public async Task ReadsBytesFromGivenFileAtGivenOffsetAsync()
{
const int fileSize = 4_001;
string filePath = GetTestFilePath();
byte[] expected = RandomNumberGenerator.GetBytes(fileSize);
File.WriteAllBytes(filePath, expected);
using (SafeFileHandle handle = File.OpenHandle(filePath, FileMode.Open, options: FileOptions.Asynchronous))
{
byte[] actual = new byte[fileSize + 1];
int current = 0;
int total = 0;
do
{
Memory <byte> buffer = actual.AsMemory(total, Math.Min(actual.Length - total, fileSize / 4));
current = await RandomAccess.ReadAsync(handle, buffer, fileOffset : total);
Assert.InRange(current, 0, buffer.Length);
total += current;
} while (current != 0);
Assert.Equal(fileSize, total);
Assert.Equal(expected, actual.Take(total).ToArray());
}
}
public async Task ReadAsyncUsingSingleBuffer()
{
const int fileSize = 1_000_000; // 1 MB
string filePath = GetTestFilePath();
byte[] expected = RandomNumberGenerator.GetBytes(fileSize);
File.WriteAllBytes(filePath, expected);
using (SafeFileHandle handle = File.OpenHandle(filePath, FileMode.Open, options: FileOptions.Asynchronous | NoBuffering))
using (SectorAlignedMemory <byte> buffer = SectorAlignedMemory <byte> .Allocate(Environment.SystemPageSize))
{
int current = 0;
int total = 0;
// From https://docs.microsoft.com/en-us/windows/win32/fileio/file-buffering:
// "File access sizes, including the optional file offset in the OVERLAPPED structure,
// if specified, must be for a number of bytes that is an integer multiple of the volume sector size."
// So if buffer and physical sector size is 4096 and the file size is 4097:
// the read from offset=0 reads 4096 bytes
// the read from offset=4096 reads 1 byte
// the read from offset=4097 THROWS (Invalid argument, offset is not a multiple of sector size!)
// That is why we stop at the first incomplete read (the next one would throw).
// It's possible to get 0 if we are lucky and file size is a multiple of physical sector size.
do
{
current = await RandomAccess.ReadAsync(handle, buffer.Memory, fileOffset : total);
Assert.True(expected.AsSpan(total, current).SequenceEqual(buffer.GetSpan().Slice(0, current)));
total += current;
}while (current == buffer.Memory.Length);
Assert.Equal(fileSize, total);
}
}
public async Task ReadWriteAsyncUsingNonPageSizedMultipleBuffers()
{
string filePath = GetTestFilePath();
// The Windows scatter/gather APIs accept segments that are exactly one page long.
// Combined with the FILE_FLAG_NO_BUFFERING's requirements, the segments must also
// be aligned at page size boundaries and have a size of a multiple of the page size.
// Using segments with a length of twice the page size adheres to the second requirement
// but not the first. The RandomAccess implementation will see it and issue sequential
// read/write syscalls per segment, instead of one scatter/gather syscall.
// This test verifies that fallback behavior.
int bufferSize = Environment.SystemPageSize * 2;
int fileSize = bufferSize * 2;
byte[] content = RandomNumberGenerator.GetBytes(fileSize);
using (SafeFileHandle handle = File.OpenHandle(filePath, FileMode.CreateNew, FileAccess.ReadWrite, FileShare.None, FileOptions.Asynchronous | NoBuffering))
using (SectorAlignedMemory <byte> buffer = SectorAlignedMemory <byte> .Allocate(fileSize))
{
Memory <byte> firstHalf = buffer.Memory.Slice(0, bufferSize);
Memory <byte> secondHalf = buffer.Memory.Slice(bufferSize);
content.AsSpan().CopyTo(buffer.GetSpan());
await RandomAccess.WriteAsync(handle, new ReadOnlyMemory <byte>[] { firstHalf, secondHalf }, 0);
buffer.GetSpan().Clear();
await RandomAccess.ReadAsync(handle, new Memory <byte>[] { firstHalf, secondHalf }, 0);
}
Assert.Equal(content, await File.ReadAllBytesAsync(filePath));
}
public void ThrowsArgumentNullExceptionForNullBuffers(FileOptions options)
{
using (SafeFileHandle handle = File.OpenHandle(GetTestFilePath(), FileMode.CreateNew, FileAccess.Write, options: options))
{
AssertExtensions.Throws <ArgumentNullException>("buffers", () => RandomAccess.ReadAsync(handle, buffers: null, 0));
}
}
public async Task ReadWriteAsyncUsingMultipleBuffers(bool memoryPageSized)
{
string filePath = GetTestFilePath();
// We test with buffers both one and two memory pages long. In the former case,
// the I/O operations will issue one scatter/gather API call, and in the latter
// case they will issue multiple calls; one per buffer. The buffers must still
// be aligned to comply with FILE_FLAG_NO_BUFFERING's requirements.
