Robert Haas <[email protected]> writes:
> On Fri, Feb 20, 2015 at 12:59 AM, Noah Misch <[email protected]> wrote:
>> On Mon, Feb 02, 2015 at 03:48:33PM -0500, Robert Haas wrote:
>>> If readir() fails and closedir() succeeds, the return will be -1 but
>>> errno will be 0.
>> Out of curiosity, have you seen a closedir() implementation behave that way?
>> It would violate C99 ("The value of errno is zero at program startup, but is
>> never set to zero by any library function.") and POSIX.
> No. Good point, I didn't think about that. I think this way is safer,
> though.
While the spec forbids library functions from setting errno to zero, there
is no restriction on them changing errno in other ways despite returning
success; their exit-time value of errno is only well-defined if they fail.
So we do need to preserve errno explicitly across closedir(), or we may
report the wrong failure from readdir().
regards, tom lane
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