src/llvm/lib/Support/Unix/Signals.inc

   1 //===- Signals.cpp - Generic Unix Signals Implementation -----*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file defines some helpful functions for dealing with the possibility of
  11 // Unix signals occurring while your program is running.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "Unix.h"
  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"
  25 #include <algorithm>
  26 #include <string>
  27 #include <vector>
  28 #if HAVE_EXECINFO_H
  29 # include <execinfo.h>         // For backtrace().
  30 #endif
  31 #if HAVE_SIGNAL_H
  32 #include <signal.h>
  33 #endif
  34 #if HAVE_SYS_STAT_H
  35 #include <sys/stat.h>
  36 #endif
  37 #if HAVE_CXXABI_H
  38 #include <cxxabi.h>
  39 #endif
  40 #if HAVE_DLFCN_H
  41 #include <dlfcn.h>
  42 #endif
  43 #if HAVE_MACH_MACH_H
  44 #include <mach/mach.h>
  45 #endif
  46 #if HAVE_LINK_H
  47 #include <link.h>
  48 #endif
  49
  50 using namespace llvm;
  51
  52 static RETSIGTYPE SignalHandler(int Sig);  // defined below.
  53
  54 static ManagedStatic<SmartMutex<true> > SignalsMutex;
  55
  56 /// InterruptFunction - The function to call if ctrl-c is pressed.
  57 static void (*InterruptFunction)() = nullptr;
  58
  59 static ManagedStatic<std::vector<std::string>> FilesToRemove;
  60 static ManagedStatic<std::vector<std::pair<void (*)(void *), void *>>>
  61     CallBacksToRun;
  62
  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
  68 };
  69
  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
  74 #ifdef SIGSYS
  75   , SIGSYS
  76 #endif
  77 #ifdef SIGXCPU
  78   , SIGXCPU
  79 #endif
  80 #ifdef SIGXFSZ
  81   , SIGXFSZ
  82 #endif
  83 #ifdef SIGEMT
  84   , SIGEMT
  85 #endif
  86 };
  87
  88 static unsigned NumRegisteredSignals = 0;
  89 static struct {
  90   struct sigaction SA;
  91   int SigNo;
  92 } RegisteredSignalInfo[(sizeof(IntSigs)+sizeof(KillSigs))/sizeof(KillSigs[0])];
  93
  94
  95 static void RegisterHandler(int Signal) {
  96   assert(NumRegisteredSignals <
  97          sizeof(RegisteredSignalInfo)/sizeof(RegisteredSignalInfo[0]) &&
  98          "Out of space for signal handlers!");
  99
 100   struct sigaction NewHandler;
 101
 102   NewHandler.sa_handler = SignalHandler;
 103   NewHandler.sa_flags = SA_NODEFER|SA_RESETHAND;
 104   sigemptyset(&NewHandler.sa_mask);
 105
 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;
 111 }
 112
 113 static void RegisterHandlers() {
 114   // If the handlers are already registered, we're done.
 115   if (NumRegisteredSignals != 0) return;
 116
 117   for (auto S : IntSigs) RegisterHandler(S);
 118   for (auto S : KillSigs) RegisterHandler(S);
 119 }
 120
 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;
 127 }
 128
 129
 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
 136   // memory.
 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();
 143
 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.
 146     struct stat buf;
 147     if (stat(path, &buf) != 0)
 148       continue;
 149
 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))
 154       continue;
 155
 156     // Otherwise, remove the file. We ignore any errors here as there is nothing
 157     // else we can do.
 158     unlink(path);
 159   }
 160 }
 161
 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();
 169
 170   // Unmask all potentially blocked kill signals.
 171   sigset_t SigMask;
 172   sigfillset(&SigMask);
 173   sigprocmask(SIG_UNBLOCK, &SigMask, nullptr);
 174
 175   {
 176     unique_lock<SmartMutex<true>> Guard(*SignalsMutex);
 177     RemoveFilesToRemove();
 178
 179     if (std::find(std::begin(IntSigs), std::end(IntSigs), Sig)
 180         != std::end(IntSigs)) {
 181       if (InterruptFunction) {
 182         void (*IF)() = InterruptFunction;
 183         Guard.unlock();
 184         InterruptFunction = nullptr;
 185         IF();        // run the interrupt function.
 186         return;
 187       }
 188
 189       Guard.unlock();
 190       raise(Sig);   // Execute the default handler.
 191       return;
 192    }
 193   }
 194
 195   // Otherwise if it is a fault (like SEGV) run any handler.
