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

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

[Romain Naour]

According to uClibc commit [1], dlinfo is not available in recent uClibc (>0.9.33),
but available in older version of uClibc (<=0.9.33) whith a different prototype than glibc.

dlinfo used by liblttng-ust-dl require RTLD_DI_LINKMAP that is not available in uClibc.

To be able to use LTTng UST with uClibc, we need to disable
the Dynamic Linker Tracing functionality [2] if RTLD_DI_LINKMAP is not detected.

[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 | 10 ++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/Makefile.am b/Makefile.am
index b79d2dd..c907ff1 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -4,11 +4,14 @@ SUBDIRS = . include snprintf libringbuffer liblttng-ust-comm \
 		liblttng-ust \
 		liblttng-ust-ctl \
 		liblttng-ust-fork \
-		liblttng-ust-dl \
 		liblttng-ust-libc-wrapper \
 		liblttng-ust-cyg-profile \
 		tools
 
+if HAVE_DLINFO
+SUBDIRS += liblttng-ust-dl
+endif
+
 if BUILD_JNI_INTERFACE
 SUBDIRS += liblttng-ust-java liblttng-ust-jul
 endif
diff --git a/configure.ac b/configure.ac
index b04d4e3..b315d54 100644
--- a/configure.ac
+++ b/configure.ac
@@ -124,6 +124,16 @@ AM_CONDITIONAL([LTTNG_UST_BUILD_WITH_LIBC_DL], [test "x$have_libc_dl" = "xyes"])
 
 AC_CHECK_LIB([pthread], [pthread_create])
 
+# Check for dlfcn.h
+AC_CHECK_HEADER([dlfcn.h])
+AS_IF([test "${ac_cv_header_dlfcn_h}" = "yes"],
+	[AC_CHECK_DECLS([RTLD_DI_LINKMAP],,,
+		[#define _GNU_SOURCE /* Required on Linux to get GNU extensions */
+		#include <dlfcn.h>])
+	],
+	[ac_cv_have_decl_RTLD_DI_LINKMAP="no"])
+AM_CONDITIONAL([HAVE_DLINFO], [test "${ac_cv_have_decl_RTLD_DI_LINKMAP}" = "yes"])
+
 # Checks for header files.
 #AC_CHECK_HEADERS([fcntl.h stdint.h stdlib.h string.h sys/socket.h sys/time.h unistd.h])
 
-- 
1.9.0

Re: [PATCH 1/1] Fix: disable liblttng-ust-dl if dlinfo is not available in C library

[Mathieu Desnoyers]

Merged, thanks!

Mathieu

----- Original Message -----
> From: "Romain Naour" <romain.naour@openwide.fr>
> To: lttng-dev@lists.lttng.org
> Cc: "mathieu desnoyers" <mathieu.desnoyers@efficios.com>, "simon marchi" <simon.marchi@polymtl.ca>, "Romain Naour"
> <romain.naour@openwide.fr>
> Sent: Wednesday, April 9, 2014 5:55:07 PM
> 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 in recent uClibc
> (>0.9.33),
> but available in older version of uClibc (<=0.9.33) whith a different
> prototype than glibc.
> 
> dlinfo used by liblttng-ust-dl require RTLD_DI_LINKMAP that is not available
> in uClibc.
> 
> To be able to use LTTng UST with uClibc, we need to disable
> the Dynamic Linker Tracing functionality [2] if RTLD_DI_LINKMAP is not
> detected.
> 
> [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 | 10 ++++++++++
>  2 files changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/Makefile.am b/Makefile.am
> index b79d2dd..c907ff1 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -4,11 +4,14 @@ SUBDIRS = . include snprintf libringbuffer
> liblttng-ust-comm \
>  		liblttng-ust \
>  		liblttng-ust-ctl \
>  		liblttng-ust-fork \
> -		liblttng-ust-dl \
>  		liblttng-ust-libc-wrapper \
>  		liblttng-ust-cyg-profile \
>  		tools
>  
> +if HAVE_DLINFO
> +SUBDIRS += liblttng-ust-dl
> +endif
> +
>  if BUILD_JNI_INTERFACE
>  SUBDIRS += liblttng-ust-java liblttng-ust-jul
>  endif
> diff --git a/configure.ac b/configure.ac
> index b04d4e3..b315d54 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -124,6 +124,16 @@ AM_CONDITIONAL([LTTNG_UST_BUILD_WITH_LIBC_DL], [test
> "x$have_libc_dl" = "xyes"])
>  
>  AC_CHECK_LIB([pthread], [pthread_create])
>  
> +# Check for dlfcn.h
> +AC_CHECK_HEADER([dlfcn.h])
> +AS_IF([test "${ac_cv_header_dlfcn_h}" = "yes"],
> +	[AC_CHECK_DECLS([RTLD_DI_LINKMAP],,,
> +		[#define _GNU_SOURCE /* Required on Linux to get GNU extensions */
> +		#include <dlfcn.h>])
> +	],
> +	[ac_cv_have_decl_RTLD_DI_LINKMAP="no"])
> +AM_CONDITIONAL([HAVE_DLINFO], [test "${ac_cv_have_decl_RTLD_DI_LINKMAP}" =
> "yes"])
> +
>  # Checks for header files.
>  #AC_CHECK_HEADERS([fcntl.h stdint.h stdlib.h string.h sys/socket.h
>  sys/time.h unistd.h])
>  
> --
> 1.9.0
> 
> 

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com