[PATCH 08/18] is_refname_available(): use dirname in first loop

[Michael Haggerty <mhagger@alum.mit.edu>]

In the first loop (over prefixes of refname), use dirname to keep
track of the current prefix. This is not an improvement in itself, but
in a moment we will start using dirname for a role where a
NUL-terminated string is needed.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
---
 refs.c | 43 ++++++++++++++++++++++++++++---------------
 1 file changed, 28 insertions(+), 15 deletions(-)

diff --git a/refs.c b/refs.c
index 0ec3f0a..8e929c7 100644
--- a/refs.c
+++ b/refs.c
@@ -883,8 +883,13 @@ static int is_refname_available(const char *refname,
 	const char *slash;
 	int pos;
 	struct strbuf dirname = STRBUF_INIT;
+	int ret = 0;
 
+	strbuf_grow(&dirname, strlen(refname) + 1);
 	for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
+		/* Expand dirname to the new prefix, not including the trailing slash: */
+		strbuf_add(&dirname, refname + dirname.len, slash - refname - dirname.len);
+
 		/*
 		 * We are still at a leading dir of the refname; we are
 		 * looking for a conflict with a leaf entry.
@@ -892,10 +897,9 @@ static int is_refname_available(const char *refname,
 		 * If we find one, we still must make sure it is
 		 * not in "skip".
 		 */
-		pos = search_ref_dir(dir, refname, slash - refname);
+		pos = search_ref_dir(dir, dirname.buf, dirname.len);
 		if (pos >= 0) {
-			struct ref_entry *entry = dir->entries[pos];
-			if (skip && string_list_has_string(skip, entry->name)) {
+			if (skip && string_list_has_string(skip, dirname.buf)) {
 				/*
 				 * The fact that entry is a ref whose
 				 * name is a prefix of refname means
@@ -907,10 +911,11 @@ static int is_refname_available(const char *refname,
 				 * is in skip), we can stop looking
 				 * now and return true.
 				 */
-				return 1;
+				ret = 1;
+				goto cleanup;
 			}
-			error("'%s' exists; cannot create '%s'", entry->name, refname);
-			return 0;
+			error("'%s' exists; cannot create '%s'", dirname.buf, refname);
+			goto cleanup;
 		}
 
 
@@ -919,9 +924,12 @@ static int is_refname_available(const char *refname,
 		 * the next component; if we come up empty, we know
 		 * there is nothing under this whole prefix.
 		 */
-		pos = search_ref_dir(dir, refname, slash + 1 - refname);
-		if (pos < 0)
-			return 1;
+		strbuf_addch(&dirname, '/');
+		pos = search_ref_dir(dir, dirname.buf, dirname.len);
+		if (pos < 0) {
+			ret = 1;
+			goto cleanup;
+		}
 
 		dir = get_ref_dir(dir->entries[pos]);
 	}
@@ -930,10 +938,9 @@ static int is_refname_available(const char *refname,
 	 * We are at the leaf of our refname; we want to
 	 * make sure there are no directories which match it.
 	 */
-	strbuf_addstr(&dirname, refname);
+	strbuf_addstr(&dirname, refname + dirname.len);
 	strbuf_addch(&dirname, '/');
 	pos = search_ref_dir(dir, dirname.buf, dirname.len);
-	strbuf_release(&dirname);
 
 	if (pos >= 0) {
 		/*
@@ -947,12 +954,14 @@ static int is_refname_available(const char *refname,
 		dir = get_ref_dir(entry);
 		data.skip = skip;
 		sort_ref_dir(dir);
-		if (!do_for_each_entry_in_dir(dir, 0, nonmatching_ref_fn, &data))
-			return 1;
+		if (!do_for_each_entry_in_dir(dir, 0, nonmatching_ref_fn, &data)) {
+			ret = 1;
+			goto cleanup;
+		}
 
 		error("'%s' exists; cannot create '%s'",
 		      data.conflicting_refname, refname);
-		return 0;
+		goto cleanup;
 	}
 
 	/*
@@ -960,7 +969,11 @@ static int is_refname_available(const char *refname,
 	 * node which matches it; such an entry would be the
 	 * ref we are looking for, not a conflict.
 	 */
-	return 1;
+	ret = 1;
+
+cleanup:
+	strbuf_release(&dirname);
+	return ret;
 }
 
 struct packed_ref_cache {
-- 
2.1.4