Re: splitting off libcups (was: Re-enabling cups option in gtk3)

[maya%NetBSD.org@localhost]

On Fri, May 15, 2020 at 01:57:49PM +0200, Edgar Fuß wrote:
> > Splitting libcups into its own package:
> Sounds like a good Idea to me.
> 
> > Index: print/libcups/options.mk
> Couldn't this be shared with cups-base?
> 
> > Index: print/cups-base/Makefile
> [...]
> >  post-install:
> > +	# Delete files installed by libcups
> > +	${RM} ${DESTDIR}${PREFIX}/bin/cups-config
> > +	${RM} -rf ${DESTDIR}${PREFIX}/lib
> > +	${RM} -rf ${DESTDIR}${PREFIX}/include/cups
> > +	${RM} -rf ${DESTDIR}${PREFIX}/share/locale
> I guess there's no --with-components setting to avoid building these in the 
> first place?

It looked like libcups is very deeply integrated into the build.
The top-level makefile descends into "cups" unconditionally, and many of
the subdirectories depend on it. I could probably skip the install step.

Also while doing this I got caught up with creating the attached diff,
which is a more "systemic" way of removing parts of another package with
additional checks.

Index: Makefile
===================================================================
RCS file: /cvsroot/pkgsrc/print/cups-base/Makefile,v
retrieving revision 1.33
diff -u -r1.33 Makefile
--- Makefile	14 May 2020 19:45:50 -0000	1.33
+++ Makefile	15 May 2020 14:29:18 -0000
@@ -153,6 +153,19 @@
 	${LN} -sf ${DESTDIR}${PREFIX}/libexec/cups/backend/dnssd ${DESTDIR}${PREFIX}/libexec/cups/backend/mdns
 .endif
 
+REMOVE_CONFLICTS_WITH_PACKAGES+=	libcups-[0-9]*
+CONFLICTING_FILES!=			pkg_info -qL ${REMOVE_CONFLICTS_WITH_PACKAGES}
+
+post-install:	remove-conflicts
+remove-conflicts:
+	@${STEP_MSG} removing files conflicting with ${REMOVE_CONFLICTS_WITH_PACKAGES}
+.for __conflicting_file__ in ${CONFLICTING_FILES}
+# XXX check for GNU readelf + PKG_DEVELOPER
+	${ECHO} ${DESTDIR}${__conflicting_file__} ${__conflicting_file__} | ${AWK} -f ./match-abi.awk
+# end check for GNU readelf + PKG_DEVELOPER
+	${RM} -f ${DESTDIR}${__conflicting_file__}
+.endfor
+
 .include "../../converters/libiconv/buildlink3.mk"
 .include "../../devel/zlib/buildlink3.mk"
 .include "../../graphics/png/buildlink3.mk"
Index: match-abi.awk
===================================================================
RCS file: match-abi.awk
diff -N match-abi.awk
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ match-abi.awk	15 May 2020 14:29:18 -0000
@@ -0,0 +1,59 @@
+# Match ABIs on two ELF libraries
+# echo "/usr/lib/libc.so.12.214 /usr/lib/libc.so.12.215" | awk -f match-abi.awk
+#
+# Symbols mismatch: exit with non-zero status
+# If no symbols are available: return zero status.
+
+{
+	first_elf = $1
+	second_elf = $2
+	cmd = "readelf --symbols " first_elf
+	second_cmd = "readelf --symbols " second_elf
+	i = 0
+	debug = 0
+	if (system(cmd " > /dev/null 2>&1") != 0) {
+		#print("Failed to get symbols from " first_elf ", ignoring") > "/dev/stderr"
+		exit 0
+	}
+	if (system(second_cmd " > /dev/null 2>&1") != 0) {
+		#print("Failed to get symbols from " second_elf ", ignoring") > "/dev/stderr"
+		exit 0
+	}
+
+	while ((cmd | getline) > 0) {
+		sname = $8
+		visibility = $7
+		if (visibility != "UND") {
+			i++
+			existing_snames[i] = sname
+		}
+	}
+
+	j = 0
+	while ((second_cmd | getline) > 0) {
+		sname = $8
+		visibility = $7
+		if (visibility != "UND") {
+			j++
+			matched = 0
+			for (iter in existing_snames) {
+				if (sname == existing_snames[iter]) {
+					matched++
+					break
+				}
+			}
+			if (matched == 0) {
+				print("Libraries " first_elf " and " second_elf " don't have the same ABI") > "/dev/stderr"
+				print("didn't find a match for symbol " sname) > "/dev/stderr"
+				exit 1
+			}
+		}
+	}
+
+	if (j != i) {
+		print("Libraries " first_elf " and " second_elf " don't have the same ABI") > "/dev/stderr"
+		print("More symbols in " first_elf) > "/dev/stderr"
+		print("i = " i ", j = ", j) > "/dev/stderr"
+		exit 1
+	}
+}