I’m assuming you are proposing to stat each candidate before trying to execve it. I’m also assuming that a stat system call is roughly as expensive as an execve of a nonexistent or non-executable path.
For every failed candidate, you are doing one system call, so roughly the same cost each way.
Now if you just do an execve, you’re just paying that cost. If you stat first, you pay the cost of another system call that doesn’t change the flow of your program at all (a nice way of saying you’re wasting time).
Unless stat is dramatically faster than exec on a nonexistent or non-executable path, there’s never a case where this is better.
For every failed candidate, you are doing one system call, so roughly the same cost each way.
Now if you just do an execve, you’re just paying that cost. If you stat first, you pay the cost of another system call that doesn’t change the flow of your program at all (a nice way of saying you’re wasting time).
Unless stat is dramatically faster than exec on a nonexistent or non-executable path, there’s never a case where this is better.