//
//===----------------------------------------------------------------------===//
#include "llvm/Support/LockFileManager.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/Support/Errc.h"
#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/raw_ostream.h"
-#include <fstream>
-#include <sys/types.h>
+#include "llvm/Support/Signals.h"
#include <sys/stat.h>
+#include <sys/types.h>
#if LLVM_ON_WIN32
#include <windows.h>
#endif
#if LLVM_ON_UNIX
#include <unistd.h>
#endif
+
+#if defined(__APPLE__) && defined(__MAC_OS_X_VERSION_MIN_REQUIRED) && (__MAC_OS_X_VERSION_MIN_REQUIRED > 1050)
+#define USE_OSX_GETHOSTUUID 1
+#else
+#define USE_OSX_GETHOSTUUID 0
+#endif
+
+#if USE_OSX_GETHOSTUUID
+#include <uuid/uuid.h>
+#endif
using namespace llvm;
/// \brief Attempt to read the lock file with the given name, if it exists.
/// \returns The process ID of the process that owns this lock file
Optional<std::pair<std::string, int> >
LockFileManager::readLockFile(StringRef LockFileName) {
- // Check whether the lock file exists. If not, clearly there's nothing
- // to read, so we just return.
- bool Exists = false;
- if (sys::fs::exists(LockFileName, Exists) || !Exists)
- return Optional<std::pair<std::string, int> >();
-
// Read the owning host and PID out of the lock file. If it appears that the
// owning process is dead, the lock file is invalid.
- int PID = 0;
- std::string Hostname;
- std::ifstream Input(LockFileName.str().c_str());
- if (Input >> Hostname >> PID && PID > 0 &&
- processStillExecuting(Hostname, PID))
- return std::make_pair(Hostname, PID);
+ ErrorOr<std::unique_ptr<MemoryBuffer>> MBOrErr =
+ MemoryBuffer::getFile(LockFileName);
+ if (!MBOrErr) {
+ sys::fs::remove(LockFileName);
+ return None;
+ }
+ MemoryBuffer &MB = *MBOrErr.get();
+
+ StringRef Hostname;
+ StringRef PIDStr;
+ std::tie(Hostname, PIDStr) = getToken(MB.getBuffer(), " ");
+ PIDStr = PIDStr.substr(PIDStr.find_first_not_of(" "));
+ int PID;
+ if (!PIDStr.getAsInteger(10, PID)) {
+ auto Owner = std::make_pair(std::string(Hostname), PID);
+ if (processStillExecuting(Owner.first, Owner.second))
+ return Owner;
+ }
// Delete the lock file. It's invalid anyway.
- bool Existed;
- sys::fs::remove(LockFileName, Existed);
- return Optional<std::pair<std::string, int> >();
+ sys::fs::remove(LockFileName);
+ return None;
}
-bool LockFileManager::processStillExecuting(StringRef Hostname, int PID) {
+static std::error_code getHostID(SmallVectorImpl<char> &HostID) {
+ HostID.clear();
+
+#if USE_OSX_GETHOSTUUID
+ // On OS X, use the more stable hardware UUID instead of hostname.
+ struct timespec wait = {1, 0}; // 1 second.
+ uuid_t uuid;
+ if (gethostuuid(uuid, &wait) != 0)
+ return std::error_code(errno, std::system_category());
+
+ uuid_string_t UUIDStr;
+ uuid_unparse(uuid, UUIDStr);
+ StringRef UUIDRef(UUIDStr);
+ HostID.append(UUIDRef.begin(), UUIDRef.end());
+
+#elif LLVM_ON_UNIX
+ char HostName[256];
+ HostName[255] = 0;
+ HostName[0] = 0;
+ gethostname(HostName, 255);
+ StringRef HostNameRef(HostName);
+ HostID.append(HostNameRef.begin(), HostNameRef.end());
+
+#else
+ StringRef Dummy("localhost");
+ HostID.append(Dummy.begin(), Dummy.end());
+#endif
+
+ return std::error_code();
+}
+
+bool LockFileManager::processStillExecuting(StringRef HostID, int PID) {
#if LLVM_ON_UNIX && !defined(__ANDROID__)
- char MyHostname[256];
- MyHostname[255] = 0;
- MyHostname[0] = 0;
- gethostname(MyHostname, 255);
+ SmallString<256> StoredHostID;
+ if (getHostID(StoredHostID))
+ return true; // Conservatively assume it's executing on error.
