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, 15 insertions, 16 deletions

diff --git a/gdb/solib-svr4.c b/gdb/solib-svr4.c
index b362e8c..4f52251 100644
--- a/gdb/solib-svr4.c
+++ b/gdb/solib-svr4.c
@@ -2355,7 +2355,6 @@ enable_break (struct svr4_info *info, int from_tty)
       int load_addr_found = 0;
       int loader_found_in_list = 0;
       struct so_list *so;
-      bfd *tmp_bfd = NULL;
       struct target_ops *tmp_bfd_target;
 
       sym_addr = 0;
@@ -2369,6 +2368,7 @@ enable_break (struct svr4_info *info, int from_tty)
          be trivial on GNU/Linux).  Therefore, we have to try an alternate
          mechanism to find the dynamic linker's base address.  */
 
+      gdb_bfd_ref_ptr tmp_bfd;
       TRY
         {
 	  tmp_bfd = solib_bfd_open (interp_name);
@@ -2382,11 +2382,9 @@ enable_break (struct svr4_info *info, int from_tty)
 	goto bkpt_at_symbol;
 
       /* Now convert the TMP_BFD into a target.  That way target, as
-         well as BFD operations can be used.  */
-      tmp_bfd_target = target_bfd_reopen (tmp_bfd);
-      /* target_bfd_reopen acquired its own reference, so we can
-         release ours now.  */
-      gdb_bfd_unref (tmp_bfd);
+         well as BFD operations can be used.  target_bfd_reopen
+         acquires its own reference.  */
+      tmp_bfd_target = target_bfd_reopen (tmp_bfd.get ());
 
       /* On a running target, we can get the dynamic linker's base
          address from the shared library table.  */
@@ -2397,7 +2395,7 @@ enable_break (struct svr4_info *info, int from_tty)
 	    {
 	      load_addr_found = 1;
 	      loader_found_in_list = 1;
-	      load_addr = lm_addr_check (so, tmp_bfd);
+	      load_addr = lm_addr_check (so, tmp_bfd.get ());
 	      break;
 	    }
 	  so = so->next;
@@ -2418,7 +2416,7 @@ enable_break (struct svr4_info *info, int from_tty)
 	    if (addr_bit < (sizeof (CORE_ADDR) * HOST_CHAR_BIT))
 	      {
 		CORE_ADDR space_size = (CORE_ADDR) 1 << addr_bit;
-		CORE_ADDR tmp_entry_point = exec_entry_point (tmp_bfd,
+		CORE_ADDR tmp_entry_point = exec_entry_point (tmp_bfd.get (),
 							      tmp_bfd_target);
 
 		gdb_assert (load_addr < space_size);
@@ -2447,7 +2445,7 @@ enable_break (struct svr4_info *info, int from_tty)
 	    = get_thread_arch_regcache (inferior_ptid, target_gdbarch ());
 
 	  load_addr = (regcache_read_pc (regcache)
-		       - exec_entry_point (tmp_bfd, tmp_bfd_target));
+		       - exec_entry_point (tmp_bfd.get (), tmp_bfd_target));
 	}
 
       if (!loader_found_in_list)
@@ -2460,29 +2458,30 @@ enable_break (struct svr4_info *info, int from_tty)
 
       /* Record the relocated start and end address of the dynamic linker
          text and plt section for svr4_in_dynsym_resolve_code.  */
-      interp_sect = bfd_get_section_by_name (tmp_bfd, ".text");
+      interp_sect = bfd_get_section_by_name (tmp_bfd.get (), ".text");
       if (interp_sect)
 	{
 	  info->interp_text_sect_low =
-	    bfd_section_vma (tmp_bfd, interp_sect) + load_addr;
+	    bfd_section_vma (tmp_bfd.get (), interp_sect) + load_addr;
 	  info->interp_text_sect_high =
 	    info->interp_text_sect_low
-	    + bfd_section_size (tmp_bfd, interp_sect);
+	    + bfd_section_size (tmp_bfd.get (), interp_sect);
 	}
-      interp_sect = bfd_get_section_by_name (tmp_bfd, ".plt");
+      interp_sect = bfd_get_section_by_name (tmp_bfd.get (), ".plt");
       if (interp_sect)
 	{
 	  info->interp_plt_sect_low =
-	    bfd_section_vma (tmp_bfd, interp_sect) + load_addr;
+	    bfd_section_vma (tmp_bfd.get (), interp_sect) + load_addr;
 	  info->interp_plt_sect_high =
 	    info->interp_plt_sect_low
-	    + bfd_section_size (tmp_bfd, interp_sect);
+	    + bfd_section_size (tmp_bfd.get (), interp_sect);
 	}
 
       /* Now try to set a breakpoint in the dynamic linker.  */
       for (bkpt_namep = solib_break_names; *bkpt_namep != NULL; bkpt_namep++)
 	{
-	  sym_addr = gdb_bfd_lookup_symbol (tmp_bfd, cmp_name_and_sec_flags,
+	  sym_addr = gdb_bfd_lookup_symbol (tmp_bfd.get (),
+					    cmp_name_and_sec_flags,
 					    *bkpt_namep);
 	  if (sym_addr != 0)
 	    break;