 196   std::vector<std::pair<void (*)(void *), void *>>& CallBacksToRunRef =
 197       *CallBacksToRun;
 198   for (unsigned i = 0, e = CallBacksToRun->size(); i != e; ++i)
 199     CallBacksToRunRef[i].first(CallBacksToRunRef[i].second);
 200
 201 #ifdef __s390__
 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)
 207     raise(Sig);
 208 #endif
 209 }
 210
 211 void llvm::sys::RunInterruptHandlers() {
 212   sys::SmartScopedLock<true> Guard(*SignalsMutex);
 213   RemoveFilesToRemove();
 214 }
 215
 216 void llvm::sys::SetInterruptFunction(void (*IF)()) {
 217   {
 218     sys::SmartScopedLock<true> Guard(*SignalsMutex);
 219     InterruptFunction = IF;
 220   }
 221   RegisterHandlers();
 222 }
 223
 224 // RemoveFileOnSignal - The public API
 225 bool llvm::sys::RemoveFileOnSignal(StringRef Filename,
 226                                    std::string* ErrMsg) {
 227   {
 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);
 233
 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();
 241     else
 242       for (unsigned i = 0, e = FilesToRemoveRef.size(); i != e; ++i)
 243         FilesToRemoveRef[i].c_str();
 244   }
 245
 246   RegisterHandlers();
 247   return false;
 248 }
 249
 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);
 258
 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)
 264     I->c_str();
 265 }
 266
 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));
 272   RegisterHandlers();
 273 }
 274
 275 #if defined(HAVE_BACKTRACE) && defined(ENABLE_BACKTRACES)
 276
 277 #if HAVE_LINK_H && (defined(__linux__) || defined(__FreeBSD__) ||              \
 278                     defined(__FreeBSD_kernel__) || defined(__NetBSD__))
 279 struct DlIteratePhdrData {
 280   void **StackTrace;
 281   int depth;
 282   bool first;
 283   const char **modules;
 284   intptr_t *offsets;
 285   const char *main_exec_name;
 286 };
 287
 288 static int dl_iterate_phdr_cb(dl_phdr_info *info, size_t size, void *arg) {
 289   DlIteratePhdrData *data = (DlIteratePhdrData*)arg;
 290   const char *name = data->first ? data->main_exec_name : info->dlpi_name;
 291   data->first = false;
 292   for (int i = 0; i < info->dlpi_phnum; i++) {
 293     const auto *phdr = &info->dlpi_phdr[i];
 294     if (phdr->p_type != PT_LOAD)
 295       continue;
 296     intptr_t beg = info->dlpi_addr + phdr->p_vaddr;
 297     intptr_t end = beg + phdr->p_memsz;
 298     for (int j = 0; j < data->depth; j++) {
 299       if (data->modules[j])
 300         continue;
 301       intptr_t addr = (intptr_t)data->StackTrace[j];
 302       if (beg <= addr && addr < end) {
 303         data->modules[j] = name;
 304         data->offsets[j] = addr - info->dlpi_addr;
 305       }
 306     }
 307   }
 308   return 0;
 309 }
 310
 311 static bool findModulesAndOffsets(void **StackTrace, int Depth,
 312                                   const char **Modules, intptr_t *Offsets,
 313                                   const char *MainExecutableName) {
 314   DlIteratePhdrData data = {StackTrace, Depth,   true,
 315                             Modules,    Offsets, MainExecutableName};
 316   dl_iterate_phdr(dl_iterate_phdr_cb, &data);
 317   return true;
 318 }
 319 #else
 320 static bool findModulesAndOffsets(void **StackTrace, int Depth,
 321                                   const char **Modules, intptr_t *Offsets,
 322                                   const char *MainExecutableName) {
 323   return false;
 324 }
 325 #endif
 326
 327 static bool printSymbolizedStackTrace(void **StackTrace, int Depth, FILE *FD) {
 328   // FIXME: Subtract necessary number from StackTrace entries to turn return addresses
 329   // into actual instruction addresses.
 330   // Use llvm-symbolizer tool to symbolize the stack traces.
 331   ErrorOr<std::string> LLVMSymbolizerPathOrErr =
 332       sys::findProgramByName("llvm-symbolizer");
 333   if (!LLVMSymbolizerPathOrErr)
 334     return false;
 335   const std::string &LLVMSymbolizerPath = *LLVMSymbolizerPathOrErr;
 336   // We don't know argv0 or the address of main() at this point, but try
 337   // to guess it anyway (it's possible on some platforms).
