/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <signal.h>
#include <libproc.h>

static  int     start(char *);
static  int     lwpstart(int *, const lwpstatus_t *, const lwpsinfo_t *);

static  char    *command;
static  const char *lwps;
static  struct  ps_prochandle *P;

int
main(int argc, char **argv)
{
        int     rc = 0;

        if ((command = strrchr(argv[0], '/')) != NULL)
                command++;
        else
                command = argv[0];

        if (argc <= 1) {
                (void) fprintf(stderr, "usage:\t%s pid[/lwps] ...\n", command);
                (void) fprintf(stderr, "  (set stopped processes or lwps "
                    "running)\n");
                return (2);
        }

        while (--argc > 0)
                rc += start(*++argv);

        return (rc);
}

static int
start(char *arg)
{
        int gcode;
        int rc = 0;

        if ((P = proc_arg_xgrab(arg, NULL, PR_ARG_PIDS, PGRAB_FORCE |
            PGRAB_RETAIN | PGRAB_NOSTOP, &gcode, &lwps)) == NULL) {
                (void) fprintf(stderr, "%s: cannot control %s: %s\n",
                    command, arg, Pgrab_error(gcode));
                return (1);
        }

        /*
         * If the victim is stopped because of a job control signal, we
         * need to send it SIGCONT to get it moving again, otherwise
         * the agent will not be able to run, and so will not be able to
         * exit the process.
         */
        (void) kill(Pstatus(P)->pr_pid, SIGCONT);

        /*
         * if the agent already exists, Pcreate_agent will adopt the
         * extant agent so that we can destroy it
         */
        if (Pstatus(P)->pr_lwp.pr_flags & PR_AGENT) {
                if (Pcreate_agent(P) != 0) {
                        (void) fprintf(stderr,
                            "%s: cannot remove agent from %s: %s\n",
                            command, arg, strerror(errno));

                        Prelease(P, 0);
                        return (1);
                }

                Pdestroy_agent(P);
        }

        if (lwps != NULL) {
                /*
                 * The user provided an lwp specification. Let's consider the
                 * lwp specification as a mask.  We iterate over all lwps in the
                 * process and set running every lwp, which matches the mask.
                 * If there is no lwp matching the mask or an error occured
                 * during the iteration, set the return code to 1 as indication
                 * of an error.  We need to unset run-on-last-close flag,
                 * otherwise *all* lwps could be set running after detaching
                 * from the process and not only lwps, which were selected.
                 */
                int lwpcount = 0;

                (void) Punsetflags(P, PR_RLC);
                (void) Plwp_iter_all(P, (proc_lwp_all_f *)lwpstart, &lwpcount);

                if (lwpcount == 0) {
                        (void) fprintf(stderr, "%s: cannot control %s:"
                            " no matching LWPs found\n", command, arg);
                        rc = 1;
                } else if (lwpcount == -1)
                        rc = 1;
        } else {
                (void) Psetrun(P, 0, 0);        /* Set the process running. */
        }

        /*
         * Prelease could change the tracing flags or leave the victim hung
         * so we free the handle by hand.
         */
        Pfree(P);
        return (rc);
}

/* ARGSUSED */
static int
lwpstart(int *lwpcount, const lwpstatus_t *status, const lwpsinfo_t *info)
{
        struct ps_lwphandle *L;
        int gcode;

        if (proc_lwp_in_set(lwps, info->pr_lwpid)) {
                /*
                 * There is a race between the callback from the iterator and
                 * grabbing of the lwp.  If the lwp has already exited, Lgrab
                 * will return the error code G_NOPROC.  It's not a real error,
                 * only if there is no lwp matching the specification.
                 */
                if ((L = Lgrab(P, info->pr_lwpid, &gcode)) != NULL) {
                        (void) Lsetrun(L, 0, 0);
                        Lfree(L);
                        if (*lwpcount >= 0)
                                (*lwpcount)++;
                } else if (gcode != G_NOPROC) {
                        (void) fprintf(stderr, "%s: cannot control %d/%d: %s\n",
                            command, (int)Pstatus(P)->pr_pid,
                            (int)info->pr_lwpid, Lgrab_error(gcode));
                        *lwpcount = -1;
                }
        }
        return (0);
}