use crate::error::VfsErrorKind;
use crate::VfsResult;
use crate::{FileSystem, VfsFileType};
use crate::{SeekAndRead, VfsMetadata};
use core::cmp;
use std::collections::hash_map::Entry;
use std::collections::HashMap;
use std::fmt;
use std::fmt::{Debug, Formatter};
use std::io::{Cursor, Read, Seek, SeekFrom, Write};
use std::mem::swap;
use std::sync::{Arc, RwLock};
type MemoryFsHandle = Arc<RwLock<MemoryFsImpl>>;
pub struct MemoryFS {
handle: MemoryFsHandle,
}
impl Debug for MemoryFS {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
f.write_str("In Memory File System")
}
}
impl MemoryFS {
pub fn new() -> Self {
MemoryFS {
handle: Arc::new(RwLock::new(MemoryFsImpl::new())),
}
}
fn ensure_has_parent(&self, path: &str) -> VfsResult<()> {
let separator = path.rfind('/');
if let Some(index) = separator {
if self.exists(&path[..index])? {
return Ok(());
}
}
Err(VfsErrorKind::Other("Parent path does not exist".into()).into())
}
}
impl Default for MemoryFS {
fn default() -> Self {
Self::new()
}
}
struct WritableFile {
content: Cursor<Vec<u8>>,
destination: String,
fs: MemoryFsHandle,
}
impl Write for WritableFile {
fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
self.content.write(buf)
}
fn flush(&mut self) -> std::io::Result<()> {
self.content.flush()
}
}
impl Drop for WritableFile {
fn drop(&mut self) {
let mut content = vec![];
swap(&mut content, self.content.get_mut());
self.fs.write().unwrap().files.insert(
self.destination.clone(),
MemoryFile {
file_type: VfsFileType::File,
content: Arc::new(content),
},
);
}
}
struct ReadableFile {
#[allow(clippy::rc_buffer)] content: Arc<Vec<u8>>,
position: u64,
}
impl ReadableFile {
fn len(&self) -> u64 {
self.content.len() as u64 - self.position
}
}
impl Read for ReadableFile {
fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
let amt = cmp::min(buf.len(), self.len() as usize);
if amt == 1 {
buf[0] = self.content[self.position as usize];
} else {
buf[..amt].copy_from_slice(
&self.content.as_slice()[self.position as usize..self.position as usize + amt],
);
}
self.position += amt as u64;
Ok(amt)
}
}
impl Seek for ReadableFile {
fn seek(&mut self, pos: SeekFrom) -> std::io::Result<u64> {
match pos {
SeekFrom::Start(offset) => self.position = offset,
SeekFrom::Current(offset) => self.position = (self.position as i64 + offset) as u64,
SeekFrom::End(offset) => self.position = (self.content.len() as i64 + offset) as u64,
}
Ok(self.position)
}
}
impl FileSystem for MemoryFS {
fn read_dir(&self, path: &str) -> VfsResult<Box<dyn Iterator<Item = String> + Send>> {
let prefix = format!("{}/", path);
let handle = self.handle.read().unwrap();
let mut found_directory = false;
#[allow(clippy::needless_collect)] let entries: Vec<_> = handle
.files
.iter()
.filter_map(|(candidate_path, _)| {
if candidate_path == path {
found_directory = true;
}
if candidate_path.starts_with(&prefix) {
let rest = &candidate_path[prefix.len()..];
if !rest.contains('/') {
return Some(rest.to_string());
}
}
None
})
.collect();
if !found_directory {
return Err(VfsErrorKind::FileNotFound.into());
}
Ok(Box::new(entries.into_iter()))
}
fn create_dir(&self, path: &str) -> VfsResult<()> {
self.ensure_has_parent(path)?;
let map = &mut self.handle.write().unwrap().files;
let entry = map.entry(path.to_string());
match entry {
Entry::Occupied(file) => {
return match file.get().file_type {
VfsFileType::File => Err(VfsErrorKind::FileExists.into()),
VfsFileType::Directory => Err(VfsErrorKind::DirectoryExists.into()),
}
}
Entry::Vacant(_) => {
map.insert(
path.to_string(),
MemoryFile {
file_type: VfsFileType::Directory,
content: Default::default(),
},
);
}
}
Ok(())
}
fn open_file(&self, path: &str) -> VfsResult<Box<dyn SeekAndRead + Send>> {
let handle = self.handle.read().unwrap();
let file = handle.files.get(path).ok_or(VfsErrorKind::FileNotFound)?;
ensure_file(file)?;
Ok(Box::new(ReadableFile {
content: file.content.clone(),
position: 0,
}))
}
fn create_file(&self, path: &str) -> VfsResult<Box<dyn Write + Send>> {
self.ensure_has_parent(path)?;
let content = Arc::new(Vec::<u8>::new());
self.handle.write().unwrap().files.insert(
path.to_string(),
MemoryFile {
file_type: VfsFileType::File,
content,
},
);
let writer = WritableFile {
content: Cursor::new(vec![]),
destination: path.to_string(),
