Re: [Xen-devel] [PATCH 3 of 3 V4] xl: SWITCH_FOREACH_OPT handles special options directly

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2013-01-03 at 11:39 +0000, Ian Campbell wrote:
> # HG changeset patch
> # User Ian Campbell <ijc@xxxxxxxxxxxxxx>
> # Date 1357213146 0
> # Node ID 0d2f4198f2c3fd6574e9058a528ac5530332b14e
> # Parent  1a1a2fa73670fd55004505b18a2b31418dcf447a
> xl: SWITCH_FOREACH_OPT handles special options directly.
> 
> This removes the need for the "case 0: case 2:" boilerplate in every
> main_foo(). Calls exit(3) directly which is OK since xl cleans up the
> context etc in an atexit(3) handler.
> 
> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> --
> v4: exit() directly instead of returning.
> 
> diff -r 1a1a2fa73670 -r 0d2f4198f2c3 tools/libxl/xl_cmdimpl.c
> --- a/tools/libxl/xl_cmdimpl.c  Thu Jan 03 11:38:48 2013 +0000
> +++ b/tools/libxl/xl_cmdimpl.c  Thu Jan 03 11:39:06 2013 +0000
> @@ -2396,12 +2396,13 @@ static int def_getopt(int argc, char * c
>   * `lopts`) should be handled by a case statement as if it were inside
>   * a switch statement.
>   *
> - * In addition to the options provided in opts callers must handle
> - * two additional pseudo options:
> - *  0 -- generated if the user passes a -h option. help will be printed,
> - *       caller should immediately return 0.
> - *  2 -- generated if the user does not provided `num_required_opts`
> - *       non-option arguments, caller should immediately return 2.
> + * In addition to the options provided in opts the macro will handle
> + * the "help" option and enforce a minimum number of non-option
> + * command line pearameters as follows:
> + *  -- if the user passes a -h or --help option. help will be printed,
> + *     and the macro will cause the process to exit with code 0.
> + *  -- if the user does not provided `num_required_opts` non-option
> + *     arguments, the macro will cause the process to exit with code 2.
>   *
>   * Example:
>   *
> @@ -2409,8 +2410,6 @@ static int def_getopt(int argc, char * c
>   *     int opt;
>   *
>   *     SWITCH_FOREACH_OPT(opt, "blah", NULL, "foo", 0) {
> - *     case 0: case2:
> - *          return opt;
>   *      case 'b':
>   *          ... handle b option...
>   *          break;
> @@ -2426,6 +2425,8 @@ static int def_getopt(int argc, char * c
>                             commandname, num_required_opts)              \
>      while (((opt) = def_getopt(argc, argv, (opts), (longopts),          \
>                                  (commandname), (num_required_opts))) != -1) \
> +        if (opt == 0) exit(0);                                          \
> +        if (opt == 2) exit(2);                                          \
>          switch (opt)

This is bogus due to the lack of a { after the while which leads to an
infinite loop (the original case I tested was lucky enough not to hit
it...)

It's obviously a brain fart anyway -- I should push the exits down into
def_getopt...

Ian.



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