binutils/

200x-xx-xx  Phil Edwards  <phil@codesourcery.com>
	    Richard Sandiford  <richard@codesourcery.com>

	* NEWS: Mention addition of --extract-symbol.
	* doc/binutils.texi: Document it.
	* objcopy.c (extract_symbol): New variable.
	(OPTION_EXTRACT_SYMBOLS): New command_line_switch.
	(copy_options): Add an entry for --extract-symbol.
	(copy_usage): Mention --extract-symbol.
	(copy_object): Set the start address to zero for --extract-symbol.
	Do not copy private BFD data in that case.
	(setup_section): Set the size, LMA and VMA to zero for
	--extract-symbol.  Do not copy private BFD data in that case.
	(copy_section): Do not copy section contents if --extract-symbol
	is passed.
	(copy_main): Set extract_symbol to TRUE if --extract-symbol
	is passed.

ld/testsuite/
	* ld-elf/extract-symbol-1sym.d, ld-elf/extract-symbol-1sec.d,
	* ld-elf/extract-symbol-1.s, ld-elf/extract-symbol-1.ld: New tests.
	* ld-elf/binutils.exp: Run them.

4 files changed, 77 insertions, 8 deletions

diff --git a/binutils/ChangeLog b/binutils/ChangeLog
index 7bbeaf7..61c07e5 100644
--- a/binutils/ChangeLog
+++ b/binutils/ChangeLog
@@ -1,3 +1,21 @@
+2007-03-01  Phil Edwards  <phil@codesourcery.com>
+	    Richard Sandiford  <richard@codesourcery.com>
+
+	* NEWS: Mention addition of --extract-symbol.
+	* doc/binutils.texi: Document it.
+	* objcopy.c (extract_symbol): New variable.
+	(OPTION_EXTRACT_SYMBOLS): New command_line_switch.
+	(copy_options): Add an entry for --extract-symbol.
+	(copy_usage): Mention --extract-symbol.
+	(copy_object): Set the start address to zero for --extract-symbol.
+	Do not copy private BFD data in that case.
+	(setup_section): Set the size, LMA and VMA to zero for
+	--extract-symbol.  Do not copy private BFD data in that case.
+	(copy_section): Do not copy section contents if --extract-symbol
+	is passed.
+	(copy_main): Set extract_symbol to TRUE if --extract-symbol
+	is passed.
+
 2007-03-01  Paul Brook  <paul@codesourcery.com>
 
 	* MAINTAINERS: Update my entry.
diff --git a/binutils/NEWS b/binutils/NEWS
index d12450e..f63a736 100644
--- a/binutils/NEWS
+++ b/binutils/NEWS
@@ -1,5 +1,10 @@
 -*- text -*-
 
+* Add --extract-symbol command line option to objcopy, which will
+  strip everything out of an ordinary object file or executable except
+  for its symbol table.  Files containing just symbols can be useful
+  to some OSes.
+
 * Add "-x NAME" to readelf in addition to "-x NUMBER".
 
 * Add -i and -t switches to cxxfilt.  -i disables the display of implementation
diff --git a/binutils/doc/binutils.texi b/binutils/doc/binutils.texi
index 3751d04..1eb854e 100644
--- a/binutils/doc/binutils.texi
+++ b/binutils/doc/binutils.texi
@@ -996,6 +996,7 @@ objcopy [@option{-F} @var{bfdname}|@option{--target=}@var{bfdname}]
         [@option{--add-gnu-debuglink=}@var{path-to-file}]
         [@option{--keep-file-symbols}]
         [@option{--only-keep-debug}]
+        [@option{--extract-symbol}]
         [@option{--writable-text}]
         [@option{--readonly-text}]
         [@option{--pure}]
@@ -1489,6 +1490,21 @@ currently only supports the presence of one filename containing
 debugging information, not multiple filenames on a one-per-object-file
 basis.
 
+@item --extract-symbol
+Keep the file's section flags and symbols but remove all section data.
+Specifically, the option:
+
+@itemize
+@item sets the virtual and load addresses of every section to zero;
+@item removes the contents of all sections;
+@item sets the size of every section to zero; and
+@item sets the file's start address to zero.
+@end itemize
+ 
+This option is used to build a @file{.sym} file for a VxWorks kernel.
+It can also be a useful way of reducing the size of a @option{--just-symbols}
+linker input file.
+
 @item -V
 @itemx --version
 Show the version number of @command{objcopy}.
diff --git a/binutils/objcopy.c b/binutils/objcopy.c
index 06dbb5d..c955e37 100644
--- a/binutils/objcopy.c
+++ b/binutils/objcopy.c
@@ -215,6 +215,9 @@ static char *prefix_symbols_string = 0;
 static char *prefix_sections_string = 0;
 static char *prefix_alloc_sections_string = 0;
 
+/* True if --extract-symbol was passed on the command line.  */
+static bfd_boolean extract_symbol = FALSE;
+
 /* 150 isn't special; it's just an arbitrary non-ASCII char value.  */
 enum command_line_switch
   {
@@ -261,7 +264,8 @@ enum command_line_switch
     OPTION_READONLY_TEXT,
     OPTION_WRITABLE_TEXT,
     OPTION_PURE,
-    OPTION_IMPURE
+    OPTION_IMPURE,
+    OPTION_EXTRACT_SYMBOL
   };
 