+
// Check whether the process is dead. If so, we're done.
- if (MyHostname == Hostname && getsid(PID) == -1 && errno == ESRCH)
+ if (StoredHostID == HostID && getsid(PID) == -1 && errno == ESRCH)
return false;
#endif
return true;
}
+namespace {
+/// An RAII helper object ensure that the unique lock file is removed.
+///
+/// Ensures that if there is an error or a signal before we finish acquiring the
+/// lock, the unique file will be removed. And if we successfully take the lock,
+/// the signal handler is left in place so that signals while the lock is held
+/// will remove the unique lock file. The caller should ensure there is a
+/// matching call to sys::DontRemoveFileOnSignal when the lock is released.
+class RemoveUniqueLockFileOnSignal {
+ StringRef Filename;
+ bool RemoveImmediately;
+public:
+ RemoveUniqueLockFileOnSignal(StringRef Name)
+ : Filename(Name), RemoveImmediately(true) {
+ sys::RemoveFileOnSignal(Filename, nullptr);
+ }
+ ~RemoveUniqueLockFileOnSignal() {
+ if (!RemoveImmediately) {
+ // Leave the signal handler enabled. It will be removed when the lock is
+ // released.
+ return;
+ }
+ sys::fs::remove(Filename);
+ sys::DontRemoveFileOnSignal(Filename);
+ }
+ void lockAcquired() { RemoveImmediately = false; }
+};
+} // end anonymous namespace
+
LockFileManager::LockFileManager(StringRef FileName)
{
- LockFileName = FileName;
+ this->FileName = FileName;
+ if (std::error_code EC = sys::fs::make_absolute(this->FileName)) {
+ Error = EC;
+ return;
+ }
+ LockFileName = this->FileName;
LockFileName += ".lock";
// If the lock file already exists, don't bother to try to create our own
UniqueLockFileName = LockFileName;
UniqueLockFileName += "-%%%%%%%%";
int UniqueLockFileID;
- if (error_code EC
- = sys::fs::unique_file(UniqueLockFileName.str(),
- UniqueLockFileID,
- UniqueLockFileName,
- /*makeAbsolute=*/false)) {
+ if (std::error_code EC = sys::fs::createUniqueFile(
+ UniqueLockFileName, UniqueLockFileID, UniqueLockFileName)) {
Error = EC;
return;
}
// Write our process ID to our unique lock file.
{
- raw_fd_ostream Out(UniqueLockFileID, /*shouldClose=*/true);
+ SmallString<256> HostID;
+ if (auto EC = getHostID(HostID)) {
+ Error = EC;
+ return;
+ }
+ raw_fd_ostream Out(UniqueLockFileID, /*shouldClose=*/true);
+ Out << HostID << ' ';
#if LLVM_ON_UNIX
- // FIXME: move getpid() call into LLVM
- char hostname[256];
- hostname[255] = 0;
- hostname[0] = 0;
- gethostname(hostname, 255);
- Out << hostname << ' ' << getpid();
+ Out << getpid();
#else
- Out << "localhost 1";
+ Out << "1";
#endif
Out.close();
// We failed to write out PID, so make up an excuse, remove the
// unique lock file, and fail.
Error = make_error_code(errc::no_space_on_device);
- bool Existed;
- sys::fs::remove(UniqueLockFileName.c_str(), Existed);
+ sys::fs::remove(UniqueLockFileName);
return;
}
}
- // Create a hard link from the lock file name. If this succeeds, we're done.
- error_code EC
- = sys::fs::create_hard_link(UniqueLockFileName.str(),
- LockFileName.str());
- if (EC == errc::success)
- return;
+ // Clean up the unique file on signal, which also releases the lock if it is
+ // held since the .lock symlink will point to a nonexistent file.
+ RemoveUniqueLockFileOnSignal RemoveUniqueFile(UniqueLockFileName);
- // Creating the hard link failed.
+ while (1) {
+ // Create a link from the lock file name. If this succeeds, we're done.
