/// <summary>
/// Helper for making system calls that involve the stream's file descriptor.
/// System calls are expected to return greather than or equal to zero on success,
/// and less than zero on failure. In the case of failure, errno is expected to
/// be set to the relevant error code.
/// </summary>
/// <typeparam name="TArg1">Specifies the type of an argument to the system call.</typeparam>
/// <typeparam name="TArg2">Specifies the type of another argument to the system call.</typeparam>
/// <param name="sysCall">A delegate that invokes the system call.</param>
/// <param name="arg1">The first argument to be passed to the system call, after the file descriptor.</param>
/// <param name="arg2">The second argument to be passed to the system call.</param>
/// <param name="throwOnError">true to throw an exception if a non-interuption error occurs; otherwise, false.</param>
/// <returns>The return value of the system call.</returns>
/// <remarks>
/// Arguments are expected to be passed via <paramref name="arg1"/> and <paramref name="arg2"/>
/// so as to avoid delegate and closure allocations at the call sites.
/// </remarks>
private long SysCall <TArg1, TArg2>(
Func <int, TArg1, TArg2, long> sysCall,
TArg1 arg1 = default(TArg1), TArg2 arg2 = default(TArg2),
bool throwOnError = true)
{
SafeFileHandle handle = _fileHandle;
Debug.Assert(sysCall != null);
Debug.Assert(handle != null);
bool gotRefOnHandle = false;
try
{
// Get the file descriptor from the handle. We increment the ref count to help
// ensure it's not closed out from under us.
handle.DangerousAddRef(ref gotRefOnHandle);
Debug.Assert(gotRefOnHandle);
int fd = (int)handle.DangerousGetHandle();
Debug.Assert(fd >= 0);
// System calls may fail due to EINTR (signal interruption). We need to retry in those cases.
while (true)
{
long result = sysCall(fd, arg1, arg2);
if (result < 0)
{
Interop.ErrorInfo errorInfo = Interop.Sys.GetLastErrorInfo();
if (errorInfo.Error == Interop.Error.EINTR)
{
continue;
}
else if (throwOnError)
{
throw Interop.GetExceptionForIoErrno(errorInfo, _path, isDirectory: false);
}
}
return(result);
}
}
finally
{
if (gotRefOnHandle)
{
handle.DangerousRelease();
}
else
{
throw new ObjectDisposedException(SR.ObjectDisposed_FileClosed);
}
}
}
