to POSIX.2. In particular:
- don't retry for ETXTBSY. This matches what sh(1) does. The retry code
was broken anyway. It only slept for several seconds for the first few
retries. Then it retried without sleeping.
- don't abort the search for errors related to the path prefix, in
particular for ENAMETOOLONG, ENOTDIR, ELOOP. This fixes PR1487. sh(1)
gets this wrong in the opposite direction by never aborting the search.
- don't confuse EACCES for errors related to the path prefix with EACCES
for errors related to the file. sh(1) gets this wrong.
- don't return a stale errno when the search terminates normally without
finding anything. The errno for the last unsuccessful execve() was
usually returned. This gave too much precedence to pathologies in the
last component of $PATH. This bug is irrelevant for sh(1).
The implementation still uses the optimization/race-inhibitor of trying
to execve() things first. POSIX.2 seems to require looking at file
permissions using stat(). We now use stat() after execve() if execve()
fails with an ambiguous error. Trying execve() first may actually be a
pessimization, since failing execve()s are fundamentally a little slower
than stat(), and are significantly slower when a file is found but has
unsuitable permissions or points to an unsuitable interpreter.
PR: 1487
Garbage in `eacces' caused the wrong errno to be set for non-EACCES errors.
Garbage in `etxtbsy' caused a semi-random retry strategy for ETXTBSY errors.
Found by: NIST-PCTS. gcc -Wall reported the problem, but -Wall is not
enabled for libc.
pointer returned by realloc(). All callers free the pointer if the
execve fails. Nuke the caching. This essentially restores buildargv()
to the 1.1.5 version. Also fix a memory leak if realloc() fails. Also
nuke similar but non-broken caching in execvp(). malloc() should be
efficient enough.
