Add support for thin archives.

    * bfd/archive.c (_bfd_find_nested_archive): New function.
    (get_extended_arelt_filename): Add origin parameter.
    (_bfd_generic_read_ar_hdr_mag): Deal with extended name
    combined with a file offset.
    (append_relative_path): New function.
    (_bfd_get_elt_at_filepos): Deal with external members and
    nested archives.
    (bfd_generic_openr_next_archived_file): Thin archives.
    (bfd_generic_archive_p): Recognize new magic string.
    (adjust_relative_path): New function.
    (_bfd_construct_extended_name_table): Construct extended
    names for thin archive members.
    (_bfd_write_archive_contents): Emit new magic string, skip
    copying files for thin archives.
    * bfd/bfd-in.h (bfd_is_thin_archive): New macro.
    * bfd/bfd.c (struct bfd): New fields for thin archives.
    * bfd/libbfd-in.h (struct areltdata): New field for thin archives.
    * bfd/opncls.c (bfd_close): Delete BFDs for nested archives.
    * binutils/ar.c (make_thin_archive): New global flag.
    (map_over_members): Deal with full pathnames in thin archives.
    (usage, main): Add 'T' option for building thin archives.
    (replace_members): Pass thin archive flag to ar_emul_append.
    * binutils/arsup.c (ar_open): Initialize new flag.
    * binutils/binemul.c (ar_emul_append): Add new parameter for
    flattening nested archives.
    (do_ar_emul_default_append): New function.
    (ar_emul_default_append): Factored out recursive code.
    * binutils/binemul.h (ar_emul_default_append): Add new parameter.
    (struct bin_emulation_xfer_struct): New parameter for ar_append.
    * binutils/dlltool.c (gen_lib_file): Initialize thin archive flag.
    * binutils/emul_aix.c (ar_emul_aix_internal): Add new flatten
    parameter, currently unimplemented.
    All callers changed.
    * binutils/objcopy.c (copy_archive): Preserve thin archive flag.
    * binutils/doc/binutils.texi: Update ar documentation.
    * binutils/testsuite/binutils-all/ar.exp: Add thin archive tests.
    * include/aout/ar.h (ARMAGT): New magic string for thin archives.

1 files changed, 20 insertions, 0 deletions

diff --git a/binutils/doc/binutils.texi b/binutils/doc/binutils.texi
index 723c3a3..44c18dc 100644
--- a/binutils/doc/binutils.texi
+++ b/binutils/doc/binutils.texi
@@ -211,6 +211,18 @@ You may use @samp{nm -s} or @samp{nm --print-armap} to list this index
 table.  If an archive lacks the table, another form of @command{ar} called
 @command{ranlib} can be used to add just the table.
 
+@cindex thin archives
+@sc{gnu} @command{ar} can optionally create a @emph{thin} archive,
+which contains a symbol index and references to the original copies
+of the member files of the archives.  Such an archive is useful
+for building libraries for use within a local build, where the
+relocatable objects are expected to remain available, and copying the
+contents of each object would only waste time and space.  Thin archives
+are also @emph{flattened}, so that adding one or more archives to a
+thin archive will add the elements of the nested archive individually.
+The paths to the elements of the archive are stored relative to the
+archive itself.
+
 @cindex compatibility, @command{ar}
 @cindex @command{ar} compatibility
 @sc{gnu} @command{ar} is designed to be compatible with two different
@@ -356,6 +368,8 @@ use the @samp{v} modifier with this operation, to request that
 If you do not specify a @var{member}, all files in the archive
 are extracted.
 
+Files cannot be extracted from a thin archive.
+
 @end table
 
 A number of modifiers (@var{mod}) may immediately follow the @var{p}
@@ -434,6 +448,12 @@ with the linker.  In order to build a symbol table, you must omit the
 @samp{S} modifier on the last execution of @samp{ar}, or you must run
 @samp{ranlib} on the archive.
 
+@item T
+@cindex creating thin archive
+Make the specified @var{archive} a @emph{thin} archive.  If it already
+exists and is a regular archive, the existing members must be present
+in the same directory as @var{archive}.
+
 @item u
 @cindex updating an archive
 Normally, @samp{ar r}@dots{} inserts all files