/// <summary>
/// Creates an empty file at a given path.
/// </summary>
public static void CreateEmptyFile(this IAbsFileSystem fileSystem, AbsolutePath path)
{
Contract.RequiresNotNull(path);
Contract.RequiresNotNull(path.Parent);
fileSystem.CreateDirectory(path.Parent);
using (fileSystem.TryOpen(path, FileAccess.Write, FileMode.Create, FileShare.None, FileOptions.None, bufferSize: 1))
{
}
}
/// <summary>
/// Tries to read the content from a file <paramref name="absolutePath"/>.
/// </summary>
/// <returns>Returns <code>null</code> if file does not exist, or content of the file otherwise.</returns>
/// <exception cref="Exception">Throws if the IO operation fails.</exception>
public static async Task <string?> TryReadFileAsync(this IAbsFileSystem fileSystem, AbsolutePath absolutePath, FileShare fileShare = FileShare.ReadWrite)
{
using Stream? readLockFile = fileSystem.TryOpen(absolutePath, FileAccess.Read, FileMode.Open, fileShare);
if (readLockFile != null)
{
using var reader = new StreamReader(readLockFile);
return(await reader.ReadToEndAsync().ConfigureAwait(false));
}
return(null);
}
static async Task openAndClose(IAbsFileSystem fileSystem, AbsolutePath path)
{
await Task.Yield();
try
{
// This operation may fail with UnauthorizedAccessException because
// the test tries to delete the file in the process.
using var f = fileSystem.TryOpen(path, FileAccess.Read, FileMode.Open, FileShare.Read | FileShare.Delete);
}
catch (UnauthorizedAccessException)
{ }
}
/// <summary>
/// Open the named file asynchronously for reading.
/// </summary>
/// <exception cref="FileNotFoundException">Throws if the file is not found.</exception>
/// <exception cref="DirectoryNotFoundException">Throws if the directory is not found.</exception>
/// <remarks>
/// Unlike <see cref="IAbsFileSystem.OpenAsync(AbsolutePath, FileAccess, FileMode, FileShare, FileOptions, int)"/> this function throws an exception if the file is missing.
/// </remarks>
public static StreamWithLength Open(this IAbsFileSystem fileSystem, AbsolutePath path, FileAccess fileAccess, FileMode fileMode, FileShare share, FileOptions options = FileOptions.None, int bufferSize = FileSystemDefaults.DefaultFileStreamBufferSize)
{
var stream = fileSystem.TryOpen(path, fileAccess, fileMode, share, options, bufferSize);
if (stream == null)
{
// Stream is null when the file or a directory is not found.
if (fileSystem.DirectoryExists(path.Parent !))
{
throw new FileNotFoundException($"The file '{path}' does not exist.");
}
throw new DirectoryNotFoundException($"The directory '{path.Parent}' does not exist.");
}
return(stream.Value);
}
/// <summary>
/// Open the named file asynchronously for reading and sets the expected file length for performance reasons if available.
/// </summary>
/// <remarks>
/// Setting the file length up-front leads to 20-30% performance improvements.
/// </remarks>
public static StreamWithLength?TryOpenForWrite(
this IAbsFileSystem fileSystem,
AbsolutePath path,
long?expectingLength,
FileMode fileMode,
FileShare share,
FileOptions options = FileOptions.None,
int bufferSize = FileSystemDefaults.DefaultFileStreamBufferSize)
{
var stream = fileSystem.TryOpen(path, FileAccess.Write, fileMode, share, options, bufferSize);
if (stream == null)
{
return(null);
}
if (expectingLength != null)
{
stream.Value.Stream.SetLength(expectingLength.Value);
}
return(stream.Value);
}
/// <summary>
/// Creates a stream to an existing file.
/// Note that the permissions are such that it is readable, but not
/// writable by the caller.
/// </summary>
public static StreamWithLength?TryOpenReadOnly(this IAbsFileSystem fileSystem, AbsolutePath path, FileShare share)
{
return(fileSystem.TryOpen(path, FileAccess.Read, FileMode.Open, share));
}
/// <summary>
/// Calls <see cref="IAbsFileSystem.OpenAsync(AbsolutePath, FileAccess, FileMode, FileShare, FileOptions, int)" /> with the default buffer stream size.
/// </summary>
public static StreamWithLength?TryOpen(this IAbsFileSystem fileSystem, AbsolutePath path, FileAccess fileAccess, FileMode fileMode, FileShare share)
{
return(fileSystem.TryOpen(path, fileAccess, fileMode, share, FileOptions.None, DefaultFileStreamBufferSize));
}