[RFA] comment cleanup in exceptions.[ch]

[Doug Evans]

Ping.

On Thu, Dec 4, 2008 at 1:20 PM, Doug Evans <dje@google.com> wrote:
> Hi.
>
> While looking into using catch_errors/exceptions for something
> I ran into some confusing/outdated comments.
> I don't know all the details of catch_exceptions to be comfortable
> that the result still doesn't have problems, but it is better
> than before.
>
> The high order bit here is that I copied the lead paragraph for
> catch_exceptions from exceptions.h to exceptions.c and added
> a reference back to exceptions.h (it seemed like some text more
> than just "see exceptions.h" was useful in exceptions.c),
> plus I moved the usage text of MASK to exceptions.h.
>
> I also removed an outdated FIXME regarding utils.c/top.c.
> Given that exceptions.[ch] exists I think this FIXME can go.
>
> Ok to check in?
>
> 2008-12-04  Doug Evans  <dje@google.com>
>
>        * exceptions.h: Clean up some comments on catch_exceptions usage.
>        * exceptions.c: Ditto.  Plus mark catch_errors as superseded by
>        catch_exceptions.
>
> Index: exceptions.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/exceptions.c,v
> retrieving revision 1.30
> diff -u -p -r1.30 exceptions.c
> --- exceptions.c        8 Sep 2008 21:46:21 -0000       1.30
> +++ exceptions.c        4 Dec 2008 21:12:21 -0000
> @@ -417,25 +417,21 @@ throw_error (enum errors error, const ch
>   va_end (args);
>  }
>
> -/* Call FUNC() with args FUNC_UIOUT and FUNC_ARGS, catching any
> -   errors.  Set FUNC_CAUGHT to an ``enum return_reason'' if the
> -   function is aborted (using throw_exception() or zero if the
> -   function returns normally.  Set FUNC_VAL to the value returned by
> -   the function or 0 if the function was aborted.
> +/* Call FUNC(UIOUT, FUNC_ARGS) but wrapped within an exception
> +   handler.  If an exception (enum return_reason) is thrown using
> +   throw_exception() than all cleanups installed since
> +   catch_exceptions() was entered are invoked, the (-ve) exception
> +   value is then returned by catch_exceptions.  If FUNC() returns
> +   normally (with a positive or zero return value) then that value is
> +   returned by catch_exceptions().  It is an internal_error() for
> +   FUNC() to return a negative value.
> +
> +   See exceptions.h for further usage details.
>
>    Must not be called with immediate_quit in effect (bad things might
>    happen, say we got a signal in the middle of a memcpy to quit_return).
>    This is an OK restriction; with very few exceptions immediate_quit can
> -   be replaced by judicious use of QUIT.
> -
> -   MASK specifies what to catch; it is normally set to
> -   RETURN_MASK_ALL, if for no other reason than that the code which
> -   calls catch_errors might not be set up to deal with a quit which
> -   isn't caught.  But if the code can deal with it, it generally
> -   should be RETURN_MASK_ERROR, unless for some reason it is more
> -   useful to abort only the portion of the operation inside the
> -   catch_errors.  Note that quit should return to the command line
> -   fairly quickly, even if some further processing is being done.  */
> +   be replaced by judicious use of QUIT.  */
>
>  /* MAYBE: cagney/1999-11-05: catch_errors() in conjunction with
>    error() et.al. could maintain a set of flags that indicate the the
> @@ -445,10 +441,6 @@ throw_error (enum errors error, const ch
>    code also randomly used a SET_TOP_LEVEL macro that directly
>    initialize the longjmp buffers. */
>
> -/* MAYBE: cagney/1999-11-05: Should the catch_errors and cleanups code
> -   be consolidated into a single file instead of being distributed
> -   between utils.c and top.c? */
> -
>  int
>  catch_exceptions (struct ui_out *uiout,
>                  catch_exceptions_ftype *func,
> @@ -505,6 +497,8 @@ catch_exceptions_with_msg (struct ui_out
>   return val;
>  }
>
> +/* This function is superseded by catch_exceptions().  */
> +
>  int
>  catch_errors (catch_errors_ftype *func, void *func_args, char *errstring,
>              return_mask mask)
> Index: exceptions.h
> ===================================================================
> RCS file: /cvs/src/src/gdb/exceptions.h,v
> retrieving revision 1.22
> diff -u -p -r1.22 exceptions.h
> --- exceptions.h        1 Jan 2008 22:53:09 -0000       1.22
> +++ exceptions.h        4 Dec 2008 21:12:21 -0000
> @@ -177,7 +177,7 @@ extern NORETURN void deprecated_throw_re
>    throw_exception() than all cleanups installed since
>    catch_exceptions() was entered are invoked, the (-ve) exception
>    value is then returned by catch_exceptions.  If FUNC() returns
> -   normally (with a postive or zero return value) then that value is
> +   normally (with a positive or zero return value) then that value is
>    returned by catch_exceptions().  It is an internal_error() for
>    FUNC() to return a negative value.
>
> @@ -191,10 +191,19 @@ extern NORETURN void deprecated_throw_re
>    copy of the gdb error message.  This is used when a silent error is
>    issued and the caller wants to manually issue the error message.
>
> +   MASK specifies what to catch; it is normally set to
> +   RETURN_MASK_ALL, if for no other reason than that the code which
> +   calls catch_errors might not be set up to deal with a quit which
> +   isn't caught.  But if the code can deal with it, it generally
> +   should be RETURN_MASK_ERROR, unless for some reason it is more
> +   useful to abort only the portion of the operation inside the
> +   catch_errors.  Note that quit should return to the command line
> +   fairly quickly, even if some further processing is being done.
> +
>    FIXME; cagney/2001-08-13: The need to override the global UIOUT
>    builder variable should just go away.
>
> -   This function superseeds catch_errors().
> +   This function supersedes catch_errors().
>
>    This function uses SETJMP() and LONGJUMP().  */
>
> @@ -225,7 +234,7 @@ extern struct gdb_exception catch_except
>    indication of the exact exception that it caught - quit_flag might
>    help.
>
> -   This function is superseeded by catch_exceptions().  */
> +   This function is superseded by catch_exceptions().  */
>
>  typedef int (catch_errors_ftype) (void *);
>  extern int catch_errors (catch_errors_ftype *, void *, char *, return_mask);
>