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pty.c
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Editing: pty.c
/*- * SPDX-License-Identifier: BSD-2-Clause-FreeBSD * * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org> * All rights reserved. * * Portions of this software were developed under sponsorship from Snow * B.V., the Netherlands. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include <sys/cdefs.h> __FBSDID("$FreeBSD$"); #include <sys/param.h> #include <sys/conf.h> #include <sys/eventhandler.h> #include <sys/fcntl.h> #include <sys/kernel.h> #include <sys/module.h> #include <sys/proc.h> #include <sys/sysctl.h> #include <sys/syslog.h> #include <sys/systm.h> #include <sys/tty.h> /* * This driver implements a BSD-style compatibility naming scheme for * the pts(4) driver. We just call into pts(4) to create the actual PTY. * To make sure we don't use the same PTY multiple times, we abuse * si_drv1 inside the cdev to mark whether the PTY is in use. * * It also implements a /dev/ptmx device node, which is useful for Linux * binary emulation. */ static unsigned pty_warningcnt = 1; SYSCTL_UINT(_kern, OID_AUTO, tty_pty_warningcnt, CTLFLAG_RW, &pty_warningcnt, 0, "Warnings that will be triggered upon legacy PTY allocation"); static int ptydev_fdopen(struct cdev *dev, int fflags, struct thread *td, struct file *fp) { int error; char name[6]; /* "ttyXX" */ if (!atomic_cmpset_ptr((uintptr_t *)&dev->si_drv1, 0, 1)) return (EBUSY); /* Generate device name and create PTY. */ strlcpy(name, devtoname(dev), sizeof(name)); name[0] = 't'; error = pts_alloc_external(fflags & (FREAD|FWRITE), td, fp, dev, name); if (error != 0) { destroy_dev_sched(dev); return (error); } /* Raise a warning when a legacy PTY has been allocated. */ counted_warning(&pty_warningcnt, "is using legacy pty devices"); return (0); } static struct cdevsw ptydev_cdevsw = { .d_version = D_VERSION, .d_fdopen = ptydev_fdopen, .d_name = "ptydev", }; static void pty_clone(void *arg, struct ucred *cr, char *name, int namelen, struct cdev **dev) { struct make_dev_args mda; int error; /* Cloning is already satisfied. */ if (*dev != NULL) return; /* Only catch /dev/ptyXX. */ if (namelen != 5 || bcmp(name, "pty", 3) != 0) return; /* Only catch /dev/pty[l-sL-S]X. */ if (!(name[3] >= 'l' && name[3] <= 's') && !(name[3] >= 'L' && name[3] <= 'S')) return; /* Only catch /dev/pty[l-sL-S][0-9a-v]. */ if (!(name[4] >= '0' && name[4] <= '9') && !(name[4] >= 'a' && name[4] <= 'v')) return; /* Create the controller device node. */ make_dev_args_init(&mda); mda.mda_flags = MAKEDEV_CHECKNAME | MAKEDEV_REF; mda.mda_devsw = &ptydev_cdevsw; mda.mda_uid = UID_ROOT; mda.mda_gid = GID_WHEEL; mda.mda_mode = 0666; error = make_dev_s(&mda, dev, "%s", name); if (error != 0) *dev = NULL; } static int ptmx_fdopen(struct cdev *dev __unused, int fflags, struct thread *td, struct file *fp) { return (pts_alloc(fflags & (FREAD|FWRITE), td, fp)); } static struct cdevsw ptmx_cdevsw = { .d_version = D_VERSION, .d_fdopen = ptmx_fdopen, .d_name = "ptmx", }; static int pty_modevent(module_t mod, int type, void *data) { switch(type) { case MOD_LOAD: EVENTHANDLER_REGISTER(dev_clone, pty_clone, 0, 1000); make_dev_credf(MAKEDEV_ETERNAL_KLD, &ptmx_cdevsw, 0, NULL, UID_ROOT, GID_WHEEL, 0666, "ptmx"); break; case MOD_SHUTDOWN: break; case MOD_UNLOAD: /* XXX: No unloading support yet. */ return (EBUSY); default: return (EOPNOTSUPP); } return (0); } DEV_MODULE(pty, pty_modevent, NULL);
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