brp: Add brp-strip-lto script

Strip LTO sections and symbols from objects and archives (static
libraries). %brp_strip_none macro is respected.

Reviewed-by: Dmitry V. Levin <ldv@altlinux.org>

.gitignore

@@ -60,6 +60,7 @@ Makefile.in
 /scripts/brp-compress
 /scripts/brp-fix-perms
 /scripts/brp-fixup
+/scripts/brp-strip-lto
 /scripts/brp-verify-info
 /scripts/brp-verify_elf
 /scripts/compress_files

configure.ac

@@ -942,6 +942,7 @@ AC_OUTPUT([ Doxyfile Makefile rpmrc macros platform rpmpopt
 	scripts/brp-sign-kmodules
 	scripts/brp-fix-perms
 	scripts/brp-fixup
+	scripts/brp-strip-lto
 	scripts/brp-verify_elf
 	scripts/brp-verify-info
 	scripts/compress_files
@@ -954,6 +955,7 @@ AC_OUTPUT([ Doxyfile Makefile rpmrc macros platform rpmpopt
 	scripts/find-package
 	scripts/find-debuginfo-files
 	scripts/process-debuginfo
+	scripts/process-lto
 	scripts/find-scriptlet-requires
 	scripts/fixup-binconfig
 	scripts/fixup-libraries

rpm-4_0.spec

@@ -361,6 +361,7 @@ mv -T %buildroot%_rpmlibdir/{,build}macros
 %rpmattr %_rpmlibdir/find-requires
 %rpmattr %_rpmlibdir/find-debuginfo-files
 %rpmattr %_rpmlibdir/process-debuginfo
+%rpmattr %_rpmlibdir/process-lto
 %rpmattr %_rpmlibdir/find-scriptlet-requires
 %rpmattr %_rpmlibdir/fixup-*
 %rpmattr %_rpmlibdir/files.*

scripts/Makefile.am

@@ -6,11 +6,11 @@ EXTRA_DIST = \
 	posttrans-filetriggers 0ldconfig.filetrigger \
 	debuginfo.req debuginfo.req.files debuginfo.prov debuginfo.prov.files \
 	functions find-package .provides.sh \
-	find-debuginfo-files process-debuginfo \
+	find-debuginfo-files process-debuginfo process-lto \
 	find-scriptlet-requires brp-sign-kmodules \
 	brp-adjust_libraries brp-alt \
 	brp-check_contents brp-cleanup brp-compress brp-debuginfo \
-	brp-fix-perms brp-fixup \
+	brp-fix-perms brp-fixup brp-strip-lto \
 	brp-verify_elf brp-verify-info \
 	compress_files \
 	cpp.req cpp.req.files \
@@ -44,7 +44,7 @@ libexecdir = ${prefix}/libexec
 config_DATA = 0common-files.req.list # .provides.sh
 config_SCRIPTS = \
 	debuginfo.req debuginfo.req.files debuginfo.prov debuginfo.prov.files \
-	find-debuginfo-files process-debuginfo \
+	find-debuginfo-files process-debuginfo process-lto \
 	find-scriptlet-requires \
 	brp-alt \
 	compress_files \
@@ -82,7 +82,9 @@ install-data-local:
 	$(INSTALL) -m755 brp-adjust_libraries $(DESTDIR)$(configdir)/brp.d/048-adjust_libraries.brp
 	$(INSTALL) -m755 brp-debuginfo $(DESTDIR)$(configdir)/brp.d/056-debuginfo.brp
 	$(INSTALL) -m755 brp-sign-kmodules $(DESTDIR)$(configdir)/brp.d/057-brp-sign-kmodules.brp
+	$(INSTALL) -m755 brp-strip-lto $(DESTDIR)$(configdir)/brp.d/061-brp-strip-lto.brp
 	$(INSTALL) -m755 process-debuginfo $(DESTDIR)$(configdir)/process-debuginfo
+	$(INSTALL) -m755 process-lto $(DESTDIR)$(configdir)/process-lto
 	$(INSTALL) -m755 brp-verify_elf $(DESTDIR)$(configdir)/brp.d/064-verify_elf.brp
 	$(INSTALL) -m755 install $(DESTDIR)$(libexecdir)/rpm-build/install
 	$(INSTALL) -m755 strip $(DESTDIR)$(libexecdir)/rpm-build/strip

