gdbserver: allow for general 'monitor set debug COMPONENT VALUE' use

Building on the last commit, which added a general --debug=COMPONENT
option to the gdbserver command line, this commit updates the monitor
command to allow for general:

  (gdb) monitor set debug COMPONENT off|on

style commands.  Just like with the previous commit, the COMPONENT can
be any one of all, threads, remote, event-loop, and correspond to the
same set of global debug flags.

While on the command line it is possible to do:

  --debug=remote,event-loop,threads

the components have to be entered one at a time with the monitor
command.  I guess there's no reason why we couldn't allow component
grouping within the monitor command, but (to me) what I have here
seemed more in the spirit of GDB's existing 'set debug ...' commands.
If people want it then we can always add component grouping later.

Notice in the above that I use 'off' and 'on' instead of '0' and '1',
which is what the 'monitor set debug' command used to use.  The 0/1
can still be used, but I now advertise off/on in all the docs and help
text, again, this feels more inline with GDB's existing boolean
settings.

I have removed the two existing monitor commands:

  monitor set remote-debug 0|1
  monitor set event-loop-debug 0|1

These are replaced by:

  monitor set debug remote off|on
  monitor set debug event-loop off|on

respectively.

Approved-By: Tom Tromey <tom@tromey.com>
Reviewed-By: Eli Zaretskii <eliz@gnu.org>

1 files changed, 143 insertions, 32 deletions

diff --git a/gdbserver/server.cc b/gdbserver/server.cc
index ea5d28c..2ec97d7 100644
--- a/gdbserver/server.cc
+++ b/gdbserver/server.cc
@@ -1143,14 +1143,15 @@ static void
 monitor_show_help (void)
 {
   monitor_output ("The following monitor commands are supported:\n");
-  monitor_output ("  set debug <0|1>\n");
+  monitor_output ("  set debug on\n");
   monitor_output ("    Enable general debugging messages\n");
+  monitor_output ("  set debug off\n");
+  monitor_output ("    Disable all debugging messages\n");
+  monitor_output ("  set debug COMPONENT <off|on>\n");
+  monitor_output ("    Enable debugging messages for COMPONENT, which is\n");
+  monitor_output ("    one of: all, threads, remote, event-loop.\n");
   monitor_output ("  set debug-hw-points <0|1>\n");
   monitor_output ("    Enable h/w breakpoint/watchpoint debugging messages\n");
-  monitor_output ("  set remote-debug <0|1>\n");
-  monitor_output ("    Enable remote protocol debugging messages\n");
-  monitor_output ("  set event-loop-debug <0|1>\n");
-  monitor_output ("    Enable event loop debugging messages\n");
   monitor_output ("  set debug-format option1[,option2,...]\n");
   monitor_output ("    Add additional information to debugging messages\n");
   monitor_output ("    Options: all, none, timestamp\n");
@@ -1575,50 +1576,160 @@ parse_debug_options (const char *options)
     }
 }
 
-/* Handle monitor commands not handled by target-specific handlers.  */
+/* Called from the 'monitor' command handler, to handle general 'set debug'
+   monitor commands with one of the formats:
 
