[RFA 1/3] Implement convenience functions to examine GDB settings.

[RFA 1/3] Implement convenience functions to examine GDB settings.

[Philippe Waroquiers]

The new convenience functions $_gdb_setting and $_gdb_int_setting
provide access to the GDB settings in user-defined commands.
---
 gdb/ChangeLog         |  10 ++++
 gdb/cli/cli-cmds.c    | 105 ++++++++++++++++++++++++++++++++++++++++++
 gdb/cli/cli-setshow.c |  71 +++++++++++++++-------------
 gdb/cli/cli-setshow.h |   5 ++
 4 files changed, 158 insertions(+), 33 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 4f595922f6..4835c6fae5 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -6023,3 +6023,13 @@ version-control: never
 coding: utf-8
 End:
 
+2019-04-28  Philippe Waroquiers  <philippe.waroquiers@skynet.be>
+
+	* cli/cli-cmds.c (setting_cmd, gdb_int_setting_internal_fn,
+	gdb_setting_internal_fn): New functions.
+	(_initialize_cli_cmds): Define the new convenience functions.
+	* cli/cli-setshow.h (do_print_setting): New declaration.
+	* cli/cli-setshow.c (do_print_setting): New function (mostly
+	copied from do_show_command).
+	(do_show_command): Call do_print_setting.
+	(do_print_setting): New function.
diff --git a/gdb/cli/cli-cmds.c b/gdb/cli/cli-cmds.c
index 5f3b973f06..b1498452ba 100644
--- a/gdb/cli/cli-cmds.c
+++ b/gdb/cli/cli-cmds.c
@@ -1664,6 +1664,100 @@ show_max_user_call_depth (struct ui_file *file, int from_tty,
 		    value);
 }
 
+/* Returns the cmd_list_element corresponding to the first argument
+   of ARGV, which must contain one single value.
+   Throws an error if no value provided, or value not correct.
+   FNNAME is used in the error message.  */
+
+static cmd_list_element *
+setting_cmd (const char *fnname, int argc, struct value **argv)
+{
+  if (argc == 0)
+    error (_("You must provide an argument to %s"), fnname);
+  if (argc != 1)
+    error (_("You can only provide one argument to %s"), fnname);
+
+  struct type *type0 = check_typedef (value_type (argv[0]));
+
+  if (TYPE_CODE (type0) != TYPE_CODE_ARRAY
+      && TYPE_CODE (type0) != TYPE_CODE_STRING)
+    error (_("First argument of %s must be a string."), fnname);
+
+  int len0 = TYPE_LENGTH (type0);
+  std::vector<char> arg0 (len0);
+
+  memcpy (arg0.data (), value_contents (argv[0]), len0);
+
+  const char *a0 = arg0.data ();
+  cmd_list_element *cmd = lookup_cmd (&a0, showlist, "", -1, 0);
+
+  if (cmd == nullptr || cmd_type (cmd) != show_cmd)
+    error (_("First argument of %s must be a "
+	     "valid setting of the 'show' command."), fnname);
+
+  return cmd;
+}
+
+/* Implementation of the convenience function $_gdb_int_setting.  */
+
+static struct value *
+gdb_int_setting_internal_fn (struct gdbarch *gdbarch,
+			     const struct language_defn *language,
+			     void *cookie, int argc, struct value **argv)
+{
+  cmd_list_element *cmd = setting_cmd ("$_gdb_int_setting", argc, argv);
+
+  switch (cmd->var_type)
+    {
+    case var_boolean:
+    case var_integer:
+    case var_zinteger:
+    case var_zuinteger_unlimited:
+      return value_from_longest (builtin_type (gdbarch)->builtin_int,
+				 *(int *) cmd->var);
+    case var_auto_boolean:
+      {
+	int val = *(int *) cmd->var;
+
+	if (val == 0)
+	  val = 1;
+	else if (val == 1)
+	  val = 0;
+	return value_from_longest (builtin_type (gdbarch)->builtin_int,
+				   val);
+      }
+    case var_uinteger:
+      if (*(unsigned int *) cmd->var == UINT_MAX)
+	return value_from_longest (builtin_type (gdbarch)->builtin_int,
+				   0);
+      else
+	return value_from_longest (builtin_type (gdbarch)->builtin_int,
+				   *(unsigned int *) cmd->var);
+    case var_zuinteger:
+      return value_from_longest (builtin_type (gdbarch)->builtin_int,
+				 *(unsigned int *) cmd->var);
+    default:
+      error (_("Setting type not convertible to integer"));
+    }
+}
+
+/* Implementation of the convenience function $_gdb_setting.  */
+
+static struct value *
+gdb_setting_internal_fn (struct gdbarch *gdbarch,
+			 const struct language_defn *language,
+			 void *cookie, int argc, struct value **argv)
+{
+  cmd_list_element *cmd = setting_cmd ("$_gdb_setting", argc, argv);
+  string_file stb;
+
+  do_print_setting (&stb, cmd);
+
+  return value_cstring (stb.c_str (), strlen (stb.c_str ()),
+			builtin_type (gdbarch)->builtin_char);
+}
+
+
 void
 _initialize_cli_cmds (void)
 {
@@ -1787,6 +1881,17 @@ Generic command for showing things about the debugger."),
   /* Another way to get at the same thing.  */
   add_info ("set", show_command, _("Show all GDB settings."));
 
