Re: [PATCH v2 2/2] [GSOC] ref-filter: add %(raw) atom

From: ZheNing Hu <adlternative@gmail.com>
Date: May 31, 2021, 14:35 UTC
Message-ID: <CAOLTT8REM7tF6ojdmnsJt7-RE6a8oX4RFXVcL215YnYTx6b62w@mail.gmail.com>
In-Reply-To: <xmqqh7ij20l8.fsf@gitster.g>

Junio C Hamano <gitster@pobox.com> 于2021年5月31日周一 上午8:44写道：

Show 18 quoted lines

>
> "ZheNing Hu via GitGitGadget" <gitgitgadget@gmail.com> writes:
>
> > Beyond, `--format=%(raw)` cannot be used with `--python`, `--shell`,
> > `--tcl`, `--perl` because if our binary raw data is passed to a variable
> > in the host language, the host languages may cause escape errors.
>
> "may cause escape errors" just says you are not escaping correctly
> in your code (implying that this patch is not good enough and with
> more effort we should be able to fix it to allow binaries), but the
> problem is the host languages may not support binaries
> (specifically, anything with a NUL in it) at all, which is
> fundamentally unfixable, in which case, rejecting is the only
> sensible choice.
>
>     ... because the host language may not support a NUL in the variables
>     of its string type.
>

I agree. But host language not only support NUL but also some Non-ASCII character and Non-UTF-8 code:

$ git hash-object a.out -w | xargs git update-ref refs/myblobs/aoutblob
$ git for-each-ref --format="name=%(raw)" refs/myblobs/aoutblob
--python | python2
  File "<stdin>", line 1
SyntaxError: Non-ASCII character '\x8b' in file <stdin> on line 2, but
no encoding declared;
 see http://python.org/dev/peps/pep-0263/ for details

$ git for-each-ref --format="name=%(raw)" refs/myblobs/aoutblob
--python |python3
SyntaxError: Non-UTF-8 code starting with '\x8b' in file <stdin> on
line 2, but no encoding declared;
 see http://python.org/dev/peps/pep-0263/ for details

Show 8 quoted lines

> > +The raw data in a object is `raw`, For commit and tag objects, `raw` contain
>
> s/contain/contains/, but more importantly, as we are not introducing
> %(header), I do not see why we want to talk about its details.  For
> commits and tags, just like for trees and blobs, 'raw' is the raw
> data in the object, so beyond "The raw data of a object is %(raw)",
> I do not think there is anything to talk about.
>

Ok, I will delete this part.

Show 10 quoted lines

> > +     const char *s = buf->buf;
> > +     size_t cur_len = 0;
> > +
> > +     while ((cur_len != buf->len) && (isspace(*s) || *s == '\0')) {
> >               s++;
> > +             cur_len++;
>
> Is NUL treated the same as a whitespace letter for the purpose of
> determining if a line is empty?  WHY?
>

Well, there seems to be no correction here. But is it true that memory like "\0abc" is considered empty?

Thanks. -- ZheNing Hu