/* vi: set sw=4 ts=4: */
/*
 * Report CPU and I/O stats, based on sysstat version 9.1.2 by Sebastien Godard
 *
 * Copyright (C) 2010 Marek Polacek <mmpolacek@gmail.com>
 *
 * Licensed under GPLv2, see file LICENSE in this source tree.
 */

//applet:IF_IOSTAT(APPLET(iostat, _BB_DIR_BIN, _BB_SUID_DROP))

//kbuild:lib-$(CONFIG_IOSTAT) += iostat.o

//config:config IOSTAT
//config:       bool "iostat"
//config:       default y
//config:       help
//config:         Report CPU and I/O statistics

#include "libbb.h"
#include <sys/utsname.h>  /* Need struct utsname */

//#define debug(fmt, ...) fprintf(stderr, fmt, ## __VA_ARGS__)
#define debug(fmt, ...) ((void)0)

#define MAX_DEVICE_NAME 12
#define CURRENT          0
#define LAST             1

#if 1
typedef unsigned long long cputime_t;
typedef long long icputime_t;
# define FMT_DATA "ll"
# define CPUTIME_MAX (~0ULL)
#else
typedef unsigned long cputime_t;
typedef long icputime_t;
# define FMT_DATA "l"
# define CPUTIME_MAX (~0UL)
#endif

struct stats_cpu {
        cputime_t cpu_user;
        cputime_t cpu_nice;
        cputime_t cpu_system;
        cputime_t cpu_idle;
        cputime_t cpu_iowait;
        cputime_t cpu_steal;
        cputime_t cpu_irq;
        cputime_t cpu_softirq;
        cputime_t cpu_guest;
};

struct stats_dev {
        char dname[MAX_DEVICE_NAME];
        unsigned long long rd_sectors;
        unsigned long long wr_sectors;
        unsigned long rd_ops;
        unsigned long wr_ops;
};

/* List of devices entered on the command line */
struct device_list {
        char dname[MAX_DEVICE_NAME];
};

/* Globals. Sort by size and access frequency. */
struct globals {
        smallint show_all;
        unsigned devlist_i;             /* Index to the list of devices */
        unsigned total_cpus;            /* Number of CPUs */
        unsigned clk_tck;               /* Number of clock ticks per second */
        struct device_list *dlist;
        struct stats_dev *saved_stats_dev;
        struct tm tmtime;
};
#define G (*ptr_to_globals)
#define INIT_G() do { \
        SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
} while (0)

/* Must match option string! */
enum {
        OPT_c = 1 << 0,
        OPT_d = 1 << 1,
        OPT_t = 1 << 2,
        OPT_z = 1 << 3,
        OPT_k = 1 << 4,
        OPT_m = 1 << 5,
};

static ALWAYS_INLINE unsigned get_user_hz(void)
{
        return sysconf(_SC_CLK_TCK);
}

static ALWAYS_INLINE int this_is_smp(void)
{
        return (G.total_cpus > 1);
}

static void print_header(void)
{
        char buf[16];
        struct utsname uts;

        if (uname(&uts) < 0)
                bb_perror_msg_and_die("uname");

        strftime(buf, sizeof(buf), "%x", &G.tmtime);

        printf("%s %s (%s) \t%s \t_%s_\t(%d CPU)\n\n",
                        uts.sysname, uts.release, uts.nodename,
                        buf, uts.machine, G.total_cpus);
}

static void get_localtime(struct tm *ptm)
{
        time_t timer;
        time(&timer);
        localtime_r(&timer, ptm);
}

static void print_timestamp(void)
{
        char buf[20];
        strftime(buf, sizeof(buf), "%x %X", &G.tmtime);
        printf("%s\n", buf);
}

/* Fetch CPU statistics from /proc/stat */
static void get_cpu_statistics(struct stats_cpu *sc)
{
        FILE *fp;
        char buf[1024];

        fp = xfopen_for_read("/proc/stat");

        memset(sc, 0, sizeof(*sc));

        while (fgets(buf, sizeof(buf), fp)) {
                /* Does the line starts with "cpu "? */
                if (starts_with_cpu(buf) && buf[3] == ' ') {
                        sscanf(buf + 4 + 1,
                                "%"FMT_DATA"u %"FMT_DATA"u %"FMT_DATA"u %"FMT_DATA"u %"
                                FMT_DATA"u %"FMT_DATA"u %"FMT_DATA"u %"FMT_DATA"u %"FMT_DATA"u",
                                &sc->cpu_user, &sc->cpu_nice, &sc->cpu_system,
                                &sc->cpu_idle, &sc->cpu_iowait, &sc->cpu_irq,
                                &sc->cpu_softirq, &sc->cpu_steal, &sc->cpu_guest);
                }
        }

