Re: [patch] Fix python gdb.execute to not paginate

[Doug Evans <dje@google.com>]

Thanks.
Comments inline.

On Fri, Aug 6, 2010 at 3:29 AM, Jan Kratochvil
<jan.kratochvil@redhat.com> wrote:
> On Fri, 06 Aug 2010 02:49:32 +0200, Doug Evans wrote:
>> IWBN to bury the implementation details.  I.e. move the setting of
>> batch_flag into utils.c.  Plus calling init_page_info here feels
>> wrong.  New function in utils.c that performs all the needed changes,
>
> OK, done.
>
>
>> and have just one make_cleanup_restore_foo routine to switch back?
>
> Using the benevolence of your '?' mark - not done in this patch.  I find the
> code is more simple without introducing new closure structure when the
> functionality can be built from the existing cleanup stubs:

Sure.
I wasn't suggesting introducing a new "closure" for this pass (at
least as far has how "closure" is currently used in gdb).
Rather, I was imagining all of these fiddly implementation details:

> +  back_to = make_cleanup (do_restore_page_info_cleanup, NULL);
> +  make_cleanup_restore_uinteger (&lines_per_page);
> +  make_cleanup_restore_uinteger (&chars_per_line);
> +
> +  make_cleanup_restore_integer (&batch_flag);

... being wrapped in functions that hid them.
There's a clear conceptual boundary here.

> On Fri, 06 Aug 2010 03:22:41 +0200, Doug Evans wrote:
>> Actually, I wonder if it makes sense to bury more implementation
>> details.  Make an API of it, running a gdb command and collecting the
>> result as a string.
>
> OK, done.  I would (also) like a normal canned commands $(...) support.
>
>
> On Fri, 06 Aug 2010 10:34:57 +0200, Eli Zaretskii wrote:
>> Okay with those changes.
>
> Used your text.
>
>
> No regressions on {x86_64,x86_64-m32,i686}-fedora14snapshot-linux-gnu.
>
>
> Thanks,
> Jan
>
>
> gdb/
> 2010-08-06  Jan Kratochvil  <jan.kratochvil@redhat.com>
>
>        * defs.h (make_cleanup_restore_uinteger, make_cleanup_restore_ui_file)
>        (set_batch_flag_and_make_cleanup_restore_page_info): New declarations.
>        * gdbcmd.h (execute_command_to_string): New declaration.
>        * python/python.c (struct restore_ui_file_closure, restore_ui_file)
>        (make_cleanup_restore_ui_file): Move to utils.c
>        (execute_gdb_command) <to_string>: Move ...
>        * top.c (execute_command_to_string): ... here.  Call
>        set_batch_flag_and_make_cleanup_restore_page_info.
>        * utils.c (make_cleanup_restore_uinteger): New.
>        (struct restore_ui_file_closure, do_restore_ui_file)
>        (make_cleanup_restore_ui_file): Move here from python/python.c.
>        (init_page_info) <batch_flag>
>        (do_restore_page_info_cleanup)
>        (set_batch_flag_and_make_cleanup_restore_page_info): New.
>
> gdb/testsuite/
> 2010-08-06  Jan Kratochvil  <jan.kratochvil@redhat.com>
>
>        * gdb.python/python.exp (show height, set height 10)
>        (verify pagination beforehand, verify pagination beforehand: q)
>        (gdb.execute does not page, verify pagination afterwards)
>        (verify pagination afterwards: q): New.
>
> gdb/doc/
> 2010-08-06  Jan Kratochvil  <jan.kratochvil@redhat.com>
>            Eli Zaretskii <eliz@gnu.org>
>
>        * gdb.texinfo (Mode Options) <-batch>
>        (Basic Python) <gdb.execute>: Describe setting width and height.
>
> --- a/gdb/defs.h
> +++ b/gdb/defs.h
> @@ -351,10 +351,14 @@ struct obstack;
>  extern struct cleanup *make_cleanup_obstack_free (struct obstack *obstack);
>
>  extern struct cleanup *make_cleanup_restore_integer (int *variable);
> +extern struct cleanup *make_cleanup_restore_uinteger (unsigned int *variable);
>
>  struct target_ops;
>  extern struct cleanup *make_cleanup_unpush_target (struct target_ops *ops);
>
> +extern
> +  struct cleanup *make_cleanup_restore_ui_file (struct ui_file **variable);
> +

