32> Lines;
378 Output.split(Lines, "\n");
379 auto CurLine = Lines.begin();
381 for (int i = 0; i < Depth; i++) {
383 fprintf(FD, "#%d %p\n", frame_no++, StackTrace[i]);
386 // Read pairs of lines (function name and file/line info) until we
387 // encounter empty line.
389 if (CurLine == Lines.end())
391 StringRef FunctionName = *CurLine++;
392 if (FunctionName.empty())
394 fprintf(FD, "#%d %p ", frame_no++, StackTrace[i]);
395 if (!FunctionName.startswith("??"))
396 fprintf(FD, "%s ", FunctionName.str().c_str());
397 if (CurLine == Lines.end())
399 StringRef FileLineInfo = *CurLine++;
400 if (!FileLineInfo.startswith("??"))
401 fprintf(FD, "%s", FileLineInfo.str().c_str());
403 fprintf(FD, "(%s+%p)", Modules[i], (void *)Offsets[i]);
410 // PrintStackTrace - In the case of a program crash or fault, print out a stack
411 // trace so that the user has an indication of why and where we died.
413 // On glibc systems we have the 'backtrace' function, which works nicely, but
414 // doesn't demangle symbols.
415 void llvm::sys::PrintStackTrace(FILE *FD) {
416 #if defined(HAVE_BACKTRACE) && defined(ENABLE_BACKTRACES)
417 static void* StackTrace[256];
418 // Use backtrace() to output a backtrace on Linux systems with glibc.
419 int depth = backtrace(StackTrace,
420 static_cast<int>(array_lengthof(StackTrace)));
421 if (printSymbolizedStackTrace(StackTrace, depth, FD))
423 #if HAVE_DLFCN_H && __GNUG__
425 for (int i = 0; i < depth; ++i) {
427 dladdr(StackTrace[i], &dlinfo);
428 const char* name = strrchr(dlinfo.dli_fname, '/');
431 if (!name) nwidth = strlen(dlinfo.dli_fname);
432 else nwidth = strlen(name) - 1;
434 if (nwidth > width) width = nwidth;
437 for (int i = 0; i < depth; ++i) {
439 dladdr(StackTrace[i], &dlinfo);
441 fprintf(FD, "%-2d", i);
443 const char* name = strrchr(dlinfo.dli_fname, '/');
444 if (!name) fprintf(FD, " %-*s", width, dlinfo.dli_fname);
445 else fprintf(FD, " %-*s", width, name+1);
447 fprintf(FD, " %#0*lx",
448 (int)(sizeof(void*) * 2) + 2, (unsigned long)StackTrace[i]);
450 if (dlinfo.dli_sname != nullptr) {
454 char* d = abi::__cxa_demangle(dlinfo.dli_sname, nullptr, nullptr, &res);
458 if (!d) fputs(dlinfo.dli_sname, FD);
462 // FIXME: When we move to C++11, use %t length modifier. It's not in
463 // C++03 and causes gcc to issue warnings. Losing the upper 32 bits of
464 // the stack offset for a stack dump isn't likely to cause any problems.
465 fprintf(FD, " + %u",(unsigned)((char*)StackTrace[i]-
466 (char*)dlinfo.dli_saddr));
471 backtrace_symbols_fd(StackTrace, depth, STDERR_FILENO);
476 static void PrintStackTraceSignalHandler(void *) {
477 PrintStackTrace(stderr);
480 /// PrintStackTraceOnErrorSignal - When an error signal (such as SIGABRT or
481 /// SIGSEGV) is delivered to the process, print a stack trace and then exit.
482 void llvm::sys::PrintStackTraceOnErrorSignal() {
483 AddSignalHandler(PrintStackTraceSignalHandler, nullptr);
485 #if defined(__APPLE__) && defined(ENABLE_CRASH_OVERRIDES)
486 // Environment variable to disable any kind of crash dialog.
487 if (getenv("LLVM_DISABLE_CRASH_REPORT")) {
488 mach_port_t self = mach_task_self();
490 exception_mask_t mask = EXC_MASK_CRASH;
492 kern_return_t ret = task_set_exception_ports(self,
495 EXCEPTION_STATE_IDENTITY | MACH_EXCEPTION_CODES,
505 // On Darwin, raise sends a signal to the main thread instead of the current
506 // thread. This has the unfortunate effect that assert() and abort() will end up
507 // bypassing our crash recovery attempts. We work around this for anything in
508 // the same linkage unit by just defining our own versions of the assert handler
511 #if defined(__APPLE__) && defined(ENABLE_CRASH_OVERRIDES)
517 return pthread_kill(pthread_self(), sig);
520 void __assert_rtn(const char *func,
525 fprintf(stderr, "Assertion failed: (%s), function %s, file %s, line %d.\n",
526 expr, func, file, line);
528 fprintf(stderr, "Assertion failed: (%s), file %s, line %d.\n",