Re: [PATCH 1/4] document index_name_pos

From: Junio C Hamano <gitster@pobox.com>
Date: Jan 18, 2017, 21:11 UTC
Message-ID: <xmqqk29s3wg0.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <20170117233503.27137-2-sbeller@google.com>

Stefan Beller <sbeller@google.com> writes:

Show 25 quoted lines

> Signed-off-by: Stefan Beller <sbeller@google.com>
> ---
>  cache.h | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
>
> diff --git a/cache.h b/cache.h
> index 1b67f078dd..270a0d0ea7 100644
> --- a/cache.h
> +++ b/cache.h
> @@ -575,7 +575,22 @@ extern int verify_path(const char *path);
>  extern int index_dir_exists(struct index_state *istate, const char *name, int namelen);
>  extern void adjust_dirname_case(struct index_state *istate, char *name);
>  extern struct cache_entry *index_file_exists(struct index_state *istate, const char *name, int namelen, int igncase);
> +
> +/*
> + * Searches for an entry defined by name and namelen in the given index.
> + * If the return value is positive (including 0) it is the position of an
> + * exact match. If the return value is negative, the negated value minus 1 is the
> + * position where the entry would be inserted.
> + * Example: In the current index we have the files b,d,e:
> + * index_name_pos(&index, "a", 1) -> -1
> + * index_name_pos(&index, "b", 1) ->  0
> + * index_name_pos(&index, "c", 1) -> -2
> + * index_name_pos(&index, "d", 1) ->  1
> + * index_name_pos(&index, "e", 1) ->  2

The above may not be wrong per-se, but it misses one important case. A conflicted entry in the index with the same name is considered to sort after the name this asks. If there are stage #1 and stage #3 entries for path "g" in addition to the above, i.e.

	[0] [1] [2] [3] [4]
	b#0 d#0 e#0 g#1 g#3

then

	index_name_pos(&index, "g", 1) -> -3 - 1 = -4
        index_name_pos(&index, "h", 1) -> -5 - 1 = -6

> + * index_name_pos(&index, "f", 1) -> -3
> + */

Shouldn't this be -4? We originally have [0], [1], and [2] in the index, and "f" needs to go to [3], so -3 - 1 = -4, no?

Show 5 quoted lines

>  extern int index_name_pos(const struct index_state *, const char *name, int namelen);
> +
>  #define ADD_CACHE_OK_TO_ADD 1		/* Ok to add */
>  #define ADD_CACHE_OK_TO_REPLACE 2	/* Ok to replace file/directory */
>  #define ADD_CACHE_SKIP_DFCHECK 4	/* Ok to skip DF conflict checks */