[PATCH] add-symbol-file-from-memory command

[Roland McGrath <roland at redhat dot com>]

I've cleaned up some nits that Daniel pointed out.  This is the current
version of my add-symbol-file-from-memory patch.  I've tested it and it
works with today's mainline gdb.  Are there any remaining problems people
see with this code?  Can it go in?


Thanks,
Roland


2004-02-11  Roland McGrath  <roland@redhat.com>

	* symfile.c (symbol_file_add_with_addrs_or_offsets): Take ABFD as
	a new argument.  Call symfile_bfd_open only if passed a null pointer.
	(symbol_file_add, reread_separate_symbols): Update callers.
	(build_addr_info): New function, helper for ...
	(symbol_file_add_from_memory): New function.
	(add_symbol_file_from_memory_command): New function using that.
	(_initialize_symfile): Register it for add-symbol-file-from-memory.
	* symfile.h (symbol_file_add_from_memory): Declare it.

Index: symfile.c
===================================================================
RCS file: /cvs/src/src/gdb/symfile.c,v
retrieving revision 1.121
diff -p -u -r1.121 symfile.c
--- symfile.c	9 Feb 2004 23:50:55 -0000	1.121
+++ symfile.c	11 Feb 2004 21:02:31 -0000
@@ -799,6 +799,10 @@ new_symfile_objfile (struct objfile *obj
    NAME is the file name (which will be tilde-expanded and made
    absolute herein) (but we don't free or modify NAME itself).
 
+   If ABFD is not null, it's already open and should be used instead of
+   opening the file by name.  This BFD will be closed on error, and
+   is always consumed by this function.
+
    FROM_TTY says how verbose to be.
 
    MAINLINE specifies whether this is the main symbol file, or whether
@@ -811,7 +815,7 @@ new_symfile_objfile (struct objfile *obj
    Upon success, returns a pointer to the objfile that was added.
    Upon failure, jumps back to command level (never returns). */
 static struct objfile *
-symbol_file_add_with_addrs_or_offsets (char *name, int from_tty,
+symbol_file_add_with_addrs_or_offsets (char *name, bfd *abfd, int from_tty,
                                        struct section_addr_info *addrs,
                                        struct section_offsets *offsets,
                                        int num_offsets,
@@ -820,14 +824,16 @@ symbol_file_add_with_addrs_or_offsets (c
   struct objfile *objfile;
   struct partial_symtab *psymtab;
   char *debugfile;
-  bfd *abfd;
   struct section_addr_info *orig_addrs;
   struct cleanup *my_cleanups;
 
   /* Open a bfd for the file, and give user a chance to burp if we'd be
      interactively wiping out any existing symbols.  */
 
-  abfd = symfile_bfd_open (name);
+  if (abfd == NULL)
+    abfd = symfile_bfd_open (name);
+
+  my_cleanups = make_cleanup_bfd_close (abfd);
 
   if ((have_full_symbols () || have_partial_symbols ())
       && mainline
@@ -836,6 +842,7 @@ symbol_file_add_with_addrs_or_offsets (c
     error ("Not confirmed.");
 
   objfile = allocate_objfile (abfd, flags);
+  discard_cleanups (my_cleanups);
 
   orig_addrs = alloc_section_addr_info (bfd_count_sections (abfd));
   my_cleanups = make_cleanup (xfree, orig_addrs);
@@ -952,7 +959,8 @@ struct objfile *
 symbol_file_add (char *name, int from_tty, struct section_addr_info *addrs,
 		 int mainline, int flags)
 {
-  return symbol_file_add_with_addrs_or_offsets (name, from_tty, addrs, 0, 0, 
+  return symbol_file_add_with_addrs_or_offsets (name, NULL, from_tty,
+						addrs, 0, 0,
                                                 mainline, flags);
 }
 
