/* vi: set sw=4 ts=4: */
/*
 * A tiny 'top' utility.
 *
 * This is written specifically for the linux /proc/<PID>/stat(m)
 * files format.
 *
 * This reads the PIDs of all processes and their status and shows
 * the status of processes (first ones that fit to screen) at given
 * intervals.
 *
 * NOTES:
 * - At startup this changes to /proc, all the reads are then
 *   relative to that.
 *
 * (C) Eero Tamminen <oak at welho dot com>
 *
 * Rewritten by Vladimir Oleynik (C) 2002 <dzo@simtreas.ru>
 *
 * Sept 2008: Vineet Gupta <vineet.gupta@arc.com>
 * Added Support for reporting SMP Information
 * - CPU where process was last seen running
 *   (to see effect of sched_setaffinity() etc)
 * - CPU time split (idle/IO/wait etc) per CPU
 *
 * Copyright (c) 1992 Branko Lankester
 * Copyright (c) 1992 Roger Binns
 * Copyright (C) 1994-1996 Charles L. Blake.
 * Copyright (C) 1992-1998 Michael K. Johnson
 *
 * Licensed under GPLv2, see file LICENSE in this source tree.
 */
/* How to snapshot /proc for debugging top problems:
 * for f in /proc/[0-9]*""/stat; do
 *         n=${f#/proc/}
 *         n=${n%/stat}_stat
 *         cp $f $n
 * done
 * cp /proc/stat /proc/meminfo /proc/loadavg .
 * top -bn1 >top.out
 *
 * ...and how to run top on it on another machine:
 * rm -rf proc; mkdir proc
 * for f in [0-9]*_stat; do
 *         p=${f%_stat}
 *         mkdir -p proc/$p
 *         cp $f proc/$p/stat
 * done
 * cp stat meminfo loadavg proc
 * chroot . ./top -bn1 >top1.out
 */
//config:config TOP
//config:       bool "top (18 kb)"
//config:       default y
//config:       help
//config:       The top program provides a dynamic real-time view of a running
//config:       system.
//config:
//config:config FEATURE_TOP_INTERACTIVE
//config:       bool "Accept keyboard commands"
//config:       default y
//config:       depends on TOP
//config:       help
//config:       Without this, top will only refresh display every 5 seconds.
//config:       No keyboard commands will work, only ^C to terminate.
//config:
//config:config FEATURE_TOP_CPU_USAGE_PERCENTAGE
//config:       bool "Show CPU per-process usage percentage"
//config:       default y
//config:       depends on TOP
//config:       help
//config:       Make top display CPU usage for each process.
//config:       This adds about 2k.
//config:
//config:config FEATURE_TOP_CPU_GLOBAL_PERCENTS
//config:       bool "Show CPU global usage percentage"
//config:       default y
//config:       depends on FEATURE_TOP_CPU_USAGE_PERCENTAGE
//config:       help
//config:       Makes top display "CPU: NN% usr NN% sys..." line.
//config:       This adds about 0.5k.
//config:
//config:config FEATURE_TOP_SMP_CPU
//config:       bool "SMP CPU usage display ('c' key)"
//config:       default y
//config:       depends on FEATURE_TOP_CPU_GLOBAL_PERCENTS
//config:       help
//config:       Allow 'c' key to switch between individual/cumulative CPU stats
//config:       This adds about 0.5k.
//config:
//config:config FEATURE_TOP_DECIMALS
//config:       bool "Show 1/10th of a percent in CPU/mem statistics"
//config:       default y
//config:       depends on FEATURE_TOP_CPU_USAGE_PERCENTAGE
//config:       help
//config:       Show 1/10th of a percent in CPU/mem statistics.
//config:       This adds about 0.3k.
//config:
//config:config FEATURE_TOP_SMP_PROCESS
//config:       bool "Show CPU process runs on ('j' field)"
//config:       default y
//config:       depends on TOP
//config:       help
//config:       Show CPU where process was last found running on.
//config:       This is the 'j' field.
//config:
//config:config FEATURE_TOPMEM
//config:       bool "Topmem command ('s' key)"
//config:       default y
//config:       depends on TOP
//config:       help
//config:       Enable 's' in top (gives lots of memory info).