        fclose(fp);
}

static cputime_t get_smp_uptime(void)
{
        FILE *fp;
        char buf[sizeof(long)*3 * 2 + 4];
        unsigned long sec, dec;

        fp = xfopen_for_read("/proc/uptime");

        if (fgets(buf, sizeof(buf), fp))
                if (sscanf(buf, "%lu.%lu", &sec, &dec) != 2)
                        bb_error_msg_and_die("can't read /proc/uptime");

        fclose(fp);

        return (cputime_t)sec * G.clk_tck + dec * G.clk_tck / 100;
}

/*
 * Obtain current uptime in jiffies.
 * Uptime is sum of individual CPUs' uptimes.
 */
static cputime_t get_uptime(const struct stats_cpu *sc)
{
        /* NB: Don't include cpu_guest, it is already in cpu_user */
        return sc->cpu_user + sc->cpu_nice + sc->cpu_system + sc->cpu_idle +
                + sc->cpu_iowait + sc->cpu_irq + sc->cpu_steal + sc->cpu_softirq;
}

static ALWAYS_INLINE cputime_t get_interval(cputime_t old, cputime_t new)
{
        cputime_t itv = new - old;

        return (itv == 0) ? 1 : itv;
}

#if CPUTIME_MAX > 0xffffffff
/*
 * Handle overflow conditions properly for counters which can have
 * less bits than cputime_t, depending on the kernel version.
 */
/* Surprisingly, on 32bit inlining is a size win */
static ALWAYS_INLINE cputime_t overflow_safe_sub(cputime_t prev, cputime_t curr)
{
        cputime_t v = curr - prev;

        if ((icputime_t)v < 0     /* curr < prev - counter overflow? */
         && prev <= 0xffffffff /* kernel uses 32bit value for the counter? */
        ) {
                /* Add 33th bit set to 1 to curr, compensating for the overflow */
                /* double shift defeats "warning: left shift count >= width of type" */
                v += ((cputime_t)1 << 16) << 16;
        }
        return v;
}
#else
static ALWAYS_INLINE cputime_t overflow_safe_sub(cputime_t prev, cputime_t curr)
{
        return curr - prev;
}
#endif

static double percent_value(cputime_t prev, cputime_t curr, cputime_t itv)
{
        return ((double)overflow_safe_sub(prev, curr)) / itv * 100;
}

static void print_stats_cpu_struct(const struct stats_cpu *p,
                const struct stats_cpu *c, cputime_t itv)
{
        printf("         %6.2f  %6.2f  %6.2f  %6.2f  %6.2f  %6.2f\n",
                percent_value(p->cpu_user   , c->cpu_user   , itv),
                percent_value(p->cpu_nice   , c->cpu_nice   , itv),
                percent_value(p->cpu_system + p->cpu_softirq + p->cpu_irq,
                        c->cpu_system + c->cpu_softirq + c->cpu_irq, itv),
                percent_value(p->cpu_iowait , c->cpu_iowait , itv),
                percent_value(p->cpu_steal  , c->cpu_steal  , itv),
                percent_value(p->cpu_idle   , c->cpu_idle   , itv)
        );
}

static void print_stats_dev_struct(const struct stats_dev *p,
                const struct stats_dev *c, cputime_t itv)
{
        int unit = 1;

        if (option_mask32 & OPT_k)
                unit = 2;
        else if (option_mask32 & OPT_m)
                unit = 2048;

        if (option_mask32 & OPT_z)
                if (p->rd_ops == c->rd_ops && p->wr_ops == c->wr_ops)
                        return;

        printf("%-13s", c->dname);
        printf(" %8.2f %12.2f %12.2f %10llu %10llu \n",
                percent_value(p->rd_ops + p->wr_ops ,
                /**/              c->rd_ops + c->wr_ops , itv),
                percent_value(p->rd_sectors, c->rd_sectors, itv) / unit,
                percent_value(p->wr_sectors, c->wr_sectors, itv) / unit,
                (c->rd_sectors - p->rd_sectors) / unit,
                (c->wr_sectors - p->wr_sectors) / unit);
}

static void cpu_report(const struct stats_cpu *last,
                const struct stats_cpu *cur,
                cputime_t itv)
{
        /* Always print a header */
        puts("avg-cpu:  %user   %nice %system %iowait  %steal   %idle");

        /* Print current statistics */
        print_stats_cpu_struct(last, cur, itv);
}

static void print_devstat_header(void)
{
        printf("Device:            tps");

        if (option_mask32 & OPT_m)
                puts("    MB_read/s    MB_wrtn/s    MB_read    MB_wrtn");
        else if (option_mask32 & OPT_k)
                puts("    kB_read/s    kB_wrtn/s    kB_read    kB_wrtn");
        else
                puts("   Blk_read/s   Blk_wrtn/s   Blk_read   Blk_wrtn");
}