scripts/brp-strip-lto.in

@@ -0,0 +1,39 @@
+#!/bin/sh -efu
+#
+# brp-strip-lto - Strip LTO sections and symbols from object files
+#
+# LTO bytecode needs to be stripped for distributions, because it's
+# GCC version dependent:
+#   "The bytecode files are versioned and there is a strict version
+#   check, so bytecode files generated in one version of GCC do not
+#   work with an older or newer version of GCC." -- gcc(1).
+#
+# Based on brp-strip-lto (Fedora) and brp-debuginfo.
+# Copyright (c) 2021 Vitaly Chikunov <vt@altlinux.org>.
+# License: GPLv2+.
+
+# Implementation notes:
+# - xargs -Px -nx to start parallelizing sooner.
+# - %brp_strip_none is respected.
+
+. @RPMCONFIGDIR@/functions
+ValidateBuildRoot
+
+cd "$RPM_BUILD_ROOT"
+mkdir -p .tmp
+
+# They skip /usr/lib/debug from the search, but why. There aren't
+# such objects nor meaning to skip stripping them.
+# Only skip internal temporary workspace.
+find -path './.*' -prune -o -name '*.[ao]' -type f -print | \
+while read -r f; do
+	for pat in ${RPM_BRP_STRIP_NONE-}; do
+		if [ -z "${f##.$pat}" ]; then
+			f=
+			continue
+		fi
+	done
+	[ -n "$f" ] && printf "%s\0" "$f"
+done | \
+eu-elfclassify --not-program --not-library --not-linux-kernel-module --stdin0 --print0 | \
+xargs -0 -r -P$(nproc) -n$(nproc) @RPMCONFIGDIR@/process-lto

scripts/process-lto.in

@@ -0,0 +1,41 @@
+#!/bin/sh -efu
+#
+# Process single file for LTO business.
+# (Will be run multiple instances in parallel.)
+#
+# Based on brp-strip-lto (Fedora).
+# Copyright (c) 2021 Vitaly Chikunov <vt@altlinux.org>.
+# License: GPLv2+.
+#
+# Implementation notes:
+# - eu-strip cannot be used due to absence of `-N`.
+
+. @RPMCONFIGDIR@/functions
+ValidateBuildRoot
+
+cd "$RPM_BUILD_ROOT"
+mkdir -p .tmp
+
+# If there is only slim lto, strip will produce "plugin needed to handle lto
+# object" warning, because of stripping __gnu_lto_v1 symbol while remaining
+# __gnu_lto_slim.
+strip -p -R '.gnu.lto_*' -R '.gnu.debuglto_*' -N '__gnu_lto_v1' "$@"
+
+# Verify that we still have exportable symbols.
+suggest="Perhaps, you need to %define optflags_lto %optflags_lto -ffat-lto-objects"
+for f
+do
+	# Output in one line per symbol format.
+	nm -g -A -P "$f" > .tmp/lto-nm.$$ 2>/dev/null
+	if grep -F -q -w ': __gnu_lto_slim' .tmp/lto-nm.$$; then
+		if grep -F -q -v -w ': __gnu_lto_slim' .tmp/lto-nm.$$; then
+			Fatal "$f: contains __gnu_lto_slim. $suggest"
+		else
+			Fatal "$f: contains __gnu_lto_slim only. $suggest"
+		fi
+	elif [ ! -s .tmp/lto-nm.$$ ]; then
+		# This is only informational call of file.
+		Warning "$f: contains no exportable symbols: $(file4 -b "$f")"
+	fi
+	rm .tmp/lto-nm.$$
+done