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llvm-mirror/unittests/Support/ReplaceFileTest.cpp
Greg Bedwell 3d11c34467 Fix rename() sometimes failing if another process uses openFileForRead()
On Windows, fs::rename() could fail is another process was reading the
file at the same time using fs::openFileForRead().  In most cases the user
wouldn't notice as fs::rename() will continue to retry for 2000ms.  Typically
this is enough for the read to complete and a retry to succeed, but if the
disk is being it too hard then the response time might be longer than the
retry time and the rename would fail with a permission error.

Add FILE_SHARE_DELETE to the sharing flags for CreateFileW() in
fs::openFileForRead() and try ReplaceFileW() prior to MoveFileExW()
in fs::rename().

Based on an initial patch by Edd Dawson!

Differential Revision: http://reviews.llvm.org/D13647

llvm-svn: 250046
2015-10-12 15:11:47 +00:00

114 lines
3.9 KiB
C++

//===- llvm/unittest/Support/ReplaceFileTest.cpp - unit tests -------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/Support/Errc.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/Process.h"
#include "gtest/gtest.h"
using namespace llvm;
using namespace llvm::sys;
#define ASSERT_NO_ERROR(x) \
do { \
if (std::error_code ASSERT_NO_ERROR_ec = x) { \
errs() << #x ": did not return errc::success.\n" \
<< "error number: " << ASSERT_NO_ERROR_ec.value() << "\n" \
<< "error message: " << ASSERT_NO_ERROR_ec.message() << "\n"; \
} \
} while (false)
namespace {
std::error_code CreateFileWithContent(const SmallString<128> &FilePath,
const StringRef &content) {
int FD = 0;
if (std::error_code ec = fs::openFileForWrite(FilePath, FD, fs::F_None))
return ec;
const bool ShouldClose = true;
raw_fd_ostream OS(FD, ShouldClose);
OS << content;
return std::error_code();
}
class ScopedFD {
int FD;
ScopedFD(const ScopedFD &) = delete;
ScopedFD &operator=(const ScopedFD &) = delete;
public:
explicit ScopedFD(int Descriptor) : FD(Descriptor) {}
~ScopedFD() { Process::SafelyCloseFileDescriptor(FD); }
};
TEST(rename, FileOpenedForReadingCanBeReplaced) {
// Create unique temporary directory for this test.
SmallString<128> TestDirectory;
ASSERT_NO_ERROR(fs::createUniqueDirectory(
"FileOpenedForReadingCanBeReplaced-test", TestDirectory));
// Add a couple of files to the test directory.
SmallString<128> SourceFileName(TestDirectory);
path::append(SourceFileName, "source");
SmallString<128> TargetFileName(TestDirectory);
path::append(TargetFileName, "target");
ASSERT_NO_ERROR(CreateFileWithContent(SourceFileName, "!!source!!"));
ASSERT_NO_ERROR(CreateFileWithContent(TargetFileName, "!!target!!"));
{
// Open the target file for reading.
int ReadFD = 0;
ASSERT_NO_ERROR(fs::openFileForRead(TargetFileName, ReadFD));
ScopedFD EventuallyCloseIt(ReadFD);
// Confirm we can replace the file while it is open.
EXPECT_TRUE(!fs::rename(SourceFileName, TargetFileName));
// We should still be able to read the old data through the existing
// descriptor.
auto Buffer = MemoryBuffer::getOpenFile(ReadFD, TargetFileName, -1);
ASSERT_TRUE(static_cast<bool>(Buffer));
EXPECT_EQ(Buffer.get()->getBuffer(), "!!target!!");
// The source file should no longer exist
EXPECT_FALSE(fs::exists(SourceFileName));
}
{
// If we obtain a new descriptor for the target file, we should find that it
// contains the content that was in the source file.
int ReadFD = 0;
ASSERT_NO_ERROR(fs::openFileForRead(TargetFileName, ReadFD));
ScopedFD EventuallyCloseIt(ReadFD);
auto Buffer = MemoryBuffer::getOpenFile(ReadFD, TargetFileName, -1);
ASSERT_TRUE(static_cast<bool>(Buffer));
EXPECT_EQ(Buffer.get()->getBuffer(), "!!source!!");
}
// Rename the target file back to the source file name to confirm that rename
// still works if the destination does not already exist.
EXPECT_TRUE(!fs::rename(TargetFileName, SourceFileName));
EXPECT_FALSE(fs::exists(TargetFileName));
ASSERT_TRUE(fs::exists(SourceFileName));
// Clean up.
ASSERT_NO_ERROR(fs::remove(SourceFileName));
ASSERT_NO_ERROR(fs::remove(TestDirectory.str()));
}
} // anonymous namespace