Is this (and below) done to avoid the 80 char limit?
I haven't seen this formatting style used in gdb (having extern on a
line by itself).

dwarf2-frame.h does this:

extern const struct frame_base *
  dwarf2_frame_base_sniffer (struct frame_info *this_frame);

I like it.
I'm not sure what the coding style manual says.

>  extern struct cleanup *make_final_cleanup (make_cleanup_ftype *, void *);
>
>  extern struct cleanup *make_my_cleanup (struct cleanup **,
> @@ -386,6 +390,9 @@ extern int yquery (const char *, ...) ATTRIBUTE_PRINTF (1, 2);
>
>  extern void init_page_info (void);
>
> +extern
> +  struct cleanup *set_batch_flag_and_make_cleanup_restore_page_info (void);
> +
>  extern char *gdb_realpath (const char *);
>  extern char *xfullpath (const char *);
>
> --- a/gdb/gdbcmd.h
> +++ b/gdb/gdbcmd.h
> @@ -129,6 +129,7 @@ extern struct cmd_list_element *showchecklist;
>  extern struct cmd_list_element *save_cmdlist;
>
>  extern void execute_command (char *, int);
> +extern char *execute_command_to_string (char *p, int from_tty);
>
>  enum command_control_type execute_control_command (struct command_line *);
>
> --- a/gdb/python/python.c
> +++ b/gdb/python/python.c
> @@ -309,33 +310,6 @@ gdbpy_target_wide_charset (PyObject *self, PyObject *args)
>   return PyUnicode_Decode (cset, strlen (cset), host_charset (), NULL);
>  }
>
> -struct restore_ui_file_closure
> -{
> -  struct ui_file **variable;
> -  struct ui_file *value;
> -};
> -
> -static void
> -restore_ui_file (void *p)
> -{
> -  struct restore_ui_file_closure *closure = p;
> -
> -  *(closure->variable) = closure->value;
> -}
> -
> -/* Remember the current value of *VARIABLE and make it restored when
> -   the cleanup is run.  */
> -struct cleanup *
> -make_cleanup_restore_ui_file (struct ui_file **variable)
> -{
> -  struct restore_ui_file_closure *c = XNEW (struct restore_ui_file_closure);
> -
> -  c->variable = variable;
> -  c->value = *variable;
> -
> -  return make_cleanup_dtor (restore_ui_file, (void *) c, xfree);
> -}
> -
>  /* A Python function which evaluates a string using the gdb CLI.  */
>
>  static PyObject *
> @@ -376,27 +350,15 @@ execute_gdb_command (PyObject *self, PyObject *args, PyObject *kw)
>       /* Copy the argument text in case the command modifies it.  */
>       char *copy = xstrdup (arg);
>       struct cleanup *cleanup = make_cleanup (xfree, copy);
> -      struct ui_file *str_file = NULL;
>
>       if (to_string)
> +       result = execute_command_to_string (copy, from_tty);
> +      else
>        {
> -         str_file = mem_fileopen ();
> -
> -         make_cleanup_restore_ui_file (&gdb_stdout);
> -         make_cleanup_restore_ui_file (&gdb_stderr);
> -         make_cleanup_ui_file_delete (str_file);
> -
> -         gdb_stdout = str_file;
> -         gdb_stderr = str_file;
> +         result = NULL;
> +         execute_command (copy, from_tty);
>        }
>
> -      execute_command (copy, from_tty);
> -
> -      if (str_file)
> -       result = ui_file_xstrdup (str_file, NULL);
> -      else
> -       result = NULL;
> -
>       do_cleanups (cleanup);
>     }
>   GDB_PY_HANDLE_EXCEPTION (except);
> --- a/gdb/top.c
> +++ b/gdb/top.c
> @@ -458,6 +458,39 @@ execute_command (char *p, int from_tty)
>     }
>  }
>
> +/* Run execute_command for P and FROM_TTY.  Capture its output into the
> +   returned string, do not display it to the screen.  BATCH_FLAG will be
> +   temporarily set to true.  */
> +
> +char *
> +execute_command_to_string (char *p, int from_tty)
> +{
> +  struct ui_file *str_file;
> +  struct cleanup *cleanup;
> +  char *retval;
> +
> +  /* GDB_STDOUT should be better already restored during these
> +     restoration callbacks.  */
> +  cleanup = set_batch_flag_and_make_cleanup_restore_page_info ();
> +
> +  str_file = mem_fileopen ();
> +
> +  make_cleanup_restore_ui_file (&gdb_stdout);
> +  make_cleanup_restore_ui_file (&gdb_stderr);
> +  make_cleanup_ui_file_delete (str_file);
> +
> +  gdb_stdout = str_file;
> +  gdb_stderr = str_file;
> +
> +  execute_command (p, from_tty);
> +
> +  retval = ui_file_xstrdup (str_file, NULL);
> +
> +  do_cleanups (cleanup);
> +
> +  return retval;
> +}
> +
>  /* Read commands from `instream' and execute them
>    until end of file or error reading instream.  */
>
> --- a/gdb/utils.c
> +++ b/gdb/utils.c
> @@ -352,6 +352,14 @@ make_cleanup_restore_integer (int *variable)
>                           xfree);
>  }
>
> +/* Remember the current value of *VARIABLE and make it restored when the cleanup
> +   is run.  */

