enlarge msgbuf, somewhat line netbsd did

3 files changed, 60 insertions, 24 deletions

diff --git a/sys/kern/kern_sysctl.c b/sys/kern/kern_sysctl.c
index 14f3da7c1ff..6afca527cb8 100644
--- a/sys/kern/kern_sysctl.c
+++ b/sys/kern/kern_sysctl.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_sysctl.c,v 1.29 1999/06/29 23:51:59 provos Exp $	*/
+/*	$OpenBSD: kern_sysctl.c,v 1.30 2000/02/22 19:28:03 deraadt Exp $	*/
 /*	$NetBSD: kern_sysctl.c,v 1.17 1996/05/20 17:49:05 mrg Exp $	*/
 
 /*-
@@ -58,6 +58,7 @@
 #include <sys/disklabel.h>
 #include <vm/vm.h>
 #include <sys/sysctl.h>
+#include <sys/msgbuf.h>
 
 #if defined(UVM)
 #include <uvm/uvm_extern.h>
@@ -349,6 +350,14 @@ kern_sysctl(name, namelen, oldp, oldlenp, newp, newlen, p)
 #else
 		return (sysctl_rdint(oldp, oldlenp, newp, 0));
 #endif
+	case KERN_MSGBUFSIZE:
+		/*
+		 * deal with cases where the message buffer has
+		 * become corrupted.
+		 */
+		if (!msgbufp || msgbufp->msg_magic != MSG_MAGIC)
+			return (ENXIO);
+		return (sysctl_rdint(oldp, oldlenp, newp, msgbufp->msg_bufs));
 	default:
 		return (EOPNOTSUPP);
 	}
diff --git a/sys/kern/subr_log.c b/sys/kern/subr_log.c
index 5d247ead19f..00eb5a93bc9 100644
--- a/sys/kern/subr_log.c
+++ b/sys/kern/subr_log.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: subr_log.c,v 1.5 1997/09/18 13:23:26 deraadt Exp $	*/
+/*	$OpenBSD: subr_log.c,v 1.6 2000/02/22 19:28:03 deraadt Exp $	*/
 /*	$NetBSD: subr_log.c,v 1.11 1996/03/30 22:24:44 christos Exp $	*/
 
 /*
@@ -65,6 +65,44 @@ struct logsoftc {
 } logsoftc;
 
 int	log_open;			/* also used in log() */
+int	msgbufmapped;			/* is the message buffer mapped */
+int	msgbufenabled;			/* is logging to the buffer enabled */
+struct	msgbuf *msgbufp;		/* the mapped buffer, itself. */
+
+#define offsetof(type, member) ((size_t)(&((type *)0)->member))
+
+void
+initmsgbuf(buf, bufsize)
+	caddr_t buf;
+	size_t bufsize;
+{
+	register struct msgbuf *mbp;
+	long new_bufs;
+
+	/* Sanity-check the given size. */
+	if (bufsize < sizeof(struct msgbuf))
+		return;
+
+	mbp = msgbufp = (struct msgbuf *)buf;
+
+	new_bufs = bufsize - offsetof(struct msgbuf, msg_bufc);
+	if ((mbp->msg_magic != MSG_MAGIC) || (mbp->msg_bufs != new_bufs) ||
+	    (mbp->msg_bufr < 0) || (mbp->msg_bufr >= mbp->msg_bufs) ||
+	    (mbp->msg_bufx < 0) || (mbp->msg_bufx >= mbp->msg_bufs)) {
+		/*
+		 * If the buffer magic number is wrong, has changed
+		 * size (which shouldn't happen often), or is
+		 * internally inconsistent, initialize it.
+		 */
+
+		bzero(buf, bufsize);
+		mbp->msg_magic = MSG_MAGIC;
+		mbp->msg_bufs = new_bufs;
+	}
+
+	/* mark it as ready for use. */
+	msgbufmapped = msgbufenabled = 1;
+}
 
 /*ARGSUSED*/
 int
@@ -73,24 +111,9 @@ logopen(dev, flags, mode, p)
 	int flags, mode;
 	struct proc *p;
 {
-	register struct msgbuf *mbp = msgbufp;
-
 	if (log_open)
 		return (EBUSY);
 	log_open = 1;
-	/*
-	 * Potential race here with putchar() but since putchar should be
-	 * called by autoconf, msg_magic should be initialized by the time
-	 * we get here.
-	 */
-	if (mbp->msg_magic != MSG_MAGIC) {
-		register int i;
-
-		mbp->msg_magic = MSG_MAGIC;
-		mbp->msg_bufx = mbp->msg_bufr = 0;
-		for (i=0; i < MSG_BSIZE; i++)
-			mbp->msg_bufc[i] = 0;
-	}
 	return (0);
 }
 
@@ -139,7 +162,7 @@ logread(dev, uio, flag)
 	while (uio->uio_resid > 0) {
 		l = mbp->msg_bufx - mbp->msg_bufr;
 		if (l < 0)
-			l = MSG_BSIZE - mbp->msg_bufr;
+			l = mbp->msg_bufs - mbp->msg_bufr;
 		l = min(l, uio->uio_resid);
 		if (l == 0)
 			break;
@@ -148,7 +171,7 @@ logread(dev, uio, flag)
 		if (error)
 			break;
 		mbp->msg_bufr += l;
-		if (mbp->msg_bufr < 0 || mbp->msg_bufr >= MSG_BSIZE)
+		if (mbp->msg_bufr < 0 || mbp->msg_bufr >= mbp->msg_bufs)
 			mbp->msg_bufr = 0;
 	}
 	return (error);
@@ -212,7 +235,7 @@ logioctl(dev, com, data, flag, p)
 		l = msgbufp->msg_bufx - msgbufp->msg_bufr;
 		splx(s);
 		if (l < 0)
-			l += MSG_BSIZE;
+			l += msgbufp->msg_bufs;
 		*(int *)data = l;
 		break;
 
diff --git a/sys/kern/subr_prf.c b/sys/kern/subr_prf.c
index 5b6eb3fd762..0ec990f67a9 100644
--- a/sys/kern/subr_prf.c
+++ b/sys/kern/subr_prf.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: subr_prf.c,v 1.26 1999/12/02 00:23:35 deraadt Exp $	*/
+/*	$OpenBSD: subr_prf.c,v 1.27 2000/02/22 19:28:04 deraadt Exp $	*/
 /*	$NetBSD: subr_prf.c,v 1.45 1997/10/24 18:14:25 chuck Exp $	*/
 
 /*-
@@ -317,12 +317,16 @@ putchar(c, flags, tp)
 	    c != '\0' && c != '\r' && c != 0177 && msgbufmapped) {
 		mbp = msgbufp;
 		if (mbp->msg_magic != MSG_MAGIC) {
-			bzero((caddr_t) mbp, sizeof(*mbp));
-			mbp->msg_magic = MSG_MAGIC;
+			/* Nothing we can do */
 		}
 		mbp->msg_bufc[mbp->msg_bufx++] = c;
-		if (mbp->msg_bufx < 0 || mbp->msg_bufx >= MSG_BSIZE)
+		if (mbp->msg_bufx < 0 || mbp->msg_bufx >= mbp->msg_bufs)
 			mbp->msg_bufx = 0;
+                /* If the buffer is full, keep the most recent data. */
+                if (mbp->msg_bufr == mbp->msg_bufx) {
+                         if (++mbp->msg_bufr >= mbp->msg_bufs)
+                                mbp->msg_bufr = 0;
+                }
 	}
 	if ((flags & TOCONS) && constty == NULL && c != '\0')
 		(*v_putc)(c);