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// Copyright (c) 2023 Nick Piaddo
// SPDX-License-Identifier: Apache-2.0 OR MIT
// From dependency library
// From standard library
use std::mem::MaybeUninit;
// From this library
use crate::core::errors::PartitionIterError;
use crate::core::partition::Partition;
use crate::core::partition::PartitionList;
use crate::core::iter::Direction;
use crate::core::iter::GenIterator;
use crate::owning_ref_from_ptr;
/// Iterator over [`Partition`]s in a [`PartitionList`].
#[derive(Debug)]
pub struct PartitionIter<'vec> {
list: &'vec PartitionList,
/// Forward iterator.
fwd_iter: GenIterator,
/// Backward iterator.
bwd_iter: GenIterator,
/// Current item in forward iteration.
fwd_cursor: *mut libfdisk::fdisk_partition,
/// Current item in backward iteration.
bwd_cursor: *mut libfdisk::fdisk_partition,
/// Indicator of forward and backward iterators meeting in the middle.
have_iterators_met: bool,
}
impl<'vec> PartitionIter<'vec> {
#[doc(hidden)]
#[allow(dead_code)]
/// Creates a new `PartitionIter`.
pub(crate) fn new(
list: &'vec PartitionList,
) -> Result<PartitionIter<'vec>, PartitionIterError> {
log::debug!("PartitionIter::new creating a new `PartitionIter` instance");
let fwd_iter = GenIterator::new(Direction::Forward)?;
let bwd_iter = GenIterator::new(Direction::Backward)?;
let fwd_cursor = std::ptr::null_mut();
let bwd_cursor = std::ptr::null_mut();
let have_iterators_met = false;
let iterator = Self {
list,
fwd_iter,
bwd_iter,
fwd_cursor,
bwd_cursor,
have_iterators_met,
};
Ok(iterator)
}
}
impl<'vec> Iterator for PartitionIter<'vec> {
type Item = &'vec Partition;
fn next(&mut self) -> Option<Self::Item> {
log::debug!("PartitionIter::next getting next item in `PartitionList`");
let mut partition_ptr = MaybeUninit::<*mut libfdisk::fdisk_partition>::zeroed();
let result = unsafe {
libfdisk::fdisk_table_next_partition(
self.list.inner,
self.fwd_iter.inner,
partition_ptr.as_mut_ptr(),
)
};
match result {
0 => {
let ptr = unsafe { partition_ptr.assume_init() };
// Per the documentation of `DoubleEndedIterator`
// "It is important to note that both back and forth work on the same range, and do not cross: iteration is over when they meet in the middle."
if self.have_iterators_met
|| (self.fwd_cursor != self.bwd_cursor && ptr == self.bwd_cursor)
{
log::debug!(
"PartitionIter::next forward and backward iterators met in the middle"
);
self.have_iterators_met = true;
None
} else {
log::debug!("PartitionIter::next got next item in `PartitionList`");
self.fwd_cursor = ptr;
let partition = owning_ref_from_ptr!(self.list, Partition, ptr);
Some(partition)
}
}
// Reached end of list.
1 => {
log::debug!("PartitionIter::next reached end of `PartitionList`");
None
}
// Error occurred.
code => {
log::debug!("PartitionIter::next failed to get next item in `PartitionList`. libfdisk::fdisk_table_next_partition returned error code: {:?}", code);
None
}
}
}
fn nth(&mut self, n: usize) -> Option<Self::Item> {
let mut result;
// Skip n-1 entries, and update the cursor along the way.
for i in 0..n {
let mut partition_ptr = MaybeUninit::<*mut libfdisk::fdisk_partition>::zeroed();
result = unsafe {
libfdisk::fdisk_table_next_partition(
self.list.inner,
self.fwd_iter.inner,
partition_ptr.as_mut_ptr(),
)
};
match result {
0 => {
let ptr = unsafe { partition_ptr.assume_init() };
// Per the documentation of `DoubleEndedIterator`
// "It is important to note that both back and forth work on the same range, and do not cross: iteration is over when they meet in the middle."
