srenblad/rust-fatfs
1
0
Fork 0
forked from M-Labs/rust-fatfs
Code Pull Requests Activity

Make sure short name generation never fails

Browse Source
This commit is contained in:
Rafał Harabień 2018-06-17 23:21:33 +02:00
parent a6b66f9434
commit f68996925f
1 changed files with 63 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

87
src/dir.rs
View File

@ -88,6 +88,11 @@ fn split_path<'c>(path: &'c str) -> (&'c str, Option<&'c str>) {
(comp, rest_opt)
}
enum DirEntryOrShortName<'a, T: ReadWriteSeek + 'a> {
DirEntry(DirEntry<'a, T>),
ShortName([u8; 11]),
}
/// A FAT filesystem directory.
pub struct Dir<'a, T: ReadWriteSeek + 'a> {
stream: DirRawStream<'a, T>,
@ -129,6 +134,24 @@ impl <'a, T: ReadWriteSeek + 'a> Dir<'a, T> {
Err(io::Error::new(ErrorKind::NotFound, "No such file or directory"))
}
fn check_for_existence(&self, name: &str, is_dir: Option<bool>) -> io::Result<DirEntryOrShortName<'a, T>> {
let mut short_name_gen = ShortNameGenerator::new(name);
loop {
let r = self.find_entry(name, is_dir, Some(&mut short_name_gen));
match r {
Err(ref err) if err.kind() == ErrorKind::NotFound => {},
// other error
Err(err) => return Err(err),
// directory already exists - return it
Ok(e) => return Ok(DirEntryOrShortName::DirEntry(e)),
};
if let Ok(name) = short_name_gen.generate() {
return Ok(DirEntryOrShortName::ShortName(name));
}
short_name_gen.next_iteration();
}
}
/// Opens existing subdirectory.
///
/// `path` is a '/' separated directory path relative to self directory.
@ -167,19 +190,15 @@ impl <'a, T: ReadWriteSeek + 'a> Dir<'a, T> {
return self.find_entry(name, Some(true), None)?.to_dir().create_file(rest);
}
// this is final filename in the path
let mut short_name_gen = ShortNameGenerator::new(name);
let r = self.find_entry(name, Some(false), Some(&mut short_name_gen));
let r = self.check_for_existence(name, Some(false))?;
match r {
// file does not exist - create it
Err(ref err) if err.kind() == ErrorKind::NotFound => {
let short_name = short_name_gen.generate()?;
DirEntryOrShortName::ShortName(short_name) => {
let sfn_entry = self.create_sfn_entry(short_name, FileAttributes::from_bits_truncate(0), None);
Ok(self.write_entry(name, sfn_entry)?.to_file())
},
// other error
Err(err) => Err(err),
// file already exists - return it
Ok(e) => Ok(e.to_file()),
DirEntryOrShortName::DirEntry(e) => Ok(e.to_file()),
}
}
@ -193,15 +212,13 @@ impl <'a, T: ReadWriteSeek + 'a> Dir<'a, T> {
return self.find_entry(name, Some(true), None)?.to_dir().create_dir(rest);
}
// this is final filename in the path
let mut short_name_gen = ShortNameGenerator::new(name);
let r = self.find_entry(name, Some(true), Some(&mut short_name_gen));
let r = self.check_for_existence(name, Some(true))?;
match r {
// directory does not exist - create it
Err(ref err) if err.kind() == ErrorKind::NotFound => {
DirEntryOrShortName::ShortName(short_name) => {
// alloc cluster for directory data
let cluster = self.fs.alloc_cluster(None)?;
// create entry in parent directory
let short_name = short_name_gen.generate()?;
let sfn_entry = self.create_sfn_entry(short_name, FileAttributes::DIRECTORY, Some(cluster));
let entry = self.write_entry(name, sfn_entry)?;
let mut dir = entry.to_dir();
@ -214,10 +231,8 @@ impl <'a, T: ReadWriteSeek + 'a> Dir<'a, T> {
dir.write_entry("..", sfn_entry)?;
Ok(dir)
},
// other error
Err(err) => Err(err),
// directory already exists - return it
Ok(e) => Ok(e.to_dir()),
DirEntryOrShortName::DirEntry(e) => Ok(e.to_dir()),
}
}
@ -294,20 +309,23 @@ impl <'a, T: ReadWriteSeek + 'a> Dir<'a, T> {
self.rename_internal(src_path, dst_dir, dst_path)
}
fn rename_internal(&self, src_name: &str, dst_dir: &Dir<T>, dst_name: &str) -> io::Result<()> {
trace!("moving {} to {}", src_name, dst_name);
// find existing file
let e = self.find_entry(src_name, None, None)?;
// check if destionation filename is unused
let mut short_name_gen = ShortNameGenerator::new(dst_name);
let r = dst_dir.find_entry(dst_name, None, Some(&mut short_name_gen));
if r.is_ok() {
// check if source and destination entry is the same
if e.is_same_entry(&r.unwrap()) {
return Ok(());
}
return Err(io::Error::new(ErrorKind::AlreadyExists, "Destination file already exists"))
}
let r = dst_dir.check_for_existence(dst_name, None)?;
let short_name = match r {
DirEntryOrShortName::DirEntry(ref dst_e) => {
// check if source and destination entry is the same
if e.is_same_entry(dst_e) {
return Ok(());
}
return Err(io::Error::new(ErrorKind::AlreadyExists, "Destination file already exists"));
},
DirEntryOrShortName::ShortName(short_name) => short_name,
};
// free long and short name entries
let mut stream = self.stream.clone();
stream.seek(SeekFrom::Start(e.offset_range.0 as u64))?;
@ -320,7 +338,6 @@ impl <'a, T: ReadWriteSeek + 'a> Dir<'a, T> {
data.serialize(&mut stream)?;
}
// save new directory entry
let short_name = short_name_gen.generate()?;
let sfn_entry = e.data.renamed(short_name);
dst_dir.write_entry(dst_name, sfn_entry)?;
Ok(())
@ -829,6 +846,14 @@ impl ShortNameGenerator {
Err(io::Error::new(ErrorKind::AlreadyExists, "short name already exists"))
}
fn next_iteration(&mut self) {
// Try different checksum in next iteration
self.chksum = (num::Wrapping(self.chksum) + num::Wrapping(1)).0;
// Zero bitmaps
self.long_prefix_bitmap = 0;
self.prefix_chksum_bitmap = 0;
}
fn build_prefixed_name(&self, num: u32, with_chksum: bool) -> [u8; 11] {
let mut buf = [0x20u8; 11];
let prefix_len = if with_chksum {
@ -908,6 +933,20 @@ mod tests {
gen.add_existing(&buf);
buf = gen.generate().unwrap();
assert_eq!(&buf, "TE527D~2TXT".as_bytes());
for i in 3..10 {
gen.add_existing(&buf);
buf = gen.generate().unwrap();
assert_eq!(&buf, format!("TE527D~{}TXT", i).as_bytes());
}
gen.add_existing(&buf);
assert!(gen.generate().is_err());
gen.next_iteration();
for _i in 0..4 {
buf = gen.generate().unwrap();
gen.add_existing(&buf);
}
buf = gen.generate().unwrap();
assert_eq!(&buf, "TE527E~1TXT".as_bytes());
}
#[test]