ref: ab9cc277c2d695b2d253610d9867256aa2a3ad8f
dir: /config/unix/net.m4/
dnl dnl The following was written by [email protected] dnl dnl AC_LIBRARY_NET: Id: net.m4,v 1.4 1997/10/25 20:49:53 jhawk Exp dnl dnl This test is for network applications that need socket() and dnl gethostbyname() -ish functions. Under Solaris, those applications need to dnl link with "-lsocket -lnsl". Under IRIX, they should *not* link with dnl "-lsocket" because libsocket.a breaks a number of things (for instance: dnl gethostbyname() under IRIX 5.2, and snoop sockets under most versions of dnl IRIX). dnl dnl Unfortunately, many application developers are not aware of this, and dnl mistakenly write tests that cause -lsocket to be used under IRIX. It is dnl also easy to write tests that cause -lnsl to be used under operating dnl systems where neither are necessary (or useful), such as SunOS 4.1.4, which dnl uses -lnsl for TLI. dnl dnl This test exists so that every application developer does not test this in dnl a different, and subtly broken fashion. dnl dnl It has been argued that this test should be broken up into two seperate dnl tests, one for the resolver libraries, and one for the libraries necessary dnl for using Sockets API. Unfortunately, the two are carefully intertwined and dnl allowing the autoconf user to use them independantly potentially results in dnl unfortunate ordering dependancies -- as such, such component macros would dnl have to carefully use indirection and be aware if the other components were dnl executed. Since other autoconf macros do not go to this trouble, and almost dnl no applications use sockets without the resolver, this complexity has not dnl been implemented. dnl dnl The check for libresolv is in case you are attempting to link statically dnl and happen to have a libresolv.a lying around (and no libnsl.a). dnl AC_DEFUN(AC_LIBRARY_NET, [ # Most operating systems have gethostbyname() in the default searched # libraries (i.e. libc): AC_CHECK_FUNC(gethostbyname, , # Some OSes (eg. Solaris) place it in libnsl: AC_CHECK_LIB(nsl, gethostbyname, , # Some strange OSes (SINIX) have it in libsocket: AC_CHECK_LIB(socket, gethostbyname, , # Unfortunately libsocket sometimes depends on libnsl. # AC_CHECK_LIB's API is essentially broken so the following # ugliness is necessary: AC_CHECK_LIB(socket, gethostbyname, LIBS="-lsocket -lnsl $LIBS", AC_CHECK_LIB(resolv, gethostbyname), -lnsl) ) ) ) AC_CHECK_FUNC(socket, , AC_CHECK_LIB(socket, socket, , AC_CHECK_LIB(socket, socket, LIBS="-lsocket -lnsl $LIBS", , -lnsl))) ])