My Linux is Ubuntu 18.04.2 with all latest updates, and its glibc is 2.27-3ubuntu1 manpages are 4.15-1 , also I looked into man7.org after you announced 5.0 I studied sources of zdkimfilter and found a place where they consult h_errno value after res_query returns -1. I turned to man res_query and did not find anything about h_errno surprised, I contacted zdkimfilter author and he told me this has always be this way as per BSD specification. also checked glibc sources and found that h_errno is really filled when underlying calls fail what is left, is to specify this behavior in Linux man pages as explicitly as it is done in BSD чт, 7 мар. 2019 г. в 12:52, Michael Kerrisk (man-pages) <mtk.manpages@xxxxxxxxx>: > > Hello Wladimir, > > On Thu, 7 Mar 2019 at 10:57, Wladimir Mutel <muwlgr@xxxxxxxxx> wrote: > > > > in https://www.freebsd.org/cgi/man.cgi?query=resolver we read : > > > > The res_mkquery(), res_search(), and res_query() functions return the > > size of the response on success, or -1 if an error occurs. The integer > > h_errno may be checked to determine the reason for error. See > > gethostbyname(3) for more information. > > > > in http://man7.org/linux/man-pages/man3/resolver.3.html , h_errno is > > not mentioned > > but in the end of this page we read > > > > CONFORMING TO > > 4.3BSD. > > > > the fact that h_errno is really modified as specified by BSD, could be > > confirmed experimentally, but would not it be more convenient if this > > was mentioned documentally ? > > Have you verified it experimentally on Linux/glibc (and for which of > the functions)? > > Thanks, > > Michael > > > > > -- > Michael Kerrisk > Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ > Linux/UNIX System Programming Training: http://man7.org/training/
