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df: refactor filter_mount_list() to be more flat

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Use a `for` loop in the `filter_mount_list()` function to make the
filtering logic easier to read.
This commit is contained in:
Jeffrey Finkelstein 2022-02-06 11:07:19 -05:00
parent 1f7c08d87b
commit 572b2e032c
1 changed files with 72 additions and 57 deletions
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129
src/uu/df/src/df.rs
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@ -161,64 +161,79 @@ impl Filesystem {
}
}
/// Keep only the specified subset of [`MountInfo`] instances.
///
/// If `paths` is non-empty, this function excludes any [`MountInfo`]
/// that is not mounted at the specified path.
///
/// The `opt` argument specifies a variety of ways of excluding
/// [`MountInfo`] instances; see [`Options`] for more information.
///
/// Finally, if there are duplicate entries, the one with the shorter
/// path is kept.
fn filter_mount_list(vmi: Vec<MountInfo>, paths: &[String], opt: &Options) -> Vec<MountInfo> {
vmi.into_iter()
.filter_map(|mi| {
if (mi.remote && opt.show_local_fs)
|| (mi.dummy && !opt.show_all_fs && !opt.show_listed_fs)
|| !opt.fs_selector.should_select(&mi.fs_type)
{
None
} else {
if paths.is_empty() {
// No path specified
return Some((mi.dev_id.clone(), mi));
}
if paths.contains(&mi.mount_dir) {
// One or more paths have been provided
Some((mi.dev_id.clone(), mi))
} else {
// Not a path we want to see
None
}
}
})
.fold(
HashMap::<String, Cell<MountInfo>>::new(),
|mut acc, (id, mi)| {
#[allow(clippy::map_entry)]
{
if acc.contains_key(&id) {
let seen = acc[&id].replace(mi.clone());
let target_nearer_root = seen.mount_dir.len() > mi.mount_dir.len();
// With bind mounts, prefer items nearer the root of the source
let source_below_root = !seen.mount_root.is_empty()
&& !mi.mount_root.is_empty()
&& seen.mount_root.len() < mi.mount_root.len();
// let "real" devices with '/' in the name win.
if (!mi.dev_name.starts_with('/') || seen.dev_name.starts_with('/'))
// let points towards the root of the device win.
&& (!target_nearer_root || source_below_root)
// let an entry over-mounted on a new device win...
&& (seen.dev_name == mi.dev_name
/* ... but only when matching an existing mnt point,
to avoid problematic replacement when given
inaccurate mount lists, seen with some chroot
environments for example. */
|| seen.mount_dir != mi.mount_dir)
{
acc[&id].replace(seen);
}
} else {
acc.insert(id, Cell::new(mi));
}
acc
}
},
)
.into_iter()
.map(|ent| ent.1.into_inner())
.collect::<Vec<_>>()
let mut mount_info_by_id = HashMap::<String, Cell<MountInfo>>::new();
for mi in vmi {
// Don't show remote filesystems if `--local` has been given.
if mi.remote && opt.show_local_fs {
continue;
}
// Don't show pseudo filesystems unless `--all` has been given.
if mi.dummy && !opt.show_all_fs && !opt.show_listed_fs {
continue;
}
// Don't show filesystems if they have been explicitly excluded.
if !opt.fs_selector.should_select(&mi.fs_type) {
continue;
}
// Don't show filesystems other than the ones specified on the
// command line, if any.
if !paths.is_empty() && !paths.contains(&mi.mount_dir) {
continue;
}
// If the device ID has not been encountered yet, just store it.
let id = mi.dev_id.clone();
#[allow(clippy::map_entry)]
if !mount_info_by_id.contains_key(&id) {
mount_info_by_id.insert(id, Cell::new(mi));
continue;
}
// Otherwise, if we have seen the current device ID before,
// then check if we need to update it or keep the previously
// seen one.
let seen = mount_info_by_id[&id].replace(mi.clone());
let target_nearer_root = seen.mount_dir.len() > mi.mount_dir.len();
// With bind mounts, prefer items nearer the root of the source
let source_below_root = !seen.mount_root.is_empty()
&& !mi.mount_root.is_empty()
&& seen.mount_root.len() < mi.mount_root.len();
// let "real" devices with '/' in the name win.
if (!mi.dev_name.starts_with('/') || seen.dev_name.starts_with('/'))
// let points towards the root of the device win.
&& (!target_nearer_root || source_below_root)
// let an entry over-mounted on a new device win...
&& (seen.dev_name == mi.dev_name
/* ... but only when matching an existing mnt point,
to avoid problematic replacement when given
inaccurate mount lists, seen with some chroot
environments for example. */
|| seen.mount_dir != mi.mount_dir)
{
mount_info_by_id[&id].replace(seen);
}
}
// Take ownership of the `MountInfo` instances and collect them
// into a `Vec`.
mount_info_by_id
.into_values()
.map(|m| m.into_inner())
.collect()
}
/// Convert `value` to a human readable string based on `base`.