lttng-libust: Disable liblttng-ust-dl with uClibc.

Disable liblttng-ust-dl if dlinfo is not available in C library.

From 44316d0214425f5ae0d8af07099caae3e95ac890 Mon Sep 17 00:00:00 2001

From: Romain Naour <romain.naour@openwide.fr>

Date: Tue, 8 Apr 2014 22:15:27 +0200

Subject: [PATCH 1/1] Fix: disable liblttng-ust-dl if dlinfo is not available

 in C library

According to uClibc commit [1], dlinfo is not available.

To be able to use LTTng UST with uClibc, we need to disable

the Dynamic Linker Tracing functionality [2].

According to uClibc commit [1], dlinfo is not available in recent uClibc (>0.9.33),

but is available in older version of uClibc (<=0.9.33) whith a different prototype

than dlinfo() in glibc.

To be able to use LTTng UST with uClibc, we need to disable the Dynamic Linker

Tracing functionality [2].

A specific test on dlinfo() prototype is performed to enable or disable this

functionality.

[1] http://git.uclibc.org/uClibc/commit/?id=f3c9dc499c5c787ddd8c4320f2d44d2ae6e40c22

[2] http://lists.lttng.org/pipermail/lttng-dev/2014-February/022423.html

Signed-off-by: Romain Naour <romain.naour@openwide.fr>

---

 Makefile.am  |  5 ++++-

 configure.ac | 3 +++

 2 files changed, 7 insertions(+), 1 deletion(-)

 configure.ac | 18 ++++++++++++++++++

 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/Makefile.am b/Makefile.am

index b79d2dd..c907ff1 100644

 SUBDIRS += liblttng-ust-java liblttng-ust-jul

 endif

diff --git a/configure.ac b/configure.ac

index f507883..5dcf0e2 100644

index b04d4e3..f4b499b 100644

--- a/configure.ac

+++ b/configure.ac

@@ -145,6 +145,9 @@ AC_C_INLINE

 AC_FUNC_MALLOC

 AC_CHECK_FUNCS([gettimeofday munmap socket strerror strtol sched_getcpu sysconf])

@@ -119,8 +119,26 @@ AC_CHECK_LIB([dl], [dlopen],

 		AC_MSG_ERROR([Cannot find dlopen in libdl nor libc. Use [LDFLAGS]=-Ldir to specify their location.])

 	])

 ])

+AS_IF([test "$x$have_libdl" = "yes" || test "x$have_libc_dl" = "xyes"],

+	[AC_MSG_CHECKING([for dlinfo()])

+		# Ensure the check is covered by the LIBS variable

+		LIBS="$LIBS -ldl"

+		AC_LINK_IFELSE(

+			[AC_LANG_PROGRAM([[#define _GNU_SOURCE /* Required on Linux to get GNU extensions */

+							#include <dlfcn.h>]],

+				[[dlinfo(0, 0, 0);]])],

+			[AC_MSG_RESULT([yes])

+				dlinfo_ok=yes;

+			],

+			[AC_MSG_RESULT([no])

+				AC_MSG_WARN([dlinfo() is not available, the Dynamic Linker Tracing functionality is disabled.])

+				dlinfo_ok=no;

+			])

+	],

+	[dlinfo_ok=no])

 AM_CONDITIONAL([LTTNG_UST_BUILD_WITH_LIBDL], [test "x$have_libdl" = "xyes"])

 AM_CONDITIONAL([LTTNG_UST_BUILD_WITH_LIBC_DL], [test "x$have_libc_dl" = "xyes"])

+AM_CONDITIONAL([HAVE_DLINFO], [test "dlinfo_ok" = "yes"])

+AC_CHECK_FUNCS([dlinfo])

+AM_CONDITIONAL([HAVE_DLINFO], [test "${ac_cv_func_dlinfo}" = "yes"])

+

 CFLAGS="-Wall $CFLAGS"

 AC_CHECK_LIB([pthread], [pthread_create])

 # URCU

-- 

1.9.0