cmake: add soname info to libgd.so

Pull out the library versioning info out of configure and into a common
script that both cmake & autotools can run.  This way we have a single
source of truth for the versioning info.

CMakeLists.txt

@@ -83,6 +83,17 @@ else (USE_EXT_GD)
 	SET(GDLIB_VERSION "${GDLIB_MAJOR}.${GDLIB_MINOR}.${GDLIB_REVISION}${GDLIB_EXTRA}")
 	MESSAGE(STATUS "gd version ${GDLIB_VERSION}")
 
+	MACRO(GV_LT VER VAR)
+		execute_process(
+			COMMAND sh ${CMAKE_CURRENT_SOURCE_DIR}/config/getlib.sh ${VER}
+			OUTPUT_VARIABLE ${VAR}
+		)
+	ENDMACRO(GV_LT)
+
+	GV_LT(SONAME GDLIB_LIB_SOVERSION)
+	GV_LT(VERSION GDLIB_LIB_VERSION)
+	MESSAGE(STATUS "gd shared lib version ${GDLIB_LIB_SOVERSION} (${GDLIB_LIB_VERSION})")
+
 	SET(CMAKE_REQUIRED_INCLUDES "/usr/include" "/usr/local/include")
 
 	include(CheckIncludeFiles)

config/getlib.sh

@@ -0,0 +1,42 @@
+#!/bin/sh
+
+GETVER="${0%/*}/getver.pl"
+GDLIB_MAJOR=$("${GETVER}" MAJOR)
+GDLIB_MINOR=$("${GETVER}" MINOR)
+GDLIB_REVISION=$("${GETVER}" RELEASE)
+
+# Dynamic library version information
+# See http://www.gnu.org/software/libtool/manual/libtool.html#Updating-version-info
+
+GDLIB_LT_CURRENT=3
+# This is the version where the soname (current above) changes.  We use it
+# to reset the revision base back to zero.  It's a bit of a pain, but some
+# systems restrict the revision range below to [0..255] (like OS X).
+GDLIB_PREV_MAJOR=2
+GDLIB_PREV_MINOR=2
+# This isn't 100% correct, but it tends to be a close enough approximation
+# for how we manage the codebase.  It's rare to do a release that doesn't
+# modify the library since this project is centered around the library.
+GDLIB_LT_REVISION=$(( ((GDLIB_MAJOR - GDLIB_PREV_MAJOR) << 6) | ((GDLIB_MINOR - GDLIB_PREV_MINOR) << 3) | GDLIB_REVISION ))
+GDLIB_LT_AGE=0
+
+# The first three fields we feed into libtool and the OS target determines how
+# they get used.  The last two fields we feed into cmake.  We use the same rules
+# as Linux SONAME versioning in libtool, but cmake should handle it for us.
+case $1 in
+CURRENT)
+	printf '%s' "${GDLIB_LT_CURRENT}"
+	;;
+REVISION)
+	printf '%s' "${GDLIB_LT_REVISION}"
+	;;
+AGE)
+	printf '%s' "${GDLIB_LT_AGE}"
+	;;
+VERSION)
+	printf '%s' "$(( GDLIB_LT_CURRENT - GDLIB_LT_AGE )).${GDLIB_LT_AGE}.${GDLIB_LT_REVISION}"
+	;;
+SONAME)
+	printf '%s' "$(( GDLIB_LT_CURRENT - GDLIB_LT_AGE ))"
+	;;
+esac

configure.ac

@@ -34,20 +34,17 @@ AC_SUBST(GDLIB_REVISION)
 AC_SUBST(GDLIB_EXTRA)
 AC_SUBST(GDLIB_VERSION)
 
-# Dynamic library version information
-# See http://www.gnu.org/software/libtool/manual/libtool.html#Updating-version-info
+dnl Keep the libtool version details in an external script so cmake can
+dnl access the values too.
+define([lt_gv], [config/getlib.sh ]$1)
+m4_define([gd_LT_CURRENT], esyscmd(lt_gv(CURRENT)))
+m4_define([gd_LT_REVISION], esyscmd(lt_gv(REVISION)))
+m4_define([gd_LT_AGE], esyscmd(lt_gv(AGE)))
+
+GDLIB_LT_CURRENT=gd_LT_CURRENT
+GDLIB_LT_REVISION=gd_LT_REVISION
+GDLIB_LT_AGE=gd_LT_AGE
 
-GDLIB_LT_CURRENT=3
-dnl This is the version where the soname (current above) changes.  We use it
-dnl to reset the revision base back to zero.  It's a bit of a pain, but some
-dnl systems restrict the revision range below to [0..255] (like OS X).
-GDLIB_PREV_MAJOR=2
-GDLIB_PREV_MINOR=2
-dnl This isn't 100% correct, but it tends to be a close enough approximation
-dnl for how we manage the codebase.  It's rare to do a release that doesn't
-dnl modify the library since this project is centered around the library.
-GDLIB_LT_REVISION=$(( ((GDLIB_MAJOR - GDLIB_PREV_MAJOR) << 6) | ((GDLIB_MINOR - GDLIB_PREV_MINOR) << 3) | GDLIB_REVISION ))
-GDLIB_LT_AGE=0
 AC_SUBST(GDLIB_LT_CURRENT)
 AC_SUBST(GDLIB_LT_REVISION)
 AC_SUBST(GDLIB_LT_AGE)

src/CMakeLists.txt

@@ -80,6 +80,8 @@ include(GNUInstallDirs)
 if (BUILD_SHARED_LIBS)
 	add_library(${GD_LIB} ${LIBGD_SRC_FILES})
 	set_target_properties(${GD_LIB} PROPERTIES
+		SOVERSION ${GDLIB_LIB_SOVERSION}
+		VERSION ${GDLIB_LIB_VERSION}
 		C_VISIBILITY_PRESET hidden
 		CXX_VISIBILITY_PRESET hidden
 	)