Use gdb_bfd_ref_ptr in objfile

This changes struct objfile to use a gdb_bfd_ref_ptr.  In addition to
removing some manual memory management, this fixes a use-after-free
that was introduced by the registry rewrite series.  The issue there
was that, in some cases, registry shutdown could refer to memory that
had already been freed.  This help fix the bug by delaying the
destruction of the BFD reference (and thus the per-bfd object) until
after the registry has been shut down.

5 files changed, 44 insertions, 40 deletions

diff --git a/gdb/dwarf2/frame.c b/gdb/dwarf2/frame.c
index d7a0639..387a2bc 100644
--- a/gdb/dwarf2/frame.c
+++ b/gdb/dwarf2/frame.c
@@ -138,7 +138,7 @@ typedef std::vector<dwarf2_fde *> dwarf2_fde_table;
 struct comp_unit
 {
   comp_unit (struct objfile *objf)
-    : abfd (objf->obfd)
+    : abfd (objf->obfd.get ())
   {
   }
 
@@ -1534,7 +1534,7 @@ bsearch_fde_cmp (const dwarf2_fde *fde, CORE_ADDR seek_pc)
 static comp_unit *
 find_comp_unit (struct objfile *objfile)
 {
-  bfd *abfd = objfile->obfd;
+  bfd *abfd = objfile->obfd.get ();
   if (gdb_bfd_requires_relocations (abfd))
     return dwarf2_frame_objfile_data.get (objfile);
 
@@ -1547,7 +1547,7 @@ find_comp_unit (struct objfile *objfile)
 static void
 set_comp_unit (struct objfile *objfile, struct comp_unit *unit)
 {
-  bfd *abfd = objfile->obfd;
+  bfd *abfd = objfile->obfd.get ();
   if (gdb_bfd_requires_relocations (abfd))
     return dwarf2_frame_objfile_data.set (objfile, unit);
 
diff --git a/gdb/dwarf2/index-cache.c b/gdb/dwarf2/index-cache.c
index a1f6ff5..6de5859 100644
--- a/gdb/dwarf2/index-cache.c
+++ b/gdb/dwarf2/index-cache.c
@@ -101,7 +101,7 @@ index_cache::store (dwarf2_per_objfile *per_objfile)
     return;
 
   /* Get build id of objfile.  */
-  const bfd_build_id *build_id = build_id_bfd_get (obj->obfd);
+  const bfd_build_id *build_id = build_id_bfd_get (obj->obfd.get ());
   if (build_id == nullptr)
     {
       index_cache_debug ("objfile %s has no build id",
diff --git a/gdb/dwarf2/index-write.c b/gdb/dwarf2/index-write.c
index efd154d..b6d8ddd 100644
--- a/gdb/dwarf2/index-write.c
+++ b/gdb/dwarf2/index-write.c
@@ -765,7 +765,7 @@ private:
     /* Object constructor to be called for current DWARF2_PER_OBJFILE.
        All .debug_str section strings are automatically stored.  */
     debug_str_lookup (dwarf2_per_objfile *per_objfile)
-      : m_abfd (per_objfile->objfile->obfd),
+      : m_abfd (per_objfile->objfile->obfd.get ()),
 	m_per_objfile (per_objfile)
     {
       per_objfile->per_bfd->str.read (per_objfile->objfile);
diff --git a/gdb/dwarf2/loc.c b/gdb/dwarf2/loc.c
index f490b68..bf0df61 100644
--- a/gdb/dwarf2/loc.c
+++ b/gdb/dwarf2/loc.c
@@ -355,7 +355,7 @@ dwarf2_find_location_expression (struct dwarf2_loclist_baton *baton,
   struct gdbarch *gdbarch = objfile->arch ();
   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
   unsigned int addr_size = baton->per_cu->addr_size ();
-  int signed_addr_p = bfd_get_sign_extend_vma (objfile->obfd);
+  int signed_addr_p = bfd_get_sign_extend_vma (objfile->obfd.get ());
   /* Adjustment for relocatable objects.  */
   CORE_ADDR text_offset = baton->per_objfile->objfile->text_section_offset ();
   CORE_ADDR base_address = baton->base_address;
@@ -3952,7 +3952,7 @@ loclist_describe_location (struct symbol *symbol, CORE_ADDR addr,
   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
   unsigned int addr_size = dlbaton->per_cu->addr_size ();
   int offset_size = dlbaton->per_cu->offset_size ();
-  int signed_addr_p = bfd_get_sign_extend_vma (objfile->obfd);
+  int signed_addr_p = bfd_get_sign_extend_vma (objfile->obfd.get ());
   /* Adjustment for relocatable objects.  */
   CORE_ADDR text_offset = objfile->text_section_offset ();
   CORE_ADDR base_address = dlbaton->base_address;
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 8c66cb8..f031519 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -1569,23 +1569,24 @@ dwarf2_has_info (struct objfile *objfile,
 	 We don't share with objfiles for which -readnow was requested,
 	 because it would complicate things when loading the same BFD with
 	 -readnow and then without -readnow.  */
-      if (!gdb_bfd_requires_relocations (objfile->obfd)
+      if (!gdb_bfd_requires_relocations (objfile->obfd.get ())
 	  && (objfile->flags & OBJF_READNOW) == 0)
 	{
 	  /* See if one has been created for this BFD yet.  */
-	  per_bfd = dwarf2_per_bfd_bfd_data_key.get (objfile->obfd);
+	  per_bfd = dwarf2_per_bfd_bfd_data_key.get (objfile->obfd.get ());
 
