ld: add --package-metadata

Generate a .note.package FDO package metadata ELF note, following
the spec: https://systemd.io/ELF_PACKAGE_METADATA/

If the jansson library is available at build time (and it is explicitly
enabled), link ld to it, and use it to validate that the input is
correct JSON, to avoid writing garbage to the file. The
configure option --enable-jansson has to be used to explicitly enable
it (error out when not found). This allows bootstrappers (or others who
are not interested) to seamlessly skip it without issues.

3 files changed, 57 insertions, 0 deletions

diff --git a/ld/testsuite/ld-bootstrap/bootstrap.exp b/ld/testsuite/ld-bootstrap/bootstrap.exp
index bc83db6..f6d38af 100644
--- a/ld/testsuite/ld-bootstrap/bootstrap.exp
+++ b/ld/testsuite/ld-bootstrap/bootstrap.exp
@@ -155,6 +155,12 @@ foreach flags $test_flags {
 	set extralibs "$extralibs -lz"
     }
 
+    # Check if the system's jansson library is used. If so, the object files will
+    # be using symbols from it, so link to it.
+    if { [lindex [remote_exec build grep "-q \"HAVE_JANSSON 1\" config.h" ] 0] == 0 } then {
+	set extralibs "$extralibs -ljansson"
+    }
+
     # Plugin support requires linking with libdl.
     if { $plugins == "yes" } {
 	if { ![istarget "*-*-freebsd*"]} {
diff --git a/ld/testsuite/ld-elf/package-note.exp b/ld/testsuite/ld-elf/package-note.exp
new file mode 100644
index 0000000..c423909
--- /dev/null
+++ b/ld/testsuite/ld-elf/package-note.exp
@@ -0,0 +1,45 @@
+# Expect script for --package-note tests.
+#   Copyright (C) 2022 Free Software Foundation, Inc.
+#
+# This file is part of the GNU Binutils.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+# MA 02110-1301, USA.
+#
+
+# Exclude non-ELF targets.
+
+if ![is_elf_format] {
+    return
+}
+
+if { !([istarget *-*-linux*]
+       || [istarget arm*-*-uclinuxfdpiceabi]
+       || [istarget *-*-nacl*]
+       || [istarget *-*-gnu*]) } then {
+    return
+}
+
+run_ld_link_tests [list \
+    [list \
+	"package-note.o" \
+	"--package-metadata='{\"foo\":\"bar\"}'" \
+	"" \
+	"" \
+	{start.s} \
+	{{readelf {--notes} package-note.rd}} \
+	"package-note.o" \
+    ] \
+]
diff --git a/ld/testsuite/ld-elf/package-note.rd b/ld/testsuite/ld-elf/package-note.rd
new file mode 100644
index 0000000..77ae473
--- /dev/null
+++ b/ld/testsuite/ld-elf/package-note.rd
@@ -0,0 +1,6 @@
+#...
+Displaying notes found in: \.note\.package
+\s+Owner\s+Data\s+size\s+Description
+\s+FDO\s+0x00000010\s+(Unknown note type:\s+\(0xcafe1a7e\)|FDO_PACKAGING_METADATA)
+\s+(description data:\s+.*|Packaging Metadata:\s+{"foo":"bar"})
+#pass