Fix: Missing libs dependencies in configure check for lttng-ust-ctl

The lttng-ust-ctl library depends on liburcu-{common,bp,cds}.  The
AC_CHECK_LIBRARY macro can't automatically resolve dependents libraries
(ala libtool), so any additionnals dependencies must be manually
specified.

Also, the AC_CHECK_LIB action-if-found case for the lttng-ust-ctl check
is modified to have a similar behavior as the default action, which is
to define HAVE_LIBxxx and append -lxxx to $LIBS, *except* for the later
step. This is to ensure that any future addition of AC_CHECK_LIB after
the one for lttng-ust-ctl will not need to append the liburcu
dependencies or fail unexpectedly.

Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Christian Babeux <christian.babeux@efficios.com>
Signed-off-by: David Goulet <dgoulet@efficios.com>

diff --git a/configure.ac b/configure.ac
index 3a023cdccb9797c636b7b46d43f0630742657541..e4b9eb1ad8054a023bb5e8f42bf50d7fc1d785d2 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -138,13 +138,16 @@ AC_ARG_ENABLE(lttng-ust,
        lttng_ust_support=$enableval, lttng_ust_support=yes)
 
 AS_IF([test "x$lttng_ust_support" = "xyes"], [
-       AC_CHECK_LIB([lttng-ust-ctl], [ustctl_create_session], [],
-               [AC_MSG_ERROR([Cannot find LTTng-UST. Use [LDFLAGS]=-Ldir to specify its location, or specify --disable-lttng-ust to build lttng-tools without LTTng-UST support.])]
+       AC_CHECK_LIB([lttng-ust-ctl], [ustctl_create_session],
+               [
+                       AC_DEFINE([HAVE_LIBLTTNG_UST_CTL], [1], [has LTTng-UST control support])
+                       lttng_ust_ctl_found=yes
+               ],
+               [AC_MSG_ERROR([Cannot find LTTng-UST. Use [LDFLAGS]=-Ldir to specify its location, or specify --disable-lttng-ust to build lttng-tools without LTTng-UST support.])],
+               [-lurcu-common -lurcu-bp -lurcu-cds]
        )
 ])
-
-AM_CONDITIONAL([HAVE_LIBLTTNG_UST_CTL], [ test "x$ac_cv_lib_lttng_ust_ctl_ustctl_create_session" = "xyes" ])
-
+AM_CONDITIONAL([HAVE_LIBLTTNG_UST_CTL], [test "x$lttng_ust_ctl_found" = xyes])
 AC_CHECK_FUNCS([sched_getcpu sysconf])
 
 # check for dlopen