| //===- 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/STLExtras.h" |
| #include "llvm/ADT/SmallString.h" |
| #include "llvm/Support/Errc.h" |
| #include "llvm/Support/Path.h" |
| #include "llvm/Support/Signals.h" |
| #include <system_error> |
| |
| #if !defined(_MSC_VER) && !defined(__MINGW32__) |
| #include <unistd.h> |
| #else |
| #include <io.h> |
| #endif |
| |
| using llvm::sys::fs::mapped_file_region; |
| |
| namespace llvm { |
| FileOutputBuffer::FileOutputBuffer(std::unique_ptr<mapped_file_region> R, |
| StringRef Path, StringRef TmpPath, |
| bool IsRegular) |
| : Region(std::move(R)), FinalPath(Path), TempPath(TmpPath), |
| IsRegular(IsRegular) {} |
| |
| FileOutputBuffer::~FileOutputBuffer() { |
| // Close the mapping before deleting the temp file, so that the removal |
| // succeeds. |
| Region.reset(); |
| sys::fs::remove(Twine(TempPath)); |
| } |
| |
| ErrorOr<std::unique_ptr<FileOutputBuffer>> |
| FileOutputBuffer::create(StringRef FilePath, size_t Size, unsigned Flags) { |
| // Check file is not a regular file, in which case we cannot remove it. |
| sys::fs::file_status Stat; |
| std::error_code EC = sys::fs::status(FilePath, Stat); |
| bool IsRegular = true; |
| 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; |
| case sys::fs::file_type::directory_file: |
| return errc::is_a_directory; |
| default: |
| if (EC) |
| return EC; |
| IsRegular = false; |
| } |
| |
| if (IsRegular) { |
| // Delete target file. |
| EC = sys::fs::remove(FilePath); |
| if (EC) |
| return EC; |
| } |
| |
| SmallString<128> TempFilePath; |
| int FD; |
| if (IsRegular) { |
| 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. |
| EC = sys::fs::createUniqueFile(Twine(FilePath) + ".tmp%%%%%%%", FD, |
| TempFilePath, Mode); |
| } else { |
| // Create a temporary file. Since this is a special file, we will not move |
| // it and the new file can be in another filesystem. This avoids trying to |
| // create a temporary file in /dev when outputting to /dev/null for example. |
| EC = sys::fs::createTemporaryFile(sys::path::filename(FilePath), "", FD, |
| TempFilePath); |
| } |
| |
| if (EC) |
| return EC; |
| |
| sys::RemoveFileOnSignal(TempFilePath); |
| |
| #ifndef LLVM_ON_WIN32 |
| // On Windows, CreateFileMapping (the mmap function on Windows) |
| // automatically extends the underlying file. We don't need to |
| // extend the file beforehand. _chsize (ftruncate on Windows) is |
| // pretty slow just like it writes specified amount of bytes, |
| // so we should avoid calling that. |
| EC = sys::fs::resize_file(FD, Size); |
| if (EC) |
| return EC; |
| #endif |
| |
| auto MappedFile = llvm::make_unique<mapped_file_region>( |
| FD, mapped_file_region::readwrite, Size, 0, EC); |
| int Ret = close(FD); |
| if (EC) |
| return EC; |
| if (Ret) |
| return std::error_code(errno, std::generic_category()); |
| |
| std::unique_ptr<FileOutputBuffer> Buf(new FileOutputBuffer( |
| std::move(MappedFile), FilePath, TempFilePath, IsRegular)); |
| return std::move(Buf); |
| } |
| |
| std::error_code FileOutputBuffer::commit() { |
| // Unmap buffer, letting OS flush dirty pages to file on disk. |
| Region.reset(); |
| |
| std::error_code EC; |
| if (IsRegular) { |
| // Rename file to final name. |
| EC = sys::fs::rename(Twine(TempPath), Twine(FinalPath)); |
| sys::DontRemoveFileOnSignal(TempPath); |
| } else { |
| EC = sys::fs::copy_file(TempPath, FinalPath); |
| std::error_code RMEC = sys::fs::remove(TempPath); |
| sys::DontRemoveFileOnSignal(TempPath); |
| if (RMEC) |
| return RMEC; |
| } |
| |
| return EC; |
| } |
| } // namespace |