if self.have_iterators_met
|| (self.fwd_cursor != self.bwd_cursor && ptr == self.bwd_cursor)
{
log::debug!(
"PartitionIter::nth forward and backward iterators met in the middle"
);
self.have_iterators_met = true;
return None;
} else {
log::debug!("PartitionIter::nth got {}th item in `PartitionList`", i);
self.fwd_cursor = ptr;
}
}
// Reached end of list.
1 => {
log::debug!("PartitionIter::nth reached end of `PartitionList`");
return None;
}
// Error occurred.
code => {
let err_msg = format!("failed to get {}th item in `PartitionList`", i);
log::debug!("PartitionIter::nth {}. libfdisk::fdisk_table_next_partition returned error code: {:?}", err_msg, code);
return None;
}
}
}
self.next()
}
}
impl<'vec> DoubleEndedIterator for PartitionIter<'vec> {
fn next_back(&mut self) -> Option<Self::Item> {
let mut partition_ptr = MaybeUninit::<*mut libfdisk::fdisk_partition>::zeroed();
let result = unsafe {
libfdisk::fdisk_table_next_partition(
self.list.inner,
self.bwd_iter.inner,
partition_ptr.as_mut_ptr(),
)
};
match result {
0 => {
let ptr = unsafe { partition_ptr.assume_init() };
// Per the documentation of `DoubleEndedIterator`
// "It is important to note that both back and forth work on the same range, and do not cross: iteration is over when they meet in the middle."
if self.have_iterators_met
|| (self.bwd_cursor != self.fwd_cursor && ptr == self.fwd_cursor)
{
log::debug!(
"PartitionIter::next forward and backward iterators met in the middle"
);
self.have_iterators_met = true;
None
} else {
log::debug!("PartitionIter::next got next item in `PartitionList`");
self.bwd_cursor = ptr;
let partition = owning_ref_from_ptr!(self.list, Partition, ptr);
Some(partition)
}
}
// Reached end of list.
1 => {
log::debug!("PartitionIter::next_back reached start of `PartitionList`");
None
}
// Error occurred.
code => {
log::debug!("PartitionIter::next_back failed to get next item in `PartitionList`. libfdisk::fdisk_table_next_partition returned error code: {:?}", code);
None
}
}
}
fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
let mut result;
// Skip n-1 entries, and update the cursor along the way.
for i in 0..n {
let mut partition_ptr = MaybeUninit::<*mut libfdisk::fdisk_partition>::zeroed();
result = unsafe {
libfdisk::fdisk_table_next_partition(
self.list.inner,
self.bwd_iter.inner,
partition_ptr.as_mut_ptr(),
)
};
match result {
0 => {
let ptr = unsafe { partition_ptr.assume_init() };
// Per the documentation of `DoubleEndedIterator`
// "It is important to note that both back and forth work on the same range, and do not cross: iteration is over when they meet in the middle."
if self.have_iterators_met
|| (self.bwd_cursor != self.fwd_cursor && ptr == self.fwd_cursor)
{
log::debug!(
"PartitionIter::nth_back forward and backward iterators met in the middle"
);
self.have_iterators_met = true;
return None;
} else {
log::debug!(
"PartitionIter::nth_back got {}th item in `PartitionList`",
i
);
self.bwd_cursor = ptr;
}
}
// Reached end of list.
1 => {
log::debug!("PartitionIter::nth_back reached end of `PartitionList`");
return None;
}
// Error occurred.
code => {
let err_msg = format!("failed to get {}th item in `PartitionList`", i);
log::debug!("PartitionIter::nth_back {}. libfdisk::fdisk_table_next_partition returned error code: {:?}", err_msg, code);
return None;
}
}
}
self.next_back()
}
}