The coding standards have this in gdbint.texinfo:

"Put a blank line between the block comments preceding function or
variable definitions, and the definition itself."

though I see an example earlier in that section that doesn't have a
blank line (though that example is for which column to put the
function name, not spacing).

At any rate, I like it and I'd like to start enforcing it for function
definitions.

> +struct cleanup *
> +make_cleanup_restore_uinteger (unsigned int *variable)
> +{
> +  return make_cleanup_restore_integer ((int *) variable);
> +}
> +
>  /* Helper for make_cleanup_unpush_target.  */
>
>  static void
> @@ -370,6 +378,33 @@ make_cleanup_unpush_target (struct target_ops *ops)
>   return make_my_cleanup (&cleanup_chain, do_unpush_target, ops);
>  }
>
> +struct restore_ui_file_closure
> +{
> +  struct ui_file **variable;
> +  struct ui_file *value;
> +};
> +
> +static void
> +do_restore_ui_file (void *p)
> +{
> +  struct restore_ui_file_closure *closure = p;
> +
> +  *(closure->variable) = closure->value;
> +}
> +
> +/* Remember the current value of *VARIABLE and make it restored when
> +   the cleanup is run.  */

Ditto.  Add blank line.

> +struct cleanup *
> +make_cleanup_restore_ui_file (struct ui_file **variable)
> +{
> +  struct restore_ui_file_closure *c = XNEW (struct restore_ui_file_closure);
> +
> +  c->variable = variable;
> +  c->value = *variable;
> +
> +  return make_cleanup_dtor (do_restore_ui_file, (void *) c, xfree);
> +}
> +
>  struct cleanup *
>  make_my_cleanup2 (struct cleanup **pmy_chain, make_cleanup_ftype *function,
>                  void *arg,  void (*free_arg) (void *))
> @@ -2052,6 +2087,12 @@ static int wrap_column;
>  void
>  init_page_info (void)
>  {
> +  if (batch_flag)
> +    {
> +      lines_per_page = UINT_MAX;
> +      chars_per_line = UINT_MAX;
> +    }
> +  else
>  #if defined(TUI)
>   if (!tui_get_command_dimension (&chars_per_line, &lines_per_page))
>  #endif
> @@ -2096,6 +2137,32 @@ init_page_info (void)
>   set_width ();
>  }
>
> +static void
> +do_restore_page_info_cleanup (void *arg)
> +{
> +  set_screen_size ();
> +  set_width ();
> +}
> +
> +/* Temporarily set BATCH_FLAG and the associated unlimited terminal size.
> +   Provide cleanup for restoring the original state.  */
> +
> +struct cleanup *
> +set_batch_flag_and_make_cleanup_restore_page_info (void)
> +{
> +  struct cleanup *back_to;
> +
> +  back_to = make_cleanup (do_restore_page_info_cleanup, NULL);
> +  make_cleanup_restore_uinteger (&lines_per_page);
> +  make_cleanup_restore_uinteger (&chars_per_line);
> +
> +  make_cleanup_restore_integer (&batch_flag);
> +  batch_flag = 1;
> +  init_page_info ();
> +
> +  return back_to;
> +}
> +
>  /* Set the screen size based on LINES_PER_PAGE and CHARS_PER_LINE.  */
