Check the device name validity on device registration.

A new function prep_devname() sanitizes a device name by removing
leading and redundant sequential slashes. The function returns an error
for names which already exist or are considered invalid.

A new flag MAKEDEV_CHECKNAME for make_dev_p(9) and make_dev_credf(9)
indicates that the caller is prepared to handle an error related to the
device name. An invalid name triggers a panic if the flag is not
specified.

Document the MAKEDEV_CHECKNAME flag in the make_dev(9) manual page.

Idea from:	kib
Reviewed by:	kib

1 files changed, 16 insertions, 7 deletions

diff --git a/share/man/man9/make_dev.9 b/share/man/man9/make_dev.9
index 9cc755f..2e35f5f 100644
--- a/share/man/man9/make_dev.9
+++ b/share/man/man9/make_dev.9
@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd September 5, 2010
+.Dd October 7, 2010
 .Dt MAKE_DEV 9
 .Os
 .Sh NAME
@@ -131,12 +131,18 @@ argument alters the operation of
 .Fn make_dev_credf .
 The following values are currently accepted:
 .Pp
-.Bd -literal -offset indent -compact
-MAKEDEV_REF	reference the created device
-MAKEDEV_NOWAIT	do not sleep, may return NULL
-MAKEDEV_WAITOK	allow the function to sleep to satisfy malloc
-MAKEDEV_ETERNAL	created device will be never destroyed
-.Ed
+.Bl -tag -width "MAKEDEV_CHECKNAME" -compact -offset indent
+.It MAKEDEV_REF
+reference the created device
+.It MAKEDEV_NOWAIT
+do not sleep, may return NULL
+.It MAKEDEV_WAITOK
+allow the function to sleep to satisfy malloc
+.It MAKEDEV_ETERNAL
+created device will be never destroyed
+.It MAKEDEV_CHECKNAME
+return NULL if the device name is invalid or already exists
+.El
 .Pp
 The
 .Dv MAKEDEV_WAITOK
@@ -166,6 +172,9 @@ For the convenience, use the
 flag for the code that can be compiled into kernel or loaded
 (and unloaded) as loadable module.
 .Pp
+A panic will occur if the MAKEDEV_CHECKNAME flag is not specified
+and the device name is invalid or already exists.
+.Pp
 The
 .Fn make_dev_cred
 function is equivalent to the call