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use std::collections::BTreeMap;
use crate::{errors::DirectoryError, path::PathComponent, proto, B3Digest, Node};
/// A Directory contains nodes, which can be Directory, File or Symlink nodes.
/// It attached names to these nodes, which is the basename in that directory.
/// These names:
/// - MUST not contain slashes or null bytes
/// - MUST not be '.' or '..'
/// - MUST be unique across all three lists
#[derive(Default, Debug, Clone, PartialEq, Eq)]
pub struct Directory {
nodes: BTreeMap<PathComponent, Node>,
}
impl Directory {
/// Constructs a new, empty Directory.
/// FUTUREWORK: provide a constructor from an interator of (sorted) names and nodes.
pub fn new() -> Self {
Directory {
nodes: BTreeMap::new(),
}
}
/// The size of a directory is the number of all regular and symlink elements,
/// the number of directory elements, and their size fields.
pub fn size(&self) -> u64 {
// It's impossible to create a Directory where the size overflows, because we
// check before every add() that the size won't overflow.
(self.nodes.len() as u64)
+ self
.nodes()
.map(|(_name, n)| match n {
Node::Directory { size, .. } => 1 + size,
Node::File { .. } | Node::Symlink { .. } => 1,
})
.sum::<u64>()
}
/// Calculates the digest of a Directory, which is the blake3 hash of a
/// Directory protobuf message, serialized in protobuf canonical form.
pub fn digest(&self) -> B3Digest {
proto::Directory::from(self.clone()).digest()
}
/// Allows iterating over all nodes (directories, files and symlinks)
/// For each, it returns a tuple of its name and node.
/// The elements are sorted by their names.
pub fn nodes(&self) -> impl Iterator<Item = (&PathComponent, &Node)> + Send + Sync + '_ {
self.nodes.iter()
}
/// Adds the specified [Node] to the [Directory] with a given name.
///
/// Inserting an element that already exists with the same name in the directory will yield an
/// error.
/// Inserting an element will validate that its name fulfills the
/// requirements for directory entries and yield an error if it is not.
pub fn add(&mut self, name: PathComponent, node: Node) -> Result<(), DirectoryError> {
// Check that the even after adding this new directory entry, the size calculation will not
// overflow
// FUTUREWORK: add some sort of batch add interface which only does this check once with
// all the to-be-added entries
checked_sum([
self.size(),
1,
match node {
Node::Directory { size, .. } => size,
_ => 0,
},
])
.ok_or(DirectoryError::SizeOverflow)?;
match self.nodes.entry(name) {
std::collections::btree_map::Entry::Vacant(e) => {
e.insert(node);
Ok(())
}
std::collections::btree_map::Entry::Occupied(occupied) => {
Err(DirectoryError::DuplicateName(occupied.key().to_owned()))
}
}
}
}
fn checked_sum(iter: impl IntoIterator<Item = u64>) -> Option<u64> {
iter.into_iter().try_fold(0u64, |acc, i| acc.checked_add(i))
}
#[cfg(test)]
mod test {
use super::{Directory, Node};
use crate::fixtures::DUMMY_DIGEST;
use crate::DirectoryError;
#[test]
fn add_nodes_to_directory() {
let mut d = Directory::new();
d.add(
"b".try_into().unwrap(),
Node::Directory {
digest: DUMMY_DIGEST.clone(),
size: 1,
},
)
.unwrap();
d.add(
"a".try_into().unwrap(),
Node::Directory {
digest: DUMMY_DIGEST.clone(),
size: 1,
},
)
.unwrap();
d.add(
"z".try_into().unwrap(),
Node::Directory {
digest: DUMMY_DIGEST.clone(),
size: 1,
},
)
.unwrap();
d.add(
"f".try_into().unwrap(),
Node::File {
digest: DUMMY_DIGEST.clone(),
size: 1,
executable: true,
},
)
.unwrap();
d.add(
"c".try_into().unwrap(),
Node::File {
digest: DUMMY_DIGEST.clone(),
size: 1,
executable: true,
},
)
.unwrap();
d.add(
"g".try_into().unwrap(),
Node::File {
digest: DUMMY_DIGEST.clone(),
size: 1,
executable: true,
},
)
.unwrap();
d.add(
"t".try_into().unwrap(),
Node::Symlink {
target: "a".try_into().unwrap(),
},
)
.unwrap();
d.add(
"o".try_into().unwrap(),
Node::Symlink {
target: "a".try_into().unwrap(),
},
)
.unwrap();
d.add(
"e".try_into().unwrap(),
Node::Symlink {
target: "a".try_into().unwrap(),
},
)
.unwrap();
// Convert to proto struct and back to ensure we are not generating any invalid structures
crate::Directory::try_from(crate::proto::Directory::from(d))
.expect("directory should be valid");
}
#[test]
fn validate_overflow() {
let mut d = Directory::new();
assert_eq!(
d.add(
"foo".try_into().unwrap(),
Node::Directory {
digest: DUMMY_DIGEST.clone(),
size: u64::MAX
}
),
Err(DirectoryError::SizeOverflow)
);
}
#[test]
fn add_duplicate_node_to_directory() {
let mut d = Directory::new();
d.add(
"a".try_into().unwrap(),
Node::Directory {
digest: DUMMY_DIGEST.clone(),
size: 1,
},
)
.unwrap();
assert_eq!(
format!(
"{}",
d.add(
"a".try_into().unwrap(),
Node::File {
digest: DUMMY_DIGEST.clone(),
size: 1,
executable: true
}
)
.expect_err("adding duplicate dir entry must fail")
),
"\"a\" is a duplicate name"
);
}
}
|
