Add gold support for --package-metadata option.

Following the same format as the implementation in ld:
9e2bb0cb5e74aed4158f08495534922d7108f928

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.

elfcpp/
	* elfcpp.h: Add FDO_PACKAGING_METADATA note type.

gold/
	* Makefile.am: Add jansson flags and libraries.
	* configure.ac: Check for jansson library.
	* layout.cc (Layout::create_notes): Call create_package_metadata().
	(Layout::create_package_metadata): New function.
	* layout.h (Layout::create_package_metadata): New function.
	(Layout::package_metadata_note_): New data member.
	* options.h (class General_options): Add --package-metadata option.
	* testsuite/Makefile.am (object_unittest): Add jansson libraries.
	(binary_unittest): Likewise.
	(leb128_unittest): Likewise.
	(overflow_unittest): Likewise.
	(package_metadata_test): New test.
	* testsuite/package_metadata_main.c: New test source.

1 files changed, 266 insertions, 0 deletions

diff --git a/gold/configure b/gold/configure
index 5f5b8c3..84c413f 100755
--- a/gold/configure
+++ b/gold/configure
@@ -631,6 +631,11 @@ HAVE_NO_USE_LINKER_PLUGIN_FALSE
 HAVE_NO_USE_LINKER_PLUGIN_TRUE
 HAVE_PUBNAMES_FALSE
 HAVE_PUBNAMES_TRUE
+JANSSON_LIBS
+JANSSON_CFLAGS
+PKG_CONFIG_LIBDIR
+PKG_CONFIG_PATH
+PKG_CONFIG
 THREADS_FALSE
 THREADS_TRUE
 PTHREAD_CFLAGS
@@ -851,6 +856,7 @@ with_gold_ldflags
 with_gold_ldadd
 with_system_zlib
 enable_threads
+enable_jansson
 enable_maintainer_mode
 '
       ac_precious_vars='build_alias
@@ -867,6 +873,11 @@ CXXFLAGS
 CCC
 YACC
 YFLAGS
+PKG_CONFIG
+PKG_CONFIG_PATH
+PKG_CONFIG_LIBDIR
+JANSSON_CFLAGS
+JANSSON_LIBS
 CXXCPP'
 
 
@@ -1503,6 +1514,7 @@ Optional Features:
   --enable-werror         treat compile warnings as errors
   --enable-build-warnings enable build-time compiler warnings
   --enable-threads[=ARG]  multi-threaded linking [ARG={auto,yes,no}]
+  --enable-jansson        enable jansson [default=no]
   --enable-maintainer-mode
                           enable make rules and dependencies not useful (and
                           sometimes confusing) to the casual installer
@@ -1533,6 +1545,15 @@ Some influential environment variables:
   YFLAGS      The list of arguments that will be passed by default to $YACC.
               This script will default YFLAGS to the empty string to avoid a
               default value of `-d' given by some make applications.
+  PKG_CONFIG  path to pkg-config utility
+  PKG_CONFIG_PATH
+              directories to add to pkg-config's search path
+  PKG_CONFIG_LIBDIR
+              path overriding pkg-config's built-in search path
+  JANSSON_CFLAGS
+              C compiler flags for JANSSON, overriding pkg-config
+  JANSSON_LIBS
+              linker flags for JANSSON, overriding pkg-config
   CXXCPP      C++ preprocessor
 
 Use these variables to override the choices made by `configure' or to help
@@ -9575,6 +9596,251 @@ else
 fi
 
