1 files changed, 67 insertions, 0 deletions
diff --git a/sys/kern/uipc_mbuf.c b/sys/kern/uipc_mbuf.c
index 3dfee69..52b6bb1 100644
--- a/sys/kern/uipc_mbuf.c
+++ b/sys/kern/uipc_mbuf.c
@@ -755,6 +755,73 @@ out:	if (((m = m0)->m_flags & M_PKTHDR) && (m->m_pkthdr.len < totlen))
 		m->m_pkthdr.len = totlen;
 }
 
+/*
+ * Apply function f to the data in an mbuf chain starting "off" bytes from
+ * the beginning, continuing for "len" bytes.
+ */
+int
+m_apply(struct mbuf *m, int off, int len,
+    int (*f)(void *, caddr_t, unsigned int), void *arg)
+{
+	unsigned int count;
+	int rval;
+
+	KASSERT(off >= 0, ("m_apply, negative off %d", off));
+	KASSERT(len >= 0, ("m_apply, negative len %d", len));
+
+	while (off > 0) {
+		KASSERT(m != NULL, ("m_apply, offset > size of mbuf chain"));
+		if (off < m->m_len)
+			break;
+		off -= m->m_len;
+		m = m->m_next;
+	}
+	while (len > 0) {
+		KASSERT(m != NULL, ("m_apply, offset > size of mbuf chain"));
+		count = min(m->m_len - off, len);
+
+		rval = (*f)(arg, mtod(m, caddr_t) + off, count);
+		if (rval)
+			return (rval);
+
+		len -= count;
+		off = 0;
+		m = m->m_next;
+	}
+
+	return (0);
+}
+
+/*
+ * Return a pointer to mbuf/offset of location in mbuf chain.
+ */
+struct mbuf *
+m_getptr(struct mbuf *m, int loc, int *off)
+{
+
+	while (loc >= 0) {
+		/* Normal end of search */
+		if (m->m_len > loc) {
+			*off = loc;
+			return (m);
+		} else {
+			loc -= m->m_len;
+
+			if (m->m_next == NULL) {
+				if (loc == 0) {
+					/* Point at the end of valid data */
+					*off = m->m_len;
+					return (m);
+				} else
+					return (NULL);
+			} else
+				m = m->m_next;
+		}
+	}
+
+	return (NULL);
+}
+
 void
 m_print(const struct mbuf *m)
 {