[ILUG] Configure

[Lars Hecking]

>     # Check libpam for pam_start()
>     AC_CHECK_LIB(pam, pam_start,

 check for pam_start() in libpam

>         HAVE_PAM=1
>         LIBS="-lpam $LIBDL $LIBS"
>     # Why check again ?
>         AC_CHECK_FUNCS(pam_setcred),

 These three lines are the "ACTION-IF-FOUND" part of AC_CHECK_LIB (note
 the comma at the end): if pam_start() was found, define HAVE_PAM=1,
 define LIBS="-lpam $LIBDL $LIBS", and also check for pam_setcred().
 As HAVE_PAM is not made to depend on the outcome of the check for
 pam_setcred(), your code will deal with the case that pam_setcred()
 is not available, i.e.

#ifndef HAVE_PAM_SETCRED
/* Roll our own */
int pam_setcred(pam_handle_t *pamh, int flags)
{
...
}
#endif

> 
>         HAVE_PAM=0,

 This is the "ACTION-IF-NOT-FOUND" part of AC_CHECK_LIB(pam, pam_start ...)

>         $LIBDL)

 The "OTHER-LIBRARIES" part, a space-separated list of libraries needed
 to link -lpam.

>     LIBS="$saveLIBS"
> fi
> AC_SUBST(LIBDL) # Is this adding those flags to the LIBS line or something ?
> AC_SUBST(HAVE_PAM)
> AM_CONDITIONAL(HAVE_PAM, test "$HAVE_PAM" = 1)   # What these mean ?
> 
> AUTHPAM=""
> if test "$HAVE_PAM" = 1
> then # I get lost here...
>     AUTHPAM=authpam
>     STATIC_LIST="$STATIC_LIST AUTHSTATIC(\"authpam\", auth_pam, auth_pam_pre)"
>     LIBAUTH="$LIBAUTH libauth-authpam.a"
> fi
 
 No idea about AUTSTATIC(). May be defined in acinclude.m4 (deprecated),
 aclocal.m4, or even some other m4 config files (typically living in the
 m4/ subdir).