/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1987, 1988, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * 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.
 */

#include <sys/types.h>
#include <sys/resource.h>
#include <sys/signal.h>
#include <sys/sysctl.h>
#include <sys/time.h>
#include <sys/wait.h>

#include <err.h>
#include <errno.h>
#include <locale.h>
#include <signal.h>
#include <stdatomic.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

static int getstathz(void);
static void humantime(FILE *, long, long);
static void showtime(FILE *, struct timespec *, struct timespec *,
    struct rusage *);
static void siginfo(int);
static void usage(void) __dead2;

static sig_atomic_t siginfo_recvd;
static char decimal_point;
static struct timespec before_ts;
static int hflag, pflag;

int
main(int argc, char **argv)
{
        int aflag, ch, lflag, status;
        int exitonsig;
        pid_t pid;
        struct rlimit rl;
        struct rusage ru;
        struct timespec after;
        char *ofn = NULL;
        FILE *out = stderr;

        (void) setlocale(LC_NUMERIC, "");
        decimal_point = localeconv()->decimal_point[0];

        aflag = hflag = lflag = pflag = 0;
        while ((ch = getopt(argc, argv, "ahlo:p")) != -1)
                switch((char)ch) {
                case 'a':
                        aflag = 1;
                        break;
                case 'h':
                        hflag = 1;
                        break;
                case 'l':
                        lflag = 1;
                        break;
                case 'o':
                        ofn = optarg;
                        break;
                case 'p':
                        pflag = 1;
                        break;
                case '?':
                default:
                        usage();
                }

        if (!(argc -= optind))
                exit(0);
        argv += optind;

        if (ofn) {
                if ((out = fopen(ofn, aflag ? "ae" : "we")) == NULL)
                        err(1, "%s", ofn);
                setvbuf(out, (char *)NULL, _IONBF, (size_t)0);
        }

        if (clock_gettime(CLOCK_MONOTONIC, &before_ts))
                err(1, "clock_gettime");
        switch(pid = fork()) {
        case -1:                        /* error */
                err(1, "time");
                /* NOTREACHED */
        case 0:                         /* child */
                execvp(*argv, argv);
                err(errno == ENOENT ? 127 : 126, "%s", *argv);
                /* NOTREACHED */
        }
        /* parent */
        (void)signal(SIGINT, SIG_IGN);
        (void)signal(SIGQUIT, SIG_IGN);
        siginfo_recvd = 0;
        (void)signal(SIGINFO, siginfo);
        (void)siginterrupt(SIGINFO, 1);
        while (wait4(pid, &status, 0, &ru) != pid) {
                bool do_siginfo = siginfo_recvd != 0;

                atomic_signal_fence(memory_order_acquire);
                if (do_siginfo) {
                        siginfo_recvd = 0;
                        if (clock_gettime(CLOCK_MONOTONIC, &after))
                                err(1, "clock_gettime");
                        getrusage(RUSAGE_CHILDREN, &ru);
                        showtime(stdout, &before_ts, &after, &ru);
                }
        }
        if (clock_gettime(CLOCK_MONOTONIC, &after))
                err(1, "clock_gettime");
        if ( ! WIFEXITED(status))
                warnx("command terminated abnormally");
        exitonsig = WIFSIGNALED(status) ? WTERMSIG(status) : 0;
        showtime(out, &before_ts, &after, &ru);
        if (lflag) {
                int hz = getstathz();
                u_long ticks;

                ticks = hz * (ru.ru_utime.tv_sec + ru.ru_stime.tv_sec) +
                     hz * (ru.ru_utime.tv_usec + ru.ru_stime.tv_usec) / 1000000;

                /*
                 * If our round-off on the tick calculation still puts us at 0,
                 * then always assume at least one tick.
                 */
                if (ticks == 0)
                        ticks = 1;