 338   std::string MainExecutableName = sys::fs::getMainExecutable(nullptr, nullptr);
 339   if (MainExecutableName.empty() ||
 340       MainExecutableName.find("llvm-symbolizer") != std::string::npos)
 341     return false;
 342
 343   std::vector<const char *> Modules(Depth, nullptr);
 344   std::vector<intptr_t> Offsets(Depth, 0);
 345   if (!findModulesAndOffsets(StackTrace, Depth, Modules.data(), Offsets.data(),
 346                              MainExecutableName.c_str()))
 347     return false;
 348   int InputFD;
 349   SmallString<32> InputFile, OutputFile;
 350   sys::fs::createTemporaryFile("symbolizer-input", "", InputFD, InputFile);
 351   sys::fs::createTemporaryFile("symbolizer-output", "", OutputFile);
 352   FileRemover InputRemover(InputFile.c_str());
 353   FileRemover OutputRemover(OutputFile.c_str());
 354
 355   {
 356     raw_fd_ostream Input(InputFD, true);
 357     for (int i = 0; i < Depth; i++) {
 358       if (Modules[i])
 359         Input << Modules[i] << " " << (void*)Offsets[i] << "\n";
 360     }
 361   }
 362
 363   StringRef InputFileStr(InputFile);
 364   StringRef OutputFileStr(OutputFile);
 365   StringRef StderrFileStr;
 366   const StringRef *Redirects[] = {&InputFileStr, &OutputFileStr,
 367                                   &StderrFileStr};
 368   const char *Args[] = {"llvm-symbolizer", "--functions=linkage", "--inlining",
 369                         "--demangle", nullptr};
 370   int RunResult =
 371       sys::ExecuteAndWait(LLVMSymbolizerPath, Args, nullptr, Redirects);
 372   if (RunResult != 0)
 373     return false;
 374
 375   auto OutputBuf = MemoryBuffer::getFile(OutputFile.c_str());
 376   if (!OutputBuf)
 377     return false;
 378   StringRef Output = OutputBuf.get()->getBuffer();
 379   SmallVector<StringRef, 32> Lines;
 380   Output.split(Lines, "\n");
 381   auto CurLine = Lines.begin();
 382   int frame_no = 0;
 383   for (int i = 0; i < Depth; i++) {
 384     if (!Modules[i]) {
 385       fprintf(FD, "#%d %p\n", frame_no++, StackTrace[i]);
 386       continue;
 387     }
 388     // Read pairs of lines (function name and file/line info) until we
 389     // encounter empty line.
 390     for (;;) {
 391       if (CurLine == Lines.end())
 392         return false;
 393       StringRef FunctionName = *CurLine++;
 394       if (FunctionName.empty())
 395         break;
 396       fprintf(FD, "#%d %p ", frame_no++, StackTrace[i]);
 397       if (!FunctionName.startswith("??"))
 398         fprintf(FD, "%s ", FunctionName.str().c_str());
 399       if (CurLine == Lines.end())
 400         return false;
 401       StringRef FileLineInfo = *CurLine++;
 402       if (!FileLineInfo.startswith("??"))
 403         fprintf(FD, "%s", FileLineInfo.str().c_str());
 404       else
 405         fprintf(FD, "(%s+%p)", Modules[i], (void *)Offsets[i]);
 406       fprintf(FD, "\n");
 407     }
 408   }
 409   return true;
 410 }
 411 #endif // defined(HAVE_BACKTRACE) && defined(ENABLE_BACKTRACES)
 412
 413 // PrintStackTrace - In the case of a program crash or fault, print out a stack
 414 // trace so that the user has an indication of why and where we died.
 415 //
 416 // On glibc systems we have the 'backtrace' function, which works nicely, but
 417 // doesn't demangle symbols.
 418 void llvm::sys::PrintStackTrace(FILE *FD) {
 419 #if defined(HAVE_BACKTRACE) && defined(ENABLE_BACKTRACES)
 420   static void* StackTrace[256];
 421   // Use backtrace() to output a backtrace on Linux systems with glibc.