 	  if (per_bfd == nullptr)
 	    {
 	      /* No, create it now.  */
-	      per_bfd = new dwarf2_per_bfd (objfile->obfd, names, can_copy);
-	      dwarf2_per_bfd_bfd_data_key.set (objfile->obfd, per_bfd);
+	      per_bfd = new dwarf2_per_bfd (objfile->obfd.get (), names,
+					    can_copy);
+	      dwarf2_per_bfd_bfd_data_key.set (objfile->obfd.get (), per_bfd);
 	    }
 	}
       else
 	{
 	  /* No sharing possible, create one specifically for this objfile.  */
-	  per_bfd = new dwarf2_per_bfd (objfile->obfd, names, can_copy);
+	  per_bfd = new dwarf2_per_bfd (objfile->obfd.get (), names, can_copy);
 	  dwarf2_per_bfd_objfile_data_key.set (objfile, per_bfd);
 	}
 
@@ -2326,7 +2327,7 @@ read_addrmap_from_aranges (dwarf2_per_objfile *per_objfile,
 			   addrmap *mutable_map)
 {
   struct objfile *objfile = per_objfile->objfile;
-  bfd *abfd = objfile->obfd;
+  bfd *abfd = objfile->obfd.get ();
   struct gdbarch *gdbarch = objfile->arch ();
   const CORE_ADDR baseaddr = objfile->text_section_offset ();
   dwarf2_per_bfd *per_bfd = per_objfile->per_bfd;
@@ -4926,7 +4927,7 @@ dw2_debug_names_iterator::next ()
 
   dwarf2_per_bfd *per_bfd = m_per_objfile->per_bfd;
   struct objfile *objfile = m_per_objfile->objfile;
-  bfd *const abfd = objfile->obfd;
+  bfd *const abfd = objfile->obfd.get ();
 
  again:
 
@@ -5297,7 +5298,7 @@ get_gdb_index_contents_from_section (objfile *obj, T *section_owner)
 static gdb::array_view<const gdb_byte>
 get_gdb_index_contents_from_cache (objfile *obj, dwarf2_per_bfd *dwarf2_per_bfd)
 {
-  const bfd_build_id *build_id = build_id_bfd_get (obj->obfd);
+  const bfd_build_id *build_id = build_id_bfd_get (obj->obfd.get ());
   if (build_id == nullptr)
     return {};
 
@@ -11118,7 +11119,7 @@ try_open_dwop_file (dwarf2_per_objfile *per_objfile,
      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 (per_objfile->objfile->obfd, sym_bfd.get ());
+  gdb_bfd_record_inclusion (per_objfile->objfile->obfd.get (), sym_bfd.get ());
 
