[DWARVES] Fixes a FIXME relating to a missing elf (libdw) symbol check.

Signed-off-by: Felipe Kellermann <felipek@socksarmor.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

cmake/modules/FindDWARF.cmake

@@ -5,6 +5,7 @@
 #  DWARF_LIBRARIES   - List of libraries when using elf utils.
 #  DWARF_FOUND       - True if fdo found.
 
+INCLUDE(CheckLibraryExists)
 
 if (DWARF_INCLUDE_DIR AND LIBDW_INCLUDE_DIR AND DWARF_LIBRARY AND ELF_LIBRARY)
 	# Already in cache, be silent
@@ -42,6 +43,9 @@ find_library(EBL_LIBRARY
 if (DWARF_INCLUDE_DIR AND LIBDW_INCLUDE_DIR AND DWARF_LIBRARY AND ELF_LIBRARY AND EBL_LIBRARY)
 	set(DWARF_FOUND TRUE)
 	set(DWARF_LIBRARIES ${DWARF_LIBRARY} ${ELF_LIBRARY} ${EBL_LIBRARY})
+
+	set(CMAKE_REQUIRED_LIBRARIES ${DWARF_LIBRARIES})
+	check_library_exists(elf dwfl_module_build_id "" HAVE_DWFL_MODULE_BUILD_ID)
 else (DWARF_INCLUDE_DIR AND LIBDW_INCLUDE_DIR AND DWARF_LIBRARY AND ELF_LIBRARY AND EBL_LIBRARY)
 	set(DWARF_FOUND FALSE)
 	set(DWARF_LIBRARIES)
@@ -77,3 +81,4 @@ endif (DWARF_FOUND)
 
 mark_as_advanced(DWARF_INCLUDE_DIR LIBDW_INCLUDE_DIR DWARF_LIBRARY ELF_LIBRARY EBL_LIBRARY)
 include_directories(${DWARF_INCLUDE_DIR} ${LIBDW_INCLUDE_DIR})
+configure_file(${CMAKE_CURRENT_SOURCE_DIR}/config.h.cmake ${CMAKE_CURRENT_SOURCE_DIR}/config.h)

config.h.cmake

@@ -0,0 +1,9 @@
+/*
+  Copyright (C) 2007 Arnaldo Carvalho de Melo <acme@redhat.com>
+
+  This program is free software; you can redistribute it and/or modify it
+  under the terms of version 2 of the GNU General Public License as
+  published by the Free Software Foundation.
+*/
+
+#cmakedefine HAVE_DWFL_MODULE_BUILD_ID

dwarves.c

@@ -24,6 +24,7 @@
 #include <string.h>
 #include <unistd.h>
 
+#include "config.h"
 #include "list.h"
 #include "dwarves.h"
 #include "dutil.h"
@@ -3482,11 +3483,8 @@ static int cus__load_module(Dwfl_Module *mod, void **userdata __unused,
 	size_t cuhl;
 	GElf_Addr vaddr;
 	const unsigned char *build_id = NULL;
-	/*
-	 * FIXME: check how to do this properly using cmake to test for
-	 * the existence of dwfl_module_build_id in the elfutils libraries.
-	 */
-#if 1
+
+#ifdef HAVE_DWFL_MODULE_BUILD_ID
 	int build_id_len = dwfl_module_build_id(mod, &build_id, &vaddr);
 #else
 	int build_id_len = 0;