Re: [PATCH] Rewritten fsck.c:fsck_commit() through using starts_with() instead of memcmp()
Thanks for the submission. Comments below to give you a feel for the Git review process...
On Thu, Mar 20, 2014 at 1:48 AM, blacksimit <cengoguzhanunlu@gmail.com> wrote:
> Subject: Rewritten fsck.c:fsck_commit() through using starts_with() instead of memcmp()
Use imperative mood ("rewrite" instead of "rewritten"). Keep it short but informative. Possibly like this:
Subject: fsck_commit: replace memcmp() with starts_with()
> Hi, I've done a microproject, number 15, "Rewrite fsck.c:fsck_commit() to use starts_with() and/or skip_prefix()." I used only starts_with().
Wrap messages to 65-70 characters.
Use the commit message for explaining and justifying the change. Commentary about GSoC and the fact that you avoided skip_prefix() won't be meaningful to someone reading the commit message in the permanent project history months or years from now. Place such commentary after the "---" line just below your sign-off.
> memcmp() returns 0 when both are equal, therefore when replacing with starts_with() , I used "!" or deleted where appropriate.
Good. Some applicants have tripped over this. Nevertheless, it's not necessary to mention this in either the commit message or the commentary below the "---" line since the inversion is an obvious requirement of using starts_with() in place of memcmp().
> I plan to apply for the GSoC 2014. I expect your feedbacks!
Place this below the "---" line after your sign-off.
Show 17 quoted lines
> Signed-off-by: Oguzhan Unlu <cengoguzhanunlu@gmail.com>
> ---
> fsck.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/fsck.c b/fsck.c
> index 64bf279..d43be98 100644
> --- a/fsck.c
> +++ b/fsck.c
> @@ -290,12 +290,12 @@ static int fsck_commit(struct commit *commit, fsck_error error_func)
> int parents = 0;
> int err;
>
> - if (memcmp(buffer, "tree ", 5))
> + if (!starts_with(buffer, "tree "))
> return error_func(&commit->object, FSCK_ERROR, "invalid format - expected 'tree' line");
> if (get_sha1_hex(buffer+5, tree_sha1) || buffer[45] != '\n')
One of the benefits of starts_with() and skip_prefix() is that they allow you to eliminate magic numbers, such as 5 in the memcmp() invocation. However, if you look a couple lines below, you see in the expression 'buffer+5' that the magic number is still present. In fact, the code becomes less clear with your change because the 5 in 'buffer+5' is much more mysterious without the preceding memcmp(foo,"bar",5). It is possible to eliminate this magic number, but starts_with() is not the answer.
Show 5 quoted lines
> return error_func(&commit->object, FSCK_ERROR, "invalid 'tree' line format - bad sha1");
> buffer += 46;
> - while (!memcmp(buffer, "parent ", 7)) {
> + while (starts_with(buffer, "parent ")) {
> if (get_sha1_hex(buffer+7, sha1) || buffer[47] != '\n')Ditto here with magic number 7 in 'buffer+7'.
Show 10 quoted lines
> return error_func(&commit->object, FSCK_ERROR, "invalid 'parent' line format - bad sha1");
> buffer += 48;
> @@ -322,13 +322,13 @@ static int fsck_commit(struct commit *commit, fsck_error error_func)
> if (p || parents)
> return error_func(&commit->object, FSCK_ERROR, "parent objects missing");
> }
> - if (memcmp(buffer, "author ", 7))
> + if (!starts_with(buffer, "author "))
> return error_func(&commit->object, FSCK_ERROR, "invalid format - expected 'author' line");
> buffer += 7;
Show 7 quoted lines
> err = fsck_ident(&buffer, &commit->object, error_func);
> if (err)
> return err;
> - if (memcmp(buffer, "committer ", strlen("committer ")))
> + if (!starts_with(buffer, "committer "))
> return error_func(&commit->object, FSCK_ERROR, "invalid format - expected 'committer' line");
> buffer += strlen("committer ");This is a similar case. You eliminated the strlen("committer ") in the line you changed, but then it appears again a couple lines below. This can be improved.
> err = fsck_ident(&buffer, &commit->object, error_func);
> --
> 1.9.1.286.g5172cb3
