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//===- 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/Errc.h"
#include "llvm/Support/FileOutputBuffer.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/raw_ostream.h"
#include <system_error>
using llvm::sys::fs::mapped_file_region;
namespace llvm {
FileOutputBuffer::FileOutputBuffer(std::unique_ptr<mapped_file_region> R,
StringRef Path, StringRef TmpPath)
: Region(std::move(R)), FinalPath(Path), TempPath(TmpPath) {}
FileOutputBuffer::~FileOutputBuffer() {
sys::fs::remove(Twine(TempPath));
}
std::error_code
FileOutputBuffer::create(StringRef FilePath, size_t Size,
std::unique_ptr<FileOutputBuffer> &Result,
unsigned Flags) {
// If file already exists, it must be a regular file (to be mappable).
sys::fs::file_status Stat;
std::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.
EC = sys::fs::remove(FilePath);
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;
auto MappedFile = llvm::make_unique<mapped_file_region>(
FD, true, mapped_file_region::readwrite, Size, 0, EC);
if (EC)
return EC;
Result.reset(
new FileOutputBuffer(std::move(MappedFile), FilePath, TempFilePath));
return std::error_code();
}
std::error_code FileOutputBuffer::commit(int64_t NewSmallerSize) {
// Unmap buffer, letting OS flush dirty pages to file on disk.
Region.reset();
// If requested, resize file as part of commit.
if ( NewSmallerSize != -1 ) {
std::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
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