 
+# Used to validate --package-metadata= input. Disabled by default.
+# Check whether --enable-jansson was given.
+if test "${enable_jansson+set}" = set; then :
+  enableval=$enable_jansson; enable_jansson=$enableval
+else
+  enable_jansson="no"
+fi
+
+
+if test "x$enable_jansson" != "xno"; then
+
+
+
+
+
+
+
+if test "x$ac_cv_env_PKG_CONFIG_set" != "xset"; then
+	if test -n "$ac_tool_prefix"; then
+  # Extract the first word of "${ac_tool_prefix}pkg-config", so it can be a program name with args.
+set dummy ${ac_tool_prefix}pkg-config; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if ${ac_cv_path_PKG_CONFIG+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  case $PKG_CONFIG in
+  [\\/]* | ?:[\\/]*)
+  ac_cv_path_PKG_CONFIG="$PKG_CONFIG" # Let the user override the test with a path.
+  ;;
+  *)
+  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
+    ac_cv_path_PKG_CONFIG="$as_dir/$ac_word$ac_exec_ext"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+  ;;
+esac
+fi
+PKG_CONFIG=$ac_cv_path_PKG_CONFIG
+if test -n "$PKG_CONFIG"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $PKG_CONFIG" >&5
+$as_echo "$PKG_CONFIG" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+
+fi
+if test -z "$ac_cv_path_PKG_CONFIG"; then
+  ac_pt_PKG_CONFIG=$PKG_CONFIG
+  # Extract the first word of "pkg-config", so it can be a program name with args.
+set dummy pkg-config; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if ${ac_cv_path_ac_pt_PKG_CONFIG+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  case $ac_pt_PKG_CONFIG in
+  [\\/]* | ?:[\\/]*)
+  ac_cv_path_ac_pt_PKG_CONFIG="$ac_pt_PKG_CONFIG" # Let the user override the test with a path.
+  ;;
+  *)
+  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
+    ac_cv_path_ac_pt_PKG_CONFIG="$as_dir/$ac_word$ac_exec_ext"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+  ;;
+esac
+fi
+ac_pt_PKG_CONFIG=$ac_cv_path_ac_pt_PKG_CONFIG
+if test -n "$ac_pt_PKG_CONFIG"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_pt_PKG_CONFIG" >&5
+$as_echo "$ac_pt_PKG_CONFIG" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+  if test "x$ac_pt_PKG_CONFIG" = x; then
+    PKG_CONFIG=""
+  else
+    case $cross_compiling:$ac_tool_warned in
+yes:)
+{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: using cross tools not prefixed with host triplet" >&5
+$as_echo "$as_me: WARNING: using cross tools not prefixed with host triplet" >&2;}
+ac_tool_warned=yes ;;
+esac
+    PKG_CONFIG=$ac_pt_PKG_CONFIG
+  fi
+else
+  PKG_CONFIG="$ac_cv_path_PKG_CONFIG"
+fi
+
+fi
+if test -n "$PKG_CONFIG"; then
+	_pkg_min_version=0.9.0
+	{ $as_echo "$as_me:${as_lineno-$LINENO}: checking pkg-config is at least version $_pkg_min_version" >&5
+$as_echo_n "checking pkg-config is at least version $_pkg_min_version... " >&6; }
+	if $PKG_CONFIG --atleast-pkgconfig-version $_pkg_min_version; then
+		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+	else
+		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+		PKG_CONFIG=""
+	fi
+fi
+  if test -n "$PKG_CONFIG"; then :
+
+
+pkg_failed=no
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for jansson" >&5
+$as_echo_n "checking for jansson... " >&6; }
+
+if test -n "$JANSSON_CFLAGS"; then
+    pkg_cv_JANSSON_CFLAGS="$JANSSON_CFLAGS"
+ elif test -n "$PKG_CONFIG"; then
+    if test -n "$PKG_CONFIG" && \
+    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"jansson\""; } >&5
+  ($PKG_CONFIG --exists --print-errors "jansson") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; then
+  pkg_cv_JANSSON_CFLAGS=`$PKG_CONFIG --cflags "jansson" 2>/dev/null`
+		      test "x$?" != "x0" && pkg_failed=yes
+else
+  pkg_failed=yes
+fi
+ else
+    pkg_failed=untried
+fi
+if test -n "$JANSSON_LIBS"; then
+    pkg_cv_JANSSON_LIBS="$JANSSON_LIBS"
+ elif test -n "$PKG_CONFIG"; then
+    if test -n "$PKG_CONFIG" && \
+    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"jansson\""; } >&5
+  ($PKG_CONFIG --exists --print-errors "jansson") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; then
+  pkg_cv_JANSSON_LIBS=`$PKG_CONFIG --libs "jansson" 2>/dev/null`
+		      test "x$?" != "x0" && pkg_failed=yes
+else
+  pkg_failed=yes
+fi
+ else
+    pkg_failed=untried
+fi
+
+if test $pkg_failed = no; then
+  pkg_save_LDFLAGS="$LDFLAGS"
+  LDFLAGS="$LDFLAGS $pkg_cv_JANSSON_LIBS"
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+
+else
+  pkg_failed=yes
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+  LDFLAGS=$pkg_save_LDFLAGS
+fi
+
+
+
+if test $pkg_failed = yes; then
+        { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+
+if $PKG_CONFIG --atleast-pkgconfig-version 0.20; then
+        _pkg_short_errors_supported=yes
+else
+        _pkg_short_errors_supported=no
+fi
+        if test $_pkg_short_errors_supported = yes; then
+	        JANSSON_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors --cflags --libs "jansson" 2>&1`
+        else
+	        JANSSON_PKG_ERRORS=`$PKG_CONFIG --print-errors --cflags --libs "jansson" 2>&1`
+        fi
+	# Put the nasty error message in config.log where it belongs
+	echo "$JANSSON_PKG_ERRORS" >&5
+
+
+	  as_fn_error $? "Cannot find jansson library" "$LINENO" 5
+
+elif test $pkg_failed = untried; then
+        { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+
+	  as_fn_error $? "Cannot find jansson library" "$LINENO" 5
+
+else
+	JANSSON_CFLAGS=$pkg_cv_JANSSON_CFLAGS
+	JANSSON_LIBS=$pkg_cv_JANSSON_LIBS
+        { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+
+
+$as_echo "#define HAVE_JANSSON 1" >>confdefs.h
+
+
+
+
+fi
+
+else
+
+      as_fn_error $? "Cannot find pkg-config" "$LINENO" 5
+
+fi
+fi
+
 ac_fn_c_check_decl "$LINENO" "basename" "ac_cv_have_decl_basename" "$ac_includes_default"
 if test "x$ac_cv_have_decl_basename" = xyes; then :
   ac_have_decl=1