Patch: RFA: operate-and-get-next fix

[Tom Tromey <tromey at redhat dot com>]

This patch fixes a recently-discovered problem with operate-and-get-next.

The problem is that C-o doesn't work when entering breakpoint
commands.  The user expects this to work, since such commands are
entered into the readline history.  Also, this is a very useful place
for C-o to work.

Unfortunately, this patch is a bit ugly.  The problem here is that we
need to use one of two different hooks, depending on the way that
readline is called.  But we can't know that in advance, since some
commands will call readline() even when event_loop_p is true.

So we route all calls to readline() through a wrapper function that
rearranges the hook values if required.

A better fix would be to change readline so that rl_pre_input_hook
works correctly even in the event-loop mode.  I believe I mentioned
this during the discussions of the original operate-and-get-next patch.
(I definitely don't have the time to investigate doing that.  Last
time I looked at it but it seemed like a real quagmire.)

Built and tested on x86 Red Hat Linux 6.2.
I tried it using things like:

    if 2 > 1
    p 5
    end

Any comments?
Is this ok to commit?

Tom

Index: ChangeLog
from  Tom Tromey  <tromey@redhat.com>

	* defs.h (gdb_readline_wrapper): Declare.
	* utils.c (prompt_for_continue): Use gdb_readline_wrapper.
	* tracepoint.c (read_actions): Use gdb_readline_wrapper.
	* top.c (gdb_readline_wrapper): New function.
	(command_line_input): Use it.

Index: defs.h
===================================================================
RCS file: /cvs/src/src/gdb/defs.h,v
retrieving revision 1.88
diff -u -r1.88 defs.h
--- defs.h 18 Apr 2002 18:08:59 -0000 1.88
+++ defs.h 24 Apr 2002 01:28:05 -0000
@@ -525,6 +525,8 @@
 
 extern char *gdb_readline (char *);
 
+extern char *gdb_readline_wrapper (char *);
+
 extern char *command_line_input (char *, int, char *);
 
 extern void print_prompt (void);
Index: top.c
===================================================================
RCS file: /cvs/src/src/gdb/top.c,v
retrieving revision 1.61
diff -u -r1.61 top.c
--- top.c 28 Mar 2002 01:35:55 -0000 1.61
+++ top.c 24 Apr 2002 01:28:12 -0000
@@ -947,6 +947,28 @@
 static int history_size;
 static char *history_filename;
 
+/* This is like readline(), but it has some gdb-specific behavior.  In
+   particular, if the user is in the middle of an
+   operate-and-get-next, we shuffle the hooks around so that the
+   expected result occurs.  This is ugly, but it is inevitable given
+   that gdb switches between the two modes (async and not) of using
+   readline and that rl_pre_input_hook doesn't work properly in async
+   mode.  */
+char *
+gdb_readline_wrapper (char *prompt)
+{
+  char *result;
+
+  /* Set the hook that works in this case.  */
+  if (event_loop_p && after_char_processing_hook)
+    {
+      rl_pre_input_hook = after_char_processing_hook;
+      after_char_processing_hook = NULL;
+    }
+
+  result = readline (prompt);
+}
+
 
 #ifdef STOP_SIGNAL
 static void
@@ -1174,7 +1196,7 @@
 	}
       else if (command_editing_p && instream == stdin && ISATTY (instream))
 	{
-	  rl = readline (local_prompt);
+	  rl = gdb_readline_wrapper (local_prompt);
 	}
       else
 	{
Index: tracepoint.c
===================================================================
RCS file: /cvs/src/src/gdb/tracepoint.c,v
retrieving revision 1.36
diff -u -r1.36 tracepoint.c
--- tracepoint.c 27 Mar 2002 21:35:35 -0000 1.36
+++ tracepoint.c 24 Apr 2002 01:28:14 -0000
@@ -854,7 +854,7 @@
 	line = (*readline_hook) (prompt);
       else if (instream == stdin && ISATTY (instream))
 	{
-	  line = readline (prompt);
+	  line = gdb_readline_wrapper (prompt);
 	  if (line && *line)	/* add it to command history */
 	    add_history (line);
 	}
Index: utils.c
===================================================================
RCS file: /cvs/src/src/gdb/utils.c,v
retrieving revision 1.72
diff -u -r1.72 utils.c
--- utils.c 5 Apr 2002 16:39:11 -0000 1.72
+++ utils.c 24 Apr 2002 01:28:15 -0000
@@ -1603,7 +1603,7 @@
   /* Call readline, not gdb_readline, because GO32 readline handles control-C
      whereas control-C to gdb_readline will cause the user to get dumped
      out to DOS.  */
-  ignore = readline (cont_prompt);
+  ignore = gdb_readline_wrapper (cont_prompt);
 
   if (annotation_level > 1)
     printf_unfiltered ("\n\032\032post-prompt-for-continue\n");