Use class to manage BFD reference counts

This introduces a new specialization of gdb::ref_ptr that can be used
to manage BFD reference counts.  Then it changes most places in gdb to
use this new class, rather than explicit reference-counting or
cleanups.  This patch removes make_cleanup_bfd_unref.

If you look you will see a couple of spots using "release" where a use
of gdb_bfd_ref_ptr would be cleaner.  These will be fixed in the next
patch.

I think this patch fixes some latent bugs.  For example, it seems to
me that previously objfpy_add_separate_debug_file leaked a BFD.

I'm not 100% certain that the macho_symfile_read_all_oso change is
correct.  The existing code here is hard for me to follow.  One goal
of this sort of automated reference counting, though, is to make it
more difficult to make logic errors; so hopefully the code is clear
now.

2017-01-10  Tom Tromey  <tom@tromey.com>

	* windows-tdep.c (windows_xfer_shared_library): Update.
	* windows-nat.c (windows_make_so): Update.
	* utils.h (make_cleanup_bfd_unref): Remove.
	* utils.c (do_bfd_close_cleanup, make_cleanup_bfd_unref): Remove.
	* symfile.h (symfile_bfd_open)
	(find_separate_debug_file_in_section): Return gdb_bfd_ref_ptr.
	* symfile.c (read_symbols, symbol_file_add)
	(separate_debug_file_exists): Update.
	(symfile_bfd_open): Return gdb_bfd_ref_ptr.
	(generic_load, reread_symbols): Update.
	* symfile-mem.c (symbol_file_add_from_memory): Update.
	* spu-linux-nat.c (spu_bfd_open): Return gdb_bfd_ref_ptr.
	(spu_symbol_file_add_from_memory): Update.
	* solist.h (struct target_so_ops) <bfd_open>: Return
	gdb_bfd_ref_ptr.
	(solib_bfd_fopen, solib_bfd_open): Return gdb_bfd_ref_ptr.
	* solib.c (solib_bfd_fopen, solib_bfd_open): Return
	gdb_bfd_ref_ptr.
	(solib_map_sections, reload_shared_libraries_1): Update.
	* solib-svr4.c (enable_break): Update.
	* solib-spu.c (spu_bfd_fopen): Return gdb_bfd_ref_ptr.
	* solib-frv.c (enable_break2): Update.
	* solib-dsbt.c (enable_break): Update.
	* solib-darwin.c (gdb_bfd_mach_o_fat_extract): Return
	gdb_bfd_ref_ptr.
	(darwin_solib_get_all_image_info_addr_at_init): Update.
	(darwin_bfd_open): Return gdb_bfd_ref_ptr.
	* solib-aix.c (solib_aix_bfd_open): Return gdb_bfd_ref_ptr.
	* record-full.c (record_full_save): Update.
	* python/py-objfile.c (objfpy_add_separate_debug_file): Update.
	* procfs.c (insert_dbx_link_bpt_in_file): Update.
	* minidebug.c (find_separate_debug_file_in_section): Return
	gdb_bfd_ref_ptr.
	* machoread.c (macho_add_oso_symfile): Change abfd to
	gdb_bfd_ref_ptr.
	(macho_symfile_read_all_oso): Update.
	(macho_check_dsym): Return gdb_bfd_ref_ptr.
	(macho_symfile_read): Update.
	* jit.c (bfd_open_from_target_memory): Return gdb_bfd_ref_ptr.
	(jit_bfd_try_read_symtab): Update.
	* gdb_bfd.h (gdb_bfd_open, gdb_bfd_fopen, gdb_bfd_openr)
	(gdb_bfd_openw, gdb_bfd_openr_iovec)
	(gdb_bfd_openr_next_archived_file, gdb_bfd_fdopenr): Return
	gdb_bfd_ref_ptr.
	(gdb_bfd_ref_policy): New struct.
	(gdb_bfd_ref_ptr): New typedef.
	* gdb_bfd.c (gdb_bfd_open, gdb_bfd_fopen, gdb_bfd_openr)
	(gdb_bfd_openw, gdb_bfd_openr_iovec)
	(gdb_bfd_openr_next_archived_file, gdb_bfd_fdopenr): Return
	gdb_bfd_ref_ptr.
	* gcore.h (create_gcore_bfd): Return gdb_bfd_ref_ptr.
	* gcore.c (create_gcore_bfd): Return gdb_bfd_ref_ptr.
	(gcore_command): Update.
	* exec.c (exec_file_attach): Update.
	* elfread.c (elf_symfile_read): Update.
	* dwarf2read.c (dwarf2_get_dwz_file): Update.
	(try_open_dwop_file, open_dwo_file): Return gdb_bfd_ref_ptr.
	(open_and_init_dwo_file): Update.
	(open_dwp_file): Return gdb_bfd_ref_ptr.
	(open_and_init_dwp_file): Update.
	* corelow.c (core_open): Update.
	* compile/compile-object-load.c (compile_object_load): Update.
	* common/gdb_ref_ptr.h (ref_ptr::operator->): New operator.
	* coffread.c (coff_symfile_read): Update.
	* cli/cli-dump.c (bfd_openr_or_error, bfd_openw_or_error): Return
	gdb_bfd_ref_ptr.  Rename.
	(dump_bfd_file, restore_command): Update.
	* build-id.h (build_id_to_debug_bfd): Return gdb_bfd_ref_ptr.
	* build-id.c (build_id_to_debug_bfd): Return gdb_bfd_ref_ptr.
	(find_separate_debug_file_by_buildid): Update.

