snmp-agent: fix build on RHEL6

libnetsnmpagent.so from net-snmp 5.5 needs some symbols from libnetsnmphelpers.so,
but does not link against it on RHEL5.

Work around this by looking for one of those symbols in the helper lib,
and if found, link against it.

Later versions of net-snmp seem to have moved those symbols to
libnetsnmpagent.so, so it's not an issue there.

diff --git a/configure.ac b/configure.ac
index 00735df..102933c 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -3770,22 +3770,22 @@ AC_SUBST([LIBNETAPP_LIBS])
 AC_ARG_WITH([libnetsnmp],
   [AS_HELP_STRING([--with-libnetsnmp@<:@=PREFIX@:>@], [Path to libnetsnmp.])],
   [
-         if test "x$withval" = "xno"; then
-                 with_libnetsnmp="no"
-         else if test "x$withval" = "xyes"; then
-                 with_libnetsnmp="yes"
-         else
-                 with_libnetsnmp_cppflags="-I$withval/include"
-                 with_libnetsnmp_ldflags="-I$withval/lib"
-                 with_libnetsnmp="yes"
-         fi; fi
+    if test "x$withval" = "xno"; then
+     with_libnetsnmp="no"
+    else if test "x$withval" = "xyes"; then
+     with_libnetsnmp="yes"
+    else
+      with_libnetsnmp_cppflags="-I$withval/include"
+      with_libnetsnmp_ldflags="-I$withval/lib"
+      with_libnetsnmp="yes"
+    fi; fi
   ],
   [with_libnetsnmp="yes"]
 )
 
 if test "x$with_libnetsnmp" = "xyes"; then
-       SAVE_CPPFLAGS="$CPPFLAGS"
-       CPPFLAGS="$CPPFLAGS $with_libnetsnmp_cppflags"
+  SAVE_CPPFLAGS="$CPPFLAGS"
+  CPPFLAGS="$CPPFLAGS $with_libnetsnmp_cppflags"
 
   AC_CHECK_HEADERS([net-snmp/net-snmp-config.h],
     [with_libnetsnmp="yes"],
@@ -3802,25 +3802,25 @@ if test "x$with_libnetsnmp" = "xyes"; then
     ]]
   )
 
-       CPPFLAGS="$SAVE_CPPFLAGS"
+  CPPFLAGS="$SAVE_CPPFLAGS"
 fi
 
 if test "x$with_libnetsnmp" = "xyes"; then
-       SAVE_LDFLAGS="$LDFLAGS"
-       LDFLAGS="$LDFLAGS $with_libnetsnmp_ldflags"
+  SAVE_LDFLAGS="$LDFLAGS"
+  LDFLAGS="$LDFLAGS $with_libnetsnmp_ldflags"
 
-       AC_CHECK_LIB([netsnmp], [init_snmp],
-               [],
-               [with_libnetsnmp="no (libnetsnmp not found)"]
+  AC_CHECK_LIB([netsnmp], [init_snmp],
+    [with_libnetsmp="yes"],
+    [with_libnetsnmp="no (libnetsnmp not found)"]
   )
 
-       LDFLAGS="$SAVE_LDFLAGS"
+  LDFLAGS="$SAVE_LDFLAGS"
 fi
 
 if test "x$with_libnetsnmp" = "xyes"; then
-       BUILD_WITH_LIBNETSNMP_CPPFLAGS="$with_libnetsnmp_cppflags"
-       BUILD_WITH_LIBNETSNMP_LDFLAGS="$with_libnetsnmp_ldflags"
-       BUILD_WITH_LIBNETSNMP_LIBS="-lnetsnmp"
+  BUILD_WITH_LIBNETSNMP_CPPFLAGS="$with_libnetsnmp_cppflags"
+  BUILD_WITH_LIBNETSNMP_LDFLAGS="$with_libnetsnmp_ldflags"
+  BUILD_WITH_LIBNETSNMP_LIBS="-lnetsnmp"
 fi
 
