Andres Freund <andres@anarazel.de> writes:
> On 2015-09-28 16:57:24 -0400, Tom Lane wrote:
>> Great detective work! But if that's broken, then surely the identical
>> code in my_sock_write is as well; and the reassignment to errno at the
>> bottom of my_sock_read needs to be SOCK_ERRNO_SET(); and why doesn't
>> my_sock_write have a reassignment at all?
> I wonder if we couldn't remove saving/restoring errno entirely from
> my_sock_*. We didn't do so before 680513ab79 and I can't see a reason
> why we'd need to now.
Agreed, see my comment to the same effect.
> What I do find curious is that afaics before 680513ab79 the code also
> looked at errno, not SOCK_ERRNO. And apparently things worked back then?
No; AFAICS, before that commit, libpq did not use a custom BIO at all.
That commit cloned the backend's custom BIO, but did not correctly
adjust the backend's errno handling for the libpq environment.
Will go fix it.
regards, tom lane