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Fix underflow when input is shorter than one sector #141

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Merged
merged 1 commit into from
Jun 16, 2025
Merged

Fix underflow when input is shorter than one sector #141

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13 changes: 13 additions & 0 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -729,6 +729,10 @@ impl GPT {
reader.seek(SeekFrom::Start(sector_size))?;
let header = GPTHeader::read_from(&mut reader).or_else(|primary_err| {
let len = reader.seek(SeekFrom::End(0))?;
if len < sector_size {
return Err(InvalidSignature);
}

reader.seek(SeekFrom::Start((len / sector_size - 1) * sector_size))?;

GPTHeader::read_from(&mut reader).map_err(|backup_err| {
Expand Down Expand Up @@ -1427,6 +1431,15 @@ mod test {
assert!(GPT::find_from(&mut fs::File::open(DISK2).unwrap()).is_ok());
}

#[test]
fn input_too_short() {
let mut empty = io::Cursor::new(vec![1; 5]);
assert!(matches!(
GPT::read_from(&mut empty, 512).expect_err("Should fail on short input"),
Error::InvalidSignature
));
}

#[test]
fn find_backup() {
fn test(path: &str, ss: u64) {
Expand Down
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