forked from OSchip/llvm-project
391 lines
12 KiB
C++
391 lines
12 KiB
C++
//===- Signals.cpp - Generic Unix Signals Implementation -----*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines some helpful functions for dealing with the possibility of
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// Unix signals occurring while your program is running.
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//
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//===----------------------------------------------------------------------===//
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#include "Unix.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/Support/Mutex.h"
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#include <algorithm>
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#include <string>
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#include <vector>
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#if HAVE_EXECINFO_H
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# include <execinfo.h> // For backtrace().
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#endif
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#if HAVE_SIGNAL_H
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#include <signal.h>
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#endif
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#if HAVE_SYS_STAT_H
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#include <sys/stat.h>
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#endif
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#if HAVE_CXXABI_H
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#include <cxxabi.h>
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#endif
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#if HAVE_DLFCN_H
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#include <dlfcn.h>
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#endif
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#if HAVE_MACH_MACH_H
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#include <mach/mach.h>
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#endif
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using namespace llvm;
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static RETSIGTYPE SignalHandler(int Sig); // defined below.
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static SmartMutex<true> SignalsMutex;
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/// InterruptFunction - The function to call if ctrl-c is pressed.
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static void (*InterruptFunction)() = nullptr;
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static std::vector<std::string> FilesToRemove;
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static std::vector<std::pair<void(*)(void*), void*> > CallBacksToRun;
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// IntSigs - Signals that represent requested termination. There's no bug
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// or failure, or if there is, it's not our direct responsibility. For whatever
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// reason, our continued execution is no longer desirable.
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static const int IntSigs[] = {
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SIGHUP, SIGINT, SIGPIPE, SIGTERM, SIGUSR1, SIGUSR2
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};
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static const int *const IntSigsEnd = std::end(IntSigs);
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// KillSigs - Signals that represent that we have a bug, and our prompt
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// termination has been ordered.
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static const int KillSigs[] = {
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SIGILL, SIGTRAP, SIGABRT, SIGFPE, SIGBUS, SIGSEGV, SIGQUIT
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#ifdef SIGSYS
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, SIGSYS
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#endif
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#ifdef SIGXCPU
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, SIGXCPU
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#endif
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#ifdef SIGXFSZ
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, SIGXFSZ
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#endif
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#ifdef SIGEMT
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, SIGEMT
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#endif
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};
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static const int *const KillSigsEnd = std::end(KillSigs);
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static unsigned NumRegisteredSignals = 0;
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static struct {
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struct sigaction SA;
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int SigNo;
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} RegisteredSignalInfo[(sizeof(IntSigs)+sizeof(KillSigs))/sizeof(KillSigs[0])];
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static void RegisterHandler(int Signal) {
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assert(NumRegisteredSignals <
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sizeof(RegisteredSignalInfo)/sizeof(RegisteredSignalInfo[0]) &&
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"Out of space for signal handlers!");
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struct sigaction NewHandler;
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NewHandler.sa_handler = SignalHandler;
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NewHandler.sa_flags = SA_NODEFER|SA_RESETHAND;
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sigemptyset(&NewHandler.sa_mask);
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// Install the new handler, save the old one in RegisteredSignalInfo.
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sigaction(Signal, &NewHandler,
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&RegisteredSignalInfo[NumRegisteredSignals].SA);
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RegisteredSignalInfo[NumRegisteredSignals].SigNo = Signal;
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++NumRegisteredSignals;
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}
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static void RegisterHandlers() {
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// If the handlers are already registered, we're done.
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if (NumRegisteredSignals != 0) return;
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std::for_each(IntSigs, IntSigsEnd, RegisterHandler);
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std::for_each(KillSigs, KillSigsEnd, RegisterHandler);
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}
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static void UnregisterHandlers() {
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// Restore all of the signal handlers to how they were before we showed up.
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for (unsigned i = 0, e = NumRegisteredSignals; i != e; ++i)
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sigaction(RegisteredSignalInfo[i].SigNo,
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&RegisteredSignalInfo[i].SA, nullptr);
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NumRegisteredSignals = 0;
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}
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/// RemoveFilesToRemove - Process the FilesToRemove list. This function
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/// should be called with the SignalsMutex lock held.
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/// NB: This must be an async signal safe function. It cannot allocate or free
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/// memory, even in debug builds.
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static void RemoveFilesToRemove() {
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// We avoid iterators in case of debug iterators that allocate or release
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// memory.
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for (unsigned i = 0, e = FilesToRemove.size(); i != e; ++i) {
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// We rely on a std::string implementation for which repeated calls to
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// 'c_str()' don't allocate memory. We pre-call 'c_str()' on all of these
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// strings to try to ensure this is safe.