//applet:IF_TOP(APPLET(top, BB_DIR_USR_BIN, BB_SUID_DROP))

//kbuild:lib-$(CONFIG_TOP) += top.o

#include "libbb.h"

#define ESC "\033"

typedef struct top_status_t {
        unsigned long vsz;
#if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
        unsigned long ticks;
        unsigned pcpu; /* delta of ticks */
#endif
        unsigned pid, ppid;
        unsigned uid;
        char state[4];
        char comm[COMM_LEN];
#if ENABLE_FEATURE_TOP_SMP_PROCESS
        int last_seen_on_cpu;
#endif
} top_status_t;

typedef struct jiffy_counts_t {
        /* Linux 2.4.x has only first four */
        unsigned long long usr, nic, sys, idle;
        unsigned long long iowait, irq, softirq, steal;
        unsigned long long total;
        unsigned long long busy;
} jiffy_counts_t;

/* This structure stores some critical information from one frame to
   the next. Used for finding deltas. */
typedef struct save_hist {
        unsigned long ticks;
        pid_t pid;
} save_hist;

typedef int (*cmp_funcp)(top_status_t *P, top_status_t *Q);


enum { SORT_DEPTH = 3 };

/* Screens wider than this are unlikely */
enum { LINE_BUF_SIZE = 512 - 64 };

struct globals {
        top_status_t *top;
        int ntop;
        smallint inverted;
#if ENABLE_FEATURE_TOPMEM
        smallint sort_field;
#endif
#if ENABLE_FEATURE_TOP_SMP_CPU
        smallint smp_cpu_info; /* one/many cpu info lines? */
#endif
        unsigned lines;  /* screen height */
#if ENABLE_FEATURE_TOP_INTERACTIVE
        struct termios initial_settings;
        int scroll_ofs;
#define G_scroll_ofs G.scroll_ofs
#else
#define G_scroll_ofs 0
#endif
#if !ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
        cmp_funcp sort_function[1];
#else
        cmp_funcp sort_function[SORT_DEPTH];
        struct save_hist *prev_hist;
        unsigned prev_hist_count;
        jiffy_counts_t cur_jif, prev_jif;
        /* int hist_iterations; */
        unsigned total_pcpu;
        /* unsigned long total_vsz; */
#endif
#if ENABLE_FEATURE_TOP_SMP_CPU
        /* Per CPU samples: current and last */
        jiffy_counts_t *cpu_jif, *cpu_prev_jif;
        unsigned num_cpus;
#endif
#if ENABLE_FEATURE_TOP_INTERACTIVE
        char kbd_input[KEYCODE_BUFFER_SIZE];
#endif
        char line_buf[LINE_BUF_SIZE];
};
#define G (*ptr_to_globals)
#define top              (G.top               )
#define ntop             (G.ntop              )
#define sort_field       (G.sort_field        )
#define inverted         (G.inverted          )
#define smp_cpu_info     (G.smp_cpu_info      )
#define initial_settings (G.initial_settings  )
#define sort_function    (G.sort_function     )
#define prev_hist        (G.prev_hist         )
#define prev_hist_count  (G.prev_hist_count   )
#define cur_jif          (G.cur_jif           )
#define prev_jif         (G.prev_jif          )
#define cpu_jif          (G.cpu_jif           )
#define cpu_prev_jif     (G.cpu_prev_jif      )
#define num_cpus         (G.num_cpus          )
#define total_pcpu       (G.total_pcpu        )
#define line_buf         (G.line_buf          )
#define INIT_G() do { \
        SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
        BUILD_BUG_ON(LINE_BUF_SIZE <= 80); \
} while (0)

enum {
        OPT_d = (1 << 0),
        OPT_n = (1 << 1),
        OPT_b = (1 << 2),
        OPT_H = (1 << 3),
        OPT_m = (1 << 4),
        OPT_EOF = (1 << 5), /* pseudo: "we saw EOF in stdin" */
};
#define OPT_BATCH_MODE (option_mask32 & OPT_b)


#if ENABLE_FEATURE_TOP_INTERACTIVE
static int pid_sort(top_status_t *P, top_status_t *Q)
{
        /* Buggy wrt pids with high bit set */
        /* (linux pids are in [1..2^15-1]) */
        return (Q->pid - P->pid);
}
#endif

static int mem_sort(top_status_t *P, top_status_t *Q)
{
        /* We want to avoid unsigned->signed and truncation errors */
        if (Q->vsz < P->vsz) return -1;
        return Q->vsz != P->vsz; /* 0 if ==, 1 if > */
}


#if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE

static int pcpu_sort(top_status_t *P, top_status_t *Q)
{
        /* Buggy wrt ticks with high bit set */
        /* Affects only processes for which ticks overflow */
        return (int)Q->pcpu - (int)P->pcpu;
}

static int time_sort(top_status_t *P, top_status_t *Q)
{
        /* We want to avoid unsigned->signed and truncation errors */
        if (Q->ticks < P->ticks) return -1;
        return Q->ticks != P->ticks; /* 0 if ==, 1 if > */
}

static int mult_lvl_cmp(void* a, void* b)
{
        int i, cmp_val;

        for (i = 0; i < SORT_DEPTH; i++) {
                cmp_val = (*sort_function[i])(a, b);
                if (cmp_val != 0)
                        break;
        }
        return inverted ? -cmp_val : cmp_val;
}

