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From: Patrick Steinhardt <ps@pks.im>
To: linux-nfs@vger.kernel.org
Cc: Patrick Steinhardt <ps@pks.im>
Subject: [PATCH 1/3] configure.ac: more carefully detect availability of res_querydomain(3)
Date: Mon,  4 Feb 2019 15:31:18 +0100	[thread overview]
Message-ID: <a6f2aaea93c1293e62d5109b10d47a7675a45393.1549290423.git.ps@pks.im> (raw)

Since glibc 2.2, the function res_querydomain(3) is implemented as a
define to `__res_querydomain`. Due to this implementation detail, using
`AC_CHECK_LIB` with a symbol name of "res_querydomain" will cause a
linking failure and thus fail to detect its availability. This is why
right now, we try to detect availability of `__res_querydomain` instead.

Unfortunately, this may break on other platforms where there is no
`__res_querydomain` but only the function without leading underscores.
To fix this, we can perform another `AC_CHECK_LIB([resolv],
[res_querydomain], ...)` call in case where the other one was not found
and only raise an error if both symbols weren't found.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 configure.ac | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index 4bf5aea..cb9d921 100644
--- a/configure.ac
+++ b/configure.ac
@@ -411,7 +411,8 @@ if test "$enable_gss" = yes; then
 fi
 
 dnl libdnsidmap specific checks
-AC_CHECK_LIB([resolv], [__res_querydomain], , AC_MSG_ERROR(res_querydomain needed))
+AC_CHECK_LIB([resolv], [__res_querydomain], ,
+	AC_CHECK_LIB([resolv], [res_querydomain], , AC_MSG_ERROR(res_querydomain needed)))
 
 AC_ARG_ENABLE([ldap],
 	[AS_HELP_STRING([--disable-ldap],[Disable support for LDAP @<:default=detect@:>@])])
-- 
2.20.1


             reply	other threads:[~2019-02-04 14:30 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-04 14:31 Patrick Steinhardt [this message]
2019-02-04 14:31 ` [PATCH 2/3] file: fix missing include for PATH_MAX constant Patrick Steinhardt
2019-02-27 17:14   ` Steve Dickson
2019-02-04 14:31 ` [PATCH 3/3] svc_socket: fix use of undefined macro HAVE_GETRPCBYNUMBER_R Patrick Steinhardt
2019-02-27 17:16   ` Steve Dickson
2019-02-27 17:37     ` Patrick Steinhardt
2019-02-22  7:52 ` [PATCH 1/3] configure.ac: more carefully detect availability of res_querydomain(3) Patrick Steinhardt
2019-02-22 20:40   ` J. Bruce Fields
2019-02-27 16:41   ` Steve Dickson
2019-02-27 17:14 ` Steve Dickson

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