@@ -1802,6 +1810,88 @@ add_shared_symbol_files_command (char *a
 #endif
 }
 
+/* Read inferior memory at ADDR to find the header of a loaded object file
+   and read its in-core symbols out of inferior memory.  TEMPL is a bfd
+   representing the target's format.  */
+struct objfile *
+symbol_file_add_from_memory (bfd *templ, CORE_ADDR addr, int from_tty)
+{
+  struct objfile *objf;
+  bfd *nbfd;
+  asection *sec;
+  bfd_vma loadbase;
+  struct section_addr_info *sai;
+  unsigned int i;
+
+  if (bfd_get_flavour (templ) != bfd_target_elf_flavour)
+    error ("add-symbol-file-from-memory not supported for this target");
+
+  nbfd = bfd_elf_bfd_from_remote_memory (templ, addr, &loadbase,
+					 target_read_memory);
+  if (nbfd == NULL)
+    {
+      error ("Failed to read a valid object file image from memory.");
+      return NULL;
+    }
+
+  nbfd->filename = xstrdup ("shared object read from target memory");
+
+  if (!bfd_check_format (nbfd, bfd_object))
+    {
+      /* FIXME: should be checking for errors from bfd_close (for one thing,
+         on error it does not free all the storage associated with the
+         bfd).  */
+      bfd_close (nbfd);
+      error ("Got object file from memory but can't read symbols: %s.",
+	     bfd_errmsg (bfd_get_error ()));
+      return NULL;
+    }
+
+  sai = alloc_section_addr_info (bfd_count_sections (nbfd));
+  make_cleanup (xfree, sai);
+  i = 0;
+  for (sec = nbfd->sections; sec != NULL; sec = sec->next)
+    if ((bfd_get_section_flags (nbfd, sec) & (SEC_ALLOC|SEC_LOAD)) != 0)
+      {
+	sai->other[i].addr = bfd_get_section_vma (nbfd, sec) + loadbase;
+	sai->other[i].name = (char *) bfd_get_section_name (nbfd, sec);
+	sai->other[i].sectindex = sec->index;
+	++i;
+      }
+
+  objf = symbol_file_add_with_addrs_or_offsets ((char *) nbfd->filename, nbfd,
+						from_tty, sai, NULL, 0, 0,
+						OBJF_SHARED);
+
+  /* This might change our ideas about frames already looked at.  */
+  reinit_frame_cache ();
+
+  return objf;
+}
+
+static void
+add_symbol_file_from_memory_command (char *args, int from_tty)
+{
+  CORE_ADDR addr;
+  bfd *templ;
+
+  if (args == NULL)
+    error ("add-symbol-file-from-memory requires an expression argument");
+
+  addr = parse_and_eval_address (args);
+
+  /* We need some representative bfd to know the target we are looking at.  */
+  if (symfile_objfile != NULL)
+    templ = symfile_objfile->obfd;
+  else
+    templ = exec_bfd;
+  if (templ == NULL)
+    error ("\
+Must use symbol-file or exec-file before add-symbol-file-from-memory.");
+
+  (void) symbol_file_add_from_memory (templ, addr, from_tty);
+}
+
 /* Re-read symbols if a symbol-file has changed.  */
 void
 reread_symbols (void)
@@ -3561,6 +3651,13 @@ with the text.  SECT is a section name t
 	       &cmdlist);
   set_cmd_completer (c, filename_completer);
 
+  c = add_cmd ("add-symbol-file-from-memory", class_files,
+	       add_symbol_file_from_memory_command,
+	       "\
+Load the symbols out of memory from a dynamically loaded object file.\n\
+Give an expression for the address of the file's shared object file header.",
+	       &cmdlist);
+
   c = add_cmd ("add-shared-symbol-files", class_files,
 	       add_shared_symbol_files_command,
    "Load the symbols from shared objects in the dynamic linker's link map.",
Index: symfile.h
===================================================================
RCS file: /cvs/src/src/gdb/symfile.h,v
retrieving revision 1.26
diff -p -u -r1.26 symfile.h
--- symfile.h	7 Feb 2004 23:13:47 -0000	1.26
+++ symfile.h	11 Feb 2004 21:02:31 -0000
@@ -306,6 +306,12 @@ extern CORE_ADDR symbol_overlayed_addres
 /* Load symbols from a file.  */
 extern void symbol_file_add_main (char *args, int from_tty);
 
+/* Read inferior memory at ADDR to find the header of a loaded object file
+   and read its in-core symbols out of inferior memory.  TEMPL is a bfd
+   representing the target's format.  */
+extern struct objfile *symbol_file_add_from_memory (bfd *templ, CORE_ADDR addr,
+						    int from_tty);
+
 /* Clear GDB symbol tables.  */
 extern void symbol_file_clear (int from_tty);