static NOINLINE int read_cpu_jiffy(FILE *fp, jiffy_counts_t *p_jif)
{
#if !ENABLE_FEATURE_TOP_SMP_CPU
        static const char fmt[] ALIGN1 = "cpu %llu %llu %llu %llu %llu %llu %llu %llu";
#else
        static const char fmt[] ALIGN1 = "cp%*s %llu %llu %llu %llu %llu %llu %llu %llu";
#endif
        int ret;

        if (!fgets(line_buf, LINE_BUF_SIZE, fp) || line_buf[0] != 'c' /* not "cpu" */)
                return 0;
        ret = sscanf(line_buf, fmt,
                        &p_jif->usr, &p_jif->nic, &p_jif->sys, &p_jif->idle,
                        &p_jif->iowait, &p_jif->irq, &p_jif->softirq,
                        &p_jif->steal);
        if (ret >= 4) {
                p_jif->total = p_jif->usr + p_jif->nic + p_jif->sys + p_jif->idle
                        + p_jif->iowait + p_jif->irq + p_jif->softirq + p_jif->steal;
                /* procps 2.x does not count iowait as busy time */
                p_jif->busy = p_jif->total - p_jif->idle - p_jif->iowait;
        }

        return ret;
}

static void get_jiffy_counts(void)
{
        FILE* fp = xfopen_for_read("stat");

        /* We need to parse cumulative counts even if SMP CPU display is on,
         * they are used to calculate per process CPU% */
        prev_jif = cur_jif;
        if (read_cpu_jiffy(fp, &cur_jif) < 4)
                bb_error_msg_and_die("can't read '%s'", "/proc/stat");

#if !ENABLE_FEATURE_TOP_SMP_CPU
        fclose(fp);
        return;
#else
        if (!smp_cpu_info) {
                fclose(fp);
                return;
        }

        if (!num_cpus) {
                /* First time here. How many CPUs?
                 * There will be at least 1 /proc/stat line with cpu%d
                 */
                while (1) {
                        cpu_jif = xrealloc_vector(cpu_jif, 1, num_cpus);
                        if (read_cpu_jiffy(fp, &cpu_jif[num_cpus]) <= 4)
                                break;
                        num_cpus++;
                }
                if (num_cpus == 0) /* /proc/stat with only "cpu ..." line?! */
                        smp_cpu_info = 0;

                cpu_prev_jif = xzalloc(sizeof(cpu_prev_jif[0]) * num_cpus);

                /* Otherwise the first per cpu display shows all 100% idles */
                usleep(50000);
        } else { /* Non first time invocation */
                jiffy_counts_t *tmp;
                int i;

                /* First switch the sample pointers: no need to copy */
                tmp = cpu_prev_jif;
                cpu_prev_jif = cpu_jif;
                cpu_jif = tmp;

                /* Get the new samples */
                for (i = 0; i < num_cpus; i++)
                        read_cpu_jiffy(fp, &cpu_jif[i]);
        }
#endif
        fclose(fp);
}

static void do_stats(void)
{
        top_status_t *cur;
        pid_t pid;
        int n;
        unsigned i, last_i;
        struct save_hist *new_hist;

        get_jiffy_counts();
        total_pcpu = 0;
        /* total_vsz = 0; */
        new_hist = xmalloc(sizeof(new_hist[0]) * ntop);
        /*
         * Make a pass through the data to get stats.
         */
        /* hist_iterations = 0; */
        i = 0;
        for (n = 0; n < ntop; n++) {
                cur = top + n;

                /*
                 * Calculate time in cur process.  Time is sum of user time
                 * and system time
                 */
                pid = cur->pid;
                new_hist[n].ticks = cur->ticks;
                new_hist[n].pid = pid;

                /* find matching entry from previous pass */
                cur->pcpu = 0;
                /* do not start at index 0, continue at last used one
                 * (brought hist_iterations from ~14000 down to 172) */
                last_i = i;
                if (prev_hist_count) do {
                        if (prev_hist[i].pid == pid) {
                                cur->pcpu = cur->ticks - prev_hist[i].ticks;
                                total_pcpu += cur->pcpu;
                                break;
                        }
                        i = (i+1) % prev_hist_count;
                        /* hist_iterations++; */
                } while (i != last_i);
                /* total_vsz += cur->vsz; */
        }

        /*
         * Save cur frame's information.
         */
        free(prev_hist);
        prev_hist = new_hist;
        prev_hist_count = ntop;
}

#endif /* FEATURE_TOP_CPU_USAGE_PERCENTAGE */

#if ENABLE_FEATURE_TOP_CPU_GLOBAL_PERCENTS && ENABLE_FEATURE_TOP_DECIMALS
/* formats 7 char string (8 with terminating NUL) */
static char *fmt_100percent_8(char pbuf[8], unsigned value, unsigned total)
{
        unsigned t;
        if (value >= total) { /* 100% ? */
                strcpy(pbuf, "  100% ");
                return pbuf;
        }
        /* else generate " [N/space]N.N% " string */
        value = 1000 * value / total;
        t = value / 100;
        value = value % 100;
        pbuf[0] = ' ';
        pbuf[1] = t ? t + '0' : ' ';
        pbuf[2] = '0' + (value / 10);
        pbuf[3] = '.';
        pbuf[4] = '0' + (value % 10);
        pbuf[5] = '%';
        pbuf[6] = ' ';
        pbuf[7] = '\0';
        return pbuf;
}
#endif

