Date: Mon, 12 Jul 2004 23:24:20 +0200 From: Robert Millan <rmh@debian.org> To: FreeBSD-gnats-submit@FreeBSD.org Subject: kern/68961: [PATCH] Implement /dev/full Message-ID: <E1Bk8Hc-0005iz-00@khazad.dyndns.org> Resent-Message-ID: <200407122130.i6CLUNL9075461@freefall.freebsd.org>
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>Number: 68961 >Category: kern >Synopsis: [PATCH] Implement /dev/full >Confidential: no >Severity: non-critical >Priority: low >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: change-request >Submitter-Id: current-users >Arrival-Date: Mon Jul 12 21:30:22 GMT 2004 >Closed-Date: >Last-Modified: >Originator: Robert Millan >Release: FreeBSD 5.2.1 >Organization: Debian >Environment: System: GNU/Linux aragorn 2.4.26-1-k7 #1 Sat May 1 21:40:09 EST 2004 i686 Architecture: i686 >Description: This patch implements /dev/full, a device that returns ENOSPC when attempting to write on it. It is commonly used on other Un*x OSes (e.g. GNU/Linux) and some applications assume it is present. Note: I'm the maintainer of the Debian package "kfreebsd5" (kernel of FreeBSD 5.x). I have made some changes to the kernel for portability and some improvements, and I'll be forwarding more patches in the future. >How-To-Repeat: >Fix: I don't know the policy for assigning minor numbers, so I just defined FULL_MINOR as 3 which apparently is free. Let me know if I missed something. --- src/sys/dev/null/null.c.old 2004-07-12 20:20:37.000000000 +0200 +++ src/sys/dev/null/null.c 2004-07-12 20:27:10.000000000 +0200 @@ -41,14 +41,17 @@ /* For use with destroy_dev(9). */ static dev_t null_dev; +static dev_t full_dev; static dev_t zero_dev; static d_write_t null_write; +static d_write_t full_write; static d_ioctl_t null_ioctl; static d_read_t zero_read; #define CDEV_MAJOR 2 #define NULL_MINOR 2 +#define FULL_MINOR 3 #define ZERO_MINOR 12 static struct cdevsw null_cdevsw = { @@ -60,6 +63,15 @@ .d_flags = D_NOGIANT, }; +static struct cdevsw full_cdevsw = { + .d_read = (d_read_t *)nullop, + .d_write = full_write, + .d_ioctl = null_ioctl, + .d_name = "full", + .d_maj = CDEV_MAJOR, + .d_flags = D_NOGIANT, +}; + static struct cdevsw zero_cdevsw = { .d_read = zero_read, .d_write = null_write, @@ -80,6 +92,14 @@ /* ARGSUSED */ static int +full_write(dev_t dev __unused, struct uio *uio, int flags __unused) +{ + uio->uio_resid = 0; + return (ENOSPC); +} + +/* ARGSUSED */ +static int null_ioctl(dev_t dev __unused, u_long cmd, caddr_t data __unused, int flags __unused, struct thread *td) { @@ -120,10 +140,13 @@ GID_WHEEL, 0666, "zero"); null_dev = make_dev(&null_cdevsw, NULL_MINOR, UID_ROOT, GID_WHEEL, 0666, "null"); + full_dev = make_dev(&full_cdevsw, FULL_MINOR, UID_ROOT, + GID_WHEEL, 0666, "full"); return 0; case MOD_UNLOAD: destroy_dev(null_dev); + destroy_dev(full_dev); destroy_dev(zero_dev); free(zbuf, M_TEMP); return 0; >Release-Note: >Audit-Trail: >Unformatted:
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