>
>  static void
> --- a/gdb/testsuite/gdb.python/python.exp
> +++ b/gdb/testsuite/gdb.python/python.exp
> @@ -87,3 +87,26 @@ gdb_test "python import itertools; print 'IMPOR'+'TED'" "IMPORTED" "pythonX.Y/li
>  gdb_test_no_output \
>     "python x = gdb.execute('printf \"%d\", 23', to_string = True)"
>  gdb_test "python print x" "23"
> +
> +# Test (no) pagination of the executed command.
> +gdb_test "show height" {Number of lines gdb thinks are in a page is unlimited\.}
> +set lines 10
> +gdb_test_no_output "set height $lines"
> +
> +set test "verify pagination beforehand"
> +gdb_test_multiple "python print \"\\n\" * $lines" $test {
> +    -re "---Type <return> to continue, or q <return> to quit---$" {
> +       pass $test
> +    }
> +}
> +gdb_test "q" "Quit" "verify pagination beforehand: q"
> +
> +gdb_test "python if gdb.execute('python print \"\\\\n\" * $lines', to_string=True) == \"\\n\" * [expr $lines + 1]: print \"yes\"" "yes" "gdb.execute does not page"
> +
> +set test "verify pagination afterwards"
> +gdb_test_multiple "python print \"\\n\" * $lines" $test {
> +    -re "---Type <return> to continue, or q <return> to quit---$" {
> +       pass $test
> +    }
> +}
> +gdb_test "q" "Quit" "verify pagination afterwards: q"
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -1031,9 +1031,9 @@ Run in batch mode.  Exit with status @code{0} after processing all the
>  command files specified with @samp{-x} (and all commands from
>  initialization files, if not inhibited with @samp{-n}).  Exit with
>  nonzero status if an error occurs in executing the @value{GDBN} commands
> -in the command files.  Batch mode also disables pagination;
> -@pxref{Screen Size} and acts as if @kbd{set confirm off} were in
> -effect (@pxref{Messages/Warnings}).
> +in the command files.  Batch mode also disables pagination, sets unlimited
> +terminal width and height @pxref{Screen Size}, and acts as if @kbd{set confirm
> +off} were in effect (@pxref{Messages/Warnings}).
>
>  Batch mode may be useful for running @value{GDBN} as a filter, for
>  example to download and run a program on another computer; in order to
> @@ -20484,7 +20484,9 @@ By default, any output produced by @var{command} is sent to
>  @value{GDBN}'s standard output.  If the @var{to_string} parameter is
>  @code{True}, then output will be collected by @code{gdb.execute} and
>  returned as a string.  The default is @code{False}, in which case the
> -return value is @code{None}.
> +return value is @code{None}.  If @var{to_string} is @code{True}, the
> +@value{GDBN} virtual terminal will be temporarily set to unlimited width
> +and height, and its pagination will be disabled; @pxref{Screen Size}.
>  @end defun
>
>  @findex gdb.breakpoints
>


Ok with those changes.