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, 30 insertions, 39 deletions

diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index 227dd5b..8a66848 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -2479,7 +2479,6 @@ locate_dwz_sections (bfd *abfd, asection *sectp, void *arg)
 static struct dwz_file *
 dwarf2_get_dwz_file (void)
 {
-  bfd *dwz_bfd;
   char *data;
   struct cleanup *cleanup;
   const char *filename;
@@ -2523,14 +2522,11 @@ dwarf2_get_dwz_file (void)
 
   /* First try the file name given in the section.  If that doesn't
      work, try to use the build-id instead.  */
-  dwz_bfd = gdb_bfd_open (filename, gnutarget, -1);
+  gdb_bfd_ref_ptr dwz_bfd (gdb_bfd_open (filename, gnutarget, -1));
   if (dwz_bfd != NULL)
     {
-      if (!build_id_verify (dwz_bfd, buildid_len, buildid))
-	{
-	  gdb_bfd_unref (dwz_bfd);
-	  dwz_bfd = NULL;
-	}
+      if (!build_id_verify (dwz_bfd.get (), buildid_len, buildid))
+	dwz_bfd.release ();
     }
 
   if (dwz_bfd == NULL)
@@ -2542,13 +2538,13 @@ dwarf2_get_dwz_file (void)
 
   result = OBSTACK_ZALLOC (&dwarf2_per_objfile->objfile->objfile_obstack,
 			   struct dwz_file);
-  result->dwz_bfd = dwz_bfd;
+  result->dwz_bfd = dwz_bfd.release ();
 
-  bfd_map_over_sections (dwz_bfd, locate_dwz_sections, result);
+  bfd_map_over_sections (result->dwz_bfd, locate_dwz_sections, result);
 
   do_cleanups (cleanup);
 
-  gdb_bfd_record_inclusion (dwarf2_per_objfile->objfile->obfd, dwz_bfd);
+  gdb_bfd_record_inclusion (dwarf2_per_objfile->objfile->obfd, result->dwz_bfd);
   dwarf2_per_objfile->dwz_file = result;
   return result;
 }
@@ -10454,10 +10450,9 @@ lookup_dwo_unit_in_dwp (struct dwp_file *dwp_file, const char *comp_dir,
    If unable to find/open the file, return NULL.
    NOTE: This function is derived from symfile_bfd_open.  */
 
-static bfd *
+static gdb_bfd_ref_ptr
 try_open_dwop_file (const char *file_name, int is_dwp, int search_cwd)
 {
-  bfd *sym_bfd;
   int desc, flags;
   char *absolute_name;
   /* Blech.  OPF_TRY_CWD_FIRST also disables searching the path list if
@@ -10486,23 +10481,20 @@ try_open_dwop_file (const char *file_name, int is_dwp, int search_cwd)
   if (desc < 0)
     return NULL;
 
-  sym_bfd = gdb_bfd_open (absolute_name, gnutarget, desc);
+  gdb_bfd_ref_ptr sym_bfd (gdb_bfd_open (absolute_name, gnutarget, desc));
   xfree (absolute_name);
   if (sym_bfd == NULL)
     return NULL;
-  bfd_set_cacheable (sym_bfd, 1);
+  bfd_set_cacheable (sym_bfd.get (), 1);
 
-  if (!bfd_check_format (sym_bfd, bfd_object))
-    {
-      gdb_bfd_unref (sym_bfd); /* This also closes desc.  */
-      return NULL;
-    }
+  if (!bfd_check_format (sym_bfd.get (), bfd_object))
+    return NULL;
 
   /* Success.  Record the bfd as having been included by the objfile's bfd.
      This is important because things like demangled_names_hash lives in the
      objfile's per_bfd space and may have references to things like symbol
      names that live in the DWO/DWP file's per_bfd space.  PR 16426.  */
-  gdb_bfd_record_inclusion (dwarf2_per_objfile->objfile->obfd, sym_bfd);
+  gdb_bfd_record_inclusion (dwarf2_per_objfile->objfile->obfd, sym_bfd.get ());
 
   return sym_bfd;
 }
@@ -10514,11 +10506,9 @@ try_open_dwop_file (const char *file_name, int is_dwp, int search_cwd)
    Upon success, the canonicalized path of the file is stored in the bfd,
    same as symfile_bfd_open.  */
 
-static bfd *
+static gdb_bfd_ref_ptr
 open_dwo_file (const char *file_name, const char *comp_dir)
 {
-  bfd *abfd;
-
   if (IS_ABSOLUTE_PATH (file_name))
     return try_open_dwop_file (file_name, 0 /*is_dwp*/, 0 /*search_cwd*/);
 
@@ -10531,7 +10521,8 @@ open_dwo_file (const char *file_name, const char *comp_dir)
 
