/* 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.
 */

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

//applet:IF_IOSTAT(APPLET(iostat, BB_DIR_BIN, BB_SUID_DROP))

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

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

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

#define MAX_DEVICE_NAME 12
#define MAX_DEVICE_NAME_STR "12"

#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

enum {
        STATS_CPU_USER,
        STATS_CPU_NICE,
        STATS_CPU_SYSTEM,
        STATS_CPU_IDLE,
        STATS_CPU_IOWAIT,
        STATS_CPU_IRQ,
        STATS_CPU_SOFTIRQ,
        STATS_CPU_STEAL,
        STATS_CPU_GUEST,

        GLOBAL_UPTIME,
        SMP_UPTIME,

        N_STATS_CPU,
};

typedef struct {
        cputime_t vector[N_STATS_CPU];
} stats_cpu_t;

typedef struct {
        stats_cpu_t *prev;
        stats_cpu_t *curr;
        cputime_t itv;
} stats_cpu_pair_t;

typedef struct {
        unsigned long long rd_sectors;
        unsigned long long wr_sectors;
        unsigned long rd_ops;
        unsigned long wr_ops;
} stats_dev_data_t;

typedef struct stats_dev {
        struct stats_dev *next;
        char dname[MAX_DEVICE_NAME + 1];
        stats_dev_data_t prev_data;
        stats_dev_data_t curr_data;
} stats_dev_t;

/* Globals. Sort by size and access frequency. */
struct globals {
        smallint show_all;
        unsigned total_cpus;            /* Number of CPUs */
        unsigned clk_tck;               /* Number of clock ticks per second */
        llist_t *dev_name_list;         /* List of devices entered on the command line */
        stats_dev_t *stats_dev_list;
        struct tm tmtime;
        struct {
                const char *str;
                unsigned div;
        } unit;
};
#define G (*ptr_to_globals)
#define INIT_G() do { \
        SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
        G.unit.str = "Blk"; \
        G.unit.div = 1; \
} 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 int this_is_smp(void)
{
        return (G.total_cpus > 1);
}

static void print_header(void)
{
        char buf[32];
        struct utsname uts;

        uname(&uts); /* never fails */

        /* Date representation for the current locale */
        strftime(buf, sizeof(buf), "%x", &G.tmtime);

        printf("%s %s (%s) \t%s \t_%s_\t(%u 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[64];
        /* %x: date representation for the current locale */
        /* %X: time representation for the current locale */
        strftime(buf, sizeof(buf), "%x %X", &G.tmtime);
        puts(buf);
}

static cputime_t get_smp_uptime(void)
{
        FILE *fp;
        unsigned long sec, dec;

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

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

        fclose(fp);

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

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

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

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

        while (fgets(buf, sizeof(buf), fp)) {
                int i;
                char *ibuf;

                /* Does the line start with "cpu "? */
                if (!starts_with_cpu(buf) || buf[3] != ' ') {
                        continue;
                }
                ibuf = buf + 4;
                for (i = STATS_CPU_USER; i <= STATS_CPU_GUEST; i++) {
                        ibuf = skip_whitespace(ibuf);
                        sscanf(ibuf, "%"FMT_DATA"u", &sc->vector[i]);
                        if (i != STATS_CPU_GUEST) {
                                sc->vector[GLOBAL_UPTIME] += sc->vector[i];
                        }
                        ibuf = skip_non_whitespace(ibuf);
                }
                break;
        }

        if (this_is_smp()) {
                sc->vector[SMP_UPTIME] = get_smp_uptime();
        }

        fclose(fp);
}

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(stats_cpu_pair_t *stats)
{
        cputime_t *p = stats->prev->vector;
        cputime_t *c = stats->curr->vector;
        printf("        %7.2f %7.2f %7.2f %7.2f %7.2f %7.2f\n",
                percent_value(p[STATS_CPU_USER]  , c[STATS_CPU_USER]  , stats->itv),
                percent_value(p[STATS_CPU_NICE]  , c[STATS_CPU_NICE]  , stats->itv),
                percent_value(p[STATS_CPU_SYSTEM] + p[STATS_CPU_SOFTIRQ] + p[STATS_CPU_IRQ],
                        c[STATS_CPU_SYSTEM] + c[STATS_CPU_SOFTIRQ] + c[STATS_CPU_IRQ], stats->itv),
                percent_value(p[STATS_CPU_IOWAIT], c[STATS_CPU_IOWAIT], stats->itv),
                percent_value(p[STATS_CPU_STEAL] , c[STATS_CPU_STEAL] , stats->itv),
                percent_value(p[STATS_CPU_IDLE]  , c[STATS_CPU_IDLE]  , stats->itv)
        );
}

static void cpu_report(stats_cpu_pair_t *stats)
{
        /* Always print a header */
        puts("avg-cpu:  %user   %nice %system %iowait  %steal   %idle");

