1 files changed, 27 insertions, 18 deletions

diff --git a/ELF/Filesystem.cpp b/ELF/Filesystem.cpp
index d468ae0c618a..8d0b5d8a2f1c 100644
--- a/ELF/Filesystem.cpp
+++ b/ELF/Filesystem.cpp
@@ -13,8 +13,13 @@
 
 #include "Filesystem.h"
 #include "Config.h"
-#include "llvm/Support/FileSystem.h"
+#include "lld/Common/Threads.h"
+#include "llvm/Config/llvm-config.h"
 #include "llvm/Support/FileOutputBuffer.h"
+#include "llvm/Support/FileSystem.h"
+#if LLVM_ON_UNIX
+#include <unistd.h>
+#endif
 #include <thread>
 
 using namespace llvm;
@@ -35,27 +40,29 @@ using namespace lld::elf;
 // Since LLD can link a 1 GB binary in about 5 seconds, that waste
 // actually counts.
 //
-// This function spawns a background thread to call unlink.
+// This function spawns a background thread to remove the file.
 // The calling thread returns almost immediately.
 void elf::unlinkAsync(StringRef Path) {
-  if (!Config->Threads || !sys::fs::exists(Config->OutputFile) ||
-      !sys::fs::is_regular_file(Config->OutputFile))
+// Removing a file is async on windows.
+#if defined(LLVM_ON_WIN32)
+  sys::fs::remove(Path);
+#else
+  if (!ThreadsEnabled || !sys::fs::exists(Path) ||
+      !sys::fs::is_regular_file(Path))
     return;
 
-  // First, rename Path to avoid race condition. We cannot remove
-  // Path from a different thread because we are now going to create
-  // Path as a new file. If we do that in a different thread, the new
-  // thread can remove the new file.
-  SmallString<128> TempPath;
-  if (sys::fs::createUniqueFile(Path + "tmp%%%%%%%%", TempPath))
-    return;
-  if (sys::fs::rename(Path, TempPath)) {
-    sys::fs::remove(TempPath);
-    return;
-  }
+  // We cannot just remove path from a different thread because we are now going
+  // to create path as a new file.
+  // Instead we open the file and unlink it on this thread. The unlink is fast
+  // since the open fd guarantees that it is not removing the last reference.
+  int FD;
+  std::error_code EC = sys::fs::openFileForRead(Path, FD);
+  sys::fs::remove(Path);
 
-  // Remove TempPath in background.
-  std::thread([=] { ::remove(TempPath.str().str().c_str()); }).detach();
+  // close and therefore remove TempPath in background.
+  if (!EC)
+    std::thread([=] { ::close(FD); }).detach();
+#endif
 }
 
 // Simulate file creation to see if Path is writable.
@@ -73,5 +80,7 @@ void elf::unlinkAsync(StringRef Path) {
 std::error_code elf::tryCreateFile(StringRef Path) {
   if (Path.empty())
     return std::error_code();
-  return FileOutputBuffer::create(Path, 1).getError();
+  if (Path == "-")
+    return std::error_code();
+  return errorToErrorCode(FileOutputBuffer::create(Path, 1).takeError());
 }