Initial commit of new FileOutputBuffer support class.
Since the llvm::sys::fs::map_file_pages() support function it relies on
is not yet implemented on Windows, the unit tests for FileOutputBuffer
are currently conditionalized to run only on unix.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161099 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/FileOutputBuffer.cpp b/lib/Support/FileOutputBuffer.cpp
new file mode 100644
index 0000000..7dc9587
--- /dev/null
+++ b/lib/Support/FileOutputBuffer.cpp
@@ -0,0 +1,148 @@
+//===- 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/FileSystem.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/system_error.h"
+
+
+namespace llvm {
+
+
+FileOutputBuffer::FileOutputBuffer(uint8_t *Start, uint8_t *End,
+ StringRef Path, StringRef TmpPath)
+ : BufferStart(Start), BufferEnd(End) {
+ FinalPath.assign(Path);
+ TempPath.assign(TmpPath);
+}
+
+
+FileOutputBuffer::~FileOutputBuffer() {
+ // If not already commited, delete buffer and remove temp file.
+ if ( BufferStart != NULL ) {
+ sys::fs::unmap_file_pages((void*)BufferStart, getBufferSize());
+ 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;
+
+ // Create new file in same directory but with random name.
+ SmallString<128> TempFilePath;
+ int FD;
+ EC = sys::fs::unique_file(Twine(FilePath) + ".tmp%%%%%%%",
+ FD, TempFilePath, false, 0644);
+ if (EC)
+ return EC;
+
+ // The unique_file() interface leaks lower layers and returns a file
+ // descriptor. There is no way to directly close it, so use this hack
+ // to hand it off to raw_fd_ostream to close for us.
+ {
+ raw_fd_ostream Dummy(FD, /*shouldClose=*/true);
+ }
+
+ // Resize file to requested initial size
+ EC = sys::fs::resize_file(Twine(TempFilePath), Size);
+ if (EC)
+ return EC;
+
+ // If requested, make the output file executable.
+ if ( Flags & F_executable ) {
+ sys::fs::file_status Stat2;
+ EC = sys::fs::status(Twine(TempFilePath), Stat2);
+ if (EC)
+ return EC;
+
+ sys::fs::perms new_perms = Stat2.permissions();
+ if ( new_perms & sys::fs::owner_read )
+ new_perms |= sys::fs::owner_exe;
+ if ( new_perms & sys::fs::group_read )
+ new_perms |= sys::fs::group_exe;
+ if ( new_perms & sys::fs::others_read )
+ new_perms |= sys::fs::others_exe;
+ new_perms |= sys::fs::add_perms;
+ EC = sys::fs::permissions(Twine(TempFilePath), new_perms);
+ if (EC)
+ return EC;
+ }
+
+ // Memory map new file.
+ void *Base;
+ EC = sys::fs::map_file_pages(Twine(TempFilePath), 0, Size, true, Base);
+ if (EC)
+ return EC;
+
+ // Create FileOutputBuffer object to own mapped range.
+ uint8_t *Start = reinterpret_cast<uint8_t*>(Base);
+ Result.reset(new FileOutputBuffer(Start, Start+Size, FilePath, TempFilePath));
+
+ return error_code::success();
+}
+
+
+error_code FileOutputBuffer::commit(int64_t NewSmallerSize) {
+ // Unmap buffer, letting OS flush dirty pages to file on disk.
+ void *Start = reinterpret_cast<void*>(BufferStart);
+ error_code EC = sys::fs::unmap_file_pages(Start, getBufferSize());
+ if (EC)
+ return EC;
+
+ // If requested, resize file as part of commit.
+ if ( NewSmallerSize != -1 ) {
+ 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
+