/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (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 2003 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 <ctype.h>
#include <string.h>
#include <signal.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <libproc.h>

#define NOREAP_TIME 60          /* wait 60 seconds before allow a reap */

static volatile int interrupt;
static int Fflag;
static char *command;

static void
intr(int sig)
{
        interrupt = sig;
}

static int
open_usage(pid_t pid, int *perr)
{
        char path[64];
        struct stat64 st;
        int fd;

        (void) snprintf(path, sizeof (path), "/proc/%d/usage", (int)pid);

        /*
         * Attempt to open the usage file, and return the fd if we can
         * confirm this is a regular file provided by /proc.
         */
        if ((fd = open64(path, O_RDONLY)) >= 0) {
                if (fstat64(fd, &st) != 0 || !S_ISREG(st.st_mode) ||
                    strcmp(st.st_fstype, "proc") != 0) {
                        (void) close(fd);
                        fd = -1;
                }
        } else if (errno == EACCES || errno == EPERM)
                *perr = G_PERM;

        return (fd);
}

static int
proc_usage(pid_t pid, prusage_t *pup, int *perr)
{
        int fd;

        *perr = G_NOPROC;

        if ((fd = open_usage(pid, perr)) != -1) {
                if (read(fd, pup, sizeof (prusage_t)) == sizeof (prusage_t)) {
                        *perr = 0;
                        (void) close(fd);
                        return (0);
                }

                /*
                 * If the read failed, the process may have gone away.
                 */
                (void) close(fd);
        }
        return (-1);
}

/*
 * Force the parent process (ppid) to wait for its child process (pid).
 */
static int
reap(char *arg, pid_t *reap_pid, int *exit_status)
{
        struct ps_prochandle *Pr;
        siginfo_t siginfo;
        psinfo_t psinfo;
        prusage_t usage;
        pid_t pid, ppid;
        time_t elapsed;
        int gret;

        /*
         * get the specified pid and the psinfo struct
         */
        if ((pid = proc_arg_psinfo(arg, PR_ARG_PIDS, &psinfo, &gret)) == -1) {
                (void) fprintf(stderr, "%s: cannot examine %s: %s\n",
                    command, arg, Pgrab_error(gret));
                return (1);
        }

        if (psinfo.pr_nlwp != 0) {
                (void) fprintf(stderr, "%s: process not defunct: %d\n",
                    command, (int)pid);
                return (1);
        }

        *exit_status = psinfo.pr_wstat;
        *reap_pid = psinfo.pr_pid;
        ppid = psinfo.pr_ppid;

        if (ppid == 1) {
                (void) fprintf(stderr, "%s: Failed to reap %d: the only "
                    "non-defunct ancestor is 'init'\n", command,
                    (int)pid);
                return (1);
        }

        if (proc_usage(pid, &usage, &gret) == 0) {
                elapsed = usage.pr_tstamp.tv_sec - usage.pr_term.tv_sec;
        } else {
                (void) fprintf(stderr, "%s: cannot examine %d: %s\n",
                    command, (int)pid, Pgrab_error(gret));
                return (1);
        }

        if ((Fflag == 0) && (elapsed < NOREAP_TIME)) {
                (void) fprintf(stderr, "%s: unsafe to reap %d; it has been "
                    "defunct less than %d seconds\n", command, (int)pid,
                    NOREAP_TIME);
                return (1);
        }

        if ((Pr = Pgrab(ppid, Fflag | PGRAB_NOSTOP, &gret)) == NULL) {
                (void) fprintf(stderr, "%s: cannot examine %d: %s\n", command,
                    (int)ppid, Pgrab_error(gret));
                return (1);
        }

        if ((Fflag == 0) && (Pstate(Pr) == PS_STOP)) {
                Prelease(Pr, 0);
                (void) fprintf(stderr, "%s: unsafe to reap %d; parent is "
                    "stopped and may reap status upon restart\n", command,
                    (int)pid);
                return (1);
        }

        /*
         * Pstop() will fail if the process to be stopped has become a zombie.
         * This means that we can say with certainty that the child of this
         * process has not changed parents (i.e. been reparented to init) once
         * the Pstop() succeeds.
         */
        if (Pstop(Pr, 1000) != 0) {
                Prelease(Pr, 0);
                (void) fprintf(stderr, "%s: failed to stop %d: %s", command,
                    (int)ppid, strerror(errno));
                return (1);
        }

        if (pr_waitid(Pr, P_PID, pid, &siginfo, WEXITED|WNOHANG) != 0) {
                Prelease(Pr, 0);
                (void) fprintf(stderr, "%s: waitid() in process %d failed: %s",
                    command, (int)ppid, strerror(errno));
                return (1);
        }

        Prelease(Pr, 0);
        return (0);
}

static void
print_exit_status(pid_t pid, int wstat)
{
        (void) printf("%d: ", (int)pid);
        if (WIFSIGNALED(wstat)) {
                char buf[SIG2STR_MAX];
                int sig = WTERMSIG(wstat);

                if (sig2str(sig, buf) == 0)
                        (void) printf("killed by signal %s", buf);
                else
                        (void) printf("killed by signal %d", sig);

                if (WCOREDUMP(wstat))
                        (void) printf(" (core dumped)");
        } else {
                (void) printf("exited with status %d", WEXITSTATUS(wstat));
        }
        (void) printf("\n");
}

int
main(int argc, char *argv[])
{
        int retc = 0;
        int opt;
        int errflg = 0;

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

        while ((opt = getopt(argc, argv, "F")) != EOF) {
                switch (opt) {
                case 'F':               /* force grabbing (no O_EXCL) */
                        Fflag = PGRAB_FORCE;
                        break;
                default:
                        errflg = 1;
                        break;
                }
        }

        argc -= optind;
        argv += optind;

        if (errflg || argc <= 0) {
                (void) fprintf(stderr, "usage:  %s pid ...\n", command);
                (void) fprintf(stderr, "  (Reap a defunct process by forcing "
                    "its parent to wait(3C) for it)\n");
                exit(2);
        }

        /* catch signals from terminal */
        if (sigset(SIGHUP, SIG_IGN) == SIG_DFL)
                (void) sigset(SIGHUP, intr);
        if (sigset(SIGINT, SIG_IGN) == SIG_DFL)
                (void) sigset(SIGINT, intr);
        if (sigset(SIGPIPE, SIG_IGN) == SIG_DFL)
                (void) sigset(SIGPIPE, intr);
        if (sigset(SIGQUIT, SIG_IGN) == SIG_DFL)
                (void) sigset(SIGQUIT, intr);
        (void) sigset(SIGTERM, intr);

        while (--argc >= 0 && !interrupt) {
                pid_t pid;
                int wstat, r;

                retc += r = reap(*argv++, &pid, &wstat);

                if (r == 0)
                        print_exit_status(pid, wstat);
        }

        if (interrupt && retc == 0)
                retc++;
        return (retc == 0 ? 0 : 1);
}