/*
 * Is input partition of format [sdaN]?
 */
static int is_partition(const char *dev)
{
        /* Ok, this is naive... */
        return ((dev[0] - 's') | (dev[1] - 'd') | (dev[2] - 'a')) == 0 && isdigit(dev[3]);
}

/*
 * Return number of numbers on cmdline.
 * Reasonable values are only 0 (no interval/count specified),
 * 1 (interval specified) and 2 (both interval and count specified)
 */
static int numbers_on_cmdline(int argc, char *argv[])
{
        int sum = 0;

        if (isdigit(argv[argc-1][0]))
                sum++;
        if (argc > 2 && isdigit(argv[argc-2][0]))
                sum++;

        return sum;
}

static int is_dev_in_dlist(const char *dev)
{
        int i;

        /* Go through the device list */
        for (i = 0; i < G.devlist_i; i++)
                if (strcmp(G.dlist[i].dname, dev) == 0)
                        /* Found a match */
                        return 1;

        /* No match found */
        return 0;
}

static void do_disk_statistics(cputime_t itv)
{
        FILE *fp;
        int rc;
        int i = 0;
        char buf[128];
        unsigned major, minor;
        unsigned long wr_ops, dummy; /* %*lu for suppress the conversion wouldn't work */
        unsigned long long rd_sec_or_wr_ops;
        unsigned long long rd_sec_or_dummy, wr_sec_or_dummy, wr_sec;
        struct stats_dev sd;

        fp = xfopen_for_read("/proc/diskstats");

        /* Read and possibly print stats from /proc/diskstats */
        while (fgets(buf, sizeof(buf), fp)) {
                rc = sscanf(buf, "%u %u %s %lu %llu %llu %llu %lu %lu %llu %lu %lu %lu %lu",
                        &major, &minor, sd.dname, &sd.rd_ops,
                        &rd_sec_or_dummy, &rd_sec_or_wr_ops, &wr_sec_or_dummy,
                        &wr_ops, &dummy, &wr_sec, &dummy, &dummy, &dummy, &dummy);

                switch (rc) {
                case 14:
                        sd.wr_ops = wr_ops;
                        sd.rd_sectors = rd_sec_or_wr_ops;
                        sd.wr_sectors = wr_sec;
                        break;
                case 7:
                        sd.rd_sectors = rd_sec_or_dummy;
                        sd.wr_ops = (unsigned long)rd_sec_or_wr_ops;
                        sd.wr_sectors = wr_sec_or_dummy;
                        break;
                default:
                        break;
                }

                if (!G.devlist_i && !is_partition(sd.dname)) {
                        /* User didn't specify device */
                        if (!G.show_all && !sd.rd_ops && !sd.wr_ops) {
                                /* Don't print unused device */
                                continue;
                        }
                        print_stats_dev_struct(&G.saved_stats_dev[i], &sd, itv);
                        G.saved_stats_dev[i] = sd;
                        i++;
                } else {
                        /* Is device in device list? */
                        if (is_dev_in_dlist(sd.dname)) {
                                /* Print current statistics */
                                print_stats_dev_struct(&G.saved_stats_dev[i], &sd, itv);
                                G.saved_stats_dev[i] = sd;
                                i++;
                        } else
                                continue;
                }
        }

        fclose(fp);
}

static void dev_report(cputime_t itv)
{
        /* Always print a header */
        print_devstat_header();

        /* Fetch current disk statistics */
        do_disk_statistics(itv);
}

static void save_to_devlist(const char *dname)
{
        int i;
        struct device_list *tmp = G.dlist;

        if (strncmp(dname, "/dev/", 5) == 0)
                /* We'll ignore prefix '/dev/' */
                dname += 5;

        /* Go through the list */
        for (i = 0; i < G.devlist_i; i++, tmp++)
                if (strcmp(tmp->dname, dname) == 0)
                        /* Already in the list */
                        return;

        /* Add device name to the list */
        strncpy(tmp->dname, dname, MAX_DEVICE_NAME - 1);

        /* Update device list index */
        G.devlist_i++;
}

static unsigned get_number_of_devices(void)
{
        FILE *fp;
        char buf[128];
        int rv;
        unsigned n = 0;
        unsigned long rd_ops, wr_ops;
        char dname[MAX_DEVICE_NAME];

        fp = xfopen_for_read("/proc/diskstats");

        while (fgets(buf, sizeof(buf), fp)) {
                rv = sscanf(buf, "%*d %*d %s %lu %*u %*u %*u %lu",
                                dname, &rd_ops, &wr_ops);
                if (rv == 2 || is_partition(dname))
                        /* A partition */
                        continue;
                if (!rd_ops && !wr_ops) {
                        /* Unused device */
                        if (!G.show_all)
                                continue;
                }
                n++;
        }

        fclose(fp);
        return n;
}

static int number_of_ALL_on_cmdline(char **argv)
{
        int alls = 0;