                fprintf(out, "%10ld  %s\n",
                        ru.ru_maxrss, "maximum resident set size");
                fprintf(out, "%10ld  %s\n",
                        ru.ru_ixrss / ticks, "average shared memory size");
                fprintf(out, "%10ld  %s\n",
                        ru.ru_idrss / ticks, "average unshared data size");
                fprintf(out, "%10ld  %s\n",
                        ru.ru_isrss / ticks, "average unshared stack size");
                fprintf(out, "%10ld  %s\n",
                        ru.ru_minflt, "page reclaims");
                fprintf(out, "%10ld  %s\n",
                        ru.ru_majflt, "page faults");
                fprintf(out, "%10ld  %s\n",
                        ru.ru_nswap, "swaps");
                fprintf(out, "%10ld  %s\n",
                        ru.ru_inblock, "block input operations");
                fprintf(out, "%10ld  %s\n",
                        ru.ru_oublock, "block output operations");
                fprintf(out, "%10ld  %s\n",
                        ru.ru_msgsnd, "messages sent");
                fprintf(out, "%10ld  %s\n",
                        ru.ru_msgrcv, "messages received");
                fprintf(out, "%10ld  %s\n",
                        ru.ru_nsignals, "signals received");
                fprintf(out, "%10ld  %s\n",
                        ru.ru_nvcsw, "voluntary context switches");
                fprintf(out, "%10ld  %s\n",
                        ru.ru_nivcsw, "involuntary context switches");
        }
        /*
         * If the child has exited on a signal, exit on the same
         * signal, too, in order to reproduce the child's exit status.
         * However, avoid actually dumping core from the current process.
         */
        if (exitonsig) {
                if (signal(exitonsig, SIG_DFL) == SIG_ERR)
                        warn("signal");
                else {
                        rl.rlim_max = rl.rlim_cur = 0;
                        if (setrlimit(RLIMIT_CORE, &rl) == -1)
                                warn("setrlimit");
                        kill(getpid(), exitonsig);
                }
        }
        exit (WIFEXITED(status) ? WEXITSTATUS(status) : EXIT_FAILURE);
}

static void
usage(void)
{
        fprintf(stderr,
            "usage: time [-al] [-h | -p] [-o file] utility [argument ...]\n");
        exit(1);
}

/*
 * Return the frequency of the kernel's statistics clock.
 */
static int
getstathz(void)
{
        int mib[2];
        size_t size;
        struct clockinfo clockrate;

        mib[0] = CTL_KERN;
        mib[1] = KERN_CLOCKRATE;
        size = sizeof clockrate;
        if (sysctl(mib, 2, &clockrate, &size, NULL, 0) == -1)
                err(1, "sysctl kern.clockrate");
        return clockrate.stathz;
}

static void
humantime(FILE *out, long sec, long centisec)
{
        long days, hrs, mins;

        days = sec / (60L * 60 * 24);
        sec %= (60L * 60 * 24);
        hrs = sec / (60L * 60);
        sec %= (60L * 60);
        mins = sec / 60;
        sec %= 60;

        fprintf(out, "\t");
        if (days)
                fprintf(out, "%ldd", days);
        if (hrs)
                fprintf(out, "%ldh", hrs);
        if (mins)
                fprintf(out, "%ldm", mins);
        fprintf(out, "%ld%c%02lds", sec, decimal_point, centisec);
}

static void
showtime(FILE *out, struct timespec *before, struct timespec *after,
    struct rusage *ru)
{

        after->tv_sec -= before->tv_sec;
        after->tv_nsec -= before->tv_nsec;
        if (after->tv_nsec < 0)
                after->tv_sec--, after->tv_nsec += 1000000000;

        if (pflag) {
                /* POSIX wants output that must look like
                "real %f\nuser %f\nsys %f\n" and requires
                at least two digits after the radix. */
                fprintf(out, "real %jd%c%02ld\n",
                        (intmax_t)after->tv_sec, decimal_point,
                        after->tv_nsec/10000000);
                fprintf(out, "user %jd%c%02ld\n",
                        (intmax_t)ru->ru_utime.tv_sec, decimal_point,
                        ru->ru_utime.tv_usec/10000);
                fprintf(out, "sys %jd%c%02ld\n",
                        (intmax_t)ru->ru_stime.tv_sec, decimal_point,
                        ru->ru_stime.tv_usec/10000);
        } else if (hflag) {
                humantime(out, after->tv_sec, after->tv_nsec/10000000);
                fprintf(out, " real\t");
                humantime(out, ru->ru_utime.tv_sec, ru->ru_utime.tv_usec/10000);
                fprintf(out, " user\t");
                humantime(out, ru->ru_stime.tv_sec, ru->ru_stime.tv_usec/10000);
                fprintf(out, " sys\n");
        } else {
                fprintf(out, "%9jd%c%02ld real ",
                        (intmax_t)after->tv_sec, decimal_point,
                        after->tv_nsec/10000000);
                fprintf(out, "%9jd%c%02ld user ",
                        (intmax_t)ru->ru_utime.tv_sec, decimal_point,
                        ru->ru_utime.tv_usec/10000);
                fprintf(out, "%9jd%c%02ld sys\n",
                        (intmax_t)ru->ru_stime.tv_sec, decimal_point,
                        ru->ru_stime.tv_usec/10000);
        }
}

static void
siginfo(int sig __unused)
{

        siginfo_recvd = 1;
        atomic_signal_fence(memory_order_release);
}