[PATCHv2] fsck.c:fsck_commit() use skip_prefix() and starts_with()

Othman Darraz· Mar 19, 2014, 13:44 UTC · lore

make buffer const char* because the content of the memory referenced by this variable doesn't change in this function. Add cast to buffer to match fsck_ident signature which is (char**,...)

use skip_prefix() instead of memcmp() to avoid using magic number.

Signed-off-by: Othman Darraz <darrazo16@gmail.com>
---
I am planning to apply for GSOC2014
 fsck.c | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/fsck.c b/fsck.c
index 5eae856..128d426 100644
--- a/fsck.c
+++ b/fsck.c
@@ -284,21 +284,22 @@ static int fsck_ident(char **ident, struct object *obj, fsck_error error_func)
 
 static int fsck_commit(struct commit *commit, fsck_error error_func)
 {
-	char *buffer = commit->buffer;
+	const char *buffer = commit->buffer;
 	unsigned char tree_sha1[20], sha1[20];
 	struct commit_graft *graft;
 	int parents = 0;
 	int err;
-
-	if (starts_with(buffer, "tree "))
+	buffer = skip_prefix(buffer, "tree ");
+	if (!buffer)
 		return error_func(&commit->object, FSCK_ERROR, "invalid format - expected 'tree' line");
-	if (get_sha1_hex(buffer+5, tree_sha1) || buffer[45] != '\n')() 
+	if (get_sha1_hex(buffer, tree_sha1) || buffer[40] != '\n')
 		return error_func(&commit->object, FSCK_ERROR, "invalid 'tree' line format - bad sha1");
-	buffer += 46;
-	while (!memcmp(buffer, "parent ", 7)) {
-		if (get_sha1_hex(buffer+7, sha1) || buffer[47] != '\n')
+	buffer += 41;
+	while (starts_with(buffer, "parent ")) {
+		buffer = skip_prefix(buffer, "parent ");
+		if (get_sha1_hex(buffer, sha1) || buffer[40] != '\n')
 			return error_func(&commit->object, FSCK_ERROR, "invalid 'parent' line format - bad sha1");
-		buffer += 48;
+		buffer += 41;
 		parents++;
 	}
 	graft = lookup_commit_graft(commit->object.sha1);
@@ -322,16 +323,16 @@ 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 (starts_with(buffer, "author "))
+	buffer = skip_prefix(buffer, "author ");
+	if (!buffer)
 		return error_func(&commit->object, FSCK_ERROR, "invalid format - expected 'author' line");
-	buffer += 7;
-	err = fsck_ident(&buffer, &commit->object, error_func);
+	err = fsck_ident((char **)&buffer, &commit->object, error_func);
 	if (err)
 		return err;
-	buffer = (char* )skip_prefix(buffer,"committer ");
+	buffer = skip_prefix(buffer,"committer ");
 	if (!buffer)
 		return error_func(&commit->object, FSCK_ERROR, "invalid format - expected 'committer' line");
-	err = fsck_ident(&buffer, &commit->object, error_func);
+	err = fsck_ident((char **)&buffer, &commit->object, error_func);
 	if (err)
 		return err;
 	if (!commit->tree)

-- 
1.9.0.258.g00eda23.dirty

Eric Sunshine· Mar 21, 2014, 00:24 UTC · re: Othman Darraz · lore

Re: [PATCHv2] fsck.c:fsck_commit() use skip_prefix() and starts_with()

On Wed, Mar 19, 2014 at 9:44 AM, Othman Darraz <darrazo16@gmail.com> wrote:

> Subject: fsck.c:fsck_commit() use skip_prefix() and starts_with()

Add a space after the colon. Add a colon after fsck_commit().

> make buffer const char* because the content of the memory referenced by this variable doesn't change in this function.

Wrap lines to 65-70 characters. Capitalize start of sentence. You don't need to spell out 'const char*'. It's okay to say that you're just making it 'const'.

Conceptually, this is a distinct change, so it deserves its own patch. Thus, your submission should become a two-patch series. See documentation for "git format-patch" and "git send-email" to learn how to create a multi-part patch series.

