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Re: make-network-process's gethostbyname usage
From: |
Chong Yidong |
Subject: |
Re: make-network-process's gethostbyname usage |
Date: |
Sat, 25 Aug 2007 15:06:10 -0400 |
User-agent: |
Gnus/5.11 (Gnus v5.11) Emacs/22.1.50 (gnu/linux) |
address@hidden (Kim F. Storm) writes:
> Richard Stallman <address@hidden> writes:
>
>> make-network-process calles gethostbyname, but never calls
>> res_init. The problem, which appears is: if contents of
>> /etc/resolv.conf was changed old dns servers are unavailable,
>> gethostbyname still tries them, not new ones. So this bug is pretty
>> much the same as http://bugs.debian.org/438680 (which has a patch).
>>
>> Would someone please DTRT about this, then ack?
>> It needs to be fixed in Emacs 22.
>
> I don't know what to do about this.
>
> configure already has a check for res_init, but on my system (GNU/Linux),
> HAVE_RES_INIT is undefined, indicating that it doesn't exist.
>
> However, I believe that it does exist, but only if -lresolv is specified.
>
> So how can we fix configure to DTRT?
See the attached patch.
Strangely enough, even though autoconf needs -lresolv to detect
res_init(), it doesn't seem as though we need to add -lresolv when
compiling Emacs itself. I don't know why this should be the case.
Does anyone have an idea?
*** emacs/configure.in.~1.444.2.2.~ 2007-08-22 17:50:31.000000000 -0400
--- emacs/configure.in 2007-08-25 14:34:43.000000000 -0400
***************
*** 2580,2586 ****
AC_CHECK_FUNCS(gethostname getdomainname dup2 \
rename closedir mkdir rmdir sysinfo getrusage get_current_dir_name \
! random lrand48 bcopy bcmp logb frexp fmod rint cbrt ftime res_init setsid \
strerror fpathconf select mktime euidaccess getpagesize tzset setlocale \
utimes setrlimit setpgid getcwd getwd shutdown getaddrinfo \
__fpending mblen mbrlen mbsinit strsignal setitimer ualarm index rindex \
--- 2580,2586 ----
AC_CHECK_FUNCS(gethostname getdomainname dup2 \
rename closedir mkdir rmdir sysinfo getrusage get_current_dir_name \
! random lrand48 bcopy bcmp logb frexp fmod rint cbrt ftime setsid \
strerror fpathconf select mktime euidaccess getpagesize tzset setlocale \
utimes setrlimit setpgid getcwd getwd shutdown getaddrinfo \
__fpending mblen mbrlen mbsinit strsignal setitimer ualarm index rindex \
***************
*** 2624,2640 ****
# than to expect to find it in ncurses.
AC_CHECK_LIB(ncurses, tparm)
# Do we need the Hesiod library to provide the support routines?
if test "$with_hesiod" = yes ; then
# Don't set $LIBS here -- see comments above.
- resolv=no
AC_CHECK_FUNC(res_send, , [AC_CHECK_FUNC(__res_send, ,
[AC_CHECK_LIB(resolv, res_send, resolv=yes,
[AC_CHECK_LIB(resolv, __res_send, resolv=yes)])])])
if test "$resolv" = yes ; then
RESOLVLIB=-lresolv
- AC_DEFINE(HAVE_LIBRESOLV, 1,
- [Define to 1 if you have the resolv library (-lresolv).])
else
RESOLVLIB=
fi
--- 2624,2662 ----
# than to expect to find it in ncurses.
AC_CHECK_LIB(ncurses, tparm)
+ resolv=no
+
+ # Do we have res_init, for detecting changes in /etc/resolv.conf?
+
+ AC_CHECK_FUNC(res_init, have_res_init=yes, have_res_init=no)
+ if test "$have_res_init" = no; then
+ OLIBS="$LIBS"
+ LIBS="$LIBS -lresolv"
+ AC_MSG_CHECKING(for res_init with -lresolv)
+ AC_TRY_LINK([#include <netinet/in.h>
+ #include <arpa/nameser.h>
+ #include <resolv.h> ],
+ [res_init();],
+ have_res_init=yes, have_res_init=no)
+ AC_MSG_RESULT($have_res_init)
+ if test "$have_res_init" = yes ; then
+ resolv=yes
+ fi
+ LIBS="$OLIBS"
+ fi
+
+ if test "$have_res_init" = yes; then
+ AC_DEFINE(HAVE_RES_INIT, 1, [Define to 1 if res_init is available.])
+ fi
+
# Do we need the Hesiod library to provide the support routines?
if test "$with_hesiod" = yes ; then
# Don't set $LIBS here -- see comments above.
AC_CHECK_FUNC(res_send, , [AC_CHECK_FUNC(__res_send, ,
[AC_CHECK_LIB(resolv, res_send, resolv=yes,
[AC_CHECK_LIB(resolv, __res_send, resolv=yes)])])])
if test "$resolv" = yes ; then
RESOLVLIB=-lresolv
else
RESOLVLIB=
fi
***************
*** 2644,2649 ****
--- 2666,2677 ----
:, $RESOLVLIB)])
fi
+ # Do we need libresolv (due to res_init or Hesiod)?
+ if test "$resolv" = yes ; then
+ AC_DEFINE(HAVE_LIBRESOLV, 1,
+ [Define to 1 if you have the resolv library (-lresolv).])
+ fi
+
# These tell us which Kerberos-related libraries to use.
if test "${with_kerberos+set}" = set; then
AC_CHECK_LIB(com_err, com_err)
*** emacs/src/process.c.~1.512.2.4.~ 2007-08-08 14:07:26.000000000 -0400
--- emacs/src/process.c 2007-08-25 14:56:59.000000000 -0400
***************
*** 129,134 ****
--- 129,140 ----
# endif
#endif
+ #ifdef HAVE_RES_INIT
+ #include <netinet/in.h>
+ #include <arpa/nameser.h>
+ #include <resolv.h>
+ #endif
+
#include "lisp.h"
#include "systime.h"
#include "systty.h"
***************
*** 3082,3087 ****
--- 3088,3098 ----
hints.ai_family = family;
hints.ai_socktype = socktype;
hints.ai_protocol = 0;
+
+ #ifdef HAVE_RES_INIT
+ res_init ();
+ #endif
+
ret = getaddrinfo (SDATA (host), portstring, &hints, &res);
if (ret)
#ifdef HAVE_GAI_STRERROR
***************
*** 3127,3132 ****
--- 3138,3148 ----
as it may `hang' Emacs for a very long time. */
immediate_quit = 1;
QUIT;
+
+ #ifdef HAVE_RES_INIT
+ res_init ();
+ #endif
+
host_info_ptr = gethostbyname (SDATA (host));
immediate_quit = 0;