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

From
Karsten Blees <karsten.blees@gmail.com>
Date
Jun 30, 2014, 15:56 UTC
Message-ID
<53B1889D.3010506@gmail.com>
In-Reply-To
<53B17696.3060808@gmail.com>
Am 30.06.2014 16:39, schrieb Tanay Abhra:
Show 54 quoted lines
> 
> On 6/30/2014 7:04 PM, Karsten Blees wrote:
>> Am 29.06.2014 13:01, schrieb Eric Sunshine:
>>> On Thu, Jun 26, 2014 at 4:19 AM, Tanay Abhra <tanayabh@gmail.com> wrote:
>>>> On 6/25/2014 1:24 PM, Eric Sunshine wrote:
>>>>> On Mon, Jun 23, 2014 at 6:41 AM, Tanay Abhra <tanayabh@gmail.com> 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 <tanayabh@gmail.com>
>>>>>> ---
>>>>>>  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).
> 
> Noted but, what I am trying to do with the rewrite is emit an error and
> not set the value if the value found is a NULL.

If you don't set the value and continue, git will proceed with the variable's default setting.

Which may not be too harmful in some cases, but if a user changes:
 gc.pruneexpire=4.weeks.ago
to
 gc.pruneexpire=4.monhts.ago

(note the typo), the next git-gc will warn the user and then happily throw away data that the user intended to keep (default is 2.weeks.ago).

Thus I think git should die() if it encounters an invalid config setting.
Show 10 quoted lines
> 
>> 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.
>>
> 
> Hmn, but during the config cache construction we parse key-value pairs through
> git_config() which still warns users about semantic errors.

If I'm not mistaken you only detect _syntax_ errors when loading the file (i.e. whether the config file is structurally correct).

The semantic value and correctness of a key (e.g. whether its a boolean or an int or a string that denotes a known merge algorithm) is only checked when it is accessed via git_config_get_<type>. And at this point, <file>:<line> information is already lost.

With the callback approach, both syntactic (structure) and semantic (meaning) errors were checked at load time, resulting in

  die("bad config file line %d in %s", cf->linenr, cf->name);
if the callback returned -1.
Previous: Tanay AbhraNext: Tanay Abhra
Message 19 of 41 in “alias.c: replace git_config with git_config_get_string”
  1. alias.c: replace git_config with git_config_get_stringTanay Abhra, Jun 23, 2014
  2. branch.c: replace git_config with git_config_get_stringTanay Abhra, Jun 23, 2014
  3. Eric SunshineJun 25, 2014
  4. Tanay AbhraJun 26, 2014
  5. Eric SunshineJun 29, 2014
  6. imap-send.c: replace git_config with git_config_get_stringTanay Abhra, Jun 23, 2014
  7. Eric SunshineJun 25, 2014
  8. Tanay AbhraJun 26, 2014
  9. Matthieu MoyJun 26, 2014
  10. Karsten BleesJun 26, 2014
  11. notes-util.c: replace git_config with git_config_get_stringTanay Abhra, Jun 23, 2014
  12. Eric SunshineJun 25, 2014
  13. Tanay AbhraJun 26, 2014
  14. Eric SunshineJun 29, 2014
  15. Karsten BleesJun 30, 2014
  16. Eric SunshineJun 30, 2014
  17. Karsten BleesJun 30, 2014
  18. Tanay AbhraJun 30, 2014
  19. Karsten BleesJun 30, 2014
  20. Tanay AbhraJun 30, 2014
  21. Junio C HamanoJun 30, 2014
  22. Matthieu MoyJul 1, 2014
  23. notes.c: replace git_config with git_config_get_stringTanay Abhra, Jun 23, 2014
  24. Eric SunshineJun 25, 2014
  25. Tanay AbhraJun 26, 2014
  26. pager.c: replace git_config with git_config_get_stringTanay Abhra, Jun 23, 2014
  27. Eric SunshineJun 25, 2014
  28. Tanay AbhraJun 26, 2014
  29. Karsten BleesJun 26, 2014
  30. Matthieu MoyJun 27, 2014
  31. Karsten BleesJun 27, 2014
  32. Matthieu MoyJun 27, 2014
  33. Karsten BleesJun 28, 2014
  34. Matthieu MoyJun 28, 2014
  35. Karsten BleesJun 28, 2014
  36. Matthieu MoyJun 29, 2014
  37. Jonathan NiederJun 23, 2014
  38. Tanay AbhraJun 24, 2014
  39. Eric SunshineJun 25, 2014
  40. Tanay AbhraJun 26, 2014
  41. Matthieu MoyJun 26, 2014

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