[PATCH v1 1/3] attr.c: read attributes in a sparse directory

[Shuqi Liang <cheskaqiqi@gmail.com>]

Before this patch,`git check-attr` can't find the attributes of a file
within a sparse directory. In order to read attributes from
'.gitattributes' files that may be in a sparse directory:

When path is in cone mode of sparse checkout:

1.If path is a sparse directory, read the tree OIDs from the sparse
directory.

2.If path is a regular files, read the attributes directly from the blob
data stored in the cache.

Helped-by: Victoria Dye <vdye@github.com>
Signed-off-by: Shuqi Liang <cheskaqiqi@gmail.com>
---
 attr.c | 64 +++++++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 43 insertions(+), 21 deletions(-)

diff --git a/attr.c b/attr.c
index 7d39ac4a29..b0d26da102 100644
--- a/attr.c
+++ b/attr.c
@@ -808,35 +808,57 @@ static struct attr_stack *read_attr_from_blob(struct index_state *istate,
 static struct attr_stack *read_attr_from_index(struct index_state *istate,
 					       const char *path, unsigned flags)
 {
+	struct attr_stack *stack = NULL;
+	int i;
+	struct strbuf path1 = STRBUF_INIT;
+	struct strbuf path2 = STRBUF_INIT;
+	char *first_slash = NULL;
 	char *buf;
 	unsigned long size;
 
 	if (!istate)
 		return NULL;
 
-	/*
-	 * The .gitattributes file only applies to files within its
-	 * parent directory. In the case of cone-mode sparse-checkout,
-	 * the .gitattributes file is sparse if and only if all paths
-	 * within that directory are also sparse. Thus, don't load the
-	 * .gitattributes file since it will not matter.
-	 *
-	 * In the case of a sparse index, it is critical that we don't go
-	 * looking for a .gitattributes file, as doing so would cause the
-	 * index to expand.
-	 */
-	if (!path_in_cone_mode_sparse_checkout(path, istate))
-		return NULL;
-
-	buf = read_blob_data_from_index(istate, path, &size);
-	if (!buf)
-		return NULL;
-	if (size >= ATTR_MAX_FILE_SIZE) {
-		warning(_("ignoring overly large gitattributes blob '%s'"), path);
-		return NULL;
+	first_slash = strchr(path, '/');
+	if (first_slash) {
+		strbuf_add(&path1, path, first_slash - path + 1);
+		strbuf_addstr(&path2, first_slash + 1);
 	}
 
-	return read_attr_from_buf(buf, path, flags);
+	if(!path_in_cone_mode_sparse_checkout(path, istate)){
+		for (i = 0; i < istate->cache_nr; i++) {
+			struct cache_entry *ce = istate->cache[i];
+			if ( !strcmp(istate->cache[i]->name, path1.buf)&&S_ISSPARSEDIR(ce->ce_mode)) {
+				stack = read_attr_from_blob(istate, &ce->oid, path2.buf, flags);
+			}else if(S_ISREG(ce->ce_mode) && !strcmp(istate->cache[i]->name, path)){
+				unsigned long sz;
+				enum object_type type;
+				void *data;
+
+				data = repo_read_object_file(the_repository, &istate->cache[i]->oid,
+							&type, &sz);
+				if (!data || type != OBJ_BLOB) {
+					free(data);
+					strbuf_release(&path1);
+					strbuf_release(&path2);
+					return NULL;
+				}
+				stack = read_attr_from_buf(data, path, flags);
+			}
+		}
+	}else{
+		buf = read_blob_data_from_index(istate, path, &size);
+		if (!buf)
+			return NULL;
+		if (size >= ATTR_MAX_FILE_SIZE) {
+			warning(_("ignoring overly large gitattributes blob '%s'"), path);
+			return NULL;
+		}
+		 stack = read_attr_from_buf(buf, path, flags);
+	}
+	strbuf_release(&path1);
+	strbuf_release(&path2);
+	return stack;
 }
 
 static struct attr_stack *read_attr(struct index_state *istate,
-- 
2.39.0