#if ENABLE_FEATURE_TOP_CPU_GLOBAL_PERCENTS
static void display_cpus(int scr_width, char *scrbuf, int *lines_rem_p)
{
        /*
         * xxx% = (cur_jif.xxx - prev_jif.xxx) / (cur_jif.total - prev_jif.total) * 100%
         */
        unsigned total_diff;
        jiffy_counts_t *p_jif, *p_prev_jif;
        int i;
# if ENABLE_FEATURE_TOP_SMP_CPU
        int n_cpu_lines;
# endif

        /* using (unsigned) casts to make operations cheaper */
# define  CALC_TOTAL_DIFF do { \
        total_diff = (unsigned)(p_jif->total - p_prev_jif->total); \
        if (total_diff == 0) total_diff = 1; \
} while (0)

# if ENABLE_FEATURE_TOP_DECIMALS
#  define CALC_STAT(xxx) char xxx[8]
#  define SHOW_STAT(xxx) fmt_100percent_8(xxx, (unsigned)(p_jif->xxx - p_prev_jif->xxx), total_diff)
#  define FMT "%s"
# else
#  define CALC_STAT(xxx) unsigned xxx = 100 * (unsigned)(p_jif->xxx - p_prev_jif->xxx) / total_diff
#  define SHOW_STAT(xxx) xxx
#  define FMT "%4u%% "
# endif

# if !ENABLE_FEATURE_TOP_SMP_CPU
        {
                i = 1;
                p_jif = &cur_jif;
                p_prev_jif = &prev_jif;
# else
        /* Loop thru CPU(s) */
        n_cpu_lines = smp_cpu_info ? num_cpus : 1;
        if (n_cpu_lines > *lines_rem_p)
                n_cpu_lines = *lines_rem_p;

        for (i = 0; i < n_cpu_lines; i++) {
                p_jif = &cpu_jif[i];
                p_prev_jif = &cpu_prev_jif[i];
# endif
                CALC_TOTAL_DIFF;

                { /* Need a block: CALC_STAT are declarations */
                        CALC_STAT(usr);
                        CALC_STAT(sys);
                        CALC_STAT(nic);
                        CALC_STAT(idle);
                        CALC_STAT(iowait);
                        CALC_STAT(irq);
                        CALC_STAT(softirq);
                        /*CALC_STAT(steal);*/

                        snprintf(scrbuf, scr_width,
                                /* Barely fits in 79 chars when in "decimals" mode. */
# if ENABLE_FEATURE_TOP_SMP_CPU
                                "CPU%s:"FMT"usr"FMT"sys"FMT"nic"FMT"idle"FMT"io"FMT"irq"FMT"sirq",
                                (smp_cpu_info ? utoa(i) : ""),
# else
                                "CPU:"FMT"usr"FMT"sys"FMT"nic"FMT"idle"FMT"io"FMT"irq"FMT"sirq",
# endif
                                SHOW_STAT(usr), SHOW_STAT(sys), SHOW_STAT(nic), SHOW_STAT(idle),
                                SHOW_STAT(iowait), SHOW_STAT(irq), SHOW_STAT(softirq)
                                /*, SHOW_STAT(steal) - what is this 'steal' thing? */
                                /* I doubt anyone wants to know it */
                        );
                        puts(scrbuf);
                }
        }
# undef SHOW_STAT
# undef CALC_STAT
# undef FMT
        *lines_rem_p -= i;
}
#else  /* !ENABLE_FEATURE_TOP_CPU_GLOBAL_PERCENTS */
# define display_cpus(scr_width, scrbuf, lines_rem) ((void)0)
#endif

enum {
        MI_MEMTOTAL,
        MI_MEMFREE,
        MI_MEMSHARED,
        MI_SHMEM,
        MI_BUFFERS,
        MI_CACHED,
        MI_SWAPTOTAL,
        MI_SWAPFREE,
        MI_DIRTY,
        MI_WRITEBACK,
        MI_ANONPAGES,
        MI_MAPPED,
        MI_SLAB,
        MI_MAX
};

static void parse_meminfo(unsigned long meminfo[MI_MAX])
{
        static const char fields[] ALIGN1 =
                "MemTotal\0"
                "MemFree\0"
                "MemShared\0"
                "Shmem\0"
                "Buffers\0"
                "Cached\0"
                "SwapTotal\0"
                "SwapFree\0"
                "Dirty\0"
                "Writeback\0"
                "AnonPages\0"
                "Mapped\0"
                "Slab\0";
        char buf[60]; /* actual lines we expect are ~30 chars or less */
        FILE *f;
        int i;

