Use a single, consistent representation for an empty minimal

symbol table in an objfile.
* objfiles.c (terminate_minimal_symbol_table): New function.
(allocate_objfile): Call it.
* objfiles.h (terminate_minimal_symbol_table): New declaration.
(ALL_MSYMBOLS): No need to test whether (objfile)->msymbols is
non-NULL.
* minsyms.c (lookup_minimal_symbol_by_pc_section): To see whether
objfile has minimal symbols, compare minimal_symbol_count to zero,
instead of comparing msymbols with NULL.
* objfiles.c (have_minimal_symbols): Same.
* solib-sunos.c (solib_add_common_symbols): Call
terminate_minimal_symbol_table.
* symfile.c (reread_symbols): Same.

gdb/ChangeLog

@@ -1,3 +1,20 @@
+2003-02-03  Jim Blandy  <jimb@redhat.com>
+
+	Use a single, consistent representation for an empty minimal
+	symbol table in an objfile.
+	* objfiles.c (terminate_minimal_symbol_table): New function.
+	(allocate_objfile): Call it.
+	* objfiles.h (terminate_minimal_symbol_table): New declaration.
+	(ALL_MSYMBOLS): No need to test whether (objfile)->msymbols is
+	non-NULL. 
+	* minsyms.c (lookup_minimal_symbol_by_pc_section): To see whether
+	objfile has minimal symbols, compare minimal_symbol_count to zero,
+	instead of comparing msymbols with NULL.
+	* objfiles.c (have_minimal_symbols): Same.
+	* solib-sunos.c (solib_add_common_symbols): Call
+	terminate_minimal_symbol_table.
+	* symfile.c (reread_symbols): Same.
+	
 2003-02-03  Kevin Buettner  <kevinb@redhat.com>
 
 	* s390-tdep.c (s390_address_class_type_flags)

gdb/minsyms.c

@@ -411,8 +411,9 @@ lookup_minimal_symbol_by_pc_section (CORE_ADDR pc, asection *section)
          "null symbol".  If there are no real symbols, then there is no
          minimal symbol table at all. */
 
-      if ((msymbol = objfile->msymbols) != NULL)
+      if (objfile->minimal_symbol_count > 0)
 	{
+          msymbol = objfile->msymbols;
 	  lo = 0;
 	  hi = objfile->minimal_symbol_count - 1;
 

gdb/objfiles.c

@@ -281,6 +281,8 @@ allocate_objfile (bfd *abfd, int flags)
       obstack_specify_allocation (&objfile->type_obstack, 0, 0, xmalloc,
 				  xfree);
       flags &= ~OBJF_MAPPED;
+
+      terminate_minimal_symbol_table (objfile);
     }
 
   /* Update the per-objfile information that comes from the bfd, ensuring
@@ -333,6 +335,33 @@ allocate_objfile (bfd *abfd, int flags)
   return (objfile);
 }
 
+
+/* Create the terminating entry of OBJFILE's minimal symbol table.
+   If OBJFILE->msymbols is zero, allocate a single entry from
+   OBJFILE->symbol_obstack; otherwise, just initialize
+   OBJFILE->msymbols[OBJFILE->minimal_symbol_count].  */
+void
+terminate_minimal_symbol_table (struct objfile *objfile)
+{
+  if (! objfile->msymbols)
+    objfile->msymbols = ((struct minimal_symbol *)
+                         obstack_alloc (&objfile->symbol_obstack,
+                                        sizeof (objfile->msymbols[0])));
+
+  {
+    struct minimal_symbol *m
+      = &objfile->msymbols[objfile->minimal_symbol_count];
+
+    memset (m, 0, sizeof (*m));
+    SYMBOL_NAME (m) = NULL;
+    SYMBOL_VALUE_ADDRESS (m) = 0;
+    MSYMBOL_INFO (m) = NULL;
+    MSYMBOL_TYPE (m) = mst_unknown;
+    SYMBOL_INIT_LANGUAGE_SPECIFIC (m, language_unknown);
+  }
+}
+
+
 /* Put one object file before a specified on in the global list.
    This can be used to make sure an object file is destroyed before
    another when using ALL_OBJFILES_SAFE to free all objfiles. */
@@ -810,7 +839,7 @@ have_minimal_symbols (void)
 
   ALL_OBJFILES (ofp)
   {
-    if (ofp->msymbols != NULL)
+    if (ofp->minimal_symbol_count > 0)
       {
 	return 1;
       }

gdb/objfiles.h

@@ -515,6 +515,8 @@ extern struct objfile *allocate_objfile (bfd *, int);
 
 extern int build_objfile_section_table (struct objfile *);
 
+extern void terminate_minimal_symbol_table (struct objfile *objfile);
+
 extern void put_objfile_before (struct objfile *, struct objfile *);
 
 extern void objfile_to_front (struct objfile *);
@@ -595,8 +597,7 @@ extern int is_in_import_list (char *, struct objfile *);
 
 #define	ALL_MSYMBOLS(objfile, m) \
   ALL_OBJFILES (objfile)	 \
-    if ((objfile)->msymbols)	 \
+    ALL_OBJFILE_MSYMBOLS (objfile, m)
-      ALL_OBJFILE_MSYMBOLS (objfile, m)
 
 #define ALL_OBJFILE_OSECTIONS(objfile, osect)	\
   for (osect = objfile->sections; osect < objfile->sections_end; osect++)

gdb/solib-sunos.c

@@ -184,6 +184,7 @@ solib_add_common_symbols (CORE_ADDR rtc_symp)
 				  xmalloc, xfree);
       rt_common_objfile->minimal_symbol_count = 0;
       rt_common_objfile->msymbols = NULL;
+      terminate_minimal_symbol_table (rt_common_objfile);
     }
 
   init_minimal_symbol_collection ();

gdb/symfile.c

@@ -2019,6 +2019,7 @@ reread_symbols (void)
 		  error ("Can't find the file sections in `%s': %s",
 			 objfile->name, bfd_errmsg (bfd_get_error ()));
 		}
+              terminate_minimal_symbol_table (objfile);
 
 	      /* We use the same section offsets as from last time.  I'm not
 	         sure whether that is always correct for shared libraries.  */