patch: added mbuf_shift()

include/re_mbuf.h

@@ -46,6 +46,7 @@ void     mbuf_init(struct mbuf *mb);
 void     mbuf_reset(struct mbuf *mb);
 int      mbuf_resize(struct mbuf *mb, size_t size);
 void     mbuf_trim(struct mbuf *mb);
+int      mbuf_shift(struct mbuf *mb, ssize_t shift);
 int      mbuf_write_mem(struct mbuf *mb, const uint8_t *buf, size_t size);
 int      mbuf_write_u8(struct mbuf *mb, uint8_t v);
 int      mbuf_write_u16(struct mbuf *mb, uint16_t v);

src/mbuf/mbuf.c

@@ -153,6 +153,48 @@ void mbuf_trim(struct mbuf *mb)
 }
 
 
+/**
+ * Shift mbuf content position
+ *
+ * @param mb    Memory buffer to shift
+ * @param shift Shift offset count
+ *
+ * @return 0 if success, otherwise errorcode
+ */
+int mbuf_shift(struct mbuf *mb, ssize_t shift)
+{
+	size_t rsize;
+	uint8_t *p;
+
+	if (!mb)
+		return EINVAL;
+
+	if (((ssize_t)mb->pos + shift) < 0 ||
+	    ((ssize_t)mb->end + shift) < 0)
+		return ERANGE;
+
+	rsize = mb->end + shift;
+
+	if (rsize > mb->size) {
+
+		int err;
+
+		err = mbuf_resize(mb, rsize);
+		if (err)
+			return err;
+	}
+
+	p = mbuf_buf(mb);
+
+	memmove(p + shift, p, mbuf_get_left(mb));
+
+	mb->pos += shift;
+	mb->end += shift;
+
+	return 0;
+}
+
+
 /**
  * Write a block of memory to a memory buffer
  *