 /* Options to handle if running as "strip".  */
@@ -317,6 +321,7 @@ static struct option copy_options[] =
   {"debugging", no_argument, 0, OPTION_DEBUGGING},
   {"discard-all", no_argument, 0, 'x'},
   {"discard-locals", no_argument, 0, 'X'},
+  {"extract-symbol", no_argument, 0, OPTION_EXTRACT_SYMBOL},
   {"format", required_argument, 0, 'F'}, /* Obsolete */
   {"gap-fill", required_argument, 0, OPTION_GAP_FILL},
   {"globalize-symbol", required_argument, 0, OPTION_GLOBALIZE_SYMBOL},
@@ -431,6 +436,7 @@ copy_usage (FILE *stream, int exit_status)
                                    Do not copy symbol <name> unless needed by\n\
                                      relocations\n\
      --only-keep-debug             Strip everything but the debug information\n\
+     --extract-symbol              Remove section contents but keep symbols\n\
   -K --keep-symbol <name>          Do not strip symbol <name>\n\
      --keep-file-symbols           Do not strip file symbol(s)\n\
      --localize-hidden             Turn all ELF hidden symbols into locals\n\
@@ -1310,11 +1316,16 @@ copy_object (bfd *ibfd, bfd *obfd)
 	    bfd_get_archive_filename (ibfd), bfd_get_target (ibfd),
 	    bfd_get_filename (obfd), bfd_get_target (obfd));
 
-  if (set_start_set)
-    start = set_start;
+  if (extract_symbol)
+    start = 0;
   else
-    start = bfd_get_start_address (ibfd);
-  start += change_start;
+    {
+      if (set_start_set)
+	start = set_start;
+      else
+	start = bfd_get_start_address (ibfd);
+      start += change_start;
+    }
 
   /* Neither the start address nor the flags
      need to be set for a core file.  */
@@ -1725,6 +1736,11 @@ copy_object (bfd *ibfd, bfd *obfd)
 	}
     }
 
+  /* Do not copy backend data if --extract-symbol is passed; anything
+     that needs to look at the section contents will fail.  */
+  if (extract_symbol)
+    return TRUE;
+
   /* Allow the BFD backend to copy any private data it understands
      from the input BFD to the output BFD.  This is done last to
      permit the routine to look at the filtered symbol table, which is
@@ -2184,6 +2200,8 @@ setup_section (bfd *ibfd, sec_ptr isection, void *obfdarg)
   size = bfd_section_size (ibfd, isection);
   if (copy_byte >= 0)
     size = (size + interleave - 1) / interleave;
+  else if (extract_symbol)
+    size = 0;
   if (! bfd_set_section_size (obfd, osection, size))
     {
       err = _("size");
@@ -2198,7 +2216,7 @@ setup_section (bfd *ibfd, sec_ptr isection, void *obfdarg)
   else
     vma += change_section_address;
 
-  if (! bfd_set_section_vma (obfd, osection, vma))
+  if (! bfd_set_section_vma (obfd, osection, extract_symbol ? 0 : vma))
     {
       err = _("vma");
       goto loser;
@@ -2217,7 +2235,7 @@ setup_section (bfd *ibfd, sec_ptr isection, void *obfdarg)
   else
     lma += change_section_address;
 
-  osection->lma = lma;
+  osection->lma = extract_symbol ? 0 : lma;
 
   /* FIXME: This is probably not enough.  If we change the LMA we
      may have to recompute the header for the file as well.  */
@@ -2236,7 +2254,12 @@ setup_section (bfd *ibfd, sec_ptr isection, void *obfdarg)
      bfd_get_section_by_name since some formats allow multiple
      sections with the same name.  */
   isection->output_section = osection;
-  isection->output_offset = 0;
+  isection->output_offset = extract_symbol ? vma : 0;
+
+  /* Do not copy backend data if --extract-symbol is passed; anything
+     that needs to look at the section contents will fail.  */
+  if (extract_symbol)
+    return;
 
   /* Allow the BFD backend to copy any private data it understands
      from the input section to the output section.  */
@@ -2354,6 +2377,9 @@ copy_section (bfd *ibfd, sec_ptr isection, void *obfdarg)
 	free (relpp);
     }
 
+  if (extract_symbol)
+    return;
+
   if (bfd_get_section_flags (ibfd, isection) & SEC_HAS_CONTENTS
       && bfd_get_section_flags (obfd, osection) & SEC_HAS_CONTENTS)
     {
@@ -3231,6 +3257,10 @@ copy_main (int argc, char *argv[])
 	  bfd_flags_to_set &= ~D_PAGED;
 	  break;
 
+	case OPTION_EXTRACT_SYMBOL:
+	  extract_symbol = TRUE;
+	  break;
+
 	case 0:
 	  /* We've been given a long option.  */
 	  break;