Make coff backend data read-only

The bfd_coff_backend_data struct should be read-only, the only thing
preventing this is that objcopy writes to one of the fields,
_bfd_coff_long_section_names.  This patch creates a copy of the field
in bfd coff_obj_tdata, which makes more sense anyway.  When enabling
long section names the intent is to do so for a particular bfd, not
for all bfds that might happen to be using the target xvec.

bfd/
	* coffcode.h: Update coff long section name comment.
	(bfd_coff_set_long_section_names_allowed): Use macro accessor
	to set flag.
	(bfd_coff_set_long_section_names_disallowed): Tidy.
	(coff_backend_info): Return a const pointer.
	(bfd_coff_std_swap_table, ticoff0_swap_table, ticoff1_swap_table),
	(bigobj_swap_table): Make const.
	(bfd_coff_long_section_names): Use tdata copy.
	(coff_mkobject): Set long_section_names from coff_backend_info.
	* coff-go32.c (_bfd_go32_mkobject): Likewise.
	* peicode.h (pe_mkobject): Likewise.
	* coff-sh.c (bfd_coff_small_swap_table): Make const.
	* libcoff-in.h (struct coff_tdata): Add long_section_names,
	reorder fields.
	* libcoff.h: Regenerate.
binutils/
	* objcopy.c (set_long_section_mode): Move earlier in file.
	(copy_object): Call set_long_section_mode here, after setting
	output format.
	(copy_file): Don't call set_long_section_mode.

1 files changed, 17 insertions, 11 deletions

diff --git a/bfd/libcoff.h b/bfd/libcoff.h
index 9d51cef..f03330f 100644
--- a/bfd/libcoff.h
+++ b/bfd/libcoff.h
@@ -83,21 +83,34 @@ typedef struct coff_tdata
   /* The unswapped external symbols.  May be NULL.  Read by
      _bfd_coff_get_external_symbols.  */
   void * external_syms;
-  /* If this is TRUE, the external_syms may not be freed.  */
-  bool keep_syms;
 
   /* The string table.  May be NULL.  Read by
      _bfd_coff_read_string_table.  */
   char *strings;
   /* The length of the strings table.  For error checking.  */
   bfd_size_type strings_len;
+
+  /* Set if long section names are supported.  A writable copy of the COFF
+     backend flag _bfd_coff_long_section_names.  */
+  bool long_section_names;
+
+  /* If this is TRUE, the external_syms may not be freed.  */
+  bool keep_syms;
   /* If this is TRUE, the strings may not be freed.  */
   bool keep_strings;
   /* If this is TRUE, the strings have been written out already.  */
   bool strings_written;
 
+  /* Is this a GO32 coff file?  */
+  bool go32;
+
   /* Is this a PE format coff file?  */
   int pe;
+
+  /* Copy of some of the f_flags bits in the COFF filehdr structure,
+     used by ARM code.  */
+  flagword flags;
+
   /* Used by the COFF backend linker.  */
   struct coff_link_hash_entry **sym_hashes;
 
@@ -115,13 +128,6 @@ typedef struct coff_tdata
   /* The timestamp from the COFF file header.  */
   long timestamp;
 
-  /* Copy of some of the f_flags bits in the COFF filehdr structure,
-     used by ARM code.  */
-  flagword flags;
-
-  /* Is this a GO32 coff file?  */
-  bool go32;
-
   /* A stub (extra data prepended before the COFF image) and its size.
      Used by coff-go32-exe, it contains executable data that loads the
      COFF object into memory.  */
@@ -841,7 +847,7 @@ typedef struct
 } bfd_coff_backend_data;
 
 #define coff_backend_info(abfd) \
-  ((bfd_coff_backend_data *) (abfd)->xvec->backend_data)
+  ((const bfd_coff_backend_data *) (abfd)->xvec->backend_data)
 
 #define bfd_coff_swap_aux_in(a,e,t,c,ind,num,i) \
   ((coff_backend_info (a)->_bfd_coff_swap_aux_in) (a,e,t,c,ind,num,i))
@@ -884,7 +890,7 @@ typedef struct
 #define bfd_coff_long_filenames(abfd) \
   (coff_backend_info (abfd)->_bfd_coff_long_filenames)
 #define bfd_coff_long_section_names(abfd) \
-  (coff_backend_info (abfd)->_bfd_coff_long_section_names)
+  (coff_data (abfd)->long_section_names)
 #define bfd_coff_set_long_section_names(abfd, enable) \
   ((coff_backend_info (abfd)->_bfd_coff_set_long_section_names) (abfd, enable))
 #define bfd_coff_default_section_alignment_power(abfd) \