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ptsname() returns a null pointer when the fd is not a pty main, and tty_ptsname passed it straight to CStr::from_ptr, which is undefined behavior reachable from safe code (e.g. tty_ptsname(-1) segfaults). Check for null first and return the errno message as an error. Fixes raphamorim#1953 Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
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tty_ptsnameis a safe function, but it passed the result ofptsname()straight toCStr::from_ptr.ptsname()returns null when the fd is not a pty main, so something liketty_ptsname(-1)was undefined behavior from safe code (it segfaults on macOS).This checks for null first and returns the errno message as an
Err. The two existing callers already handleErrwithunwrap_or_else, so nothing else changes. I also dropped the stale "Unsafe" note from the doc comment, since the function is notunsafe fn.Testing
ptsname_testsinteletypewriter/src/unix/mod.rs:tty_ptsname(-1)returnsErr, and a realposix_openptmain returns a/dev/...path.invalid_fd_returns_errtest crashes with SIGSEGV on currentmainand passes with the fix.cargo test -p teletypewriter,cargo fmt -- --check,cargo clippy -p teletypewriter --all-targets --all-featuresall pass (macOS arm64).I used Claude Code to help with this change and reviewed and tested it myself.
Fixes #1953
🤖 Generated with Claude Code