 AC_SUBST([BUILD_WITH_LIBNETSNMP_CPPFLAGS])
@@ -3832,22 +3832,22 @@ AC_SUBST([BUILD_WITH_LIBNETSNMP_LIBS])
 AC_ARG_WITH([libnetsnmpagent],
   [AS_HELP_STRING([--with-libnetsnmpagent@<:@=PREFIX@:>@], [Path to libnetsnmpagent.])],
   [
-         if test "x$withval" = "xno"; then
-                 with_libnetsnmpagent="no"
-         else if test "x$withval" = "xyes"; then
-                 with_libnetsnmpagent="yes"
-         else
-                 with_libnetsnmpagent_cppflags="-I$withval/include"
-                 with_libnetsnmpagent_ldflags="-I$withval/lib"
-                 with_libnetsnmpagent="yes"
-         fi; fi
+    if test "x$withval" = "xno"; then
+      with_libnetsnmpagent="no"
+    else if test "x$withval" = "xyes"; then
+      with_libnetsnmpagent="yes"
+    else
+      with_libnetsnmpagent_cppflags="-I$withval/include"
+      with_libnetsnmpagent_ldflags="-I$withval/lib"
+      with_libnetsnmpagent="yes"
+    fi; fi
   ],
   [with_libnetsnmpagent="yes"]
 )
 
 if test "x$with_libnetsnmpagent" = "xyes"; then
-       SAVE_CPPFLAGS="$CPPFLAGS"
-       CPPFLAGS="$CPPFLAGS $with_libnetsnmpagent_cppflags"
+  SAVE_CPPFLAGS="$CPPFLAGS"
+  CPPFLAGS="$CPPFLAGS $with_libnetsnmpagent_cppflags"
 
   AC_CHECK_HEADERS([net-snmp/agent/net-snmp-agent-includes.h],
     [],
@@ -3862,23 +3862,31 @@ if test "x$with_libnetsnmpagent" = "xyes"; then
     ]]
   )
 
-       CPPFLAGS="$SAVE_CPPFLAGS"
+  CPPFLAGS="$SAVE_CPPFLAGS"
 fi
 
 if test "x$with_libnetsnmpagent" = "xyes"; then
-       SAVE_LDFLAGS="$LDFLAGS"
-       LDFLAGS="$LDFLAGS $with_libnetsnmpagent_ldflags"
+  SAVE_LDFLAGS="$LDFLAGS"
+  LDFLAGS="$LDFLAGS $with_libnetsnmpagent_ldflags"
 
-       AC_CHECK_LIB([netsnmpagent], [init_agent],
-               [],
-               [with_libnetsnmpagent="no (libnetsnmpagent not found)"]
+  # older versions of libnetsnmpagent fail to link
+  # against the helpers library, so do that explicitly
+  AC_CHECK_LIB([netsnmphelpers], [netsnmp_init_helpers],
+    [libnetsnmphelpers="-lnetsnmphelpers"],
+    [libnetsnmphelpers=""]
   )
 
-       LDFLAGS="$SAVE_LDFLAGS"
+  AC_CHECK_LIB([netsnmpagent], [init_agent],
+    [with_libnetsnmpagent="yes"],
+    [with_libnetsnmpagent="no (libnetsnmpagent not found)"],
+    [$libnetsnmphelpers]
+  )
+
+  LDFLAGS="$SAVE_LDFLAGS"
 fi
 
 if test "x$with_libnetsnmpagent" = "xyes"; then
-       BUILD_WITH_LIBNETSNMPAGENT_LIBS="-lnetsnmpagent"
+  BUILD_WITH_LIBNETSNMPAGENT_LIBS="-lnetsnmpagent $libnetsnmphelpers"
 fi
 
 AC_SUBST([BUILD_WITH_LIBNETSNMPAGENT_CPPFLAGS])