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