Subject: Re: [PATCH v2 6/6] exclude: filter patterns by directory level

From: Junio C Hamano <[email-masked]>
Date: Sun, 10 Mar 2013 00:20:00 -0800

Nguyễn Thái Ngọc Duy  <[email-masked]> writes:

> A non-basename pattern that does not contain /**/ can't match anything
> outside the attached directory. Record its directory level and avoid
> matching unless the pathname is also at the same directory level.

Without defining what a "directory level" is, the above is a bit
hard to grok, but I think you mean an entry "b/c/*.c" that appears
in "a/.gitignore" file will want to match a path that is directly
in "a/b/c" directory (and not in its subdirectories),
"a/b/x.c" at the two levels deep subdirectory or "a/b/c/d/x.c" that is
four levels deep will never match the pattern.

The logic feels sound.

> diff --git a/dir.c b/dir.c
> index 880b5e6..de7a6ba 100644
> --- a/dir.c
> +++ b/dir.c
> @@ -360,10 +360,12 @@ static int no_wildcard(const char *string)
>  void parse_exclude_pattern(const char **pattern,
>  			   int *patternlen,
>  			   int *flags,
> -			   int *nowildcardlen)
> +			   int *nowildcardlen,
> +			   int *dirs_p)
>  {
>  	const char *p = *pattern;
>  	size_t i, len;
> +	int dirs;
>  
>  	*flags = 0;
>  	if (*p == '!') {
> @@ -375,12 +377,15 @@ void parse_exclude_pattern(const char **pattern,
>  		len--;
>  		*flags |= EXC_FLAG_MUSTBEDIR;
>  	}
> -	for (i = 0; i < len; i++) {
> +	for (i = 0, dirs = 0; i < len; i++) {
>  		if (p[i] == '/')
> -			break;
> +			dirs++;
>  	}
> -	if (i == len)
> +	if (!dirs)
>  		*flags |= EXC_FLAG_NODIR;
> +	else if (*p == '/')
> +		dirs--;

I presume this is to compensate for a pattern like "/pat" whose
leading slash is only to anchor the pattern at the level.  Correct?

> @@ -415,11 +423,26 @@ void add_exclude(const char *string, const char *base,
>  		x = xmalloc(sizeof(*x));
>  		x->pattern = string;
>  	}
> +	/*
> +	 * TODO: nowildcardlen < patternlen is a stricter than
> +	 * necessary mainly to exclude "**" that breaks directory
> +	 * boundary. Patterns like "/foo-*" should be fine.
> +	 */
> +	if ((flags & EXC_FLAG_NODIR) || nowildcardlen < patternlen)
> +		dirs = -1;

OK, so an entry "README" to match README in any subdirectory will
becomes (dirs < 0) and the matcher below will not short-circuit the
comparison.  Good.

> +	else {
> +		int i;
> +		for (i = 0; i < baselen; i++) {
> +			if (base[i] == '/')
> +				dirs++;
> +		}
> +	}
>  	x->patternlen = patternlen;
>  	x->nowildcardlen = nowildcardlen;
>  	x->base = base;
>  	x->baselen = baselen;
>  	x->flags = flags;
> +	x->dirs = dirs;
>  	x->srcpos = srcpos;
>  	ALLOC_GROW(el->excludes, el->nr + 1, el->alloc);
>  	el->excludes[el->nr++] = x;
> @@ -701,7 +724,7 @@ int match_pathname(const char *pathname, int pathlen,
>   * matched, or NULL for undecided.
>   */
>  static struct exclude *last_exclude_matching_from_list(const char *pathname,
> -						       int pathlen,
> +						       int pathlen, int dirs,
>  						       const char *basename,
>  						       int *dtype,
>  						       struct exclude_list *el)
> @@ -732,6 +755,9 @@ static struct exclude *last_exclude_matching_from_list(const char *pathname,
>  			continue;
>  		}
>  
> +		if (dirs >= 0 && x->dirs >= 0 && x->dirs != dirs)
> +			continue;