Re the proposed patch to try to avoid access calls on arguments that contain just a single dot (changing the code to look for ".."):
There are no filenames with any dots in the zoneinfo tree produced from an unmodified tz distribution. So whether or not access is called, there will be one system call for a dot-containing argument; either access or open will fail and no further calls will be made. Avoiding the access call doesn't save a system call.
(Looking for ".." rather than "." will save a call on customized systems that put dot-containing names in the zoneinfo tree.)
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