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const char *path = FilesToRemove[i].c_str();
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// Get the status so we can determine if it's a file or directory. If we
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// can't stat the file, ignore it.
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struct stat buf;
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if (stat(path, &buf) != 0)
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continue;
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// If this is not a regular file, ignore it. We want to prevent removal of
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// special files like /dev/null, even if the compiler is being run with the
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// super-user permissions.
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if (!S_ISREG(buf.st_mode))
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continue;
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// Otherwise, remove the file. We ignore any errors here as there is nothing
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// else we can do.
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unlink(path);
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}
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}
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// SignalHandler - The signal handler that runs.
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static RETSIGTYPE SignalHandler(int Sig) {
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// Restore the signal behavior to default, so that the program actually
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// crashes when we return and the signal reissues. This also ensures that if
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// we crash in our signal handler that the program will terminate immediately
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// instead of recursing in the signal handler.
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UnregisterHandlers();
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// Unmask all potentially blocked kill signals.
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sigset_t SigMask;
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sigfillset(&SigMask);
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sigprocmask(SIG_UNBLOCK, &SigMask, nullptr);
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SignalsMutex.acquire();
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RemoveFilesToRemove();
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if (std::find(IntSigs, IntSigsEnd, Sig) != IntSigsEnd) {
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if (InterruptFunction) {
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void (*IF)() = InterruptFunction;
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SignalsMutex.release();
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InterruptFunction = nullptr;
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IF(); // run the interrupt function.
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return;
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}
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SignalsMutex.release();
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raise(Sig); // Execute the default handler.
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return;
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}
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SignalsMutex.release();
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// Otherwise if it is a fault (like SEGV) run any handler.
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for (unsigned i = 0, e = CallBacksToRun.size(); i != e; ++i)
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CallBacksToRun[i].first(CallBacksToRun[i].second);
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#ifdef __s390__
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// On S/390, certain signals are delivered with PSW Address pointing to
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// *after* the faulting instruction. Simply returning from the signal
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// handler would continue execution after that point, instead of
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// re-raising the signal. Raise the signal manually in those cases.
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if (Sig == SIGILL || Sig == SIGFPE || Sig == SIGTRAP)
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raise(Sig);
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#endif
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}
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void llvm::sys::RunInterruptHandlers() {
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SignalsMutex.acquire();
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RemoveFilesToRemove();
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SignalsMutex.release();
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}
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void llvm::sys::SetInterruptFunction(void (*IF)()) {
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SignalsMutex.acquire();
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InterruptFunction = IF;
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SignalsMutex.release();
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RegisterHandlers();
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}
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// RemoveFileOnSignal - The public API
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bool llvm::sys::RemoveFileOnSignal(StringRef Filename,
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std::string* ErrMsg) {
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SignalsMutex.acquire();
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std::string *OldPtr = FilesToRemove.empty() ? nullptr : &FilesToRemove[0];
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FilesToRemove.push_back(Filename);
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// We want to call 'c_str()' on every std::string in this vector so that if
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// the underlying implementation requires a re-allocation, it happens here
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// rather than inside of the signal handler. If we see the vector grow, we
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// have to call it on every entry. If it remains in place, we only need to
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// call it on the latest one.
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if (OldPtr == &FilesToRemove[0])
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FilesToRemove.back().c_str();
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else
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for (unsigned i = 0, e = FilesToRemove.size(); i != e; ++i)
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FilesToRemove[i].c_str();
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SignalsMutex.release();
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RegisterHandlers();
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return false;
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}
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// DontRemoveFileOnSignal - The public API
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void llvm::sys::DontRemoveFileOnSignal(StringRef Filename) {
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SignalsMutex.acquire();
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std::vector<std::string>::reverse_iterator RI =
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std::find(FilesToRemove.rbegin(), FilesToRemove.rend(), Filename);
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std::vector<std::string>::iterator I = FilesToRemove.end();
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if (RI != FilesToRemove.rend())
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I = FilesToRemove.erase(RI.base()-1);
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// We need to call c_str() on every element which would have been moved by
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// the erase. These elements, in a C++98 implementation where c_str()
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// requires a reallocation on the first call may have had the call to c_str()
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// made on insertion become invalid by being copied down an element.
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for (std::vector<std::string>::iterator E = FilesToRemove.end(); I != E; ++I)
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I->c_str();
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SignalsMutex.release();
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}
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/// AddSignalHandler - Add a function to be called when a signal is delivered
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/// to the process. The handler can have a cookie passed to it to identify
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/// what instance of the handler it is.
