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From: Martin Ågren <martin.agren@gmail.com>
To: Olga Telezhnaya <olyatelezhnaya@gmail.com>
Cc: Git Mailing List <git@vger.kernel.org>
Subject: Re: [RFC 3/4] ref-filter: change parsing function error handling
Date: Tue, 13 Mar 2018 20:18:31 +0100
Message-ID: <CAN0heSrogCMT-8R4nht=_9syMNUfJe21BvZSVD4AUcf9PwN7rQ@mail.gmail.com> (raw)
In-Reply-To: <010201621edc982f-92123a33-386b-4b94-be0c-f793856e6c16-000000@eu-west-1.amazonses.com>

On 13 March 2018 at 11:16, Olga Telezhnaya <olyatelezhnaya@gmail.com> wrote:
> Continue removing any printing from ref-filter formatting logic,
> so that it could be more general.
>
> Change the signature of parse_ref_filter_atom() by changing return value,
> adding previous return value to function parameter and also adding
> strbuf parameter for error message.

I think the current return value is always non-negative. Maybe it would
be easier to leave the return value as-is, except return negative on
error? Unless I am missing something?

>
> Signed-off-by: Olga Telezhnaia <olyatelezhnaya@gmail.com>
> ---
>  ref-filter.c | 45 ++++++++++++++++++++++++++++++++-------------
>  1 file changed, 32 insertions(+), 13 deletions(-)
>
> diff --git a/ref-filter.c b/ref-filter.c
> index 07bedc636398c..e146215bf1e64 100644
> --- a/ref-filter.c
> +++ b/ref-filter.c
> @@ -397,7 +397,8 @@ struct atom_value {
>   * Used to parse format string and sort specifiers
>   */
>  static int parse_ref_filter_atom(const struct ref_format *format,
> -                                const char *atom, const char *ep)
> +                                const char *atom, const char *ep, int *res,
> +                                struct strbuf *err)
>  {
>         const char *sp;
>         const char *arg;
> @@ -406,14 +407,18 @@ static int parse_ref_filter_atom(const struct ref_format *format,
>         sp = atom;
>         if (*sp == '*' && sp < ep)
>                 sp++; /* deref */
> -       if (ep <= sp)
> -               die(_("malformed field name: %.*s"), (int)(ep-atom), atom);
> +       if (ep <= sp) {
> +               strbuf_addf(err, _("malformed field name: %.*s"), (int)(ep-atom), atom);
> +               return -1;
> +       }
>
>         /* Do we have the atom already used elsewhere? */
>         for (i = 0; i < used_atom_cnt; i++) {
>                 int len = strlen(used_atom[i].name);
> -               if (len == ep - atom && !memcmp(used_atom[i].name, atom, len))
> -                       return i;
> +               if (len == ep - atom && !memcmp(used_atom[i].name, atom, len)) {
> +                       *res = i;
> +                       return 0;
> +               }
>         }

If you did so, this hunk above would not need to be changed ...

> @@ -458,7 +465,8 @@ static int parse_ref_filter_atom(const struct ref_format *format,
>                 need_tagged = 1;
>         if (!strcmp(valid_atom[i].name, "symref"))
>                 need_symref = 1;
> -       return at;
> +       *res = at;
> +       return 0;
>  }

... nor this one above ...

>                 if (!ep)
>                         return error(_("malformed format string %s"), sp);
>                 /* sp points at "%(" and ep points at the closing ")" */
> -               at = parse_ref_filter_atom(format, sp + 2, ep);
> +               if (parse_ref_filter_atom(format, sp + 2, ep, &at, &err))
> +                       die("%s", err.buf);

And this would be more like "if (at < 0) die(...)".

>         for (cp = format->format; *cp && (sp = find_next(cp)); cp = ep + 1) {
>                 struct atom_value *atomv;
> +               struct strbuf err = STRBUF_INIT;
> +               int pos;
>
>                 ep = strchr(sp, ')');
>                 if (cp < sp)
>                         append_literal(cp, sp, &state);
> -               get_ref_atom_value(info,
> -                                  parse_ref_filter_atom(format, sp + 2, ep),
> -                                  &atomv);
> +               if (parse_ref_filter_atom(format, sp + 2, ep, &pos, &err))
> +                       return -1;
> +               get_ref_atom_value(info, pos, &atomv);
>                 if (atomv->handler(atomv, &state, error_buf))
>                         return -1;
> +               strbuf_release(&err);

This looks leaky: if we get an error, we've got something in the buffer
but we do not release it because we return early. Stepping back a bit, I
wonder why we do not do anything at all with "err". Stepping back a bit
more :-) I wonder if you could get rid of "err" and pass "error_buf" to
parse_ref_filter_atom() instead. Our caller would like to have access to
the error string?

This ties back to my comment on the first patch -- "return negative if
and only if you add some error string to the buffer" might be a useful
rule?