        memset(meminfo, 0, sizeof(meminfo[0]) * MI_MAX);
        f = xfopen_for_read("meminfo");
        while (fgets(buf, sizeof(buf), f) != NULL) {
                char *c = strchr(buf, ':');
                if (!c)
                        continue;
                *c = '\0';
                i = index_in_strings(fields, buf);
                if (i >= 0)
                        meminfo[i] = strtoul(c+1, NULL, 10);
        }
        fclose(f);
}

static unsigned long display_header(int scr_width, int *lines_rem_p)
{
        char scrbuf[100]; /* [80] was a bit too low on 8Gb ram box */
        char *buf;
        unsigned long meminfo[MI_MAX];

        parse_meminfo(meminfo);

        /* Output memory info */
        if (scr_width > (int)sizeof(scrbuf))
                scr_width = sizeof(scrbuf);
        snprintf(scrbuf, scr_width,
                "Mem: %luK used, %luK free, %luK shrd, %luK buff, %luK cached",
                meminfo[MI_MEMTOTAL] - meminfo[MI_MEMFREE],
                meminfo[MI_MEMFREE],
                meminfo[MI_MEMSHARED] + meminfo[MI_SHMEM],
                meminfo[MI_BUFFERS],
                meminfo[MI_CACHED]);
        /* Go to top & clear to the end of screen */
        printf(OPT_BATCH_MODE ? "%s\n" : ESC"[H" ESC"[J" "%s\n", scrbuf);
        (*lines_rem_p)--;

        /* Display CPU time split as percentage of total time.
         * This displays either a cumulative line or one line per CPU.
         */
        display_cpus(scr_width, scrbuf, lines_rem_p);

        /* Read load average as a string */
        buf = stpcpy(scrbuf, "Load average: ");
        open_read_close("loadavg", buf, sizeof(scrbuf) - sizeof("Load average: "));
        scrbuf[scr_width - 1] = '\0';
        strchrnul(buf, '\n')[0] = '\0';
        puts(scrbuf);
        (*lines_rem_p)--;

        return meminfo[MI_MEMTOTAL];
}

static NOINLINE void display_process_list(int lines_rem, int scr_width)
{
        enum {
                BITS_PER_INT = sizeof(int) * 8
        };

        top_status_t *s;
        unsigned long total_memory = display_header(scr_width, &lines_rem); /* or use total_vsz? */
        /* xxx_shift and xxx_scale variables allow us to replace
         * expensive divides with multiply and shift */
        unsigned pmem_shift, pmem_scale, pmem_half;
#if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
        unsigned tmp_unsigned;
        unsigned pcpu_shift, pcpu_scale, pcpu_half;
        unsigned busy_jifs;
#endif

        /* what info of the processes is shown */
        printf(OPT_BATCH_MODE ? "%.*s" : ESC"[7m" "%.*s" ESC"[m", scr_width,
                "  PID  PPID USER     STAT   VSZ %VSZ"
                IF_FEATURE_TOP_SMP_PROCESS(" CPU")
                IF_FEATURE_TOP_CPU_USAGE_PERCENTAGE(" %CPU")
                " COMMAND");
        lines_rem--;

#if ENABLE_FEATURE_TOP_DECIMALS
# define UPSCALE 1000
# define CALC_STAT(name, val) div_t name = div((val), 10)
# define SHOW_STAT(name) name.quot, '0'+name.rem
# define FMT "%3u.%c"
#else
# define UPSCALE 100
# define CALC_STAT(name, val) unsigned name = (val)
# define SHOW_STAT(name) name
# define FMT "%4u%%"
#endif
        /*
         * %VSZ = s->vsz/MemTotal
         */
        pmem_shift = BITS_PER_INT-11;
        pmem_scale = UPSCALE*(1U<<(BITS_PER_INT-11)) / total_memory;
        /* s->vsz is in kb. we want (s->vsz * pmem_scale) to never overflow */
        while (pmem_scale >= 512) {
                pmem_scale /= 4;
                pmem_shift -= 2;
        }
        pmem_half = (1U << pmem_shift) / (ENABLE_FEATURE_TOP_DECIMALS ? 20 : 2);
#if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
        busy_jifs = cur_jif.busy - prev_jif.busy;
        /* This happens if there were lots of short-lived processes
         * between two top updates (e.g. compilation) */
        if (total_pcpu < busy_jifs) total_pcpu = busy_jifs;