int bufferSize = Environment.SystemPageSize * (memoryPageSized ? 1 : 2);
int fileSize = bufferSize * 2;
byte[] content = RandomNumberGenerator.GetBytes(fileSize);
using (SafeFileHandle handle = File.OpenHandle(filePath, FileMode.CreateNew, FileAccess.ReadWrite, FileShare.None, FileOptions.Asynchronous | NoBuffering))
using (SectorAlignedMemory <byte> buffer = SectorAlignedMemory <byte> .Allocate(fileSize))
{
Memory <byte> firstHalf = buffer.Memory.Slice(0, bufferSize);
Memory <byte> secondHalf = buffer.Memory.Slice(bufferSize);
content.AsSpan().CopyTo(buffer.GetSpan());
await RandomAccess.WriteAsync(handle, new ReadOnlyMemory <byte>[] { firstHalf, secondHalf }, 0);
buffer.GetSpan().Clear();
long nRead = await RandomAccess.ReadAsync(handle, new Memory <byte>[] { firstHalf, secondHalf }, 0);
Assert.Equal(buffer.GetSpan().Length, nRead);
AssertExtensions.SequenceEqual(buffer.GetSpan(), content.AsSpan());
}
}
public async Task ReadUsingSingleBuffer(bool asyncOperation, bool asyncHandle)
{
const int fileSize = 1_000_000; // 1 MB
string filePath = GetTestFilePath();
byte[] expected = RandomNumberGenerator.GetBytes(fileSize);
File.WriteAllBytes(filePath, expected);
using (SafeFileHandle handle = File.OpenHandle(filePath, FileMode.Open, options: GetFileOptions(asyncHandle)))
using (SectorAlignedMemory <byte> buffer = SectorAlignedMemory <byte> .Allocate(Environment.SystemPageSize))
{
int current = 0;
int total = 0;
do
{
current = asyncOperation
? await RandomAccess.ReadAsync(handle, buffer.Memory, fileOffset : total)
: RandomAccess.Read(handle, buffer.GetSpan(), fileOffset: total);
Assert.True(expected.AsSpan(total, current).SequenceEqual(buffer.GetSpan().Slice(0, current)));
total += current;
}while (current != 0);
Assert.Equal(fileSize, total);
}
}
public async Task ReadToAnEmptyBufferReturnsZeroAsync()
{
string filePath = GetTestFilePath();
File.WriteAllBytes(filePath, new byte[1]);
using (SafeFileHandle handle = File.OpenHandle(filePath, FileMode.Open, options: FileOptions.Asynchronous))
{
Assert.Equal(0, await RandomAccess.ReadAsync(handle, Array.Empty <byte>(), fileOffset: 0));
}
}
public async Task ReadWriteAsyncUsingEmptyBuffers()
{
string filePath = GetTestFilePath();
using SafeFileHandle handle = File.OpenHandle(filePath, FileMode.CreateNew, FileAccess.ReadWrite, FileShare.None, FileOptions.Asynchronous | NoBuffering);
long nRead = await RandomAccess.ReadAsync(handle, Array.Empty <Memory <byte> >(), 0);
Assert.Equal(0, nRead);
await RandomAccess.WriteAsync(handle, Array.Empty <ReadOnlyMemory <byte> >(), 0);
}
public async Task ReadFromBeyondEndOfFileReturnsZeroAsync(FileOptions options)
{
string filePath = GetTestFilePath();
File.WriteAllBytes(filePath, new byte[100]);
using (SafeFileHandle handle = File.OpenHandle(filePath, FileMode.Open, options: options))
{
long eof = RandomAccess.GetLength(handle);
Assert.Equal(0, await RandomAccess.ReadAsync(handle, new Memory <byte>[] { new byte[1] }, fileOffset: eof + 1));
}
}
public async Task TaskAlreadyCanceledAsync()
{
using (SafeFileHandle handle = File.OpenHandle(GetTestFilePath(), FileMode.CreateNew, FileAccess.ReadWrite, options: FileOptions.Asynchronous))
{
CancellationTokenSource cts = GetCancelledTokenSource();
CancellationToken token = cts.Token;
Assert.True(RandomAccess.ReadAsync(handle, new byte[1], 0, token).IsCanceled);
TaskCanceledException ex = await Assert.ThrowsAsync <TaskCanceledException>(() => RandomAccess.ReadAsync(handle, new byte[1], 0, token).AsTask());
Assert.Equal(token, ex.CancellationToken);
}
}
public async Task ReadToTheSameBufferOverwritesContent(FileOptions options)
{
string filePath = GetTestFilePath();
File.WriteAllBytes(filePath, new byte[3] {
1, 2, 3
});
using (SafeFileHandle handle = File.OpenHandle(filePath, FileMode.Open, options: options))
{
byte[] buffer = new byte[1];
