libsinsp: Refine pkg-config file generation.

The generated pkg-config file now makes use of pkg-config Requires and
Requires.static fields, which should reduce over-linking when linking
to shared libraries.

* cmake/modules/BuildPkgConfigDependencies.cmake
(add_pkgconfig_library): Add debug messages and fix an issue where
IN_LIST had no effect.
* cmake/modules/libscap.cmake: Add json, pman, protobuf and zlib to
ignored link dependencies, since these are now recorded as Requires
in the pkg-config file.
* userspace/libscap/libscap.pc.in (prefix): Set directly to
CMAKE_INSTALL_PREFIX.
(Requires, Requires.private): New fields.
* userspace/libsinsp/CMakeLists.txt: Separate libraries into
pkg-config Requires and Requires.private lists.  Add the pkg-config
requirements to the ignored link dependencies, since these are now
recorded as Requires in the pkg-config file.
* userspace/libsinsp/libsinsp.pc.in (Requires): Add
@LIBSINSP_REQUIRES@.
(Requires.private): New field.
(Libs): Remove -lsinsp, automatically computed in SINSP_PKG_CONFIG_LIBS.

Signed-off-by: Maxim Cournoyer <[email protected]>

cmake/modules/BuildPkgConfigDependencies.cmake

@@ -3,6 +3,7 @@
 # libsinsp.pc (which requires libscap.pc and pulls them in that way)
 function(add_pkgconfig_library LIBDIRS_VAR LIBS_VAR lib ignored)
 
+	message(DEBUG "[add_pkgconfig_library] processing lib \"${lib}\"")
 	# if it's not a target, it doesn't have dependencies we know or care about
 	if(NOT TARGET ${lib})
 		return()
@@ -14,14 +15,25 @@ function(add_pkgconfig_library LIBDIRS_VAR LIBS_VAR lib ignored)
 		return()
 	endif()
 
+	message(DEBUG "[add_pkgconfig_library] LINK_LIBRARIES property: \"${PKGCONFIG_LIBRARIES}\"")
+
 	get_property(
 		target_type
 		TARGET ${lib}
 		PROPERTY TYPE
 	)
+	message(DEBUG "[add_pkgconfig_library] ignored list: \"${ignored}\"")
 	foreach(dep ${PKGCONFIG_LIBRARIES})
-		# ignore dependencies in the list ${ignored}
-		if(${dep} IN_LIST "${ignored}")
+		# XXX: We use a (very) loose match as we are potentially
+		# comparing absolute library file names (dep) to pkg-config
+		# library names to be ignored.  The only alternative I can
+		# think of would be to maintain a map associating pkg-config
+		# names to their library file name.
+		get_filename_component(dep_base ${dep} NAME_WE)
+		string(REGEX REPLACE "^lib" "" dep_name ${dep_base})
+		message(DEBUG "[add_pkgconfig_library] processing dep ${dep}")
+		if("${ignored}" MATCHES "${dep_name}")
+			message(DEBUG "[add_pkgconfig_library] \"${dep}\" ignored")
 			continue()
 		endif()
 

cmake/modules/libscap.cmake

@@ -93,7 +93,11 @@ if(NOT HAVE_LIBSCAP)
 
 	set(libscap_link_flags)
 	set(libscap_link_libdirs "")
-	add_pkgconfig_dependency(libscap_link_libdirs libscap_link_flags scap "")
+	add_pkgconfig_dependency(libscap_link_libdirs libscap_link_flags scap
+		# Avoid using these in libscap.pc Libs field, as they are
+		# already listed in Requires.  lbpf is transitively required
+		# via libpman.pc.
+		"jsoncpp;libelf;libpman;protobuf;zlib")
 
 	string(REPLACE ";" " " LIBSCAP_LINK_LIBRARIES_FLAGS "${libscap_link_flags}")
 	string(REPLACE ";" " " LIBSCAP_LINK_LIBDIRS_FLAGS "${libscap_link_libdirs}")

userspace/libscap/libscap.pc.in

@@ -1,10 +1,15 @@
-prefix=${pcfiledir}/../..
+prefix=@CMAKE_INSTALL_PREFIX@
 libdir=${prefix}/@CMAKE_INSTALL_LIBDIR@
 includedir=${prefix}/@CMAKE_INSTALL_INCLUDEDIR@/@LIBS_PACKAGE_NAME@
 
 Name: libscap
 Description: lib for System CAPture
 Version: @FALCOSECURITY_LIBS_VERSION@
 
+# Note: jsoncpp and protobuf are required by scap_engine_gvisor, which
+# currently lacks its own pkg-config file.  Similarly, libelf is
+# required by scap_engine_bpf.
+Requires: jsoncpp libelf libpman protobuf
+Requires.private: zlib
 Libs: -L${libdir} @LIBSCAP_LINK_LIBDIRS_FLAGS@ @LIBSCAP_LINK_LIBRARIES_FLAGS@
 Cflags: -I${includedir} -I${includedir}/libscap -I${includedir}/driver -I@UTHASH_INCLUDE@

userspace/libsinsp/CMakeLists.txt

@@ -177,12 +177,17 @@ target_link_libraries(
 	PRIVATE "${CURL_LIBRARIES}" "${JSONCPP_LIB}" "${RE2_LIB}"
 )
 