Martin

  reply index

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-13 10:16 [RFC 1/4] ref-filter: start adding strbufs with errors Olga Telezhnaya
2018-03-13 10:16 ` [RFC 4/4] ref-filter: add return value to parsers Olga Telezhnaya
2018-03-13 10:16 ` [RFC 2/4] ref-filter: add return value && strbuf to handlers Olga Telezhnaya
2018-03-13 19:13   ` Martin Ågren
2018-03-13 10:16 ` [RFC 3/4] ref-filter: change parsing function error handling Olga Telezhnaya
2018-03-13 19:18   ` Martin Ågren [this message]
2018-03-14 13:36     ` Оля Тележная
2018-03-13 19:12 ` [RFC 1/4] ref-filter: start adding strbufs with errors Martin Ågren
2018-03-14 13:30   ` Оля Тележная
2018-03-14 19:04 ` [PATCH v2 1/5] " Olga Telezhnaya
2018-03-14 19:04   ` [PATCH v2 5/5] ref-filter: get_ref_atom_value() error handling Olga Telezhnaya
2018-03-15 20:47     ` Martin Ågren
2018-03-15 21:01       ` Eric Sunshine
2018-03-16  7:20         ` Оля Тележная
2018-03-15 21:05       ` Junio C Hamano
2018-03-16  7:17       ` Оля Тележная
2018-03-14 19:04   ` [PATCH v2 4/5] ref-filter: add return value to parsers Olga Telezhnaya
2018-03-14 19:04   ` [PATCH v2 3/5] ref-filter: change parsing function error handling Olga Telezhnaya
2018-03-15 22:48     ` Junio C Hamano
2018-03-16  7:22       ` Оля Тележная
2018-03-14 19:04   ` [PATCH v2 2/5] ref-filter: add return value && strbuf to handlers Olga Telezhnaya
2018-03-19 13:01   ` [PATCH v3 1/5] ref-filter: start adding strbufs with errors Olga Telezhnaya
2018-03-19 13:01     ` [PATCH v3 5/5] ref-filter: get_ref_atom_value() error handling Olga Telezhnaya
2018-03-19 13:01     ` [PATCH v3 4/5] ref-filter: add return value to parsers Olga Telezhnaya
2018-03-19 13:01     ` [PATCH v3 3/5] ref-filter: change parsing function error handling Olga Telezhnaya
2018-03-19 19:41       ` Junio C Hamano
2018-03-19 13:01     ` [PATCH v3 2/5] ref-filter: add return value && strbuf to handlers Olga Telezhnaya
2018-03-19 19:24       ` Junio C Hamano
2018-03-20 16:05     ` [PATCH v4 1/5] ref-filter: start adding strbufs with errors Olga Telezhnaya
2018-03-20 16:05       ` [PATCH v4 2/5] ref-filter: add return value && strbuf to handlers Olga Telezhnaya
2018-03-20 18:18         ` Eric Sunshine
2018-03-20 16:05       ` [PATCH v4 4/5] ref-filter: add return value to parsers Olga Telezhnaya
2018-03-20 16:05       ` [PATCH v4 3/5] ref-filter: change parsing function error handling Olga Telezhnaya
2018-03-20 16:05       ` [PATCH v4 5/5] ref-filter: get_ref_atom_value() " Olga Telezhnaya
2018-03-20 18:19         ` Eric Sunshine
2018-03-20 22:30           ` Junio C Hamano
2018-03-20 22:50             ` Eric Sunshine
2018-03-21 19:30               ` Junio C Hamano
2018-03-21 19:58                 ` Eric Sunshine
2018-03-21 18:28       ` [PATCH v5 1/6] strbuf: add shortcut to work with error messages Olga Telezhnaya
2018-03-21 18:28         ` [PATCH v5 3/6] ref-filter: add return value && strbuf to handlers Olga Telezhnaya
2018-03-21 18:28         ` [PATCH v5 6/6] ref-filter: libify get_ref_atom_value() Olga Telezhnaya
2018-03-21 18:28         ` [PATCH v5 4/6] ref-filter: change parsing function error handling Olga Telezhnaya
2018-03-21 20:36           ` Junio C Hamano
2018-03-23  6:56             ` Оля Тележная
2018-03-21 18:28         ` [PATCH v5 2/6] ref-filter: start adding strbufs with errors Olga Telezhnaya
2018-03-21 18:28         ` [PATCH v5 5/6] ref-filter: add return value to parsers Olga Telezhnaya
2018-03-21 20:20         ` [PATCH v5 1/6] strbuf: add shortcut to work with error messages Junio C Hamano
2018-03-23  6:48           ` Оля Тележная
2018-03-29 12:49         ` [PATCH v6 1/6] ref-filter: add shortcut to work with strbufs Olga Telezhnaya
2018-03-29 12:49           ` [PATCH v6 5/6] ref-filter: add return value to parsers Olga Telezhnaya
2018-03-29 12:49           ` [PATCH v6 3/6] ref-filter: add return value && strbuf to handlers Olga Telezhnaya
2018-03-29 12:49           ` [PATCH v6 6/6] ref-filter: libify get_ref_atom_value() Olga Telezhnaya
2018-03-29 12:49           ` [PATCH v6 2/6] ref-filter: start adding strbufs with errors Olga Telezhnaya
2018-03-29 12:49           ` [PATCH v6 4/6] ref-filter: change parsing function error handling Olga Telezhnaya

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