diff options
| -rw-r--r-- | llvm/lib/Support/LockFileManager.cpp | 41 |
1 files changed, 40 insertions, 1 deletions
diff --git a/llvm/lib/Support/LockFileManager.cpp b/llvm/lib/Support/LockFileManager.cpp index d07c5f0f682..95e0ece9245 100644 --- a/llvm/lib/Support/LockFileManager.cpp +++ b/llvm/lib/Support/LockFileManager.cpp @@ -12,6 +12,7 @@ #include "llvm/Support/FileSystem.h" #include "llvm/Support/MemoryBuffer.h" #include "llvm/Support/raw_ostream.h" +#include "llvm/Support/Signals.h" #include <sys/stat.h> #include <sys/types.h> #if LLVM_ON_WIN32 @@ -69,6 +70,35 @@ bool LockFileManager::processStillExecuting(StringRef Hostname, int PID) { 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) { this->FileName = FileName; @@ -119,12 +149,18 @@ LockFileManager::LockFileManager(StringRef FileName) } } + // 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); + 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) + if (!EC) { + RemoveUniqueFile.lockAcquired(); return; + } if (EC != errc::file_exists) { Error = EC; @@ -171,6 +207,9 @@ LockFileManager::~LockFileManager() { // Since we own the lock, remove the lock file and our own unique lock file. 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); } LockFileManager::WaitForUnlockResult LockFileManager::waitForUnlock() { |