        /* Iterate over cmd line arguments, count "ALL" */
        while (*argv)
                if (strcmp(*argv++, "ALL") == 0)
                        alls++;

        return alls;
}

//usage:#define iostat_trivial_usage
//usage:       "[-c] [-d] [-t] [-z] [-k|-m] [ALL|BLOCKDEV...] [INTERVAL [COUNT]]"
//usage:#define iostat_full_usage "\n\n"
//usage:       "Report CPU and I/O statistics\n"
//usage:     "\nOptions:"
//usage:     "\n        -c      Show CPU utilization"
//usage:     "\n        -d      Show device utilization"
//usage:     "\n        -t      Print current time"
//usage:     "\n        -z      Omit devices with no activity"
//usage:     "\n        -k      Use kb/s"
//usage:     "\n        -m      Use Mb/s"

int iostat_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int iostat_main(int argc, char **argv)
{
        int opt, dev_num;
        unsigned interval = 0;
        int count;
        cputime_t global_uptime[2] = { 0 };
        cputime_t smp_uptime[2] = { 0 };
        cputime_t itv;
        struct stats_cpu stats_cur, stats_last;

        INIT_G();

        memset(&stats_last, 0, sizeof(stats_last));

        /* Get number of clock ticks per sec */
        G.clk_tck = get_user_hz();

        /* Determine number of CPUs */
        G.total_cpus = get_cpu_count();
        if (G.total_cpus == 0)
                G.total_cpus = 1;

        /* Parse and process arguments */
        /* -k and -m are mutually exclusive */
        opt_complementary = "k--m:m--k";
        opt = getopt32(argv, "cdtzkm");
        if (!(opt & (OPT_c + OPT_d)))
                /* Default is -cd */
                opt |= OPT_c + OPT_d;

        argv += optind;
        argc -= optind;

        dev_num = argc - numbers_on_cmdline(argc, argv);
        /* We don't want to allocate space for 'ALL' */
        dev_num -= number_of_ALL_on_cmdline(argv);
        if (dev_num > 0)
                /* Make space for device list */
                G.dlist = xzalloc(sizeof(G.dlist[0]) * dev_num);

        /* Store device names into device list */
        while (*argv && !isdigit(*argv[0])) {
                if (strcmp(*argv, "ALL") != 0)
                        /* If not ALL, save device name */
                        save_to_devlist(*argv);
                else
                        G.show_all = 1;
                argv++;
        }

        count = 1;
        if (*argv) {
                /* Get interval */
                interval = xatoi_positive(*argv);
                count = (interval != 0 ? -1 : 1);
                argv++;
                if (*argv)
                        /* Get count value */
                        count = xatoi_positive(*argv);
        }

        /* Allocate space for device stats */
        if (opt & OPT_d) {
                G.saved_stats_dev = xzalloc(sizeof(G.saved_stats_dev[0]) *
                                (dev_num ? dev_num : get_number_of_devices())
                );
        }

        /* Display header */
        print_header();

        /* Main loop */
        for (;;) {
                /* Fill the time structure */
                get_localtime(&G.tmtime);

                /* Fetch current CPU statistics */
                get_cpu_statistics(&stats_cur);

                /* Fetch current uptime */
                global_uptime[CURRENT] = get_uptime(&stats_cur);

                /* Get interval */
                itv = get_interval(global_uptime[LAST], global_uptime[CURRENT]);

                if (opt & OPT_t)
                        print_timestamp();

                if (opt & OPT_c) {
                        cpu_report(&stats_last, &stats_cur, itv);
                        if (opt & OPT_d)
                                /* Separate outputs by a newline */
                                bb_putchar('\n');
                }

                if (opt & OPT_d) {
                        if (this_is_smp()) {
                                smp_uptime[CURRENT] = get_smp_uptime();
                                itv = get_interval(smp_uptime[LAST], smp_uptime[CURRENT]);
                                smp_uptime[LAST] = smp_uptime[CURRENT];
                        }
                        dev_report(itv);
                }

                if (count > 0) {
                        if (--count == 0)
                                break;
                }

                /* Backup current stats */
                global_uptime[LAST] = global_uptime[CURRENT];
                stats_last = stats_cur;

                bb_putchar('\n');
                sleep(interval);
        }

        bb_putchar('\n');

        if (ENABLE_FEATURE_CLEAN_UP) {
                free(&G);
                free(G.dlist);
                free(G.saved_stats_dev);
        }

        return EXIT_SUCCESS;
}