improve the mbuf m_print function.. Only pull length from pkthdr if there

is one, detect mbuf loops and stop, add an extra arg so you can only print
the first x bytes of the data per mbuf (print all if arg is -1), print
flags using %b (bitmask)...

No code in the tree appears to use m_print, and it's just a maner of adding
-1 as an additional arg to m_print to restore original behavior..

MFC after:	4 days

2 files changed, 21 insertions, 6 deletions

diff --git a/sys/kern/uipc_mbuf.c b/sys/kern/uipc_mbuf.c
index a1449d8..1c2e410 100644
--- a/sys/kern/uipc_mbuf.c
+++ b/sys/kern/uipc_mbuf.c
@@ -995,18 +995,33 @@ m_getptr(struct mbuf *m, int loc, int *off)
 }
 
 void
-m_print(const struct mbuf *m)
+m_print(const struct mbuf *m, int maxlen)
 {
 	int len;
+	int pdata;
 	const struct mbuf *m2;
 
-	len = m->m_pkthdr.len;
+	if (m->m_flags & M_PKTHDR)
+		len = m->m_pkthdr.len;
+	else
+		len = -1;
 	m2 = m;
-	while (len) {
-		printf("%p %*D\n", m2, m2->m_len, (u_char *)m2->m_data, "-");
-		len -= m2->m_len;
+	while (m2 != NULL && (len == -1 || len)) {
+		pdata = m2->m_len;
+		if (maxlen != -1 && pdata > maxlen)
+			pdata = maxlen;
+		printf("mbuf: %p len: %d, next: %p, %b%s", m2, m2->m_len,
+		    m2->m_next, m2->m_flags, "\20\20freelist\17skipfw"
+		    "\11proto5\10proto4\7proto3\6proto2\5proto1\4rdonly"
+		    "\3eor\2pkthdr\1ext", pdata ? "" : "\n");
+		if (pdata)
+			printf(", %*D\n", m2->m_len, (u_char *)m2->m_data, "-");
+		if (len != -1)
+			len -= m2->m_len;
 		m2 = m2->m_next;
 	}
+	if (len > 0)
+		printf("%d bytes unaccounted for.\n", len);
 	return;
 }
 
diff --git a/sys/sys/mbuf.h b/sys/sys/mbuf.h
index 0c65b8e..78053e9 100644
--- a/sys/sys/mbuf.h
+++ b/sys/sys/mbuf.h
@@ -556,7 +556,7 @@ struct	mbuf	*m_getptr(struct mbuf *, int, int *);
 u_int		 m_length(struct mbuf *, struct mbuf **);
 void		 m_move_pkthdr(struct mbuf *, struct mbuf *);
 struct	mbuf	*m_prepend(struct mbuf *, int, int);
-void		 m_print(const struct mbuf *);
+void		 m_print(const struct mbuf *, int);
 struct	mbuf	*m_pulldown(struct mbuf *, int, int, int *);
 struct	mbuf	*m_pullup(struct mbuf *, int);
 struct	mbuf	*m_split(struct mbuf *, int, int);