[GSoC] Git Blog 1

[ZheNing Hu <adlternative@gmail.com>]

My first week blog finished:
The web version is here:
https://adlternative.github.io/GSOC-Git-Blog-1/

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## Week1: Git Adventure Begin

Use Git to submit Git patches to the Git community.
Does it sound magical? I fell very lucky to be selected
by the Git community this year and start my Git Adventure
in GSoC.

I am no stranger to Git usage, and before the start of GSoC,
I have learned some Git source code content, but I only saw
the tip of the iceberg of Git source code, there are still many
things that I need to explore.

### What happened this week
- In [[GSoC] Hello
Git](https://lore.kernel.org/git/CAOLTT8SHE-ok3D+oLNSWFi7KPU==VQnTMDmC4YxUyNBJKmBD8A@mail.gmail.com/),
Christian and JiangXin interacted with me.
- I checked Olga's patch at Christian's prompt and learned a way
to make `cat-file --batch` use `ref-filter` logic: Use `format_ref_array_item()`
in `batch_object_write()`, this is indeed a good entry point. But
before implementing this function, we must make `ref-filter`
support the function of printing the original data of the object
(as `cat-file --batch` does). I decided to reuse the atom
`%(content:raw)` in ref-filter to implement this function.

### The difficulties I met
In [[PATCH] [GSOC] ref-filter: add contents:raw
atom](https://lore.kernel.org/git/pull.958.git.1621500593126.gitgitgadget@gmail.com/),
I submitted a patch, which support atom `%(content:raw)`
for `ref-filter`.

Unfortunately, this patch has a big problem:
I ignored the breakage on the test. This led me to
discover a bigger problem:

If our references points to a blob or a tree, and  these objects may
be binary files, this means that we cannot use functions related
to `strcmp()`,`strlen()` or `strbuf_addstr()`. The possible '\0' will
cause the output to be truncated. We have to think of a way to make
`ref-filter` can accept the output of these binary content.

So I searched for all the codes in `ref-filter.c` that buffer might be
truncated by '\0' and use the appropriate method to replace them.

Just like replacing `strcmp()` with `memcmp()`, We can use `strbuf_add()`
instead of `strbuf_addstr()`,
At the same time I also wrote the equivalent `*._quote_buf_with_size()`
to replace `*._quote_buf()`.

I just submit it to the mailing list right now:
[[GSOC][RFC] ref-filter: add contents:raw atom]
(https://lore.kernel.org/git/pull.959.git.1621763612.gitgitgadget@gmail.com/)

I don’t know if this is the right approach at the moment, let
us slowly wait for the suggestions of mentors and reviewers... ;-)

Thanks!
--
ZheNing Hu