/*
 * Copyright (c) 1993 Jan-Simon Pendry
 * Copyright (c) 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Jan-Simon Pendry.
 *
 * 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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 *
 *      @(#)procfs_ctl.c        8.4 (Berkeley) 6/15/94
 *
 * From:
 * $FreeBSD: src/sys/miscfs/procfs/procfs_ctl.c,v 1.20.2.2 2002/01/22 17:22:59 nectar Exp $
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/caps.h>
#include <sys/vnode.h>
#include <sys/ptrace.h>
#include <sys/signalvar.h>
#include <vfs/procfs/procfs.h>

#include <sys/signal2.h>
#include <sys/spinlock2.h>

#include <vm/vm.h>

#ifndef FIX_SSTEP
#define FIX_SSTEP(lp)
#endif

/*
 * True iff process (p) is in trace wait state
 * relative to process (curp)
 */
#define TRACE_WAIT_P(curp, p) \
        (((p)->p_stat == SSTOP) && \
         (p)->p_pptr == (curp) && \
         ((p)->p_flags & P_TRACED))

#define PROCFS_CTL_ATTACH       1
#define PROCFS_CTL_DETACH       2
#define PROCFS_CTL_STEP         3
#define PROCFS_CTL_RUN          4
#define PROCFS_CTL_WAIT         5

static vfs_namemap_t ctlnames[] = {
        /* special /proc commands */
        { "attach",     PROCFS_CTL_ATTACH },
        { "detach",     PROCFS_CTL_DETACH },
        { "step",       PROCFS_CTL_STEP },
        { "run",        PROCFS_CTL_RUN },
        { "wait",       PROCFS_CTL_WAIT },
        { 0 },
};

static vfs_namemap_t signames[] = {
        /* regular signal names */
        { "hup",        SIGHUP },       { "int",        SIGINT },
        { "quit",       SIGQUIT },      { "ill",        SIGILL },
        { "trap",       SIGTRAP },      { "abrt",       SIGABRT },
        { "iot",        SIGIOT },       { "emt",        SIGEMT },
        { "fpe",        SIGFPE },       { "kill",       SIGKILL },
        { "bus",        SIGBUS },       { "segv",       SIGSEGV },
        { "sys",        SIGSYS },       { "pipe",       SIGPIPE },
        { "alrm",       SIGALRM },      { "term",       SIGTERM },
        { "urg",        SIGURG },       { "stop",       SIGSTOP },
        { "tstp",       SIGTSTP },      { "cont",       SIGCONT },
        { "chld",       SIGCHLD },      { "ttin",       SIGTTIN },
        { "ttou",       SIGTTOU },      { "io",         SIGIO },
        { "xcpu",       SIGXCPU },      { "xfsz",       SIGXFSZ },
        { "vtalrm",     SIGVTALRM },    { "prof",       SIGPROF },
        { "winch",      SIGWINCH },     { "info",       SIGINFO },
        { "usr1",       SIGUSR1 },      { "usr2",       SIGUSR2 },
        { 0 },
};

static int      procfs_control (struct proc *curp, struct lwp *lp, int op);

static int
procfs_control(struct proc *curp, struct lwp *lp, int op)
{
        struct proc *p = lp->lwp_proc;
        int error;

        ASSERT_LWKT_TOKEN_HELD(&p->p_token);

        /* Can't trace a process that's currently exec'ing. */
        if ((p->p_flags & P_INEXEC) != 0)
                return EAGAIN;
        /*
         * Authorization check: rely on normal debugging protection, except
         * allow processes to disengage debugging on a process onto which
         * they have previously attached, but no longer have permission to
         * debug.
         */
        if (op != PROCFS_CTL_DETACH) {
                if (securelevel > 0 && p->p_pid == 1)
                        return (EPERM);

                if (!CHECKIO(curp, p) || p_trespass(curp->p_ucred, p->p_ucred))
                        return (EPERM);
        }

        /*
         * Attach - attaches the target process for debugging
         * by the calling process.
         */
        if (op == PROCFS_CTL_ATTACH) {
                /* check whether already being traced */
                if (p->p_flags & P_TRACED)
                        return (EBUSY);

                /* can't trace yourself! */
                if (p->p_pid == curp->p_pid)
                        return (EINVAL);

                /*
                 * Go ahead and set the trace flag.
                 * Save the old parent (it's reset in
                 *   _DETACH, and also in kern_exit.c:wait4()
                 * Reparent the process so that the tracing
                 *   proc gets to see all the action.
                 * Stop the target.
                 */
                p->p_flags |= P_TRACED;
                p->p_xstat = 0;         /* XXX ? */
                if (p->p_pptr != curp) {
                        p->p_oppid = p->p_pptr->p_pid;
                        proc_reparent(p, curp);
                }
                proc_stop(p, SSTOP);
                return (0);
        }