   return sym_bfd;
 }
@@ -12645,7 +12646,7 @@ dwarf2_rnglists_process (unsigned offset, struct dwarf2_cu *cu,
 {
   dwarf2_per_objfile *per_objfile = cu->per_objfile;
   struct objfile *objfile = per_objfile->objfile;
-  bfd *obfd = objfile->obfd;
+  bfd *obfd = objfile->obfd.get ();
   /* Base address selection entry.  */
   gdb::optional<CORE_ADDR> base;
   const gdb_byte *buffer;
@@ -12841,7 +12842,7 @@ dwarf2_ranges_process (unsigned offset, struct dwarf2_cu *cu, dwarf_tag tag,
   dwarf2_per_objfile *per_objfile = cu->per_objfile;
   struct objfile *objfile = per_objfile->objfile;
   struct comp_unit_head *cu_header = &cu->header;
-  bfd *obfd = objfile->obfd;
+  bfd *obfd = objfile->obfd.get ();
   unsigned int addr_size = cu_header->addr_size;
   CORE_ADDR mask = ~(~(CORE_ADDR)1 << (addr_size * 8 - 1));
   /* Base address selection entry.  */
@@ -16683,7 +16684,8 @@ get_mpz (struct dwarf2_cu *cu, gdb_mpz *value, struct attribute *attr)
 	  if (ptr - blk->data + len <= blk->size)
 	    {
 	      mpz_import (value->val, len,
-			  bfd_big_endian (cu->per_objfile->objfile->obfd) ? 1 : -1,
+			  bfd_big_endian (cu->per_objfile->objfile->obfd.get ())
+			  ? 1 : -1,
 			  1, 0, 0, ptr);
 	      return;
 	    }
@@ -16696,7 +16698,8 @@ get_mpz (struct dwarf2_cu *cu, gdb_mpz *value, struct attribute *attr)
     {
       dwarf_block *blk = attr->as_block ();
       mpz_import (value->val, blk->size,
-		  bfd_big_endian (cu->per_objfile->objfile->obfd) ? 1 : -1,
+		  bfd_big_endian (cu->per_objfile->objfile->obfd.get ())
+		  ? 1 : -1,
 		  1, 0, 0, blk->data);
     }
   else
@@ -18791,7 +18794,7 @@ read_loclist_index (struct dwarf2_cu *cu, ULONGEST loclist_index)
 {
   dwarf2_per_objfile *per_objfile = cu->per_objfile;
   struct objfile *objfile = per_objfile->objfile;
-  bfd *abfd = objfile->obfd;
+  bfd *abfd = objfile->obfd.get ();
   ULONGEST loclist_header_size =
     (cu->header.initial_length_size == 4 ? LOCLIST_HEADER_SIZE32
      : LOCLIST_HEADER_SIZE64);
@@ -18850,7 +18853,7 @@ read_rnglist_index (struct dwarf2_cu *cu, ULONGEST rnglist_index,
 {
   struct dwarf2_per_objfile *dwarf2_per_objfile = cu->per_objfile;
   struct objfile *objfile = dwarf2_per_objfile->objfile;
-  bfd *abfd = objfile->obfd;
+  bfd *abfd = objfile->obfd.get ();
   ULONGEST rnglist_header_size =
     (cu->header.initial_length_size == 4 ? RNGLIST_HEADER_SIZE32
      : RNGLIST_HEADER_SIZE64);
@@ -19285,7 +19288,7 @@ const char *
 dwarf2_per_objfile::read_line_string (const gdb_byte *buf,
 				      unsigned int offset_size)
 {
-  bfd *abfd = objfile->obfd;
+  bfd *abfd = objfile->obfd.get ();
   ULONGEST str_offset = read_offset (abfd, buf, offset_size);
 
   return per_bfd->line_str.read_string (objfile, str_offset, "DW_FORM_line_strp");
@@ -19298,7 +19301,7 @@ dwarf2_per_objfile::read_line_string (const gdb_byte *buf,
 				      const struct comp_unit_head *cu_header,
 				      unsigned int *bytes_read_ptr)
 {
-  bfd *abfd = objfile->obfd;
+  bfd *abfd = objfile->obfd.get ();
   LONGEST str_offset = cu_header->read_offset (abfd, buf, bytes_read_ptr);
 
   return per_bfd->line_str.read_string (objfile, str_offset, "DW_FORM_line_strp");
@@ -19313,7 +19316,7 @@ read_addr_index_1 (dwarf2_per_objfile *per_objfile, unsigned int addr_index,
 		   gdb::optional<ULONGEST> addr_base, int addr_size)
 {
   struct objfile *objfile = per_objfile->objfile;
-  bfd *abfd = objfile->obfd;
+  bfd *abfd = objfile->obfd.get ();
   const gdb_byte *info_ptr;
   ULONGEST addr_base_or_zero = addr_base.has_value () ? *addr_base : 0;
 
@@ -19349,7 +19352,7 @@ static CORE_ADDR
 read_addr_index_from_leb128 (struct dwarf2_cu *cu, const gdb_byte *info_ptr,
 			     unsigned int *bytes_read)
 {
-  bfd *abfd = cu->per_objfile->objfile->obfd;
+  bfd *abfd = cu->per_objfile->objfile->obfd.get ();
   unsigned int addr_index = read_unsigned_leb128 (abfd, info_ptr, bytes_read);
 
   return read_addr_index (cu, addr_index);
@@ -19411,7 +19414,7 @@ read_str_index (struct dwarf2_cu *cu,
   dwarf2_per_objfile *per_objfile = cu->per_objfile;
   struct objfile *objfile = per_objfile->objfile;
   const char *objf_name = objfile_name (objfile);
-  bfd *abfd = objfile->obfd;
+  bfd *abfd = objfile->obfd.get ();
   const gdb_byte *info_ptr;
   ULONGEST str_offset;
   static const char form_name[] = "DW_FORM_GNU_str_index or DW_FORM_strx";
@@ -20298,7 +20301,7 @@ dwarf_decode_lines_1 (struct line_header *lh, struct dwarf2_cu *cu,
   unsigned char op_code, extended_op;
   CORE_ADDR baseaddr;
   struct objfile *objfile = cu->per_objfile->objfile;
-  bfd *abfd = objfile->obfd;
+  bfd *abfd = objfile->obfd.get ();
   struct gdbarch *gdbarch = objfile->arch ();
 