+ std::error_code EC =
+ sys::fs::create_link(UniqueLockFileName, LockFileName);
+ if (!EC) {
+ RemoveUniqueFile.lockAcquired();
+ return;
+ }
-#ifdef LLVM_ON_UNIX
- // The creation of the hard link may appear to fail, but if stat'ing the
- // unique file returns a link count of 2, then we can still declare success.
- struct stat StatBuf;
- if (stat(UniqueLockFileName.c_str(), &StatBuf) == 0 &&
- StatBuf.st_nlink == 2)
- return;
-#endif
+ if (EC != errc::file_exists) {
+ Error = EC;
+ return;
+ }
- // Someone else managed to create the lock file first. Wipe out our unique
- // lock file (it's useless now) and read the process ID from the lock file.
- bool Existed;
- sys::fs::remove(UniqueLockFileName.str(), Existed);
- if ((Owner = readLockFile(LockFileName)))
- return;
+ // Someone else managed to create the lock file first. Read the process ID
+ // from the lock file.
+ if ((Owner = readLockFile(LockFileName))) {
+ // Wipe out our unique lock file (it's useless now)
+ sys::fs::remove(UniqueLockFileName);
+ return;
+ }
+
+ if (!sys::fs::exists(LockFileName)) {
+ // The previous owner released the lock file before we could read it.
+ // Try to get ownership again.
+ continue;
+ }
- // There is a lock file that nobody owns; try to clean it up and report
- // an error.
- sys::fs::remove(LockFileName.str(), Existed);
- Error = EC;
+ // There is a lock file that nobody owns; try to clean it up and get
+ // ownership.
+ if ((EC = sys::fs::remove(LockFileName))) {
+ Error = EC;
+ return;
+ }
+ }
}
LockFileManager::LockFileState LockFileManager::getState() const {
return;
// Since we own the lock, remove the lock file and our own unique lock file.
- bool Existed;
- sys::fs::remove(LockFileName.str(), Existed);
- sys::fs::remove(UniqueLockFileName.str(), Existed);
+ sys::fs::remove(LockFileName);
+ sys::fs::remove(UniqueLockFileName);
+ // The unique file is now gone, so remove it from the signal handler. This
+ // matches a sys::RemoveFileOnSignal() in LockFileManager().
+ sys::DontRemoveFileOnSignal(UniqueLockFileName);
}
-void LockFileManager::waitForUnlock() {
+LockFileManager::WaitForUnlockResult LockFileManager::waitForUnlock() {
if (getState() != LFS_Shared)
- return;
+ return Res_Success;
#if LLVM_ON_WIN32
unsigned long Interval = 1;
Interval.tv_sec = 0;
Interval.tv_nsec = 1000000;
#endif
- // Don't wait more than an hour for the file to appear.
- const unsigned MaxSeconds = 3600;
+ // Don't wait more than five minutes per iteration. Total timeout for the file
+ // to appear is ~8.5 mins.
+ const unsigned MaxSeconds = 5*60;
do {
// Sleep for the designated interval, to allow the owning process time to
// finish up and remove the lock file.
#if LLVM_ON_WIN32
Sleep(Interval);
#else
- nanosleep(&Interval, NULL);
+ nanosleep(&Interval, nullptr);
#endif
- // If the file no longer exists, we're done.
- bool Exists = false;
- if (!sys::fs::exists(LockFileName.str(), Exists) && !Exists)
- return;
+ if (sys::fs::access(LockFileName.c_str(), sys::fs::AccessMode::Exist) ==
+ errc::no_such_file_or_directory) {
+ // If the original file wasn't created, somone thought the lock was dead.
+ if (!sys::fs::exists(FileName))
+ return Res_OwnerDied;
+ return Res_Success;
+ }
+
+ // If the process owning the lock died without cleaning up, just bail out.
if (!processStillExecuting((*Owner).first, (*Owner).second))
- return;
+ return Res_OwnerDied;
// Exponentially increase the time we wait for the lock to be removed.
#if LLVM_ON_WIN32
);
// Give up.
+ return Res_Timeout;
+}
+
+std::error_code LockFileManager::unsafeRemoveLockFile() {
+ return sys::fs::remove(LockFileName);
}