 422   int depth = backtrace(StackTrace,
 423                         static_cast<int>(array_lengthof(StackTrace)));
 424   if (printSymbolizedStackTrace(StackTrace, depth, FD))
 425     return;
 426 #if HAVE_DLFCN_H && __GNUG__
 427   int width = 0;
 428   for (int i = 0; i < depth; ++i) {
 429     Dl_info dlinfo;
 430     dladdr(StackTrace[i], &dlinfo);
 431     const char* name = strrchr(dlinfo.dli_fname, '/');
 432
 433     int nwidth;
 434     if (!name) nwidth = strlen(dlinfo.dli_fname);
 435     else       nwidth = strlen(name) - 1;
 436
 437     if (nwidth > width) width = nwidth;
 438   }
 439
 440   for (int i = 0; i < depth; ++i) {
 441     Dl_info dlinfo;
 442     dladdr(StackTrace[i], &dlinfo);
 443
 444     fprintf(FD, "%-2d", i);
 445
 446     const char* name = strrchr(dlinfo.dli_fname, '/');
 447     if (!name) fprintf(FD, " %-*s", width, dlinfo.dli_fname);
 448     else       fprintf(FD, " %-*s", width, name+1);
 449
 450     fprintf(FD, " %#0*lx",
 451             (int)(sizeof(void*) * 2) + 2, (unsigned long)StackTrace[i]);
 452
 453     if (dlinfo.dli_sname != nullptr) {
 454       fputc(' ', FD);
 455 #  if HAVE_CXXABI_H
 456       int res;
 457       char* d = abi::__cxa_demangle(dlinfo.dli_sname, nullptr, nullptr, &res);
 458 #  else
 459       char* d = NULL;
 460 #  endif
 461       if (!d) fputs(dlinfo.dli_sname, FD);
 462       else    fputs(d, FD);
 463       free(d);
 464
 465       // FIXME: When we move to C++11, use %t length modifier. It's not in
 466       // C++03 and causes gcc to issue warnings. Losing the upper 32 bits of
 467       // the stack offset for a stack dump isn't likely to cause any problems.
 468       fprintf(FD, " + %u",(unsigned)((char*)StackTrace[i]-
 469                                      (char*)dlinfo.dli_saddr));
 470     }
 471     fputc('\n', FD);
 472   }
 473 #else
 474   backtrace_symbols_fd(StackTrace, depth, STDERR_FILENO);
 475 #endif
 476 #endif
 477 }
 478
 479 static void PrintStackTraceSignalHandler(void *) {
 480   PrintStackTrace(stderr);
 481 }
 482
 483 /// PrintStackTraceOnErrorSignal - When an error signal (such as SIGABRT or
 484 /// SIGSEGV) is delivered to the process, print a stack trace and then exit.
 485 void llvm::sys::PrintStackTraceOnErrorSignal() {
 486   AddSignalHandler(PrintStackTraceSignalHandler, nullptr);
 487
 488 #if defined(__APPLE__) && defined(ENABLE_CRASH_OVERRIDES)
 489   // Environment variable to disable any kind of crash dialog.
 490   if (getenv("LLVM_DISABLE_CRASH_REPORT")) {
 491     mach_port_t self = mach_task_self();
 492
 493     exception_mask_t mask = EXC_MASK_CRASH;
 494
 495     kern_return_t ret = task_set_exception_ports(self,
 496                              mask,
 497                              MACH_PORT_NULL,
 498                              EXCEPTION_STATE_IDENTITY | MACH_EXCEPTION_CODES,
 499                              THREAD_STATE_NONE);
 500     (void)ret;
 501   }
 502 #endif
 503 }
 504
 505
 506 /***/
 507
 508 // On Darwin, raise sends a signal to the main thread instead of the current
 509 // thread. This has the unfortunate effect that assert() and abort() will end up
 510 // bypassing our crash recovery attempts. We work around this for anything in
 511 // the same linkage unit by just defining our own versions of the assert handler
 512 // and abort.
 513
 514 #if defined(__APPLE__) && defined(ENABLE_CRASH_OVERRIDES)
 515
 516 #include <signal.h>
 517 #include <pthread.h>
 518
 519 int raise(int sig) {
 520   return pthread_kill(pthread_self(), sig);
 521 }
 522
 523 void __assert_rtn(const char *func,
 524                   const char *file,
 525                   int line,
 526                   const char *expr) {
 527   if (func)
 528     fprintf(stderr, "Assertion failed: (%s), function %s, file %s, line %d.\n",
 529             expr, func, file, line);
 530   else
 531     fprintf(stderr, "Assertion failed: (%s), file %s, line %d.\n",
 532             expr, file, line);
 533   abort();
 534 }
 535
 536 void abort() {
 537   raise(SIGABRT);
 538   usleep(1000);
 539   __builtin_trap();
 540 }
 541
 542 #endif