+  add_internal_function ("_gdb_setting", _("\
+$_gdb_setting - returns the value of a GDB setting as a string.\n\
+Usage: $_gdb_setting (setting)"),
+			 gdb_setting_internal_fn, NULL);
+
+  add_internal_function ("_gdb_int_setting", _("\
+$_gdb_int_setting - returns the value of an integer GDB setting as an integer.\n\
+Usage: $_int_gdb_int_setting (setting)\n\
+Throws an error if SETTING cannot be converted to an integer."),
+			 gdb_int_setting_internal_fn, NULL);
+
   add_cmd ("commands", no_set_class, show_commands, _("\
 Show the history of commands you typed.\n\
 You can supply a command number to start with, or a `+' to start after\n\
diff --git a/gdb/cli/cli-setshow.c b/gdb/cli/cli-setshow.c
index 5b87f905d0..eac5d48ea3 100644
--- a/gdb/cli/cli-setshow.c
+++ b/gdb/cli/cli-setshow.c
@@ -551,55 +551,42 @@ do_set_command (const char *arg, int from_tty, struct cmd_list_element *c)
     }
 }
 
-/* Do a "show" command.  ARG is NULL if no argument, or the
-   text of the argument, and FROM_TTY is nonzero if this command is
-   being entered directly by the user (i.e. these are just like any
-   other command).  C is the command list element for the command.  */
+/* See cli-setshow.h.  */
 
 void
-do_show_command (const char *arg, int from_tty, struct cmd_list_element *c)
+do_print_setting (string_file *stb, struct cmd_list_element *c)
 {
-  struct ui_out *uiout = current_uiout;
-
-  gdb_assert (c->type == show_cmd);
-
-  string_file stb;
-
-  /* Possibly call the pre hook.  */
-  if (c->pre_show_hook)
-    (c->pre_show_hook) (c);
-
   switch (c->var_type)
     {
     case var_string:
       if (*(char **) c->var)
-	stb.putstr (*(char **) c->var, '"');
+	stb->putstr (*(char **) c->var, '"');
       break;
     case var_string_noescape:
     case var_optional_filename:
     case var_filename:
     case var_enum:
       if (*(char **) c->var)
-	stb.puts (*(char **) c->var);
+	stb->puts (*(char **) c->var);
       break;
     case var_boolean:
-      stb.puts (*(int *) c->var ? "on" : "off");
+      stb->puts (*(int *) c->var ? "on" : "off");
       break;
     case var_auto_boolean:
       switch (*(enum auto_boolean*) c->var)
 	{
 	case AUTO_BOOLEAN_TRUE:
-	  stb.puts ("on");
+	  stb->puts ("on");
 	  break;
 	case AUTO_BOOLEAN_FALSE:
-	  stb.puts ("off");
+	  stb->puts ("off");
 	  break;
 	case AUTO_BOOLEAN_AUTO:
-	  stb.puts ("auto");
+	  stb->puts ("auto");
 	  break;
 	default:
 	  internal_error (__FILE__, __LINE__,
-			  _("do_show_command: "
+			  _("do_print_setting: "
 			    "invalid var_auto_boolean"));
 	  break;
 	}
@@ -608,35 +595,53 @@ do_show_command (const char *arg, int from_tty, struct cmd_list_element *c)
     case var_zuinteger:
       if (c->var_type == var_uinteger
 	  && *(unsigned int *) c->var == UINT_MAX)
-	stb.puts ("unlimited");
+	stb->puts ("unlimited");
       else
-	stb.printf ("%u", *(unsigned int *) c->var);
+	stb->printf ("%u", *(unsigned int *) c->var);
       break;
     case var_integer:
     case var_zinteger:
       if (c->var_type == var_integer
 	  && *(int *) c->var == INT_MAX)
-	stb.puts ("unlimited");
+	stb->puts ("unlimited");
       else
-	stb.printf ("%d", *(int *) c->var);
+	stb->printf ("%d", *(int *) c->var);
       break;
     case var_zuinteger_unlimited:
       {
 	if (*(int *) c->var == -1)
-	  stb.puts ("unlimited");
+	  stb->puts ("unlimited");
 	else
-	  stb.printf ("%d", *(int *) c->var);
+	  stb->printf ("%d", *(int *) c->var);
       }
       break;
     default:
-      error (_("gdb internal error: bad var_type in do_show_command"));
+      error (_("gdb internal error: bad var_type in do_print_setting"));
     }
+}
+
+/* Do a "show" command.  ARG is NULL if no argument, or the
+   text of the argument, and FROM_TTY is nonzero if this command is
+   being entered directly by the user (i.e. these are just like any
+   other command).  C is the command list element for the command.  */
+
+void
+do_show_command (const char *arg, int from_tty, struct cmd_list_element *c)
+{
+  struct ui_out *uiout = current_uiout;
+
+  gdb_assert (c->type == show_cmd);
+
+  string_file stb;
+
+  /* Possibly call the pre hook.  */
+  if (c->pre_show_hook)
+    (c->pre_show_hook) (c);
 
