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.

1 files changed, 8 insertions, 0 deletions

diff --git a/bfd/elf-bfd.h b/bfd/elf-bfd.h
index c7c0a79..65bd112 100644
--- a/bfd/elf-bfd.h
+++ b/bfd/elf-bfd.h
@@ -1918,6 +1918,14 @@ struct output_elf_obj_tdata
     asection *sec;
   } build_id;
 
+  /* FDO_PACKAGING_METADATA note type info.  */
+  struct
+  {
+    bool (*after_write_object_contents) (bfd *);
+    const char *json;
+    asection *sec;
+  } package_metadata;
+
   /* Records the result of `get_program_header_size'.  */
   bfd_size_type program_header_size;