submodule: don't pass empty string arguments to submodule--helper clone

diff --git a/strbuf.c b/strbuf.c
index 47ac0457f761152451994cf8d9e6dd14f086b283..bab316dda8f4946efb9a908f17c98b4db3d21e98 100644 (file)
--- a/strbuf.c
+++ b/strbuf.c
@@ -384,6 +384,17 @@ ssize_t strbuf_read(struct strbuf *sb, int fd, size_t hint)
        return sb->len - oldlen;
 }
 
+ssize_t strbuf_read_once(struct strbuf *sb, int fd, size_t hint)
+{
+       ssize_t cnt;
+
+       strbuf_grow(sb, hint ? hint : 8192);
+       cnt = xread(fd, sb->buf + sb->len, sb->alloc - sb->len - 1);
+       if (cnt > 0)
+               strbuf_setlen(sb, sb->len + cnt);
+       return cnt;
+}
+
 #define STRBUF_MAXLINK (2*PATH_MAX)
 
 int strbuf_readlink(struct strbuf *sb, const char *path, size_t hint)