/// <summary>Initializes a stream for reading or writing a Unix file.</summary>
/// <param name="path">The path to the file.</param>
/// <param name="mode">How the file should be opened.</param>
/// <param name="access">Whether the file will be read, written, or both.</param>
/// <param name="share">What other access to the file should be allowed. This is currently ignored.</param>
/// <param name="bufferSize">The size of the buffer to use when buffering.</param>
/// <param name="options">Additional options for working with the file.</param>
internal UnixFileStream(String path, FileMode mode, FileAccess access, FileShare share, int bufferSize, FileOptions options, FileStream parent)
: base(parent)
{
// FileStream performs most of the general argument validation. We can assume here that the arguments
// are all checked and consistent (e.g. non-null-or-empty path; valid enums in mode, access, share, and options; etc.)
// Store the arguments
_path = path;
_access = access;
_mode = mode;
_options = options;
_bufferLength = bufferSize;
_useAsyncIO = (options & FileOptions.Asynchronous) != 0;
// Translate the arguments into arguments for an open call
Interop.libc.OpenFlags openFlags = PreOpenConfigurationFromOptions(mode, access, options); // FileShare currently ignored
Interop.libc.Permissions openPermissions = Interop.libc.Permissions.S_IRWXU; // creator has read/write/execute permissions; no permissions for anyone else
// Open the file and store the safe handle. Subsequent code in this method expects the safe handle to be initialized.
_fileHandle = SafeFileHandle.Open(path, openFlags, (int)openPermissions);
_fileHandle.IsAsync = _useAsyncIO;
// Lock the file if requested via FileShare. This is only advisory locking. FileShare.None implies an exclusive
// lock on the file and all other modes use a shared lock. While this is not as granular as Windows, not mandatory,
// and not atomic with file opening, it's better than nothing.
try
{
Interop.libc.LockOperations lockOperation = (share == FileShare.None) ? Interop.libc.LockOperations.LOCK_EX : Interop.libc.LockOperations.LOCK_SH;
SysCall <Interop.libc.LockOperations, int>((fd, op, _) => Interop.libc.flock(fd, op), lockOperation | Interop.libc.LockOperations.LOCK_NB);
}
catch
{
_fileHandle.Dispose();
throw;
}
// Support additional options after the file has been opened.
// These provide hints around how the file will be accessed.
Interop.libc.Advice fadv =
_options == FileOptions.RandomAccess ? Interop.libc.Advice.POSIX_FADV_RANDOM :
_options == FileOptions.SequentialScan ? Interop.libc.Advice.POSIX_FADV_SEQUENTIAL :
0;
if (fadv != 0)
{
SysCall <Interop.libc.Advice, int>((fd, advice, _) => Interop.libc.posix_fadvise(fd, 0, 0, advice), fadv);
}
// Jump to the end of the file if opened as Append.
if (_mode == FileMode.Append)
{
_appendStart = SeekCore(0, SeekOrigin.End);
}
}
/// <summary>Performs additional configuration of the opened stream based on provided options.</summary>
partial void PostOpenConfigureStreamFromOptions()
{
// Support additional options after the file has been opened.
// These provide hints around how the file will be accessed.
Interop.libc.Advice fadv =
_options == FileOptions.RandomAccess ? Interop.libc.Advice.POSIX_FADV_RANDOM :
_options == FileOptions.SequentialScan ? Interop.libc.Advice.POSIX_FADV_SEQUENTIAL :
0;
if (fadv != 0)
{
SysCall <Interop.libc.Advice, int>((fd, advice, _) => Interop.libc.posix_fadvise(fd, 0, 0, advice), fadv);
}
}
