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.


/// Enables parsing of known file system mounts.
#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
struct MountsWrapper(*mut FILE);

impl Drop for MountsWrapper
{
	//noinspection SpellCheckingInspection
	#[inline(always)]
	fn drop(&mut self)
	{
		match unsafe { endmntent(self.0) }
		{
			1 => (),
			illegal @ _ => panic!("endmntent() returned '{}'; it should never return anything other than 1", illegal),
		}
	}
}

impl MountsWrapper
{
	fn new(mounts_file_path: &Path, read_only: bool) -> Result<Self, io::Error>
	{
		let mounts_file_path = mounts_file_path.to_c_string();

		const ReadOnlyFlag: ConstCStr = ConstCStr(b"r\0");
		const ReadWriteFlag: ConstCStr = ConstCStr(b"ra\0");

		let flag = match read_only
		{
			false => ReadOnlyFlag,
			true => ReadWriteFlag,
		};

		let handle = unsafe { setmntent(mounts_file_path.as_ptr(), flag.as_ptr()) };
		if unlikely!(handle.is_null())
		{
			Err(io_error_not_found("setmntent() returned NULL - not found or couldn't open or read_only was false and file permissions prevent writing"))
		}
		else
		{
			Ok(MountsWrapper(handle))
		}
	}

	fn use_mount<F>(&self, mut called_for_each_mount_point: F) -> Result<(), io::Error>
	where F: FnMut(Mount<'static>) -> Result<(), io::Error>
	{
		let mut mount_entry_pointer;
		while
		{
			mount_entry_pointer = unsafe { getmntent(self.0) };
			!mount_entry_pointer.is_null()
		}
		{
			let result = called_for_each_mount_point(Mount::from_mntent(mount_entry_pointer));
			if unlikely!(result.is_err())
			{
				return result;
			}
		}
		Ok(())
	}
}