/// <summary>Initializes a stream for reading or writing a Unix file.</summary>
/// <param name="mode">How the file should be opened.</param>
/// <param name="share">What other access to the file should be allowed. This is currently ignored.</param>
/// <param name="originalPath">The original path specified for the FileStream.</param>
private void Init(FileMode mode, FileShare share, string originalPath)
{
_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.
Interop.Sys.LockOperations lockOperation = (share == FileShare.None) ? Interop.Sys.LockOperations.LOCK_EX : Interop.Sys.LockOperations.LOCK_SH;
if (Interop.Sys.FLock(_fileHandle, lockOperation | Interop.Sys.LockOperations.LOCK_NB) < 0)
{
// The only error we care about is EWOULDBLOCK, which indicates that the file is currently locked by someone
// else and we would block trying to access it. Other errors, such as ENOTSUP (locking isn't supported) or
// EACCES (the file system doesn't allow us to lock), will only hamper FileStream's usage without providing value,
// given again that this is only advisory / best-effort.
Interop.ErrorInfo errorInfo = Interop.Sys.GetLastErrorInfo();
if (errorInfo.Error == Interop.Error.EWOULDBLOCK)
{
throw Interop.GetExceptionForIoErrno(errorInfo, _path, isDirectory: false);
}
}
// These provide hints around how the file will be accessed. Specifying both RandomAccess
// and Sequential together doesn't make sense as they are two competing options on the same spectrum,
// so if both are specified, we prefer RandomAccess (behavior on Windows is unspecified if both are provided).
Interop.Sys.FileAdvice fadv =
(_options & FileOptions.RandomAccess) != 0 ? Interop.Sys.FileAdvice.POSIX_FADV_RANDOM :
(_options & FileOptions.SequentialScan) != 0 ? Interop.Sys.FileAdvice.POSIX_FADV_SEQUENTIAL :
0;
if (fadv != 0)
{
CheckFileCall(Interop.Sys.PosixFAdvise(_fileHandle, 0, 0, fadv),
ignoreNotSupported: true); // just a hint.
}
if (_mode == FileMode.Append)
{
// Jump to the end of the file if opened as Append.
_appendStart = SeekCore(_fileHandle, 0, SeekOrigin.End);
}
else if (mode == FileMode.Create || mode == FileMode.Truncate)
{
// Truncate the file now if the file mode requires it. This ensures that the file only will be truncated
// if opened successfully.
if (Interop.Sys.FTruncate(_fileHandle, 0) < 0)
{
Interop.ErrorInfo errorInfo = Interop.Sys.GetLastErrorInfo();
if (errorInfo.Error != Interop.Error.EBADF && errorInfo.Error != Interop.Error.EINVAL)
{
// We know the file descriptor is valid and we know the size argument to FTruncate is correct,
// so if EBADF or EINVAL is returned, it means we're dealing with a special file that can't be
// truncated. Ignore the error in such cases; in all others, throw.
throw Interop.GetExceptionForIoErrno(errorInfo, _path, isDirectory: false);
}
}
}
}
/// <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.Sys.FileAdvice fadv =
_options == FileOptions.RandomAccess ? Interop.Sys.FileAdvice.POSIX_FADV_RANDOM :
_options == FileOptions.SequentialScan ? Interop.Sys.FileAdvice.POSIX_FADV_SEQUENTIAL :
0;
if (fadv != 0)
{
SysCall <Interop.Sys.FileAdvice, int>((fd, advice, _) => Interop.Sys.PosixFAdvise(fd, 0, 0, advice), fadv);
}
}
/// <summary>Initializes a stream for reading or writing a Unix file.</summary>
/// <param name="mode">How the file should be opened.</param>
/// <param name="share">What other access to the file should be allowed. This is currently ignored.</param>
/// <param name="originalPath">The original path specified for the FileStream.</param>
/// <param name="options">Options, passed via arguments as we have no guarantee that _options field was already set.</param>
/// <param name="preallocationSize">passed to posix_fallocate</param>
private void Init(FileMode mode, FileShare share, string originalPath, FileOptions options, long preallocationSize)
{
// 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
_mode = mode;
_options = options;
if (_useAsyncIO)
{
_asyncState = new AsyncState();
}
_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.
Interop.Sys.LockOperations lockOperation = (share == FileShare.None) ? Interop.Sys.LockOperations.LOCK_EX : Interop.Sys.LockOperations.LOCK_SH;
if (Interop.Sys.FLock(_fileHandle, lockOperation | Interop.Sys.LockOperations.LOCK_NB) < 0)
{
// The only error we care about is EWOULDBLOCK, which indicates that the file is currently locked by someone
// else and we would block trying to access it. Other errors, such as ENOTSUP (locking isn't supported) or
// EACCES (the file system doesn't allow us to lock), will only hamper FileStream's usage without providing value,
// given again that this is only advisory / best-effort.
Interop.ErrorInfo errorInfo = Interop.Sys.GetLastErrorInfo();
if (errorInfo.Error == Interop.Error.EWOULDBLOCK)
{
throw Interop.GetExceptionForIoErrno(errorInfo, _path, isDirectory: false);
}
}
// These provide hints around how the file will be accessed. Specifying both RandomAccess
// and Sequential together doesn't make sense as they are two competing options on the same spectrum,
// so if both are specified, we prefer RandomAccess (behavior on Windows is unspecified if both are provided).
Interop.Sys.FileAdvice fadv =
(options & FileOptions.RandomAccess) != 0 ? Interop.Sys.FileAdvice.POSIX_FADV_RANDOM :
(options & FileOptions.SequentialScan) != 0 ? Interop.Sys.FileAdvice.POSIX_FADV_SEQUENTIAL :
0;
if (fadv != 0)
{
CheckFileCall(Interop.Sys.PosixFAdvise(_fileHandle, 0, 0, fadv),
ignoreNotSupported: true); // just a hint.
}
if (mode == FileMode.Append)
{
// Jump to the end of the file if opened as Append.
_appendStart = SeekCore(_fileHandle, 0, SeekOrigin.End);
}
else if (mode == FileMode.Create || mode == FileMode.Truncate)
{
// Truncate the file now if the file mode requires it. This ensures that the file only will be truncated
// if opened successfully.
if (Interop.Sys.FTruncate(_fileHandle, 0) < 0)
{
Interop.ErrorInfo errorInfo = Interop.Sys.GetLastErrorInfo();
if (errorInfo.Error != Interop.Error.EBADF && errorInfo.Error != Interop.Error.EINVAL)
{
// We know the file descriptor is valid and we know the size argument to FTruncate is correct,
// so if EBADF or EINVAL is returned, it means we're dealing with a special file that can't be
// truncated. Ignore the error in such cases; in all others, throw.
throw Interop.GetExceptionForIoErrno(errorInfo, _path, isDirectory: false);
}
}
}
// If preallocationSize has been provided for a creatable and writeable file
if (FileStreamHelpers.ShouldPreallocate(preallocationSize, _access, mode))
{
int fallocateResult = Interop.Sys.PosixFAllocate(_fileHandle, 0, preallocationSize);
if (fallocateResult != 0)
{
_fileHandle.Dispose();
Interop.Sys.Unlink(_path !); // remove the file to mimic Windows behaviour (atomic operation)
if (fallocateResult == -1)
{
throw new IOException(SR.Format(SR.IO_DiskFull_Path_AllocationSize, _path, preallocationSize));
}
Debug.Assert(fallocateResult == -2);
throw new IOException(SR.Format(SR.IO_FileTooLarge_Path_AllocationSize, _path, preallocationSize));
}
}
}