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, 50 insertions, 31 deletions

diff --git a/gdb/gdb_bfd.h b/gdb/gdb_bfd.h
index 3d837d2..a36d782 100644
--- a/gdb/gdb_bfd.h
+++ b/gdb/gdb_bfd.h
@@ -21,6 +21,7 @@
 #define GDB_BFD_H
 
 #include "registry.h"
+#include "common/gdb_ref_ptr.h"
 
 DECLARE_REGISTRY (bfd);
 
@@ -39,6 +40,34 @@ int is_target_filename (const char *name);
 
 int gdb_bfd_has_target_filename (struct bfd *abfd);
 
+/* Increment the reference count of ABFD.  It is fine for ABFD to be
+   NULL; in this case the function does nothing.  */
+
+void gdb_bfd_ref (struct bfd *abfd);
+
+/* Decrement the reference count of ABFD.  If this is the last
+   reference, ABFD will be freed.  If ABFD is NULL, this function does
+   nothing.  */
+
+void gdb_bfd_unref (struct bfd *abfd);
+
+/* A policy class for gdb::ref_ptr for BFD reference counting.  */
+struct gdb_bfd_ref_policy
+{
+  static void incref (struct bfd *abfd)
+  {
+    gdb_bfd_ref (abfd);
+  }
+
+  static void decref (struct bfd *abfd)
+  {
+    gdb_bfd_unref (abfd);
+  }
+};
+
+/* A gdb::ref_ptr that has been specialized for BFD objects.  */
+typedef gdb::ref_ptr<struct bfd, gdb_bfd_ref_policy> gdb_bfd_ref_ptr;
+
 /* Open a read-only (FOPEN_RB) BFD given arguments like bfd_fopen.
    If NAME starts with TARGET_SYSROOT_PREFIX then the BFD will be
    opened using target fileio operations if necessary.  Returns NULL
@@ -51,18 +80,7 @@ int gdb_bfd_has_target_filename (struct bfd *abfd);
    not be exactly NAME but rather NAME with TARGET_SYSROOT_PREFIX
    stripped.  */
 
-struct bfd *gdb_bfd_open (const char *name, const char *target, int fd);
-
-/* Increment the reference count of ABFD.  It is fine for ABFD to be
-   NULL; in this case the function does nothing.  */
-
-void gdb_bfd_ref (struct bfd *abfd);
-
-/* Decrement the reference count of ABFD.  If this is the last
-   reference, ABFD will be freed.  If ABFD is NULL, this function does
-   nothing.  */
-
-void gdb_bfd_unref (struct bfd *abfd);
+gdb_bfd_ref_ptr gdb_bfd_open (const char *name, const char *target, int fd);
 
 /* Mark the CHILD BFD as being a member of PARENT.  Also, increment
    the reference count of CHILD.  Calling this function ensures that
@@ -110,45 +128,46 @@ int gdb_bfd_crc (struct bfd *abfd, unsigned long *crc_out);
 /* A wrapper for bfd_fopen that initializes the gdb-specific reference
    count.  */
 
-bfd *gdb_bfd_fopen (const char *, const char *, const char *, int);
+gdb_bfd_ref_ptr gdb_bfd_fopen (const char *, const char *, const char *, int);
 
 /* A wrapper for bfd_openr that initializes the gdb-specific reference
    count.  */
 
-bfd *gdb_bfd_openr (const char *, const char *);
+gdb_bfd_ref_ptr gdb_bfd_openr (const char *, const char *);
 
 /* A wrapper for bfd_openw that initializes the gdb-specific reference
    count.  */
 
-bfd *gdb_bfd_openw (const char *, const char *);
+gdb_bfd_ref_ptr gdb_bfd_openw (const char *, const char *);
 
 /* A wrapper for bfd_openr_iovec that initializes the gdb-specific
    reference count.  */
 
-bfd *gdb_bfd_openr_iovec (const char *filename, const char *target,
-			  void *(*open_func) (struct bfd *nbfd,
-					      void *open_closure),
-			  void *open_closure,
-			  file_ptr (*pread_func) (struct bfd *nbfd,
-						  void *stream,
-						  void *buf,
-						  file_ptr nbytes,
-						  file_ptr offset),
-			  int (*close_func) (struct bfd *nbfd,
-					     void *stream),
-			  int (*stat_func) (struct bfd *abfd,
-					    void *stream,
-					    struct stat *sb));
+gdb_bfd_ref_ptr gdb_bfd_openr_iovec (const char *filename, const char *target,
+				     void *(*open_func) (struct bfd *nbfd,
+							 void *open_closure),
+				     void *open_closure,
+				     file_ptr (*pread_func) (struct bfd *nbfd,
+							     void *stream,
+							     void *buf,
+							     file_ptr nbytes,
+							     file_ptr offset),
+				     int (*close_func) (struct bfd *nbfd,
+							void *stream),
+				     int (*stat_func) (struct bfd *abfd,
+						       void *stream,
+						       struct stat *sb));
 
 /* A wrapper for bfd_openr_next_archived_file that initializes the
    gdb-specific reference count.  */
 
-bfd *gdb_bfd_openr_next_archived_file (bfd *archive, bfd *previous);
+gdb_bfd_ref_ptr gdb_bfd_openr_next_archived_file (bfd *archive, bfd *previous);
 
 /* A wrapper for bfd_fdopenr that initializes the gdb-specific
    reference count.  */
 
-bfd *gdb_bfd_fdopenr (const char *filename, const char *target, int fd);
+gdb_bfd_ref_ptr gdb_bfd_fdopenr (const char *filename, const char *target,
+				 int fd);