+  do_print_setting (&stb, c);
 
-  /* FIXME: cagney/2005-02-10: Need to split this in half: code to
-     convert the value into a string (esentially the above); and
-     code to print the value out.  For the latter there should be
-     MI and CLI specific versions.  */
+  /* FIXME: cagney/2005-02-10: For code to print the value out,
+     there should be MI and CLI specific versions.  */
 
   if (uiout->is_mi_like_p ())
     uiout->field_stream ("value", stb);
diff --git a/gdb/cli/cli-setshow.h b/gdb/cli/cli-setshow.h
index e4d13c3510..27ef5ea387 100644
--- a/gdb/cli/cli-setshow.h
+++ b/gdb/cli/cli-setshow.h
@@ -31,4 +31,9 @@ extern void do_show_command (const char *arg, int from_tty,
 extern void cmd_show_list (struct cmd_list_element *list, int from_tty,
 			   const char *prefix);
 
+/* Prints in STB the current value of the GDB setting shown by C.  */
+
+void
+do_print_setting (string_file *stb, struct cmd_list_element *c);
+
 #endif /* CLI_CLI_SETSHOW_H */
-- 
2.20.1

[RFA 0/3] Convenience functions $_gdb_setting/$_gdb_int_setting

[Philippe Waroquiers]

As part of the discussion of 'show | set may-call-functions [on|off]',
Eli suggested to have a way to access the GDB settings from
user defined commands.

So, this patch series implements this.

2 functions are provided:
  * $_gdb_setting that gives access to all settings, giving back a string value.
  * $_gdb_int_setting, giving access to boolean, auto-boolean and integers.
    This is easier to use for such types than the string version.

[RFA 3/3] NEWS and documentation for $_gdb_setting and $_gdb_int_setting.

[Philippe Waroquiers]

---
 gdb/ChangeLog       |  3 +++
 gdb/NEWS            |  5 +++++
 gdb/doc/ChangeLog   |  5 +++++
 gdb/doc/gdb.texinfo | 32 ++++++++++++++++++++++++++++++++
 4 files changed, 45 insertions(+)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 4835c6fae5..4f37db24fd 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -6022,6 +6022,9 @@ fill-column: 74
 version-control: never
 coding: utf-8
 End:
+2019-04-28  Philippe Waroquiers  <philippe.waroquiers@skynet.be>
+
+	* NEWS: Mention $_gdb_setting and $_gdb_int_setting.
 
 2019-04-28  Philippe Waroquiers  <philippe.waroquiers@skynet.be>
 
diff --git a/gdb/NEWS b/gdb/NEWS
index 42b04e952a..a84509d1c5 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -9,6 +9,11 @@
   scripts that should work error-free with many different versions,
   such as in system-wide init files.
 
+* New built-in convenience functions $_gdb_setting and $_gdb_int_setting
+  provide access to the value of the GDB settings.  They are handy
+  for changing the logic of user defined commands depending on the
+  current GDB settings.
+
 * GDB now supports Thread Local Storage (TLS) variables on several
   FreeBSD architectures (amd64, i386, powerpc, riscv).  Other
   architectures require kernel changes.  TLS is not yet supported for
diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index 3efed670fa..a5a559e2b8 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -12811,3 +12811,8 @@ fill-column: 74
 version-control: never
 coding: utf-8
 End:
+2019-04-27  Philippe Waroquiers  <philippe.waroquiers@skynet.be>
+
+	* gdb.texinfo (Convenience Funs): Document the new
+	$_gdb_setting and $_gdb_int_setting convenience functions.
+
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index cf8333d86b..688613ce07 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -11307,6 +11307,38 @@ $3 = void
 $4 = 1
 @end smallexample
 