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void llvm::sys::AddSignalHandler(void (*FnPtr)(void *), void *Cookie) {
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CallBacksToRun.push_back(std::make_pair(FnPtr, Cookie));
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RegisterHandlers();
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}
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// PrintStackTrace - In the case of a program crash or fault, print out a stack
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// trace so that the user has an indication of why and where we died.
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//
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// On glibc systems we have the 'backtrace' function, which works nicely, but
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// doesn't demangle symbols.
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void llvm::sys::PrintStackTrace(FILE *FD) {
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#if defined(HAVE_BACKTRACE) && defined(ENABLE_BACKTRACES)
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static void* StackTrace[256];
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// Use backtrace() to output a backtrace on Linux systems with glibc.
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int depth = backtrace(StackTrace,
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static_cast<int>(array_lengthof(StackTrace)));
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#if HAVE_DLFCN_H && __GNUG__
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int width = 0;
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for (int i = 0; i < depth; ++i) {
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Dl_info dlinfo;
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dladdr(StackTrace[i], &dlinfo);
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const char* name = strrchr(dlinfo.dli_fname, '/');
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int nwidth;
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if (!name) nwidth = strlen(dlinfo.dli_fname);
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else nwidth = strlen(name) - 1;
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if (nwidth > width) width = nwidth;
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}
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for (int i = 0; i < depth; ++i) {
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Dl_info dlinfo;
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dladdr(StackTrace[i], &dlinfo);
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fprintf(FD, "%-2d", i);
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const char* name = strrchr(dlinfo.dli_fname, '/');
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if (!name) fprintf(FD, " %-*s", width, dlinfo.dli_fname);
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else fprintf(FD, " %-*s", width, name+1);
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fprintf(FD, " %#0*lx",
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(int)(sizeof(void*) * 2) + 2, (unsigned long)StackTrace[i]);
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if (dlinfo.dli_sname != nullptr) {
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fputc(' ', FD);
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# if HAVE_CXXABI_H
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int res;
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char* d = abi::__cxa_demangle(dlinfo.dli_sname, nullptr, nullptr, &res);
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# else
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char* d = NULL;
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# endif
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if (!d) fputs(dlinfo.dli_sname, FD);
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else fputs(d, FD);
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free(d);
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// FIXME: When we move to C++11, use %t length modifier. It's not in
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// C++03 and causes gcc to issue warnings. Losing the upper 32 bits of
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// the stack offset for a stack dump isn't likely to cause any problems.
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fprintf(FD, " + %u",(unsigned)((char*)StackTrace[i]-
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(char*)dlinfo.dli_saddr));
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}
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fputc('\n', FD);
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}
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#else
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backtrace_symbols_fd(StackTrace, depth, STDERR_FILENO);
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#endif
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#endif
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}
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static void PrintStackTraceSignalHandler(void *) {
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PrintStackTrace(stderr);
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}
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/// PrintStackTraceOnErrorSignal - When an error signal (such as SIGABRT or
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/// SIGSEGV) is delivered to the process, print a stack trace and then exit.
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void llvm::sys::PrintStackTraceOnErrorSignal() {
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AddSignalHandler(PrintStackTraceSignalHandler, nullptr);
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#if defined(__APPLE__) && defined(ENABLE_CRASH_OVERRIDES)
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// Environment variable to disable any kind of crash dialog.
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if (getenv("LLVM_DISABLE_CRASH_REPORT")) {
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mach_port_t self = mach_task_self();
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exception_mask_t mask = EXC_MASK_CRASH;
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kern_return_t ret = task_set_exception_ports(self,
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mask,
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MACH_PORT_NULL,
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EXCEPTION_STATE_IDENTITY | MACH_EXCEPTION_CODES,
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THREAD_STATE_NONE);
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(void)ret;
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}
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#endif
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}
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/***/
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// On Darwin, raise sends a signal to the main thread instead of the current
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// thread. This has the unfortunate effect that assert() and abort() will end up
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// bypassing our crash recovery attempts. We work around this for anything in
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// the same linkage unit by just defining our own versions of the assert handler
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// and abort.
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#if defined(__APPLE__) && defined(ENABLE_CRASH_OVERRIDES)
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#include <signal.h>
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#include <pthread.h>
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int raise(int sig) {
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return pthread_kill(pthread_self(), sig);
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}
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void __assert_rtn(const char *func,
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const char *file,
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int line,
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const char *expr) {
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if (func)
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fprintf(stderr, "Assertion failed: (%s), function %s, file %s, line %d.\n",
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expr, func, file, line);
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else
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fprintf(stderr, "Assertion failed: (%s), file %s, line %d.\n",
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expr, file, line);
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abort();
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}
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void abort() {
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raise(SIGABRT);
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usleep(1000);
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__builtin_trap();
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}
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#endif
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