1 files changed, 104 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Support/FileOutputBuffer.cpp b/contrib/llvm/lib/Support/FileOutputBuffer.cpp
new file mode 100644
index 000000000000..ed084faed789
--- /dev/null
+++ b/contrib/llvm/lib/Support/FileOutputBuffer.cpp
@@ -0,0 +1,104 @@
+//===- FileOutputBuffer.cpp - File Output Buffer ----------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Utility for creating a in-memory buffer that will be written to a file.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/FileOutputBuffer.h"
+#include "llvm/ADT/OwningPtr.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/system_error.h"
+
+using llvm::sys::fs::mapped_file_region;
+
+namespace llvm {
+FileOutputBuffer::FileOutputBuffer(mapped_file_region * R,
+                                   StringRef Path, StringRef TmpPath)
+  : Region(R)
+  , FinalPath(Path)
+  , TempPath(TmpPath) {
+}
+
+FileOutputBuffer::~FileOutputBuffer() {
+  bool Existed;
+  sys::fs::remove(Twine(TempPath), Existed);
+}
+
+error_code FileOutputBuffer::create(StringRef FilePath,
+                                    size_t Size,
+                                    OwningPtr<FileOutputBuffer> &Result,
+                                    unsigned Flags) {
+  // If file already exists, it must be a regular file (to be mappable).
+  sys::fs::file_status Stat;
+  error_code EC = sys::fs::status(FilePath, Stat);
+  switch (Stat.type()) {
+    case sys::fs::file_type::file_not_found:
+      // If file does not exist, we'll create one.
+      break;
+    case sys::fs::file_type::regular_file: {
+        // If file is not currently writable, error out.
+        // FIXME: There is no sys::fs:: api for checking this.
+        // FIXME: In posix, you use the access() call to check this.
+      }
+      break;
+    default:
+      if (EC)
+        return EC;
+      else
+        return make_error_code(errc::operation_not_permitted);
+  }
+
+  // Delete target file.
+  bool Existed;
+  EC = sys::fs::remove(FilePath, Existed);
+  if (EC)
+    return EC;
+
+  unsigned Mode = sys::fs::all_read | sys::fs::all_write;
+  // If requested, make the output file executable.
+  if (Flags & F_executable)
+    Mode |= sys::fs::all_exe;
+
+  // Create new file in same directory but with random name.
+  SmallString<128> TempFilePath;
+  int FD;
+  EC = sys::fs::createUniqueFile(Twine(FilePath) + ".tmp%%%%%%%", FD,
+                                 TempFilePath, Mode);
+  if (EC)
+    return EC;
+
+  OwningPtr<mapped_file_region> MappedFile(new mapped_file_region(
+      FD, true, mapped_file_region::readwrite, Size, 0, EC));
+  if (EC)
+    return EC;
+
+  Result.reset(new FileOutputBuffer(MappedFile.get(), FilePath, TempFilePath));
+  if (Result)
+    MappedFile.take();
+
+  return error_code::success();
+}
+
+error_code FileOutputBuffer::commit(int64_t NewSmallerSize) {
+  // Unmap buffer, letting OS flush dirty pages to file on disk.
+  Region.reset(0);
+
+  // If requested, resize file as part of commit.
+  if ( NewSmallerSize != -1 ) {
+    error_code EC = sys::fs::resize_file(Twine(TempPath), NewSmallerSize);
+    if (EC)
+      return EC;
+  }
+
+  // Rename file to final name.
+  return sys::fs::rename(Twine(TempPath), Twine(FinalPath));
+}
+} // namespace