+@item $_gdb_setting (@var{setting})
+@findex $_gdb_setting@r{, convenience function}
+Return the value of the @value{GDBN} @var{setting} as a string value.
+@var{setting} argument is the suffix to use in the @code{show} command
+to examine this setting in the @value{GDBN} command line interface.
+
+@smallexample
+(@value{GDBP}) show print frame-arguments
+Printing of non-scalar frame arguments is "scalars".
+(@value{GDBP}) p $_gdb_setting("print frame-arguments")
+$2 = "scalars"
+(@value{GDBP}) p $_gdb_setting("height")
+$3 = "30"
+((@value{GDBP})
+@end smallexample
+
+@item $_gdb_int_setting (@var{setting})
+@findex $_gdb_int_setting@r{, convenience function}
+Return the value of the @value{GDBN} @var{setting} as an integer value.
+This only works for boolean, auto boolean and integer settings.
+The boolean values @code{false} and @code{true} are converted to
+the integer values @code{0} and @code{1}. The value @code{auto} is
+converted to the value  @code{2}.
+
+@smallexample
+(@value{GDBP}) p $_gdb_setting("height")
+$3 = "30"
+(@value{GDBP}) p $_gdb_int_setting("height")
+$4 = 30
+((@value{GDBP})
+@end smallexample
+
 @end table
 
 These functions require @value{GDBN} to be configured with
-- 
2.20.1

[RFA 2/3] Test the convenience functions $_gdb_setting and $_gdb_int_setting.

[Philippe Waroquiers]

---
 gdb/testsuite/ChangeLog            |  4 ++++
 gdb/testsuite/gdb.base/default.exp |  2 ++
 gdb/testsuite/gdb.base/setshow.exp | 27 ++++++++++++++++++++++++++-
 3 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index e81409387e..4b767d95da 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -15747,3 +15747,7 @@ For older changes see ChangeLog-1993-2013.
     Copyright 2014-2019 Free Software Foundation, Inc.
   Copying and distribution of this file, with or without modification,
   are permitted provided the copyright notice and this notice are preserved.
+2019-04-27  Philippe Waroquiers  <philippe.waroquiers@skynet.be>
+
+	* gdb.base/setshow.exp: Test $_gdb_setting and $_gdb_int_setting.
+	* gdb.base/default.exp: Update show_conv_list.
diff --git a/gdb/testsuite/gdb.base/default.exp b/gdb/testsuite/gdb.base/default.exp
index 56ec917aa3..dab66080a7 100644
--- a/gdb/testsuite/gdb.base/default.exp
+++ b/gdb/testsuite/gdb.base/default.exp
@@ -604,6 +604,8 @@ set show_conv_list \
 	{$_cimag = <internal function _cimag>} \
 	{$_creal = <internal function _creal>} \
 	{$_isvoid = <internal function _isvoid>} \
+	{$_gdb_int_setting = <internal function _gdb_int_setting>} \
+	{$_gdb_setting = <internal function _gdb_setting>} \
 	{$_gdb_major = 8} \
 	{$_gdb_minor = 4} \
     }
diff --git a/gdb/testsuite/gdb.base/setshow.exp b/gdb/testsuite/gdb.base/setshow.exp
index d807d75a66..b78bea8e18 100644
--- a/gdb/testsuite/gdb.base/setshow.exp
+++ b/gdb/testsuite/gdb.base/setshow.exp
@@ -100,17 +100,23 @@ if { !$use_gdb_stub && ![target_info exists noargs] } {
     gdb_test "run" "Starting program:.*foo bar blup baz bubble.*" "passing args"
 }
 #test set check range on
-gdb_test "set check range on" ".*" "set check range on" 
+gdb_test "set check range on" ".*" "set check range on"
+gdb_test "p \$_gdb_setting(\"check range\")" ".*\"on\"" \
+    "_gdb_setting check range on"
 #test show check range on
 gdb_test "show check range" "Range checking is \"on\"\..*" "show check range (on)" 
 #test set check range off with trailing space
 gdb_test_no_output "set check range off " "set check range off" 
 #test show check range off
 gdb_test "show check range" "Range checking is \"off\"\..*" "show check range (off)" 
+gdb_test "p \$_gdb_setting(\"check range\")" ".*\"off\"" \
+    "_gdb_setting check range off"
 #test set check range auto
 gdb_test_no_output "set check range auto" "set check range auto" 
 #test show check range auto
 gdb_test "show check range" "Range checking is \"auto; currently .*" "show check range (auto)"
+gdb_test "p \$_gdb_setting(\"check range\")" ".*\"auto\"" \
+    "_gdb_setting check range auto"
 