+set(SINSP_PKGCONFIG_REQUIRES jsoncpp)
+set(SINSP_PKGCONFIG_REQUIRES_PRIVATE libcurl re2)
+
 if(NOT EMSCRIPTEN)
 	target_link_libraries(
 		sinsp
 		INTERFACE "${CARES_LIB}"
 		PRIVATE "${TBB_LIB}"
 	)
+	list(APPEND SINSP_PKGCONFIG_REQUIRES libcares)
+	list(APPEND SINSP_PKGCONFIG_REQUIRES_PRIVATE tbb)
 endif()
 
 if(USE_BUNDLED_VALIJSON)
@@ -275,6 +280,12 @@ if(NOT WIN32)
 			)
 
 			target_link_libraries(sinsp PRIVATE cri_v1alpha2 cri_v1 containerd_interface)
+			list(APPEND SINSP_PKGCONFIG_REQUIRES
+				gpr
+				grpc
+				grpc++
+				protobuf
+				libcares)
 
 			if(NOT MUSL_OPTIMIZED_BUILD)
 				find_library(LIB_ANL anl)
@@ -290,6 +301,8 @@ if(NOT WIN32)
 		endif() # NOT MINIMAL_BUILD
 	endif() # NOT APPLE
 
+	list(APPEND SINSP_PKGCONFIG_REQUIRES libcrypto libssl)
+
 	target_link_libraries(sinsp INTERFACE dl pthread)
 
 	if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
@@ -329,14 +342,17 @@ add_definitions(-DSINSP_AGENT_CGROUP_MEM_PATH_ENV_VAR="${SINSP_AGENT_CGROUP_MEM_
 # https://github.com/curl/curl/blob/curl-7_84_0/CMakeLists.txt#L1539
 set(SINSP_PKG_CONFIG_LIBS)
 set(SINSP_PKG_CONFIG_LIBDIRS "")
-add_pkgconfig_dependency(SINSP_PKG_CONFIG_LIBDIRS SINSP_PKG_CONFIG_LIBS sinsp scap)
+add_pkgconfig_dependency(SINSP_PKG_CONFIG_LIBDIRS SINSP_PKG_CONFIG_LIBS sinsp
+	"scap;${SINSP_PKGCONFIG_REQUIRES};${SINSP_PKGCONFIG_REQUIRES_PRIVATE}")
 
 # Build our pkg-config "Cflags:" flags.
 set(SINSP_PKG_CONFIG_INCLUDES "")
 foreach(sinsp_include_directory ${LIBSINSP_INCLUDE_DIRS})
 	list(APPEND SINSP_PKG_CONFIG_INCLUDES -I${sinsp_include_directory})
 endforeach()
 
+string(REPLACE ";" " " LIBSINSP_REQUIRES "${SINSP_PKGCONFIG_REQUIRES}")
+string(REPLACE ";" " " LIBSINSP_REQUIRES_PRIVATE "${SINSP_PKGCONFIG_REQUIRES_PRIVATE}")
 string(REPLACE ";" " " SINSP_PKG_CONFIG_LIBS "${SINSP_PKG_CONFIG_LIBS}")
 list(REMOVE_DUPLICATES SINSP_PKG_CONFIG_LIBDIRS)
 string(REPLACE ";" " " SINSP_PKG_CONFIG_LIBDIRS "${SINSP_PKG_CONFIG_LIBDIRS}")

userspace/libsinsp/libsinsp.pc.in

@@ -1,11 +1,12 @@
-prefix=${pcfiledir}/../..
+prefix=@CMAKE_INSTALL_PREFIX@
 libdir=${prefix}/@CMAKE_INSTALL_LIBDIR@
 includedir=${prefix}/@CMAKE_INSTALL_INCLUDEDIR@/@LIBS_PACKAGE_NAME@
 
 Name: libsinsp
 Description: lib for System INSPection
 Version: @FALCOSECURITY_LIBS_VERSION@
 
-Requires: libscap
-Libs: -L${libdir} -lsinsp @SINSP_PKG_CONFIG_LIBDIRS@ @SINSP_PKG_CONFIG_LIBS@
+Requires: libscap @LIBSINSP_REQUIRES@
+Requires.private: @LIBSINSP_REQUIRES_PRIVATE@
+Libs: -L${libdir} @SINSP_PKG_CONFIG_LIBDIRS@ @SINSP_PKG_CONFIG_LIBS@
 Cflags: -I${includedir} -I${includedir}/libsinsp -I${includedir}/driver @SINSP_PKG_CONFIG_INCLUDES@