1 files changed, 10 insertions, 20 deletions

diff --git a/gdb/build-id.c b/gdb/build-id.c
index ed66bc6..0f63223 100644
--- a/gdb/build-id.c
+++ b/gdb/build-id.c
@@ -67,14 +67,14 @@ build_id_verify (bfd *abfd, size_t check_len, const bfd_byte *check)
 
 /* See build-id.h.  */
 
-bfd *
+gdb_bfd_ref_ptr
 build_id_to_debug_bfd (size_t build_id_len, const bfd_byte *build_id)
 {
   char *link, *debugdir;
   VEC (char_ptr) *debugdir_vec;
   struct cleanup *back_to;
   int ix;
-  bfd *abfd = NULL;
+  gdb_bfd_ref_ptr abfd;
   int alloc_len;
 
   /* DEBUG_FILE_DIRECTORY/.build-id/ab/cdef */
@@ -127,11 +127,10 @@ build_id_to_debug_bfd (size_t build_id_len, const bfd_byte *build_id)
       if (abfd == NULL)
 	continue;
 
-      if (build_id_verify (abfd, build_id_len, build_id))
+      if (build_id_verify (abfd.get(), build_id_len, build_id))
 	break;
 
-      gdb_bfd_unref (abfd);
-      abfd = NULL;
+      abfd.release ();
     }
 
   do_cleanups (back_to);
@@ -148,25 +147,16 @@ find_separate_debug_file_by_buildid (struct objfile *objfile)
   build_id = build_id_bfd_get (objfile->obfd);
   if (build_id != NULL)
     {
-      bfd *abfd;
-
-      abfd = build_id_to_debug_bfd (build_id->size, build_id->data);
+      gdb_bfd_ref_ptr abfd (build_id_to_debug_bfd (build_id->size,
+						   build_id->data));
       /* Prevent looping on a stripped .debug file.  */
       if (abfd != NULL
-	  && filename_cmp (bfd_get_filename (abfd),
+	  && filename_cmp (bfd_get_filename (abfd.get ()),
 			   objfile_name (objfile)) == 0)
-        {
-	  warning (_("\"%s\": separate debug info file has no debug info"),
-		   bfd_get_filename (abfd));
-	  gdb_bfd_unref (abfd);
-	}
+	warning (_("\"%s\": separate debug info file has no debug info"),
+		 bfd_get_filename (abfd.get ()));
       else if (abfd != NULL)
-	{
-	  char *result = xstrdup (bfd_get_filename (abfd));
-
-	  gdb_bfd_unref (abfd);
-	  return result;
-	}
+	return xstrdup (bfd_get_filename (abfd.get ()));
     }
   return NULL;
 }