/*
 * iostat - bsd like iostat for Linux
 *
 * Copyright (c) 1995-1997, Matthew Jacob
 *
 *	This software is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU Library General Public
 *	License as published by the Free Software Foundation; version 2.
 *
 *	This software is distributed in the hope that it will be useful,
 *	but WITHOUT ANY WARRANTY; without even the implied warranty of
 *	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *	Library General Public License for more details.
 *
 *	You should have received a copy of the GNU Library General Public
 *	License along with this software; if not, write to the Free
 *	Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *	The author may be reached via electronic communications at
 *
 *		mjacob@feral.com
 *
 *	or, via United States Postal Address
 *
 *		Matthew Jacob
 *		2343 3rd Street
 *		Suite 30
 *		San Francisco, CA, 94107
 */

/*
 * $Id: iostat.c,v 1.4 1995/07/13 22:11:01 mjacob Exp mjacob $
 *
 * $Log: iostat.c,v $
 * Revision 1.4  1995/07/13 22:11:01  mjacob
 * Matt, I tried your iostat program under Linux 1.2.8, and I found that
 * it got divide-by-0 errs when run with a sleep time.  Apparently
 * this Linux version always produces the same results when reading
 * /proc/stat, despite the rewind.  I changed it to open the file each
 * time get_stats() is called, and now it works.  Maybe there's a
 * cleverer way than this ... but now it works better!
 *
 * Regards,
 * -- James Dugal, jpd@usl.edu
 *
 * Revision 1.3  1995/07/10  01:53:26  mjacob
 * make totcpu an inline
 *
 * Revision 1.2  1995/07/10  01:49:11  mjacob
 * first version- kinda sloppy, but mostly does the trick.
 *
 */

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <memory.h>
#include <sys/param.h>

#ifndef	STATFILE
#define	STATFILE	"/proc/stat"
#endif

#define	DK_NDRIVE	4
#define	CPU_USER	0
#define	CPU_NICE	1
#define	CPU_SYSTEM	2
#define	CPU_IDLE	3

static int get_stats(unsigned int cpu[4], unsigned int dk[4]);
static void print_hdr(void);

static inline double
totcpu(unsigned int c[4])
{
    double rv;
    rv = (double) c[0] + (double) c[1] + (double) c[2] + (double) c[3];
    return (rv);
}

int
main(int a, char **v)
{
    int i, nprint;
    unsigned int cpu_times[4], ocpu_times[4];
    unsigned int dk_drive[DK_NDRIVE], odk_drive[DK_NDRIVE];
    register double ctime, lctime;
    long sleepincr;

    sleepincr = 0;

    if (a > 1) {
        sleepincr = strtol(v[1], (char **) NULL, 10);
        if (sleepincr <= 0) {
            fprintf(stderr, "usage: %s [ repeat-interval ]\n", *v);
            return (1);
        }
    }

    if (get_stats(ocpu_times, odk_drive)) {
        return (1);
    }
    print_hdr();
    for (i = 0; i < DK_NDRIVE; i++)
        fprintf(stdout, "% 8d", odk_drive[i]);
    lctime = ctime = totcpu(ocpu_times);
    fprintf(stdout, "  %2.0f %2.0f %2.0f %2.0f\n",
            (((double) ocpu_times[0]) / ctime) * (double) 100.0,
            (((double) ocpu_times[1]) / ctime) * (double) 100.0,
            (((double) ocpu_times[2]) / ctime) * (double) 100.0,
            (((double) ocpu_times[3]) / ctime) * (double) 100.0);

    nprint = 0;
    while (sleepincr > 0) {
        sleep(sleepincr);
        if (get_stats(cpu_times, dk_drive))
            break;
        for (i = 0; i < DK_NDRIVE; i++)
            odk_drive[i] = dk_drive[i] - odk_drive[i];
        for (i = 0; i < DK_NDRIVE; i++) {
            fprintf(stdout, "%8.0f",
                    (double) odk_drive[i] / (double) sleepincr);
            odk_drive[i] = dk_drive[i];
        }
        ctime = totcpu(cpu_times);
        for (i = 0; i < 4; i++) {
            ocpu_times[i] = cpu_times[i] - ocpu_times[i];
        }
        putchar(' ');
        for (i = 0; i < 4; i++) {
            fprintf(stdout, " %2.0f",
                    (((double) ocpu_times[i]) / (ctime - lctime)) * 100.0);
            ocpu_times[i] = cpu_times[i];
        }
        putchar('\n');
        lctime = ctime;
        if (nprint++ >= 16) {
            print_hdr();
            nprint = 0;
        }
    }
    return (0);
}

static int
get_stats(unsigned int cpu[4], unsigned int dk[4])
{
    int gotcpu, gotdk;
    char lbuf[132];
    FILE *statfp;

    statfp = fopen(STATFILE, "r");
    if (statfp == NULL) {
        perror(STATFILE);
        return (-1);
    }

    gotcpu = gotdk = 0;
    while (gotcpu == 0 || gotdk == 0) {
        if (fgets(lbuf, 132, statfp) == (char *) NULL) {
            break;
        }
        if (strncmp(lbuf, "cpu", 3) == 0) {
            if (sscanf(lbuf+4, "%u %u %u %u\n",
                       &cpu[0], &cpu[1], &cpu[2], &cpu[3]) != 4) {
                fprintf(stderr, "bad cpu line in %s\n", STATFILE);
            }
            gotcpu++;
            continue;
        }
        if (strncmp(lbuf, "disk", 4) == 0) {
            if (sscanf(lbuf+5, "%u %u %u %u\n",
                       &dk[0], &dk[1], &dk[2], &dk[3]) != 4) {
                fprintf(stderr, "bad disk line in %s\n", STATFILE);
            }
            gotdk++;
            continue;
        }
    }
    (void) fclose(statfp);
    return ((gotcpu && gotdk)? 0 : -1);
}

static void
print_hdr(void)
{
    int i;
    for (i = 0; i < DK_NDRIVE; i++) {
        (void) fprintf(stdout, "     dk%d", i);
    }
    fprintf(stdout, "  us ni sy id\n");
}

/*
 * Overrides for Emacs so that we almost follow Linus's tabbing style.
 * Emacs will notice this stuff at the end of the file and automatically
 * adjust the settings for this buffer only.  This must remain at the end
 * of the file.
 * ---------------------------------------------------------------------------
 * Local variables:
 * c-indent-level: 4
 * c-brace-imaginary-offset: 0
 * c-brace-offset: -4
 * c-argdecl-indent: 4
 * c-label-offset: -4
 * c-continued-statement-offset: 4
 * c-continued-brace-offset: 0
 * indent-tabs-mode: nil
 * tab-width: 8
 * End:
 */