Re: [PATCH v2] packfile: Correct zlib buffer handling

From: Eric Sunshine <sunshine@sunshineco.com>
Date: Jun 13, 2018, 17:21 UTC
Message-ID: <CAPig+cQ1s7QFjEFrOHMYZR8qja5yTjV5D3ksUXXqFL61YthA3g@mail.gmail.com>
In-Reply-To: <20180613142207.14385-1-lintonrjeremy@gmail.com>

A couple comments if you happen to re-roll...

On Wed, Jun 13, 2018 at 10:22 AM Jeremy Linton <lintonrjeremy@gmail.com> wrote:

> The buffer being passed to zlib includes a null terminator that

On this project, the character mnemonic "NUL" is typically used, not "null" or "NULL" (which is typically reserved for pointers), so: s/null/NUL/g

Show 17 quoted lines

> git needs to keep in place. unpack_compressed_entry() attempts to
> detect the case that the source buffer hasn't been fully consumed
> by checking to see if the destination buffer has been over consumed.
>
> This causes a problem, that more recent zlib patches have been
> poisoning the unconsumed portions of the buffer which overwrites
> the null, while correctly returning length and status.
>
> Let's replace the null at the end of the buffer to assure that
> if its been overwritten by zlib it doesn't result in problems for
> git.
>
> Signed-off-by: Jeremy Linton <lintonrjeremy@gmail.com>
> ---
> diff --git a/packfile.c b/packfile.c
> @@ -1433,6 +1433,8 @@ static void *unpack_compressed_entry(struct packed_git *p,
> +       buffer[size] = 0; /* assure that the buffer is still terminated */

I think we normally use '\0' for NUL on this project rather than simply 0.

The comment is also effectively pure noise since it merely repeats what the code already states clearly (especially when the code says "buffer[size] = '\0';"), so dropping the comment altogether would be reasonable.