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Improve variable names and comments readability

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This commit is contained in:
Egor Duda
2022-06-06 15:08:42 +03:00
parent 660b6b76b2
commit 2708074949
1 changed files with 27 additions and 24 deletions
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51
libraries/persistent_store/src/file.rs
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@@ -26,20 +26,22 @@ use std::path::Path;
/// Simulates a flash storage using a host-based file.
///
/// This is usable for emulating authenticator hardware on VM hypervisor's host OS
/// This is usable for emulating authenticator hardware on VM hypervisor's host OS.
pub struct FileStorage {
// Options of the storage
// Options of the storage.
options: FileOptions,
/// File for persisting contents of the storage
/// File for persisting contents of the storage.
///
/// Reading data from File requires mutable reference, as seeking and reading data
/// changes file's current position.
///
/// All operations on backing file internally always first seek to needed position,
/// so it's safe to borrow mutable reference to backing file for the time of operation.
backing_file_ref: RefCell<File>,
file: RefCell<File>,
}
/// Options for file-backed storage
/// Options for file-backed storage.
pub struct FileOptions {
/// Size of a word in bytes.
pub word_size: usize,
@@ -47,28 +49,28 @@ pub struct FileOptions {
/// Size of a page in bytes.
pub page_size: usize,
/// Number of pages in storage
/// Number of pages in storage.
pub num_pages: usize,
}
impl FileStorage {
pub fn new(path: &Path, options: FileOptions) -> StorageResult<FileStorage> {
let mut backing_file_ref = RefCell::new(
let mut file_ref = RefCell::new(
OpenOptions::new()
.read(true)
.write(true)
.create(true)
.open(path)?,
);
let backing_file = backing_file_ref.get_mut();
let file_len = backing_file.metadata()?.len();
let file = file_ref.get_mut();
let file_len = file.metadata()?.len();
let store_len: u64 = (options.page_size * options.num_pages) as u64;
if file_len == 0 {
backing_file.seek(SeekFrom::Start(0))?;
file.seek(SeekFrom::Start(0))?;
let buf = vec![0xffu8; options.page_size];
for _ in 0..options.num_pages {
backing_file.write(&buf)?;
file.write(&buf)?;
}
} else if file_len != store_len {
// FileStorage buffer should be of fixed size, opening previously saved file
@@ -77,7 +79,7 @@ impl FileStorage {
}
Ok(FileStorage {
options,
backing_file_ref,
file: file_ref,
})
}
}
@@ -104,28 +106,29 @@ impl Storage for FileStorage {
}
fn read_slice(&self, index: StorageIndex, length: usize) -> StorageResult<Cow<[u8]>> {
let mut backing_file = self.backing_file_ref.borrow_mut();
backing_file.seek(SeekFrom::Start(
(index.page * self.page_size() + index.byte) as u64,
))?;
let mut file = self.file.borrow_mut();
file.seek(SeekFrom::Start(index.range(length, self)?.start as u64))?;
let mut buf = vec![0u8; length];
backing_file.read_exact(&mut buf)?;
file.read_exact(&mut buf)?;
Ok(Cow::Owned(buf))
}
fn write_slice(&mut self, index: StorageIndex, value: &[u8]) -> StorageResult<()> {
let mut backing_file = self.backing_file_ref.borrow_mut();
backing_file.seek(SeekFrom::Start(
(index.page * self.page_size() + index.byte) as u64,
let mut file = self.file.borrow_mut();
file.seek(SeekFrom::Start(
index.range(value.len(), self)?.start as u64,
))?;
backing_file.write_all(value)?;
file.write_all(value)?;
Ok(())
}
fn erase_page(&mut self, page: usize) -> StorageResult<()> {
let mut backing_file = self.backing_file_ref.borrow_mut();
backing_file.seek(SeekFrom::Start((page * self.page_size()) as u64))?;
backing_file.write_all(&vec![0xffu8; self.page_size()][..])?;
let mut file = self.file.borrow_mut();
let index = StorageIndex { page, byte: 0 };
file.seek(SeekFrom::Start(
index.range(self.page_size(), self)?.start as u64,
))?;
file.write_all(&vec![0xffu8; self.page_size()][..])?;
Ok(())
}
}