1 files changed, 27 insertions, 9 deletions

diff --git a/sys/dev/null/null.c b/sys/dev/null/null.c
index 4f7bd9c8742a..653d732aa8a1 100644
--- a/sys/dev/null/null.c
+++ b/sys/dev/null/null.c
@@ -43,14 +43,17 @@ __FBSDID("$FreeBSD$");
 /* For use with destroy_dev(9). */
 static struct cdev *null_dev;
 static struct cdev *zero_dev;
+static struct cdev *full_dev;
 
 static d_write_t null_write;
 static d_ioctl_t null_ioctl;
 static d_read_t zero_read;
+static d_write_t full_write;
 
 #define CDEV_MAJOR	2
-#define NULL_MINOR	2
-#define ZERO_MINOR	12
+#define NULL_MINOR	0
+#define ZERO_MINOR	1
+#define FULL_MINOR	2
 
 static struct cdevsw null_cdevsw = {
 	.d_version =	D_VERSION,
@@ -70,6 +73,14 @@ static struct cdevsw zero_cdevsw = {
 	.d_flags =	D_MMAP_ANON,
 };
 
+static struct cdevsw full_cdevsw = {
+	.d_version =	D_VERSION,
+	.d_read =	(d_read_t *)nullop,
+	.d_write =	full_write,
+	.d_name =	"full",
+	.d_maj =	CDEV_MAJOR,
+};
+
 static void *zbuf;
 
 /* ARGSUSED */
@@ -100,19 +111,23 @@ null_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused,
 static int
 zero_read(struct cdev *dev __unused, struct uio *uio, int flags __unused)
 {
-	int c;
 	int error = 0;
 
-	while (uio->uio_resid > 0 && error == 0) {
-		c = uio->uio_resid < PAGE_SIZE ? uio->uio_resid : PAGE_SIZE;
-		error = uiomove(zbuf, c, uio);
-	}
+	while (uio->uio_resid > 0 && error == 0)
+		error = uiomove(zbuf, MIN(uio->uio_resid, PAGE_SIZE), uio);
 
 	return (error);
 }
 
 /* ARGSUSED */
 static int
+full_write(struct cdev *dev __unused, struct uio *uio, int flags __unused)
+{
+	return (ENOSPC);
+}
+
+/* ARGSUSED */
+static int
 null_modevent(module_t mod __unused, int type, void *data __unused)
 {
 	switch(type) {
@@ -120,15 +135,18 @@ null_modevent(module_t mod __unused, int type, void *data __unused)
 		if (bootverbose)
 			printf("null: <null device, zero device>\n");
 		zbuf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK | M_ZERO);
-		zero_dev = make_dev(&zero_cdevsw, ZERO_MINOR, UID_ROOT,
-			GID_WHEEL, 0666, "zero");
 		null_dev = make_dev(&null_cdevsw, NULL_MINOR, UID_ROOT,
 			GID_WHEEL, 0666, "null");
+		zero_dev = make_dev(&zero_cdevsw, ZERO_MINOR, UID_ROOT,
+			GID_WHEEL, 0666, "zero");
+		full_dev = make_dev(&full_cdevsw, FULL_MINOR, UID_ROOT,
+			GID_WHEEL, 0666, "full");
 		break;
 
 	case MOD_UNLOAD:
 		destroy_dev(null_dev);
 		destroy_dev(zero_dev);
+		destroy_dev(full_dev);
 		free(zbuf, M_TEMP);
 		break;