linux-support 0.0.25

Comprehensive Linux support for namespaces, cgroups, processes, scheduling, parsing /proc, parsing /sys, signals, hyper threads, CPUS, NUMA nodes, unusual file descriptors, PCI devices and much, much more
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// This file is part of linux-support. It is subject to the license terms in the COPYRIGHT file found in the top-level directory of this distribution and at https://raw.githubusercontent.com/lemonrock/linux-support/master/COPYRIGHT. No part of linux-support, including this file, may be copied, modified, propagated, or distributed except according to the terms contained in the COPYRIGHT file.
// Copyright © 2020 The developers of linux-support. See the COPYRIGHT file in the top-level directory of this distribution and at https://raw.githubusercontent.com/lemonrock/linux-support/master/COPYRIGHT.


/// Origin of file descriptor to use.
#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub enum FileDescriptorOrigin<'a, FD: 'a + FileDescriptor>
{
	/// An index into the file descriptors previously registered with the `IoUring`.
	Index(RegisteredFileDescriptorIndex),

	/// A file descriptor reference.
	///
	/// Not permitted if using an IoUring created with `SetupFlags::SubmissionQueuePoll`.
	Absolute(&'a FD),
}

impl<'a, FD: 'a + FileDescriptor> FileDescriptorOrigin<'a, FD>
{
	#[inline(always)]
	fn into_and_adjust_flags(&self, options: SubmissionQueueEntryOptions, using_kernel_submission_queue_poll: bool) -> (FileDescriptorKind, SubmissionQueueEntryFlags)
	{
		use self::FileDescriptorOrigin::*;

		let flags = options.into_flags();
		
		match self
		{
			&Index(index) => (FileDescriptorKind::Index(index), flags | SubmissionQueueEntryFlags::FixedFile),
			
			&Absolute(file_descriptor) =>
			{
				Self::guard(using_kernel_submission_queue_poll);
				(FileDescriptorKind::from(file_descriptor), flags)
			}
		}
	}
	
	#[inline(always)]
	fn into_and_adjust_splice_flags(&self, flags: SpliceFlags, using_kernel_submission_queue_poll: bool) -> (FileDescriptorKind, u32)
	{
		use self::FileDescriptorOrigin::*;
		
		let flags = flags.bits();
		
		match self
		{
			&Index(index) => (FileDescriptorKind::Index(index), flags | SPLICE_F_FD_IN_FIXED),
			
			&Absolute(file_descriptor) =>
			{
				Self::guard(using_kernel_submission_queue_poll);
				(FileDescriptorKind::from(file_descriptor), flags)
			}
		}
	}
	
	#[inline(always)]
	fn guard(using_kernel_submission_queue_poll: bool)
	{
		debug_assert!(!using_kernel_submission_queue_poll, "Can not use absolute file descriptor when using a kernel thread for submission queue polling");
	}
}