 # Test set check type on
 gdb_test "set check type on" ".*" "set check type on"
@@ -118,9 +124,17 @@ gdb_test "set check type on" ".*" "set check type on"
 # Test show check type on
 gdb_test "show check type" "Strict type checking is on\..*" \
     "show check type (on)"
+gdb_test "p \$_gdb_setting(\"check type\")" ".*\"on\"" \
+    "_gdb_setting check type on"
+gdb_test "p \$_gdb_int_setting(\"check type\")" ".*= 1" \
+    "_gdb_setting check type on 1"
 
 # Test set check type off with trailing space
 gdb_test_no_output "set check type off " "set check type off"
+gdb_test "p \$_gdb_setting(\"check type\")" ".*\"off\"" \
+    "_gdb_setting check type off"
+gdb_test "p \$_gdb_int_setting(\"check type\")" ".*= 0" \
+    "_gdb_setting check type off 0"
 
 # Test show check type off
 gdb_test "show check type" "Strict type checking is off\..*" \
@@ -159,9 +173,17 @@ gdb_test "show environment FOOBARBAZ" "FOOBARBAZ = grbxgrbxgrbx.*"  "show enviro
 gdb_test_no_output "set height 100" "set height 100" 
 #test show height 100
 gdb_test "show height" "Number of lines gdb thinks are in a page is 100..*" "show height" 
+gdb_test "p \$_gdb_setting(\"height\")" ".*\"100\"" \
+    "_gdb_setting height 100"
+gdb_test "p \$_gdb_int_setting(\"height\")" ".*= 100" \
+    "_gdb_int_setting height 100"
 # Back to infinite height to avoid pagers.  While at it, check that
 # literal "unlimited" works just as well as 0.
 gdb_test_no_output "set height unlimited"
+gdb_test "p \$_gdb_setting(\"height\")" ".*\"unlimited\"" \
+    "_gdb_setting height unlimited"
+gdb_test "p \$_gdb_int_setting(\"height\")" ".*= 0" \
+    "_gdb_int_setting height unlimited"
 #test set history expansion on
 gdb_test_no_output "set history expansion on" "set history expansion on" 
 #test show history expansion on
@@ -182,6 +204,9 @@ gdb_test_no_output "set history filename ~/foobar.baz" \
 gdb_test "show history filename" \
     "The filename in which to record the command history is \"[string_to_regexp $HOME]/foobar.baz\"..*" \
     "show history filename (~/foobar.baz)"
+gdb_test "p \$_gdb_setting(\"history filename\")" \
+    ".*\"[string_to_regexp $HOME]/foobar.baz\"..*" \
+    "_gdb_setting history filename"
 #get current working directory
 set PWD ""
 set test "show working directory"
-- 
2.20.1

Re: [RFA 3/3] NEWS and documentation for $_gdb_setting and $_gdb_int_setting.

[Eli Zaretskii]

> From: Philippe Waroquiers <philippe.waroquiers@skynet.be>
> Cc: Philippe Waroquiers <philippe.waroquiers@skynet.be>
> Date: Sun, 28 Apr 2019 17:18:16 +0200
> 
> +* New built-in convenience functions $_gdb_setting and $_gdb_int_setting
> +  provide access to the value of the GDB settings.  They are handy
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
"provide access to values of ..."

> +@findex $_gdb_setting@r{, convenience function}
> +Return the value of the @value{GDBN} @var{setting} as a string value.
                                                      ^^^^^^^^^^^^^^^^^
"as a string", the "value" part is redundant.

> +@var{setting} argument is the suffix to use in the @code{show} command

I'd drop the "argument" part.

I also think that "suffix to use in the 'show' command" is a
potentially confusing description.  How about

  @var{setting} is any setting that can be used in a @code{set} or
  @code{show} command (@pxref{Controlling GDB}).

> +@item $_gdb_int_setting (@var{setting})
> +@findex $_gdb_int_setting@r{, convenience function}
> +Return the value of the @value{GDBN} @var{setting} as an integer value.
                                                         ^^^^^^^^^^^^^^^^
Again, I'd drop the "value" part.

> +This only works for boolean, auto boolean and integer settings.
> +The boolean values @code{false} and @code{true} are converted to
> +the integer values @code{0} and @code{1}. The value @code{auto} is
                                           ^^
Two spaces.

> +converted to the value  @code{2}.

What about the value "infinite" or "unlimited"?

Thanks.