Re: [rfc] Stop unlikely "run"'s earlier

[Daniel Jacobowitz <drow at false dot org>]

On Sat, Nov 17, 2007 at 01:32:16PM +0200, Eli Zaretskii wrote:
> Well, under "target remote" (in the node "Connecting") we say:
> 
>     Once the connection has been established, you can use all the usual
>     commands to examine and change data and to step and continue the
>     remote program.
> 
> Given you description, I'd say this should be augmented by explaining
> that the program is already running at this stage, and telling the
> user to use "continue", as opposed to "run" in local debugging.
> 
> Also, under "run" (in node "Starting"), it'd be a good thing to cite
> the error message you want top introduce:
> 
>   The "remote" target can not run programs.  Try "help target" or "continue".
> 
> and tell the reader that the most probable cause here is that "run"
> was used rather than "continue".  Without such an explanation, I'd be
> quite lost if I saw this message (what do you mean ``can't run''? how
> can I debug the darn thing it it cannot be run?)
> 
> WDYT?

Hi Eli, sorry for the delay.  Is this documentation OK?  I also
changed the error message, to one I hope is slightly less confusing:

The "remote" target does not support "run".  Try "help target" or "continue".

-- 
Daniel Jacobowitz
CodeSourcery

2008-02-27  Daniel Jacobowitz  <dan@codesourcery.com>

	* infcmd.c (kill_if_already_running): Make static.  Use
	target_require_runnable.
	* target.c (target_require_runnable): New.
	* target.h (target_require_runnable): Declare.

2008-02-27  Daniel Jacobowitz  <dan@codesourcery.com>

	* gdb.texinfo (Starting): Mention always-running targets.
	(Target Commands): Add an anchor for load.
	(Connecting): Explain continue instead of run.

Index: infcmd.c
===================================================================
RCS file: /cvs/src/src/gdb/infcmd.c,v
retrieving revision 1.169
diff -u -p -r1.169 infcmd.c
--- infcmd.c	31 Jan 2008 13:37:21 -0000	1.169
+++ infcmd.c	27 Feb 2008 20:23:57 -0000
@@ -444,11 +444,15 @@ post_create_inferior (struct target_ops 
    from the beginning.  Ask the user to confirm that he wants to restart
    the program being debugged when FROM_TTY is non-null.  */
 
-void
+static void
 kill_if_already_running (int from_tty)
 {
   if (! ptid_equal (inferior_ptid, null_ptid) && target_has_execution)
     {
+      /* Bail out before killing the program if we will not be able to
+	 restart it.  */
+      target_require_runnable ();
+
       if (from_tty
 	  && !query ("The program being debugged has been started already.\n\
 Start it from the beginning? "))
Index: target.c
===================================================================
RCS file: /cvs/src/src/gdb/target.c,v
retrieving revision 1.154
diff -u -p -r1.154 target.c
--- target.c	25 Jan 2008 00:09:49 -0000	1.154
+++ target.c	27 Feb 2008 20:23:57 -0000
@@ -1723,6 +1723,41 @@ target_read_description (struct target_o
   return NULL;
 }
 
+/* Look through the currently pushed targets.  If none of them will
+   be able to restart the currently running process, issue an error
+   message.  */
+
+void
+target_require_runnable (void)
+{
+  struct target_ops *t;
+
+  for (t = target_stack; t != NULL; t = t->beneath)
+    {
+      /* If this target knows how to create a new program, then
+	 assume we will still be able to after killing the current
+	 one.  Either killing and mourning will not pop T, or else
+	 find_default_run_target will find it again.  */
+      if (t->to_create_inferior != NULL)
+	return;
+
+      /* Do not worry about thread_stratum targets that can not
+	 create inferiors.  Assume they will be pushed again if
+	 necessary, and continue to the process_stratum.  */
+      if (t->to_stratum == thread_stratum)
+	continue;
+
+      error (_("\
+The \"%s\" target does not support \"run\".  Try \"help target\" or \"continue\"."),
+	     t->to_shortname);
+    }
+
+  /* This function is only called if the target is running.  In that
+     case there should have been a process_stratum target and it
+     should either know how to create inferiors, or not... */
+  internal_error (__FILE__, __LINE__, "No targets found");
+}
+
 /* Look through the list of possible targets for a target that can
    execute a run or attach command without any other data.  This is
    used to locate the default process stratum.
Index: target.h
===================================================================
RCS file: /cvs/src/src/gdb/target.h,v
retrieving revision 1.110
diff -u -p -r1.110 target.h
--- target.h	20 Feb 2008 14:31:40 -0000	1.110
+++ target.h	27 Feb 2008 20:23:58 -0000
@@ -1188,6 +1188,8 @@ extern void initialize_targets (void);
 
 extern void noprocess (void);
 
+extern void target_require_runnable (void);
+
 extern void find_default_attach (char *, int);
 
 extern void find_default_create_inferior (char *, char *, char **, int);
Index: doc/gdb.texinfo
===================================================================
RCS file: /cvs/src/src/gdb/doc/gdb.texinfo,v
retrieving revision 1.469
diff -u -p -r1.469 gdb.texinfo
--- doc/gdb.texinfo	25 Feb 2008 20:34:40 -0000	1.469
+++ doc/gdb.texinfo	27 Feb 2008 20:24:00 -0000
@@ -1818,8 +1818,19 @@ argument to @value{GDBN} (@pxref{Invocat
 
 If you are running your program in an execution environment that
 supports processes, @code{run} creates an inferior process and makes
-that process run your program.  (In environments without processes,
-@code{run} jumps to the start of your program.)
+that process run your program.  In some environments without processes,
+@code{run} jumps to the start of your program.  Other targets,
+like @samp{remote}, are always running.  If you get an error
+message like this one:
+
+@smallexample
+The "remote" target does not support "run".
+Try "help target" or "continue".
+@end smallexample
+
+@noindent
+then use @code{continue} to run your program.  You may need @code{load}
+first (@pxref{load}).
 
 The execution of a program is affected by certain information it
 receives from its superior.  @value{GDBN} provides ways to specify this
@@ -12669,6 +12680,7 @@ Show the current status of displaying co
 
 @kindex load @var{filename}
 @item load @var{filename}
+@anchor{load}
 Depending on what remote debugging facilities are configured into
 @value{GDBN}, the @code{load} command may be available.  Where it exists, it
 is meant to make @var{filename} (an executable) available for debugging
@@ -12847,8 +12859,9 @@ program has already exited, this will ha
 @end table
 
 Once the connection has been established, you can use all the usual
-commands to examine and change data and to step and continue the
-remote program.
+commands to examine and change data.  The remote program is already
+running; you can use @kbd{step} and @kbd{continue}, and you do not
+need to use @kbd{run}.
 
 @cindex interrupting remote programs
 @cindex remote programs, interrupting