[PATCH] execlp, execvp, execvpe: Don't fall back to sh on ENOEXEC.

[Paul Eggert]

On 12/15/20 8:05 AM, Zack Weinberg wrote:
> When direct execution of a program fails with ENOEXEC, do not attempt
> to run that program as if it were a shell script.

A less-intrusive approach would be for execlp etc.'s fallback to look at the 
first 1024 bytes (or whatever) of the file and fail with ENOEXEC if it finds 
a NUL byte, before trying to exec /bin/sh on the file.  This heuristic 
surely would have addressed your problem since machine executables 
invariably contain NUL bytes, and since NUL bytes cannot appear in 
conforming POSIX shell scripts the heuristic would also maintain POSIX 
compatibility. And as a practical matter the heuristic would continue to 
support whatever random application out there is actually relying on this 
longstanding POSIX-required misfeature.