       /* NOTE: If comp_dir is a relative path, this will also try the
 	 search path, which seems useful.  */
-      abfd = try_open_dwop_file (path_to_try, 0 /*is_dwp*/, 1 /*search_cwd*/);
+      gdb_bfd_ref_ptr abfd (try_open_dwop_file (path_to_try, 0 /*is_dwp*/,
+						1 /*search_cwd*/));
       xfree (path_to_try);
       if (abfd != NULL)
 	return abfd;
@@ -10617,10 +10608,9 @@ open_and_init_dwo_file (struct dwarf2_per_cu_data *per_cu,
 {
   struct objfile *objfile = dwarf2_per_objfile->objfile;
   struct dwo_file *dwo_file;
-  bfd *dbfd;
   struct cleanup *cleanups;
 
-  dbfd = open_dwo_file (dwo_name, comp_dir);
+  gdb_bfd_ref_ptr dbfd (open_dwo_file (dwo_name, comp_dir));
   if (dbfd == NULL)
     {
       if (dwarf_read_debug)
@@ -10630,11 +10620,12 @@ open_and_init_dwo_file (struct dwarf2_per_cu_data *per_cu,
   dwo_file = OBSTACK_ZALLOC (&objfile->objfile_obstack, struct dwo_file);
   dwo_file->dwo_name = dwo_name;
   dwo_file->comp_dir = comp_dir;
-  dwo_file->dbfd = dbfd;
+  dwo_file->dbfd = dbfd.release ();
 
   cleanups = make_cleanup (free_dwo_file_cleanup, dwo_file);
 
-  bfd_map_over_sections (dbfd, dwarf2_locate_dwo_sections, &dwo_file->sections);
+  bfd_map_over_sections (dwo_file->dbfd, dwarf2_locate_dwo_sections,
+			 &dwo_file->sections);
 
   dwo_file->cu = create_dwo_cu (dwo_file);
 
@@ -10786,12 +10777,11 @@ allocate_dwp_loaded_cutus_table (struct objfile *objfile)
    Upon success, the canonicalized path of the file is stored in the bfd,
    same as symfile_bfd_open.  */
 
-static bfd *
+static gdb_bfd_ref_ptr
 open_dwp_file (const char *file_name)
 {
-  bfd *abfd;
-
-  abfd = try_open_dwop_file (file_name, 1 /*is_dwp*/, 1 /*search_cwd*/);
+  gdb_bfd_ref_ptr abfd (try_open_dwop_file (file_name, 1 /*is_dwp*/,
+					    1 /*search_cwd*/));
   if (abfd != NULL)
     return abfd;
 
@@ -10825,7 +10815,6 @@ open_and_init_dwp_file (void)
   struct objfile *objfile = dwarf2_per_objfile->objfile;
   struct dwp_file *dwp_file;
   char *dwp_name;
-  bfd *dbfd;
   struct cleanup *cleanups = make_cleanup (null_cleanup, 0);
 
   /* Try to find first .dwp for the binary file before any symbolic links
@@ -10847,7 +10836,7 @@ open_and_init_dwp_file (void)
     dwp_name = xstrprintf ("%s.dwp", objfile->original_name);
   make_cleanup (xfree, dwp_name);
 
-  dbfd = open_dwp_file (dwp_name);
+  gdb_bfd_ref_ptr dbfd (open_dwp_file (dwp_name));
   if (dbfd == NULL
       && strcmp (objfile->original_name, objfile_name (objfile)) != 0)
     {
@@ -10865,17 +10854,18 @@ open_and_init_dwp_file (void)
       return NULL;
     }
   dwp_file = OBSTACK_ZALLOC (&objfile->objfile_obstack, struct dwp_file);
-  dwp_file->name = bfd_get_filename (dbfd);
-  dwp_file->dbfd = dbfd;
+  dwp_file->name = bfd_get_filename (dbfd.get ());
+  dwp_file->dbfd = dbfd.release ();
   do_cleanups (cleanups);
 
   /* +1: section 0 is unused */
-  dwp_file->num_sections = bfd_count_sections (dbfd) + 1;
+  dwp_file->num_sections = bfd_count_sections (dwp_file->dbfd) + 1;
   dwp_file->elf_sections =
     OBSTACK_CALLOC (&objfile->objfile_obstack,
 		    dwp_file->num_sections, asection *);
 
-  bfd_map_over_sections (dbfd, dwarf2_locate_common_dwp_sections, dwp_file);
+  bfd_map_over_sections (dwp_file->dbfd, dwarf2_locate_common_dwp_sections,
+			 dwp_file);
 
   dwp_file->cus = create_dwp_hash_table (dwp_file, 0);
 
@@ -10895,7 +10885,8 @@ open_and_init_dwp_file (void)
   dwp_file->version = dwp_file->cus->version;
 
   if (dwp_file->version == 2)
-    bfd_map_over_sections (dbfd, dwarf2_locate_v2_dwp_sections, dwp_file);
+    bfd_map_over_sections (dwp_file->dbfd, dwarf2_locate_v2_dwp_sections,
+			   dwp_file);
 
   dwp_file->loaded_cus = allocate_dwp_loaded_cutus_table (objfile);
   dwp_file->loaded_tus = allocate_dwp_loaded_cutus_table (objfile);