        /*
         * CPU% = s->pcpu/sum(s->pcpu) * busy_cpu_ticks/total_cpu_ticks
         * (pcpu is delta of sys+user time between samples)
         */
        /* (cur_jif.xxx - prev_jif.xxx) and s->pcpu are
         * in 0..~64000 range (HZ*update_interval).
         * we assume that unsigned is at least 32-bit.
         */
        pcpu_shift = 6;
        pcpu_scale = UPSCALE*64 * (uint16_t)busy_jifs;
        if (pcpu_scale == 0)
                pcpu_scale = 1;
        while (pcpu_scale < (1U << (BITS_PER_INT-2))) {
                pcpu_scale *= 4;
                pcpu_shift += 2;
        }
        tmp_unsigned = (uint16_t)(cur_jif.total - prev_jif.total) * total_pcpu;
        if (tmp_unsigned != 0)
                pcpu_scale /= tmp_unsigned;
        /* we want (s->pcpu * pcpu_scale) to never overflow */
        while (pcpu_scale >= 1024) {
                pcpu_scale /= 4;
                pcpu_shift -= 2;
        }
        pcpu_half = (1U << pcpu_shift) / (ENABLE_FEATURE_TOP_DECIMALS ? 20 : 2);
        /* printf(" pmem_scale=%u pcpu_scale=%u ", pmem_scale, pcpu_scale); */
#endif

        /* Ok, all preliminary data is ready, go through the list */
        scr_width += 2; /* account for leading '\n' and trailing NUL */
        if (lines_rem > ntop - G_scroll_ofs)
                lines_rem = ntop - G_scroll_ofs;
        s = top + G_scroll_ofs;
        while (--lines_rem >= 0) {
                int n;
                char *ppu;
                char ppubuf[sizeof(int)*3 * 2 + 12];
                char vsz_str_buf[8];
                unsigned col;

                CALC_STAT(pmem, (s->vsz*pmem_scale + pmem_half) >> pmem_shift);
#if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
                CALC_STAT(pcpu, (s->pcpu*pcpu_scale + pcpu_half) >> pcpu_shift);
#endif

                smart_ulltoa5(s->vsz, vsz_str_buf, " mgtpezy");
                /* PID PPID USER STAT VSZ %VSZ [%CPU] COMMAND */
                n = sprintf(ppubuf, "%5u %5u %-8.8s", s->pid, s->ppid, get_cached_username(s->uid));
                ppu = ppubuf;
                if (n != 6+6+8) {
                        /* Format PID PPID USER part into 6+6+8 chars:
                         * shrink PID/PPID if possible, then truncate USER
                         */
                        char *p, *pp;
                        if (*ppu == ' ') {
                                do {
                                        ppu++, n--;
                                        if (n == 6+6+8)
                                                goto shortened;
                                } while (*ppu == ' ');
                        }
                        pp = p = skip_non_whitespace(ppu) + 1;
                        if (*p == ' ') {
                                do
                                        p++, n--;
                                while (n != 6+6+8 && *p == ' ');
                                overlapping_strcpy(pp, p); /* shrink PPID */
                        }
                        ppu[6+6+8] = '\0'; /* truncate USER */
                }
 shortened:
                col = snprintf(line_buf, scr_width,
                                "\n" "%s %s  %.5s" FMT
                                IF_FEATURE_TOP_SMP_PROCESS(" %3d")
                                IF_FEATURE_TOP_CPU_USAGE_PERCENTAGE(FMT)
                                " ",
                                ppu,
                                s->state, vsz_str_buf,
                                SHOW_STAT(pmem)
                                IF_FEATURE_TOP_SMP_PROCESS(, s->last_seen_on_cpu)
                                IF_FEATURE_TOP_CPU_USAGE_PERCENTAGE(, SHOW_STAT(pcpu))
                );
                if ((int)(scr_width - col) > 1)
                        read_cmdline(line_buf + col, scr_width - col, s->pid, s->comm);
                fputs_stdout(line_buf);
                /* printf(" %d/%d %lld/%lld", s->pcpu, total_pcpu,
                        cur_jif.busy - prev_jif.busy, cur_jif.total - prev_jif.total); */
                s++;
        }
        /* printf(" %d", hist_iterations); */
        bb_putchar(OPT_BATCH_MODE ? '\n' : '\r');
        fflush_all();
}
#undef UPSCALE
#undef SHOW_STAT
#undef CALC_STAT
#undef FMT

static void clearmems(void)
{
        clear_username_cache();
        free(top);
        top = NULL;
}

#if ENABLE_FEATURE_TOP_INTERACTIVE
static void reset_term(void)
{
        if (!OPT_BATCH_MODE)
                tcsetattr_stdin_TCSANOW(&initial_settings);
}

static void sig_catcher(int sig)
{
        reset_term();
        kill_myself_with_sig(sig);
}
#endif /* FEATURE_TOP_INTERACTIVE */

/*
 * TOPMEM support
 */

typedef unsigned long mem_t;

typedef struct topmem_status_t {
        unsigned pid;
        char comm[COMM_LEN];
        /* vsz doesn't count /dev/xxx mappings except /dev/zero */
        mem_t vsz     ;
        mem_t vszrw   ;
        mem_t rss     ;
        mem_t rss_sh  ;
        mem_t dirty   ;
        mem_t dirty_sh;
        mem_t stack   ;
} topmem_status_t;

enum { NUM_SORT_FIELD = 7 };