   baseaddr = objfile->text_section_offset ();
@@ -20635,7 +20638,7 @@ var_decode_location (struct attribute *attr, struct symbol *sym,
 
 	  if (block->data[0] == DW_OP_addr)
 	    sym->set_value_address
-	      (cu->header.read_address (objfile->obfd, block->data + 1,
+	      (cu->header.read_address (objfile->obfd.get (), block->data + 1,
 					&dummy));
 	  else
 	    sym->set_value_address
@@ -21107,7 +21110,7 @@ dwarf2_const_value_data (const struct attribute *attr, struct obstack *obstack,
 			 struct dwarf2_cu *cu, LONGEST *value, int bits)
 {
   struct objfile *objfile = cu->per_objfile->objfile;
-  enum bfd_endian byte_order = bfd_big_endian (objfile->obfd) ?
+  enum bfd_endian byte_order = bfd_big_endian (objfile->obfd.get ()) ?
 				BFD_ENDIAN_BIG : BFD_ENDIAN_LITTLE;
   LONGEST l = attr->constant_value (0);
 
@@ -21145,7 +21148,7 @@ dwarf2_const_value_attr (const struct attribute *attr, struct type *type,
   struct objfile *objfile = per_objfile->objfile;
   struct comp_unit_head *cu_header = &cu->header;
   struct dwarf_block *blk;
-  enum bfd_endian byte_order = (bfd_big_endian (objfile->obfd) ?
+  enum bfd_endian byte_order = (bfd_big_endian (objfile->obfd.get ()) ?
 				BFD_ENDIAN_BIG : BFD_ENDIAN_LITTLE);
 
   *value = 0;
@@ -22497,7 +22500,7 @@ dwarf2_fetch_constant_bytes (sect_offset sect_off,
   if (attr == NULL)
     return NULL;
 
-  byte_order = (bfd_big_endian (objfile->obfd)
+  byte_order = (bfd_big_endian (objfile->obfd.get ())
 		? BFD_ENDIAN_BIG : BFD_ENDIAN_LITTLE);
 
   switch (attr->form)
@@ -23009,43 +23012,44 @@ decode_locdesc (struct dwarf_block *blk, struct dwarf2_cu *cu, bool *computed)
 	  break;
 
 	case DW_OP_addr:
-	  stack[++stacki] = cu->header.read_address (objfile->obfd, &data[i],
+	  stack[++stacki] = cu->header.read_address (objfile->obfd.get (),
+						     &data[i],
 						     &bytes_read);
 	  i += bytes_read;
 	  break;
 
 	case DW_OP_const1u:
-	  stack[++stacki] = read_1_byte (objfile->obfd, &data[i]);
+	  stack[++stacki] = read_1_byte (objfile->obfd.get (), &data[i]);
 	  i += 1;
 	  break;
 
 	case DW_OP_const1s:
-	  stack[++stacki] = read_1_signed_byte (objfile->obfd, &data[i]);
+	  stack[++stacki] = read_1_signed_byte (objfile->obfd.get (), &data[i]);
 	  i += 1;
 	  break;
 
 	case DW_OP_const2u:
-	  stack[++stacki] = read_2_bytes (objfile->obfd, &data[i]);
+	  stack[++stacki] = read_2_bytes (objfile->obfd.get (), &data[i]);
 	  i += 2;
 	  break;
 
 	case DW_OP_const2s:
-	  stack[++stacki] = read_2_signed_bytes (objfile->obfd, &data[i]);
+	  stack[++stacki] = read_2_signed_bytes (objfile->obfd.get (), &data[i]);
 	  i += 2;
 	  break;
 
 	case DW_OP_const4u:
-	  stack[++stacki] = read_4_bytes (objfile->obfd, &data[i]);
+	  stack[++stacki] = read_4_bytes (objfile->obfd.get (), &data[i]);
 	  i += 4;
 	  break;
 
 	case DW_OP_const4s:
-	  stack[++stacki] = read_4_signed_bytes (objfile->obfd, &data[i]);
+	  stack[++stacki] = read_4_signed_bytes (objfile->obfd.get (), &data[i]);
 	  i += 4;
 	  break;
 
 	case DW_OP_const8u:
-	  stack[++stacki] = read_8_bytes (objfile->obfd, &data[i]);
+	  stack[++stacki] = read_8_bytes (objfile->obfd.get (), &data[i]);
 	  i += 8;
 	  break;