branch: correctly reject refs/heads/{-dash,HEAD}

diff --git a/sha1_name.c b/sha1_name.c
index 134ac9742f9eed3dc6e587875bdb9aa77b7a8307..67961d6e47b67eac4372cbe5ffb37fa3d97c5861 100644 (file)
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -157,7 +157,7 @@ static void unique_in_pack(struct packed_git *p,
        num = p->num_objects;
        last = num;
        while (first < last) {
-               uint32_t mid = (first + last) / 2;
+               uint32_t mid = first + (last - first) / 2;
                const unsigned char *current;
                int cmp;
 
@@ -1332,9 +1332,19 @@ void strbuf_branchname(struct strbuf *sb, const char *name, unsigned allowed)
 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
 {
        strbuf_branchname(sb, name, INTERPRET_BRANCH_LOCAL);
-       if (name[0] == '-')
-               return -1;
+
+       /*
+        * This splice must be done even if we end up rejecting the
+        * name; builtin/branch.c::copy_or_rename_branch() still wants
+        * to see what the name expanded to so that "branch -m" can be
+        * used as a tool to correct earlier mistakes.
+        */
        strbuf_splice(sb, 0, 0, "refs/heads/", 11);
+
+       if (*name == '-' ||
+           !strcmp(sb->buf, "refs/heads/HEAD"))
+               return -1;
+
        return check_refname_format(sb->buf, 0);
 }