#define topmem ((topmem_status_t*)top)

#if ENABLE_FEATURE_TOPMEM

static int topmem_sort(char *a, char *b)
{
        int n;
        mem_t l, r;

        n = offsetof(topmem_status_t, vsz) + (sort_field * sizeof(mem_t));
        l = *(mem_t*)(a + n);
        r = *(mem_t*)(b + n);
        if (l == r) {
                l = ((topmem_status_t*)a)->dirty;
                r = ((topmem_status_t*)b)->dirty;
        }
        /* We want to avoid unsigned->signed and truncation errors */
        /* l>r: -1, l=r: 0, l<r: 1 */
        n = (l > r) ? -1 : (l != r);
        return inverted ? -n : n;
}

/* display header info (meminfo / loadavg) */
static void display_topmem_header(int scr_width, int *lines_rem_p)
{
        unsigned long meminfo[MI_MAX];

        parse_meminfo(meminfo);

        snprintf(line_buf, LINE_BUF_SIZE,
                "Mem total:%lu anon:%lu map:%lu free:%lu",
                meminfo[MI_MEMTOTAL],
                meminfo[MI_ANONPAGES],
                meminfo[MI_MAPPED],
                meminfo[MI_MEMFREE]);
        printf(OPT_BATCH_MODE ? "%.*s\n" : ESC"[H" ESC"[J" "%.*s\n", scr_width, line_buf);

        snprintf(line_buf, LINE_BUF_SIZE,
                " slab:%lu buf:%lu cache:%lu dirty:%lu write:%lu",
                meminfo[MI_SLAB],
                meminfo[MI_BUFFERS],
                meminfo[MI_CACHED],
                meminfo[MI_DIRTY],
                meminfo[MI_WRITEBACK]);
        printf("%.*s\n", scr_width, line_buf);

        snprintf(line_buf, LINE_BUF_SIZE,
                "Swap total:%lu free:%lu", // TODO: % used?
                meminfo[MI_SWAPTOTAL],
                meminfo[MI_SWAPFREE]);
        printf("%.*s\n", scr_width, line_buf);

        (*lines_rem_p) -= 3;
}

static void ulltoa6_and_space(unsigned long long ul, char buf[6])
{
        /* see http://en.wikipedia.org/wiki/Tera */
        smart_ulltoa5(ul, buf, " mgtpezy")[0] = ' ';
}

static NOINLINE void display_topmem_process_list(int lines_rem, int scr_width)
{
#define HDR_STR "  PID   VSZ VSZRW   RSS (SHR) DIRTY (SHR) STACK"
#define MIN_WIDTH sizeof(HDR_STR)
        const topmem_status_t *s = topmem + G_scroll_ofs;
        char *cp, ch;

        display_topmem_header(scr_width, &lines_rem);

        strcpy(line_buf, HDR_STR " COMMAND");
        /* Mark the ^FIELD^ we sort by */
        cp = &line_buf[5 + sort_field * 6];
        ch = "^_"[inverted];
        cp[6] = ch;
        do *cp++ = ch; while (*cp == ' ');

        printf(OPT_BATCH_MODE ? "%.*s" : ESC"[7m" "%.*s" ESC"[m", scr_width, line_buf);
        lines_rem--;

        if (lines_rem > ntop - G_scroll_ofs)
                lines_rem = ntop - G_scroll_ofs;
        while (--lines_rem >= 0) {
                /* PID VSZ VSZRW RSS (SHR) DIRTY (SHR) COMMAND */
                int n = sprintf(line_buf, "%5u ", s->pid);
                ulltoa6_and_space(s->vsz     , &line_buf[1*6]);
                if (n > 7 || (n == 7 && line_buf[6] != ' '))
                        /* PID and VSZ are clumped together, truncate PID */
                        line_buf[5] = '.';
                ulltoa6_and_space(s->vszrw   , &line_buf[2*6]);
                ulltoa6_and_space(s->rss     , &line_buf[3*6]);
                ulltoa6_and_space(s->rss_sh  , &line_buf[4*6]);
                ulltoa6_and_space(s->dirty   , &line_buf[5*6]);
                ulltoa6_and_space(s->dirty_sh, &line_buf[6*6]);
                ulltoa6_and_space(s->stack   , &line_buf[7*6]);
                line_buf[8*6] = '\0';
                if (scr_width > (int)MIN_WIDTH) {
                        read_cmdline(&line_buf[8*6], scr_width - MIN_WIDTH, s->pid, s->comm);
                }
                printf("\n""%.*s", scr_width, line_buf);
                s++;
        }
        bb_putchar(OPT_BATCH_MODE ? '\n' : '\r');
        fflush_all();
#undef HDR_STR
#undef MIN_WIDTH
}

#else
void display_topmem_process_list(int lines_rem, int scr_width);
int topmem_sort(char *a, char *b);
#endif /* TOPMEM */