Assert.Equal(buffer.Length + buffer.Length, await RandomAccess.ReadAsync(handle, Enumerable.Repeat(buffer.AsMemory(), 2).ToList(), fileOffset: 0));
Assert.Equal(2, buffer[0]);
}
}
public async Task ReadsBytesFromGivenFileAtGivenOffsetAsync(FileOptions options)
{
const int fileSize = 4_001;
string filePath = GetTestFilePath();
byte[] expected = RandomNumberGenerator.GetBytes(fileSize);
File.WriteAllBytes(filePath, expected);
using (SafeFileHandle handle = File.OpenHandle(filePath, FileMode.Open, options: options))
{
byte[] actual = new byte[fileSize + 1];
long current = 0;
long total = 0;
do
{
int firstBufferLength = (int)Math.Min(actual.Length - total, fileSize / 4);
Memory <byte> buffer_1 = actual.AsMemory((int)total, firstBufferLength);
Memory <byte> buffer_2 = actual.AsMemory((int)total + firstBufferLength);
current = await RandomAccess.ReadAsync(
handle,
new Memory <byte>[]
{
buffer_1,
Array.Empty <byte>(),
buffer_2
},
fileOffset : total);
Assert.InRange(current, 0, buffer_1.Length + buffer_2.Length);
total += current;
} while (current != 0);
Assert.Equal(fileSize, total);
Assert.Equal(expected, actual.Take((int)total).ToArray());
}
}
public async Task ReadAsyncUsingMultipleBuffers(bool asyncOperation, bool asyncHandle)
{
const int fileSize = 1_000_000; // 1 MB
string filePath = GetTestFilePath();
byte[] expected = RandomNumberGenerator.GetBytes(fileSize);
File.WriteAllBytes(filePath, expected);
using (SafeFileHandle handle = File.OpenHandle(filePath, FileMode.Open, options: GetFileOptions(asyncHandle)))
using (SectorAlignedMemory <byte> buffer_1 = SectorAlignedMemory <byte> .Allocate(Environment.SystemPageSize))
using (SectorAlignedMemory <byte> buffer_2 = SectorAlignedMemory <byte> .Allocate(Environment.SystemPageSize))
{
long current = 0;
long total = 0;
IReadOnlyList <Memory <byte> > buffers = new Memory <byte>[]
{
buffer_1.Memory,
buffer_2.Memory,
};
do
{
current = asyncOperation
? await RandomAccess.ReadAsync(handle, buffers, fileOffset : total)
: RandomAccess.Read(handle, buffers, fileOffset: total);
int takeFromFirst = Math.Min(buffer_1.Memory.Length, (int)current);
Assert.True(expected.AsSpan((int)total, takeFromFirst).SequenceEqual(buffer_1.GetSpan().Slice(0, takeFromFirst)));
int takeFromSecond = (int)current - takeFromFirst;
Assert.True(expected.AsSpan((int)total + takeFromFirst, takeFromSecond).SequenceEqual(buffer_2.GetSpan().Slice(0, takeFromSecond)));
total += current;
} while (current == buffer_1.Memory.Length + buffer_2.Memory.Length);
Assert.Equal(fileSize, total);
}
}
public async Task ThrowsOnWriteAccess()
{
using (SafeFileHandle handle = GetHandleToExistingFile(FileAccess.Write))
{
await Assert.ThrowsAsync <UnauthorizedAccessException>(async() => await RandomAccess.ReadAsync(handle, new byte[1], 0));
}
}
protected override ValueTask <int> MethodUnderTest(SafeFileHandle handle, byte[] bytes, long fileOffset) => RandomAccess.ReadAsync(handle, bytes, fileOffset);
static async Task Validate(SafeFileHandle handle, FileOptions options, bool[] syncWrites, bool[] syncReads)
{
byte[] writeBuffer = new byte[1];
byte[] readBuffer = new byte[2];
long fileOffset = 0;
foreach (bool syncWrite in syncWrites)
{
foreach (bool syncRead in syncReads)
{
writeBuffer[0] = (byte)fileOffset;
if (syncWrite)
{
RandomAccess.Write(handle, writeBuffer, fileOffset);
}
else
{
await RandomAccess.WriteAsync(handle, writeBuffer, fileOffset);
}
Assert.Equal(writeBuffer.Length, syncRead ? RandomAccess.Read(handle, readBuffer, fileOffset) : await RandomAccess.ReadAsync(handle, readBuffer, fileOffset));
Assert.Equal(writeBuffer[0], readBuffer[0]);
fileOffset += 1;
}
}
}
protected override ValueTask <long> MethodUnderTest(SafeFileHandle handle, byte[] bytes, long fileOffset)
=> RandomAccess.ReadAsync(handle, new Memory <byte>[] { bytes }, fileOffset);