-static void
-handle_monitor_command (char *mon, char *own_buf)
+     set debug COMPONENT VALUE
+     set debug VALUE
+
+   In both of these command formats VALUE can be 'on', 'off', '1', or '0'
+   with 1/0 being equivalent to on/off respectively.
+
+   In the no-COMPONENT version of the command, if VALUE is 'on' (or '1')
+   then the component 'threads' is assumed, this is for backward
+   compatibility, but maybe in the future we might find a better "default"
+   set of debug flags to enable.
+
+   In the no-COMPONENT version of the command, if VALUE is 'off' (or '0')
+   then all debugging is turned off.
+
+   Otherwise, COMPONENT must be one of the known debug components, and that
+   component is either enabled or disabled as appropriate.
+
+   The string MON contains either 'COMPONENT VALUE' or just the 'VALUE' for
+   the second command format, the 'set debug ' has been stripped off
+   already.
+
+   Return a string containing an error message if something goes wrong,
+   this error can be returned as part of the monitor command output.  If
+   everything goes correctly then the debug global will have been updated,
+   and an empty string is returned.  */
+
+static std::string
+handle_general_monitor_debug (const char *mon)
 {
-  if (strcmp (mon, "set debug 1") == 0)
+  mon = skip_spaces (mon);
+
+  if (*mon == '\0')
+    return "No debug component name found.\n";
+
+  /* Find the first word within MON.  This is either the component name,
+     or the value if no component has been given.  */
+  const char *end = skip_to_space (mon);
+  std::string component (mon, end - mon);
+  if (component.find (',') != component.npos || component[0] == '-'
+      || component[0] == '+')
+    return "Invalid character found in debug component name.\n";
+
+  /* In ACTION_STR we create a string that will be passed to the
+     parse_debug_options string.  This will be either '+COMPONENT' or
+     '-COMPONENT' depending on whether we want to enable or disable
+     COMPONENT.  */
+  std::string action_str;
+
+  /* If parse_debug_options succeeds, then MSG will be returned to the user
+     as the output of the monitor command.  */
+  std::string msg;
+
+  /* Check for 'set debug off', this disables all debug output.  */
+  if (component == "0" || component == "off")
     {
-      debug_threads = true;
-      monitor_output ("Debug output enabled.\n");
+      if (*skip_spaces (end) != '\0')
+	return string_printf
+	  ("Junk '%s' found at end of 'set debug %s' command.\n",
+	   skip_spaces (end), std::string (mon, end - mon).c_str ());
+
+      action_str = "-all";
+      msg = "All debug output disabled.\n";
     }
-  else if (strcmp (mon, "set debug 0") == 0)
+  /* Check for 'set debug on', this disables a general set of debug.  */
+  else if (component == "1" || component == "on")
     {
-      debug_threads = false;
-      monitor_output ("Debug output disabled.\n");
+      if (*skip_spaces (end) != '\0')
+	return string_printf
+	  ("Junk '%s' found at end of 'set debug %s' command.\n",
+	   skip_spaces (end), std::string (mon, end - mon).c_str ());
+
+      action_str = "+threads";
+      msg = "General debug output enabled.\n";
     }
-  else if (strcmp (mon, "set debug-hw-points 1") == 0)
+  /* Otherwise we should have 'set debug COMPONENT VALUE'.  Extract the two
+     parts and validate.  */
+  else
     {
-      show_debug_regs = 1;
-      monitor_output ("H/W point debugging output enabled.\n");
+      /* Figure out the value the user passed.  */
+      const char *value_start = skip_spaces (end);
+      if (*value_start == '\0')
+	return string_printf ("Missing value for 'set debug %s' command.\n",
+			      mon);
+
+      const char *after_value = skip_to_space (value_start);
+      if (*skip_spaces (after_value) != '\0')
+	return string_printf
+	  ("Junk '%s' found at end of 'set debug %s' command.\n",
+	   skip_spaces (after_value),
+	   std::string (mon, after_value - mon).c_str ());
+
+      std::string value (value_start, after_value - value_start);
+
+      /* Check VALUE to see if we are enabling, or disabling.  */
+      bool enable;
+      if (value == "0" || value == "off")
+	enable = false;
+      else if (value == "1" || value == "on")
+	enable = true;
+      else
+	return string_printf ("Invalid value '%s' for 'set debug %s'.\n",
+			      value.c_str (),
+			      std::string (mon, end - mon).c_str ());
+
+      action_str = std::string (enable ? "+" : "-") + component;
+      msg = string_printf ("Debug output for '%s' %s.\n", component.c_str (),
+			   enable ? "enabled" : "disabled");
     }
-  else if (strcmp (mon, "set debug-hw-points 0") == 0)
+
+  gdb_assert (!msg.empty ());
+  gdb_assert (!action_str.empty ());
+
+  try
     {
-      show_debug_regs = 0;
-      monitor_output ("H/W point debugging output disabled.\n");
+      parse_debug_options (action_str.c_str ());
+      monitor_output (msg.c_str ());
     }
-  else if (strcmp (mon, "set remote-debug 1") == 0)
+  catch (const gdb_exception_error &exception)
     {
-      remote_debug = true;
-      monitor_output ("Protocol debug output enabled.\n");
+      return string_printf ("Error: %s\n", exception.what ());
     }
-  else if (strcmp (mon, "set remote-debug 0") == 0)
+
+  return {};
+}
+
+/* Handle monitor commands not handled by target-specific handlers.  */
+
+static void
+handle_monitor_command (char *mon, char *own_buf)
+{
+  if (startswith (mon, "set debug "))
     {
-      remote_debug = false;
-      monitor_output ("Protocol debug output disabled.\n");
+      std::string error_msg
+	= handle_general_monitor_debug (mon + sizeof ("set debug ") - 1);
+
+      if (!error_msg.empty ())
+	{
+	  monitor_output (error_msg.c_str ());
+	  monitor_show_help ();
+	  write_enn (own_buf);
+	}
     }
-  else if (strcmp (mon, "set event-loop-debug 1") == 0)
+  else if (strcmp (mon, "set debug-hw-points 1") == 0)
     {
-      debug_event_loop = debug_event_loop_kind::ALL;
-      monitor_output ("Event loop debug output enabled.\n");
+      show_debug_regs = 1;
+      monitor_output ("H/W point debugging output enabled.\n");
     }
-  else if (strcmp (mon, "set event-loop-debug 0") == 0)
+  else if (strcmp (mon, "set debug-hw-points 0") == 0)
     {
-      debug_event_loop = debug_event_loop_kind::OFF;
-      monitor_output ("Event loop debug output disabled.\n");
+      show_debug_regs = 0;
+      monitor_output ("H/W point debugging output disabled.\n");
     }
   else if (startswith (mon, "set debug-format "))
     {