Subject: Re: [RFC/PATCH] notes-util.c: replace git_config with git_config_get_string

From: Karsten Blees <[email-masked]>
Date: Mon, 30 Jun 2014 15:34:00 +0200

Am 29.06.2014 13:01, schrieb Eric Sunshine:
> On Thu, Jun 26, 2014 at 4:19 AM, Tanay Abhra <[email-masked]> wrote:
>> On 6/25/2014 1:24 PM, Eric Sunshine wrote:
>>> On Mon, Jun 23, 2014 at 6:41 AM, Tanay Abhra <[email-masked]> wrote:
>>>> Use git_config_get_string instead of git_config to take advantage of
>>>> the config hash-table api which provides a cleaner control flow.
>>>>
>>>> Signed-off-by: Tanay Abhra <[email-masked]>
>>>> ---
>>>>  notes-utils.c | 31 +++++++++++++++----------------
>>>>  1 file changed, 15 insertions(+), 16 deletions(-)
>>>>
>>>> diff --git a/notes-utils.c b/notes-utils.c
>>>> index a0b1d7b..fdc9912 100644
>>>> --- a/notes-utils.c
>>>> +++ b/notes-utils.c
>>>> @@ -68,22 +68,23 @@ static combine_notes_fn parse_combine_notes_fn(const char *v)
>>>>                 return NULL;
>>>>  }
>>>>
>>>> -static int notes_rewrite_config(const char *k, const char *v, void *cb)
>>>> +static void notes_rewrite_config(struct notes_rewrite_cfg *c)
>>>>  {
>>>> -       struct notes_rewrite_cfg *c = cb;
>>>> -       if (starts_with(k, "notes.rewrite.") && !strcmp(k+14, c->cmd)) {
>>>> -               c->enabled = git_config_bool(k, v);
>>>> -               return 0;
>>>> -       } else if (!c->mode_from_env && !strcmp(k, "notes.rewritemode")) {
>>>> +       struct strbuf key = STRBUF_INIT;
>>>> +       const char *v;
>>>> +       strbuf_addf(&key, "notes.rewrite.%s", c->cmd);
>>>> +
>>>> +       if (!git_config_get_string(key.buf, &v))
>>>> +               c->enabled = git_config_bool(key.buf, v);
>>>> +
>>>> +       if (!c->mode_from_env && !git_config_get_string("notes.rewritemode", &v)) {
>>>>                 if (!v)
>>>> -                       return config_error_nonbool(k);
>>>> +                       config_error_nonbool("notes.rewritemode");
>>>
>>> There's a behavior change here. In the original code, the callback
>>> function would return -1, which would cause the program to die() if
>>> the config.c:die_on_error flag was set. The new code merely emits an
>>> error.
>>
>> Is this change serious enough? Can I ignore it?

IMO its better to Fail Fast than continue with some invalid config (which
may lead to more severe errors such as data corruption / data loss).

> 
> I don't know. Even within this single function there is no consistency
> about whether such problems should die() or just emit a message and
> continue. For instance:
> 
> - if "notes.rewritemode" is bool, it die()s.
> 
> - if "notes.rewritemode" doesn't specify a recognized mode, it
> error()s but continues
> 

I think this would also die in git_parse_source():
...
    if (get_value(fn, data, var) < 0)
      break;
  }
  if (cf->die_on_error)
    die("bad config file line %d in %s", cf->linenr, cf->name);
...

(AFAICT, die_on_error is always true, except if invoked via 'git-config
--blob', which isn't used anywhere...)

This, however, raises another issue: switching to the config cache looses
file/line-precise error reporting for semantic errors. I don't know if
this feature is important enough to do something about it, though. A
message of the form "Key 'xyz' is bad" should usually enable a user to
locate the problematic file and line.