        /*
         * Target process must be stopped, owned by (curp) and
         * be set up for tracing (P_TRACED flag set).
         * Allow DETACH to take place at any time for sanity.
         * Allow WAIT any time, of course.
         */
        switch (op) {
        case PROCFS_CTL_DETACH:
        case PROCFS_CTL_WAIT:
                break;

        default:
                if (!TRACE_WAIT_P(curp, p))
                        return (EBUSY);
        }


#ifdef FIX_SSTEP
        /*
         * do single-step fixup if needed
         */
        FIX_SSTEP(lp);
#endif

        /*
         * Don't deliver any signal by default.
         * To continue with a signal, just send
         * the signal name to the ctl file
         */
        p->p_xstat = 0;

        switch (op) {
        /*
         * Detach.  Cleans up the target process, reparent it if possible
         * and set it running once more.
         */
        case PROCFS_CTL_DETACH:
                /* if not being traced, then this is a painless no-op */
                if ((p->p_flags & P_TRACED) == 0)
                        return (0);

                /* not being traced any more */
                p->p_flags &= ~P_TRACED;

                /* remove pending SIGTRAP, else the process will die */
                spin_lock(&lp->lwp_spin);
                lwp_delsig(lp, SIGTRAP, 1);
                spin_unlock(&lp->lwp_spin);

                /* give process back to original parent */
                if (p->p_oppid != p->p_pptr->p_pid) {
                        struct proc *pp;

                        pp = pfs_pfind(p->p_oppid);
                        if (pp) {
                                proc_reparent(p, pp);
                                pfs_pdone(pp);
                        }
                }

                p->p_oppid = 0;
                p->p_flags &= ~P_WAITED;        /* XXX ? */
                wakeup((caddr_t) curp);         /* XXX for CTL_WAIT below ? */

                break;

        /*
         * Step.  Let the target process execute a single instruction.
         */
        case PROCFS_CTL_STEP:
                LWPHOLD(lp);
                error = procfs_sstep(lp);
                LWPRELE(lp);
                if (error)
                        return (error);
                break;

        /*
         * Run.  Let the target process continue running until a breakpoint
         * or some other trap.
         */
        case PROCFS_CTL_RUN:
                break;

        /*
         * Wait for the target process to stop.
         * If the target is not being traced then just wait
         * to enter
         */
        case PROCFS_CTL_WAIT:
                error = 0;
                if (p->p_flags & P_TRACED) {
                        while (error == 0 &&
                               p->p_stat != SSTOP &&
                               (p->p_flags & P_TRACED) &&
                               (p->p_pptr == curp))
                        {
                                error = tsleep((caddr_t) p, PCATCH,
                                               "procfsx", 0);
                        }
                        if (error == 0 && !TRACE_WAIT_P(curp, p))
                                error = EBUSY;
                } else {
                        while (error == 0 && p->p_stat != SSTOP) {
                                error = tsleep((caddr_t) p, PCATCH,
                                               "procfs", 0);
                        }
                }
                return (error);

        default:
                panic("procfs_control");
        }

        /*
         * If the process is in a stopped state, make it runnable again.
         * Do not set LWP_MP_BREAKTSLEEP - that is, do not break a tsleep
         * that might be in progress.
         */
        if (p->p_stat == SSTOP)
                proc_unstop(p, SSTOP);
        return (0);
}

int
procfs_doctl(struct proc *curp, struct lwp *lp, struct pfsnode *pfs,
             struct uio *uio)
{
        struct proc *p = lp->lwp_proc;
        int xlen;
        int error;
        char msg[PROCFS_CTLLEN+1];
        vfs_namemap_t *nm;

        ASSERT_LWKT_TOKEN_HELD(&p->p_token);

        if (uio->uio_rw != UIO_WRITE)
                return (EOPNOTSUPP);

        xlen = PROCFS_CTLLEN;
        error = vfs_getuserstr(uio, msg, &xlen);
        if (error)
                return (error);

        /*
         * Map signal names into signal generation
         * or debug control.  Unknown commands and/or signals
         * return EOPNOTSUPP.
         *
         * Sending a signal while the process is being debugged
         * also has the side effect of letting the target continue
         * to run.  There is no way to single-step a signal delivery.
         */
        error = EOPNOTSUPP;

        nm = vfs_findname(ctlnames, msg, xlen);
        if (nm) {
                error = procfs_control(curp, lp, nm->nm_val);
        } else {
                nm = vfs_findname(signames, msg, xlen);
                if (nm) {
                        if (TRACE_WAIT_P(curp, p)) {
                                p->p_xstat = nm->nm_val;
#ifdef FIX_SSTEP
                                FIX_SSTEP(lp);
#endif
                                /*
                                 * Make the process runnable but do not
                                 * break its tsleep.
                                 */
                                proc_unstop(p, SSTOP);
                        } else {
                                ksignal(p, nm->nm_val);
                        }
                        error = 0;
                }
        }

        return (error);
}