        /* Print current statistics */
        print_stats_cpu_struct(stats);
}

static void print_stats_dev_struct(stats_dev_t *stats_dev, cputime_t itv)
{
        stats_dev_data_t *p = &stats_dev->prev_data;
        stats_dev_data_t *c = &stats_dev->curr_data;
        if (option_mask32 & OPT_z)
                if (p->rd_ops == c->rd_ops && p->wr_ops == c->wr_ops)
                        return;

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

static void print_devstat_header(void)
{
        printf("Device:%15s%6s%s/s%6s%s/s%6s%s%6s%s\n",
                "tps",
                G.unit.str, "_read", G.unit.str, "_wrtn",
                G.unit.str, "_read", G.unit.str, "_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]);
}

static stats_dev_t *stats_dev_find_or_new(const char *dev_name)
{
        stats_dev_t **curr = &G.stats_dev_list;

        while (*curr != NULL) {
                if (strcmp((*curr)->dname, dev_name) == 0)
                        return *curr;
                curr = &(*curr)->next;
        }

        *curr = xzalloc(sizeof(stats_dev_t));
        strncpy((*curr)->dname, dev_name, MAX_DEVICE_NAME);
        return *curr;
}

static void stats_dev_free(stats_dev_t *stats_dev)
{
        if (stats_dev) {
                stats_dev_free(stats_dev->next);
                free(stats_dev);
        }
}

static void do_disk_statistics(cputime_t itv)
{
        char buf[128];
        char dev_name[MAX_DEVICE_NAME + 1];
        unsigned long long rd_sec_or_dummy;
        unsigned long long wr_sec_or_dummy;
        stats_dev_data_t *curr_data;
        stats_dev_t *stats_dev;
        FILE *fp;
        int rc;

        fp = xfopen_for_read("/proc/diskstats");
        /* Read and possibly print stats from /proc/diskstats */
        while (fgets(buf, sizeof(buf), fp)) {
                sscanf(buf, "%*s %*s %"MAX_DEVICE_NAME_STR"s", dev_name);
                if (G.dev_name_list) {
                        /* Is device name in list? */
                        if (!llist_find_str(G.dev_name_list, dev_name))
                                continue;
                } else if (is_partition(dev_name)) {
                        continue;
                }

                stats_dev = stats_dev_find_or_new(dev_name);
                curr_data = &stats_dev->curr_data;

                rc = sscanf(buf, "%*s %*s %*s %lu %llu %llu %llu %lu %*s %llu",
                        &curr_data->rd_ops,
                        &rd_sec_or_dummy,
                        &curr_data->rd_sectors,
                        &wr_sec_or_dummy,
                        &curr_data->wr_ops,
                        &curr_data->wr_sectors);
                if (rc != 6) {
                        curr_data->rd_sectors = rd_sec_or_dummy;
                        curr_data->wr_sectors = wr_sec_or_dummy;
                        //curr_data->rd_ops = ;
                        curr_data->wr_ops = (unsigned long)curr_data->rd_sectors;
                }

                if (!G.dev_name_list /* User didn't specify device */
                 && !G.show_all
                 && curr_data->rd_ops == 0
                 && curr_data->wr_ops == 0
                ) {
                        /* Don't print unused device */
                        continue;
                }

                /* Print current statistics */
                print_stats_dev_struct(stats_dev, itv);
                stats_dev->prev_data = *curr_data;
        }

        fclose(fp);
}

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

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

//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:     "\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 UNUSED_PARAM, char **argv)
{
        int opt;
        unsigned interval;
        int count;
        stats_cpu_t stats_data[2];
        smallint current_stats;

        INIT_G();

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

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

        /* 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;

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

        interval = 0;
        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);
        }

        if (opt & OPT_m) {
                G.unit.str = " MB";
                G.unit.div = 2048;
        }

        if (opt & OPT_k) {
                G.unit.str = " kB";
                G.unit.div = 2;
        }

        get_localtime(&G.tmtime);

        /* Display header */
        print_header();

        current_stats = 0;
        /* Main loop */
        for (;;) {
                stats_cpu_pair_t stats;

                stats.prev = &stats_data[current_stats ^ 1];
                stats.curr = &stats_data[current_stats];

                /* Fill the time structure */
                get_localtime(&G.tmtime);

                /* Fetch current CPU statistics */
                get_cpu_statistics(stats.curr);

                /* Get interval */
                stats.itv = get_interval(
                        stats.prev->vector[GLOBAL_UPTIME],
                        stats.curr->vector[GLOBAL_UPTIME]
                );

                if (opt & OPT_t)
                        print_timestamp();

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

                if (opt & OPT_d) {
                        if (this_is_smp()) {
                                stats.itv = get_interval(
                                        stats.prev->vector[SMP_UPTIME],
                                        stats.curr->vector[SMP_UPTIME]
                                );
                        }
                        dev_report(stats.itv);
                }

                bb_putchar('\n');

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

                /* Swap stats */
                current_stats ^= 1;

                sleep(interval);
        }

        if (ENABLE_FEATURE_CLEAN_UP) {
                llist_free(G.dev_name_list, NULL);
                stats_dev_free(G.stats_dev_list);
                free(&G);
        }

        return EXIT_SUCCESS;
}