[RFC] Add commands to dynamically enable/disable shared library support

[Antony KING <antony dot king at st dot com>]

Hi,

Attached is a patch I have constructed against GDB 6.6 which adds the
following commands to GDB:

* disable sharedlibrary

  This command removes the shared library breakpoints and implicitly
calls the "nosharedlibrary" command. The solib_create_inferior_hook()
API is also disabled (until re-enabled by "enable sharedlibrary").

* enable sharedlibrary

  This command explicitly calls the solib_create_inferior_hook() API and
re-enables the auto loading of shared libraries.

The intent of this patch is to be able to control the insertion of the
breakpoint used to monitor when a shared library is loaded (and so
update GDB's symbolic information). The reason for this is that when
debugging boot from ROM applications it is only legitimate to insert a
breakpoint when the application has been re-located from ROM to RAM. At
present it is only possible to control this by removing the symbolic
information (so that GDB does not "see" the special symbol in the target
application). This is not desirable if one wishes to set a breakpoint
(using a hardware breakpoint) in the loaded application.

I plan to add these commands to the version of GDB we support, unless
someone suggests a better solution, but I would also like to get a wider
opinion (other than my own) on the implementation and whether the
changes a desirable in standard GDB.

Cheers,

Antony.

--- gdb/solib.c@@/main/INSIGHT-6.6-ST-1.0-int/LATEST	2007-08-28 11:30:33.257546000 +0100
+++ gdb/solib.c	2007-08-28 11:26:54.360656000 +0100
@@ -82,6 +82,8 @@
 
 static int solib_cleanup_queued = 0;	/* make_run_cleanup called */
 
+static int solib_enabled = 1;		/* Shared libraries enabled ? */
+
 /* Local function prototypes */
 
 static void do_clear_solib (void *);
@@ -869,7 +871,8 @@
 solib_create_inferior_hook (void)
 {
   struct target_so_ops *ops = solib_ops (current_gdbarch);
-  ops->solib_create_inferior_hook();
+  if (solib_enabled)
+    ops->solib_create_inferior_hook();
 }
 
 /* GLOBAL FUNCTION
@@ -951,6 +954,39 @@
 		    value);
 }
 
+/* LOCAL FUNCTION
+
+   disable_shared_libraries -- handle command to disable shared library
+   support.
+
+   DESCRIPTION
+
+   Implements the command "disable sharedlibrary".  */
+
+static void
+disable_shared_libraries (char *ignored, int from_tty)
+{
+  solib_enabled = 0;
+  remove_solib_event_breakpoints ();
+  no_shared_libraries (NULL, from_tty);
+}
+
+/* LOCAL FUNCTION
+
+   enable_shared_libraries -- handle command to enable shared library
+   support.
+
+   DESCRIPTION
+
+   Implements the command "enable sharedlibrary".  */
+
+static void
+enable_shared_libraries (char *ignored, int from_tty)
+{
+  solib_enabled = 1;
+  solib_create_inferior_hook ();
+  solib_add (NULL, from_tty, NULL, auto_solib_add);
+}
 
 extern initialize_file_ftype _initialize_solib; /* -Wmissing-prototypes */
 
@@ -1001,4 +1037,12 @@
 				     reload_shared_libraries,
 				     show_solib_search_path,
 				     &setlist, &showlist);
+
+  add_cmd ("sharedlibrary", class_support, disable_shared_libraries, _("\
+Disable shared library support."),
+	   &disablelist);
+
+  add_cmd ("sharedlibrary", class_support, enable_shared_libraries, _("\
+Enable shared library support."),
+	   &enablelist);
 }