From 42330adcefcd1830dad89e2a960c93d8dd1da125 Mon Sep 17 00:00:00 2001
From: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Date: Tue, 21 Feb 2017 16:00:27 -0500
Subject: [PATCH] Validate the presence of dlmopen at configure time

Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
[Backport from upstream commit 42330adcefcd1830dad89e2a960c93d8dd1da125.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
---
 configure.ac                   | 8 ++++++++
 liblttng-ust-dl/lttng-ust-dl.c | 8 ++++++++
 liblttng-ust-dl/ust_dl.h       | 2 ++
 3 files changed, 18 insertions(+)

diff --git a/configure.ac b/configure.ac
index 450b43b..023cfd4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -125,15 +125,23 @@ AS_IF([test "x${ax_cv_sys_weak_alias}" = "xno"], [
 # Checks for libraries.
 AC_CHECK_LIB([dl], [dlopen], [
 	have_libdl=yes
+	libdl_name=dl
 ], [
 	#libdl not found, check for dlopen in libc.
 	AC_CHECK_LIB([c], [dlopen], [
 		have_libc_dl=yes
+		libdl_name=c
 	], [
 		AC_MSG_ERROR([Cannot find dlopen in libdl nor libc. Use [LDFLAGS]=-Ldir to specify their location.])
 	])
 ])
 
+# Check if libdl has dlmopen support.
+AH_TEMPLATE([HAVE_DLMOPEN], ["Define to 1 if dlmopen is available."])
+AC_CHECK_LIB([$libdl_name], [dlmopen],
+	[AC_DEFINE([HAVE_DLMOPEN], [1])]
+)
+
 AM_CONDITIONAL([LTTNG_UST_BUILD_WITH_LIBDL], [test "x$have_libdl" = "xyes"])
 AM_CONDITIONAL([LTTNG_UST_BUILD_WITH_LIBC_DL], [test "x$have_libc_dl" = "xyes"])
 
diff --git a/liblttng-ust-dl/lttng-ust-dl.c b/liblttng-ust-dl/lttng-ust-dl.c
index b0737b6..ce2ae0e 100644
--- a/liblttng-ust-dl/lttng-ust-dl.c
+++ b/liblttng-ust-dl/lttng-ust-dl.c
@@ -38,8 +38,10 @@
 #include "ust_dl.h"
 
 static void *(*__lttng_ust_plibc_dlopen)(const char *filename, int flags);
+#ifdef HAVE_DLMOPEN
 static void *(*__lttng_ust_plibc_dlmopen)(Lmid_t nsid, const char *filename,
 		int flags);
+#endif
 static int (*__lttng_ust_plibc_dlclose)(void *handle);
 
 static
@@ -55,6 +57,7 @@ void *_lttng_ust_dl_libc_dlopen(const char *filename, int flags)
 	return __lttng_ust_plibc_dlopen(filename, flags);
 }
 
+#ifdef HAVE_DLMOPEN
 static
 void *_lttng_ust_dl_libc_dlmopen(Lmid_t nsid, const char *filename,
 		int flags)
@@ -68,6 +71,7 @@ void *_lttng_ust_dl_libc_dlmopen(Lmid_t nsid, const char *filename,
 	}
 	return __lttng_ust_plibc_dlmopen(nsid, filename, flags);
 }
+#endif
 
 static
 int _lttng_ust_dl_libc_dlclose(void *handle)
@@ -143,6 +147,7 @@ end:
 	return;
 }
 
+#ifdef HAVE_DLMOPEN
 static
 void lttng_ust_dl_dlmopen(void *so_base, Lmid_t nsid, const char *so_name,
 		int flags, void *ip)
@@ -203,6 +208,7 @@ end:
 	lttng_ust_elf_destroy(elf);
 	return;
 }
+#endif
 
 void *dlopen(const char *filename, int flags)
 {
@@ -223,6 +229,7 @@ void *dlopen(const char *filename, int flags)
 	return handle;
 }
 
+#ifdef HAVE_DLMOPEN
 void *dlmopen(Lmid_t nsid, const char *filename, int flags)
 {
 	void *handle;
@@ -243,6 +250,7 @@ void *dlmopen(Lmid_t nsid, const char *filename, int flags)
 	return handle;
 
 }
+#endif
 
 int dlclose(void *handle)
 {
diff --git a/liblttng-ust-dl/ust_dl.h b/liblttng-ust-dl/ust_dl.h
index b8cfe82..afa8e84 100644
--- a/liblttng-ust-dl/ust_dl.h
+++ b/liblttng-ust-dl/ust_dl.h
@@ -51,6 +51,7 @@ TRACEPOINT_EVENT(lttng_ust_dl, dlopen,
 	)
 )
 
+#ifdef HAVE_DLMOPEN
 TRACEPOINT_EVENT(lttng_ust_dl, dlmopen,
 	TP_ARGS(void *, ip, void *, baddr, Lmid_t, nsid,
 		const char *, path, int, flags,
@@ -66,6 +67,7 @@ TRACEPOINT_EVENT(lttng_ust_dl, dlmopen,
 		ctf_integer(uint8_t, has_debug_link, has_debug_link)
 	)
 )
+#endif
 
 TRACEPOINT_EVENT(lttng_ust_dl, build_id,
 	TP_ARGS(
-- 
2.7.4