Segfault when using an invalid TID for a BAM HeaderView

[tculvahouse-atlasds]

The bug

Hello! I found that indexing into a BAM HeaderView with a TID outside of its range of references causes a segfault. Specifically, this happens when rust_htslib::bam::HeaderView::tid2name(…) is called. Here's a minimal example:

fn main() {
    use ::rust_htslib::bam::{Header, HeaderView};
    let header = Header::new();
    let header_view = HeaderView::from_header(&header);
    _ = header_view.tid2name(0);
}

It looks to me like the problem is that tid2name(…) doesn't check its input before calling the C binding for htslib's sam_hdr_tid2name. Maybe some edit to its definition like this would help, without changing the API:

pub fn tid2name(&self, tid: u32) -> &[u8] {
    if self.target_count() > tid { 
        unsafe { ffi::CStr::from_ptr(htslib::sam_hdr_tid2name(self.inner, tid as i32)).to_bytes() }
    } else {
        panic!(<some error message>)
    }
}

But I'm no expert on the inner workings of htslib, so I'm not certain that that's a complete solution. Just a guess.

From what I can tell, the only place in rust-htslib that tid2name(…) is being used is in the rust_htslib::bam::record::Record implementation of bio_types::genome::AbstractInterval::contig(). That's where I ran into this issue: I called .contig() after setting the Record's TID to an invalid value.

I hope this was helpful!

Some version details

rust-htslib version: 0.51.0

output from cargo -v version:

cargo 1.92.0 (Homebrew)
release: 1.92.0
host: aarch64-apple-darwin
libgit2: 1.9.2 (sys:0.20.2 system)
libcurl: 8.7.1 (sys:0.4.83+curl-8.15.0 system ssl:(SecureTransport) LibreSSL/3.3.6)
os: Mac OS 15.7.3 [64-bit]

output from rustc -v version:

rustc 1.92.0 (ded5c06cf 2025-12-08) (Homebrew)
binary: rustc
commit-hash: ded5c06cf21d2b93bffd5d884aa6e96934ee4234
commit-date: 2025-12-08
host: aarch64-apple-darwin
release: 1.92.0
LLVM version: 21.1.7

Please let me know if there's any other info I ought to provide. Thank you!