[PATCH 03/13] dir: select directories correctly

From: Derrick Stolee via GitGitGadget <gitgitgadget@gmail.com>
Date: Aug 24, 2021, 21:54 UTC
Message-ID: <d47c7a1cf2a3fa8cfdcfc6be1ac800af123e7efc.1629842085.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.1018.git.1629842085.gitgitgadget@gmail.com>

From: Derrick Stolee <dstolee@microsoft.com>

When matching a path against a list of patterns, the ones that require a directory match previously did not work when a filename is specified. This was fine when all pattern-matching was done within methods such as unpack_trees() that check a directory before recursing into the contained files. However, other commands will start matching individual files against pattern lists without that recursive approach.

We modify path_matches_dir_pattern() to take a strbuf 'path_parent' that is used to store the parent directory of 'pathname' between multiple pattern matching tests. This is loaded lazily, only on the first pattern it finds that has the PATTERN_FLAG_MUSTBEDIR flag.

If we find that a path has a parent directory, we start by checking to see if that parent directory matches the pattern. If so, then we do not need to query the index for the type (which can be expensive). If we find that the parent does not match, then we still must check the type from the index for the given pathname.

Note that this does not affect cone mode pattern matching, but instead the more general -- and slower -- full pattern set. Thus, this does not affect the sparse index.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 dir.c | 34 ++++++++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/dir.c b/dir.c
index 652135df896..fe5ee87bb5f 100644
--- a/dir.c
+++ b/dir.c
@@ -1305,10 +1305,38 @@ int match_pathname(const char *pathname, int pathlen,
 
 static int path_matches_dir_pattern(const char *pathname,
 				    int pathlen,
+				    struct strbuf *path_parent,
 				    int *dtype,
 				    struct path_pattern *pattern,
 				    struct index_state *istate)
 {
+	/*
+	 * Use 'alloc' as an indicator that the string has not been
+	 * initialized, in case the parent is the root directory.
+	 */
+	if (!path_parent->alloc) {
+		char *slash;
+		strbuf_addstr(path_parent, pathname);
+		slash = find_last_dir_sep(path_parent->buf);
+
+		if (slash)
+			*slash = '\0';
+		else
+			strbuf_setlen(path_parent, 0);
+	}
+
+	/*
+	 * If the parent directory matches the pattern, then we do not
+	 * need to check for dtype.
+	 */
+	if (path_parent->len &&
+	    match_pathname(path_parent->buf, path_parent->len,
+			   pattern->base,
+			   pattern->baselen ? pattern->baselen - 1 : 0,
+			   pattern->pattern, pattern->nowildcardlen,
+			   pattern->patternlen, pattern->flags))
+		return 1;
+
 	*dtype = resolve_dtype(*dtype, istate, pathname, pathlen);
 	if (*dtype != DT_DIR)
 		return 0;
@@ -1331,6 +1359,7 @@ static struct path_pattern *last_matching_pattern_from_list(const char *pathname
 {
 	struct path_pattern *res = NULL; /* undecided */
 	int i;
+	struct strbuf path_parent = STRBUF_INIT;
 
 	if (!pl->nr)
 		return NULL;	/* undefined */
@@ -1340,8 +1369,8 @@ static struct path_pattern *last_matching_pattern_from_list(const char *pathname
 		const char *exclude = pattern->pattern;
 		int prefix = pattern->nowildcardlen;
 
-		if ((pattern->flags & PATTERN_FLAG_MUSTBEDIR) &&
-		    !path_matches_dir_pattern(pathname, pathlen,
+		if (pattern->flags & PATTERN_FLAG_MUSTBEDIR &&
+		    !path_matches_dir_pattern(pathname, pathlen, &path_parent,
 					      dtype, pattern, istate))
 			continue;
 
@@ -1367,6 +1396,7 @@ static struct path_pattern *last_matching_pattern_from_list(const char *pathname
 			break;
 		}
 	}
+	strbuf_release(&path_parent);
 	return res;
 }

-- 
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