/// <summary>
/// Tries to create the file for provided name.
/// </summary>
/// <remarks>
/// This method tries to create the file for provided name. The file creation
/// takes place according to additional parameters. A possibly existing file
/// will be overwritten if parameter <paramref name="overwrite"/> is <c>true</c>.
/// The length of the new file is adjusted if parameter <paramref name="length"/>
/// is greater than zero.
/// </remarks>
/// <param name="filename">
/// The fully qualified name of the file.
/// </param>
/// <param name="overwrite">
/// True to force an overwrite of an existing file and false otherwise.
/// The method throws an exception if parameter <paramref name="overwrite"/>
/// is <c>false</c> and provided file already exists.
/// </param>
/// <param name="length">
/// The length of the new file to be adjusted.
/// </param>
/// <exception cref="ArgumentException">
/// Either the provided filename is invalid or the provided length is less
/// than zero.
/// </exception>
/// <exception cref="NativeException">
/// Something went wrong while creating the new file. The property
/// <see cref="NativeException.HResult"/> of the exception contains
/// the detailed error code.
/// </exception>
public static void Create(String filename, Boolean overwrite, Int64 length)
{
if (String.IsNullOrWhiteSpace(filename))
{
throw new ArgumentException("File name must not be null or empty or only consists of white spaces.");
}
if (length < 0)
{
throw new ArgumentException($"Requested length for file \"{filename}\" must be greater than zero.");
}
Int32 nMode = (Int32)(overwrite ? FileMode.CREATE_ALWAYS : FileMode.CREATE_NEW);
Int32 nAccess = (Int32)FileAccess.GENERIC_WRITE;
Int32 nShare = (Int32)FileShare.FILE_SHARE_WRITE;
Int32 nFlags = (Int32)FileFlags.FILE_FLAG_NONE | (Int32)FileAttributes.FILE_ATTRIBUTE_NORMAL;
IntPtr handle = AccessHandler.CreateFileW(filename, nAccess, nShare, IntPtr.Zero, nMode, nFlags, IntPtr.Zero);
try
{
if (!AccessHandler.IsHandle(handle))
{
throw new NativeException($"Creating of file \"{filename}\" has failed.", Marshal.GetHRForLastWin32Error());
}
if (length > 0)
{
// Resize file up to requested file size.
if (!AccessHandler.SetFilePointerEx(handle, length, out Int64 result, MoveMethod.FILE_BEGIN))
{
throw new NativeException($"Changing length of file \"{filename}\" has failed.", Marshal.GetHRForLastWin32Error());
}
// According to docs this is required for changing current file size.
if (!AccessHandler.SetEndOfFile(handle))
{
throw new NativeException($"Writing length of file \"{filename}\" has failed.", Marshal.GetHRForLastWin32Error());
}
}
}
finally
{
if (AccessHandler.IsHandle(handle))
{
AccessHandler.CloseHandle(handle);
}
}
}
private Boolean OpenFile(String filename, FileMode mode, FileAccess access, FileShare share, FileFlags flags, FileAttributes attributes)
{
Int32 nMode = (Int32)mode;
Int32 nAccess = (Int32)access;
Int32 nShare = (Int32)share;
Int32 nFlags = (Int32)flags | (Int32)attributes;
IntPtr handle = AccessHandler.CreateFileW(filename, nAccess, nShare, IntPtr.Zero, nMode, nFlags, IntPtr.Zero);
if (!AccessHandler.IsHandle(handle))
{
return(false);
}
this.IsWritable = (access & FileAccess.GENERIC_WRITE) == FileAccess.GENERIC_WRITE;
this.handle = handle;
this.filename = filename;
return(true);
}
/// <summary>
/// Tries to obtain the length in byte of provided file.
/// </summary>
/// <remarks>
/// This method tries to obtain the length of provided file and returns
/// it if successful. The length returned by this method represents the
/// number of bytes of that file.
/// </remarks>
/// <param name="filename">
/// The fully qualified name of the file.
/// </param>
/// <returns>
/// The length in byte of the file.
/// </returns>
/// <exception cref="ArgumentException">
/// The provided filename is invalid.
/// </exception>
/// <exception cref="NativeException">
/// Something went wrong while obtaining the length of the file. The property
/// <see cref="NativeException.HResult"/> of the exception contains
/// the detailed error code.
/// </exception>
public static Int64 GetLength(String filename)
{
if (String.IsNullOrWhiteSpace(filename))
{
throw new ArgumentException("File name must not be null or empty or only consists of white spaces.");
}
Int32 nMode = (Int32)FileMode.OPEN_EXISTING;
Int32 nAccess = (Int32)FileAccess.GENERIC_READ;
Int32 nShare = (Int32)FileShare.FILE_SHARE_READ;
Int32 nFlags = (Int32)FileFlags.FILE_FLAG_NONE | (Int32)FileAttributes.FILE_ATTRIBUTE_NORMAL;
IntPtr handle = AccessHandler.CreateFileW(filename, nAccess, nShare, IntPtr.Zero, nMode, nFlags, IntPtr.Zero);
try
{
if (!AccessHandler.IsHandle(handle))
{
throw new NativeException($"Accessing file \"{filename}\" for read has failed.", Marshal.GetHRForLastWin32Error());
}
if (!AccessHandler.GetFileSizeEx(handle, out Int64 length))
{
throw new NativeException($"Obtaining length of file \"{filename}\" has failed.", Marshal.GetHRForLastWin32Error());
}
return(length);
}
finally
{
if (AccessHandler.IsHandle(handle))
{
AccessHandler.CloseHandle(handle);
}
}
}
