1 files changed, 45 insertions, 38 deletions

diff --git a/sha1_file.c b/sha1_file.c
index 057262d46e..3d8c1e88a5 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -235,6 +235,36 @@ struct alternate_object_database *alt_odb_list;
 static struct alternate_object_database **alt_odb_tail;
 
 /*
+ * Return non-zero iff the path is usable as an alternate object database.
+ */
+static int alt_odb_usable(struct strbuf *path, const char *normalized_objdir)
+{
+	struct alternate_object_database *alt;
+
+	/* Detect cases where alternate disappeared */
+	if (!is_directory(path->buf)) {
+		error("object directory %s does not exist; "
+		      "check .git/objects/info/alternates.",
+		      path->buf);
+		return 0;
+	}
+
+	/*
+	 * Prevent the common mistake of listing the same
+	 * thing twice, or object directory itself.
+	 */
+	for (alt = alt_odb_list; alt; alt = alt->next) {
+		if (path->len == alt->name - alt->base - 1 &&
+		    !memcmp(path->buf, alt->base, path->len))
+			return 0;
+	}
+	if (!fspathcmp(path->buf, normalized_objdir))
+		return 0;
+
+	return 1;
+}
+
+/*
  * Prepare alternate object database registry.
  *
  * The variable alt_odb_list points at the list of struct
@@ -253,8 +283,7 @@ static int link_alt_odb_entry(const char *entry, const char *relative_base,
 	int depth, const char *normalized_objdir)
 {
 	struct alternate_object_database *ent;
-	struct alternate_object_database *alt;
-	size_t pfxlen, entlen;
+	size_t entlen;
 	struct strbuf pathbuf = STRBUF_INIT;
 
 	if (!is_absolute_path(entry) && relative_base) {
@@ -270,47 +299,26 @@ static int link_alt_odb_entry(const char *entry, const char *relative_base,
 		return -1;
 	}
 
-	pfxlen = strlen(pathbuf.buf);
-
 	/*
 	 * The trailing slash after the directory name is given by
 	 * this function at the end. Remove duplicates.
 	 */
-	while (pfxlen && pathbuf.buf[pfxlen-1] == '/')
-		pfxlen -= 1;
-
-	entlen = st_add(pfxlen, 43); /* '/' + 2 hex + '/' + 38 hex + NUL */
-	ent = xmalloc(st_add(sizeof(*ent), entlen));
-	memcpy(ent->base, pathbuf.buf, pfxlen);
-	strbuf_release(&pathbuf);
-
-	ent->name = ent->base + pfxlen + 1;
-	ent->base[pfxlen + 3] = '/';
-	ent->base[pfxlen] = ent->base[entlen-1] = 0;
+	while (pathbuf.len && pathbuf.buf[pathbuf.len - 1] == '/')
+		strbuf_setlen(&pathbuf, pathbuf.len - 1);
 
-	/* Detect cases where alternate disappeared */
-	if (!is_directory(ent->base)) {
-		error("object directory %s does not exist; "
-		      "check .git/objects/info/alternates.",
-		      ent->base);
-		free(ent);
+	if (!alt_odb_usable(&pathbuf, normalized_objdir)) {
+		strbuf_release(&pathbuf);
 		return -1;
 	}
 
-	/* Prevent the common mistake of listing the same
-	 * thing twice, or object directory itself.
-	 */
-	for (alt = alt_odb_list; alt; alt = alt->next) {
-		if (pfxlen == alt->name - alt->base - 1 &&
-		    !memcmp(ent->base, alt->base, pfxlen)) {
-			free(ent);
-			return -1;
-		}
-	}
-	if (!fspathcmp(ent->base, normalized_objdir)) {
-		free(ent);
-		return -1;
-	}
+	entlen = st_add(pathbuf.len, 43); /* '/' + 2 hex + '/' + 38 hex + NUL */
+	ent = xmalloc(st_add(sizeof(*ent), entlen));
+	memcpy(ent->base, pathbuf.buf, pathbuf.len);
+
+	ent->name = ent->base + pathbuf.len + 1;
+	ent->base[pathbuf.len] = '/';
+	ent->base[pathbuf.len + 3] = '/';
+	ent->base[entlen-1] = 0;
 
 	/* add the alternate entry */
 	*alt_odb_tail = ent;
@@ -318,10 +326,9 @@ static int link_alt_odb_entry(const char *entry, const char *relative_base,
 	ent->next = NULL;
 
 	/* recursively add alternates */
-	read_info_alternates(ent->base, depth + 1);
-
-	ent->base[pfxlen] = '/';
+	read_info_alternates(pathbuf.buf, depth + 1);
 
+	strbuf_release(&pathbuf);
 	return 0;
 }