> Add cast to buffer to match fsck_ident signature which is (char**,...)

But, is _this_ cast really needed? In my earlier review, I asked if you could drop the cast you had in that attempt by making 'buffer' const. I also mentioned that you might have to fix some small fallout from making it const. That was a hint that you should dig a bit deeper. It is possible to eliminate the casts. See if you can figure out how.

> use skip_prefix() instead of memcmp() to avoid using magic number.

Capitalize start of sentence. You might want to explain a bit that skip_prefix() conveys more clearly than memcmp() that the code is checking the string for a prefix. An added benefit is that it allows you to eliminate some magic numbers.

Show 23 quoted lines

> Signed-off-by: Othman Darraz <darrazo16@gmail.com>
> ---
> I am planning to apply for GSOC2014
>  fsck.c | 27 ++++++++++++++-------------
>  1 file changed, 14 insertions(+), 13 deletions(-)
>
> diff --git a/fsck.c b/fsck.c
> index 5eae856..128d426 100644
> --- a/fsck.c
> +++ b/fsck.c
> @@ -284,21 +284,22 @@ static int fsck_ident(char **ident, struct object *obj, fsck_error error_func)
>
>  static int fsck_commit(struct commit *commit, fsck_error error_func)
>  {
> -       char *buffer = commit->buffer;
> +       const char *buffer = commit->buffer;
>         unsigned char tree_sha1[20], sha1[20];
>         struct commit_graft *graft;
>         int parents = 0;
>         int err;
> -
> -       if (starts_with(buffer, "tree "))
> +       buffer = skip_prefix(buffer, "tree ");

Unfortunately, this patch is quite broken since it is based upon your previous patch rather than upon a clean copy of fsck.c. I'll abort the review at this point since this and your previous attempt are intermingled, and the patch does not provide a clear picture of how the original fsck.c gets changed.

Show 42 quoted lines

> +       if (!buffer)
>                 return error_func(&commit->object, FSCK_ERROR, "invalid format - expected 'tree' line");
> -       if (get_sha1_hex(buffer+5, tree_sha1) || buffer[45] != '\n')()
> +       if (get_sha1_hex(buffer, tree_sha1) || buffer[40] != '\n')
>                 return error_func(&commit->object, FSCK_ERROR, "invalid 'tree' line format - bad sha1");
> -       buffer += 46;
> -       while (!memcmp(buffer, "parent ", 7)) {
> -               if (get_sha1_hex(buffer+7, sha1) || buffer[47] != '\n')
> +       buffer += 41;
> +       while (starts_with(buffer, "parent ")) {
> +               buffer = skip_prefix(buffer, "parent ");
> +               if (get_sha1_hex(buffer, sha1) || buffer[40] != '\n')
>                         return error_func(&commit->object, FSCK_ERROR, "invalid 'parent' line format - bad sha1");
> -               buffer += 48;
> +               buffer += 41;
>                 parents++;
>         }
>         graft = lookup_commit_graft(commit->object.sha1);
> @@ -322,16 +323,16 @@ 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 (starts_with(buffer, "author "))
> +       buffer = skip_prefix(buffer, "author ");
> +       if (!buffer)
>                 return error_func(&commit->object, FSCK_ERROR, "invalid format - expected 'author' line");
> -       buffer += 7;
> -       err = fsck_ident(&buffer, &commit->object, error_func);
> +       err = fsck_ident((char **)&buffer, &commit->object, error_func);
>         if (err)
>                 return err;
> -       buffer = (char* )skip_prefix(buffer,"committer ");
> +       buffer = skip_prefix(buffer,"committer ");
>         if (!buffer)
>                 return error_func(&commit->object, FSCK_ERROR, "invalid format - expected 'committer' line");
> -       err = fsck_ident(&buffer, &commit->object, error_func);
> +       err = fsck_ident((char **)&buffer, &commit->object, error_func);
>         if (err)
>                 return err;
>         if (!commit->tree)
> --
> 1.9.0.258.g00eda23.dirty