fs: self.handle.clone(),
};
Ok(Box::new(writer))
}
fn append_file(&self, path: &str) -> VfsResult<Box<dyn Write + Send>> {
let handle = self.handle.write().unwrap();
let file = handle.files.get(path).ok_or(VfsErrorKind::FileNotFound)?;
let mut content = Cursor::new(file.content.as_ref().clone());
content.seek(SeekFrom::End(0))?;
let writer = WritableFile {
content,
destination: path.to_string(),
fs: self.handle.clone(),
};
Ok(Box::new(writer))
}
fn metadata(&self, path: &str) -> VfsResult<VfsMetadata> {
let guard = self.handle.read().unwrap();
let files = &guard.files;
let file = files.get(path).ok_or(VfsErrorKind::FileNotFound)?;
Ok(VfsMetadata {
file_type: file.file_type,
len: file.content.len() as u64,
})
}
fn exists(&self, path: &str) -> VfsResult<bool> {
Ok(self.handle.read().unwrap().files.contains_key(path))
}
fn remove_file(&self, path: &str) -> VfsResult<()> {
let mut handle = self.handle.write().unwrap();
handle
.files
.remove(path)
.ok_or(VfsErrorKind::FileNotFound)?;
Ok(())
}
fn remove_dir(&self, path: &str) -> VfsResult<()> {
if self.read_dir(path)?.next().is_some() {
return Err(VfsErrorKind::Other("Directory to remove is not empty".into()).into());
}
let mut handle = self.handle.write().unwrap();
handle
.files
.remove(path)
.ok_or(VfsErrorKind::FileNotFound)?;
Ok(())
}
}
struct MemoryFsImpl {
files: HashMap<String, MemoryFile>,
}
impl MemoryFsImpl {
pub fn new() -> Self {
let mut files = HashMap::new();
files.insert(
"".to_string(),
MemoryFile {
file_type: VfsFileType::Directory,
content: Arc::new(vec![]),
},
);
Self { files }
}
}
struct MemoryFile {
file_type: VfsFileType,
#[allow(clippy::rc_buffer)] content: Arc<Vec<u8>>,
}
#[cfg(test)]
mod tests {
use super::*;
use crate::VfsPath;
test_vfs!(MemoryFS::new());
#[test]
fn write_and_read_file() -> VfsResult<()> {
let root = VfsPath::new(MemoryFS::new());
let path = root.join("foobar.txt").unwrap();
let _send = &path as &dyn Send;
{
let mut file = path.create_file().unwrap();
write!(file, "Hello world").unwrap();
write!(file, "!").unwrap();
}
{
let mut file = path.open_file().unwrap();
let mut string: String = String::new();
file.read_to_string(&mut string).unwrap();
assert_eq!(string, "Hello world!");
}
assert!(path.exists()?);
assert!(!root.join("foo").unwrap().exists()?);
let metadata = path.metadata().unwrap();
assert_eq!(metadata.len, 12);
assert_eq!(metadata.file_type, VfsFileType::File);
Ok(())
}
#[test]
fn append_file() {
let root = VfsPath::new(MemoryFS::new());
let _string = String::new();
let path = root.join("test_append.txt").unwrap();
path.create_file().unwrap().write_all(b"Testing 1").unwrap();
path.append_file().unwrap().write_all(b"Testing 2").unwrap();
{
let mut file = path.open_file().unwrap();
let mut string: String = String::new();
file.read_to_string(&mut string).unwrap();
assert_eq!(string, "Testing 1Testing 2");
}
}
#[test]
fn create_dir() {
let root = VfsPath::new(MemoryFS::new());
let _string = String::new();
let path = root.join("foo").unwrap();
path.create_dir().unwrap();
let metadata = path.metadata().unwrap();
assert_eq!(metadata.file_type, VfsFileType::Directory);
}
#[test]
fn remove_dir_error_message() {
let root = VfsPath::new(MemoryFS::new());
let path = root.join("foo").unwrap();
let result = path.remove_dir();
assert_eq!(
format!("{}", result.unwrap_err()),
"Could not remove directory for '/foo': The file or directory could not be found"
);
}
#[test]
fn read_dir_error_message() {
let root = VfsPath::new(MemoryFS::new());
let path = root.join("foo").unwrap();
let result = path.read_dir();
match result {
Ok(_) => panic!("Error expected"),
Err(err) => {
assert_eq!(
format!("{}", err),
"Could not read directory for '/foo': The file or directory could not be found"
);
}
}
}
#[test]
fn copy_file_across_filesystems() -> VfsResult<()> {
let root_a = VfsPath::new(MemoryFS::new());
let root_b = VfsPath::new(MemoryFS::new());
let src = root_a.join("a.txt")?;
let dest = root_b.join("b.txt")?;
src.create_file()?.write_all(b"Hello World")?;
src.copy_file(&dest)?;
assert_eq!(&dest.read_to_string()?, "Hello World");
Ok(())
}
}
fn ensure_file(file: &MemoryFile) -> VfsResult<()> {
if file.file_type != VfsFileType::File {
return Err(VfsErrorKind::Other("Not a file".into()).into());
}
Ok(())
}