/*
 * end TOPMEM support
 */

enum {
        TOP_MASK = 0
                | PSSCAN_PID
                | PSSCAN_PPID
                | PSSCAN_VSZ
                | PSSCAN_STIME
                | PSSCAN_UTIME
                | PSSCAN_STATE
                | PSSCAN_COMM
                | PSSCAN_CPU
                | PSSCAN_UIDGID,
        TOPMEM_MASK = 0
                | PSSCAN_PID
                | PSSCAN_SMAPS
                | PSSCAN_COMM,
        EXIT_MASK = 0,
        NO_RESCAN_MASK = (unsigned)-1,
};

#if ENABLE_FEATURE_TOP_INTERACTIVE
static unsigned handle_input(unsigned scan_mask, duration_t interval)
{
        if (option_mask32 & OPT_EOF) {
                /* EOF on stdin ("top </dev/null") */
                sleep_for_duration(interval);
                return scan_mask;
        }

        while (1) {
                int32_t c;

                c = safe_read_key(STDIN_FILENO, G.kbd_input, interval * 1000);
                if (c == -1 && errno != EAGAIN) {
                        /* error/EOF */
                        option_mask32 |= OPT_EOF;
                        break;
                }
                interval = 0;

                if (c == initial_settings.c_cc[VINTR])
                        return EXIT_MASK;
                if (c == initial_settings.c_cc[VEOF])
                        return EXIT_MASK;

                if (c == KEYCODE_UP) {
                        G_scroll_ofs--;
                        goto normalize_ofs;
                }
                if (c == KEYCODE_DOWN) {
                        G_scroll_ofs++;
                        goto normalize_ofs;
                }
                if (c == KEYCODE_HOME) {
                        G_scroll_ofs = 0;
                        goto normalize_ofs;
                }
                if (c == KEYCODE_END) {
                        G_scroll_ofs = ntop - G.lines / 2;
                        goto normalize_ofs;
                }
                if (c == KEYCODE_PAGEUP) {
                        G_scroll_ofs -= G.lines / 2;
                        goto normalize_ofs;
                }
                if (c == KEYCODE_PAGEDOWN) {
                        G_scroll_ofs += G.lines / 2;
 normalize_ofs:
                        if (G_scroll_ofs >= ntop)
                                G_scroll_ofs = ntop - 1;
                        if (G_scroll_ofs < 0)
                                G_scroll_ofs = 0;
                        return NO_RESCAN_MASK;
                }

                c |= 0x20; /* lowercase */
                if (c == 'q')
                        return EXIT_MASK;

                if (c == 'n') {
                        IF_FEATURE_TOPMEM(scan_mask = TOP_MASK;)
                        sort_function[0] = pid_sort;
                        continue;
                }
                if (c == 'm') {
                        IF_FEATURE_TOPMEM(scan_mask = TOP_MASK;)
                        sort_function[0] = mem_sort;

# if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
                        sort_function[1] = pcpu_sort;
                        sort_function[2] = time_sort;
# endif
                        continue;
                }
# if ENABLE_FEATURE_SHOW_THREADS
                if (c == 'h'
                IF_FEATURE_TOPMEM(&& scan_mask != TOPMEM_MASK)
                ) {
                        scan_mask ^= PSSCAN_TASKS;
#  if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
                        free(prev_hist);
                        prev_hist = NULL;
                        prev_hist_count = 0;
#   endif
                        continue;
                }
# endif
# if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
                if (c == 'p') {
                        IF_FEATURE_TOPMEM(scan_mask = TOP_MASK;)
                        sort_function[0] = pcpu_sort;
                        sort_function[1] = mem_sort;
                        sort_function[2] = time_sort;
                        continue;
                }
                if (c == 't') {
                        IF_FEATURE_TOPMEM(scan_mask = TOP_MASK;)
                        sort_function[0] = time_sort;
                        sort_function[1] = mem_sort;
                        sort_function[2] = pcpu_sort;
                        continue;
                }
#  if ENABLE_FEATURE_TOPMEM
                if (c == 's') {
                        scan_mask = TOPMEM_MASK;
                        sort_field = (sort_field + 1) % NUM_SORT_FIELD;
                        free(prev_hist);
                        prev_hist = NULL;
                        prev_hist_count = 0;
                        continue;
                }
#  endif
                if (c == 'r') {
                        inverted ^= 1;
                        continue;
                }
#  if ENABLE_FEATURE_TOP_SMP_CPU
                /* procps-2.0.18 uses 'C', 3.2.7 uses '1' */
                if (c == 'c' || c == '1') {
                        /* User wants to toggle per cpu <> aggregate */
                        if (smp_cpu_info) {
                                free(cpu_prev_jif);
                                free(cpu_jif);
                                cpu_jif = &cur_jif;
                                cpu_prev_jif = &prev_jif;
                        } else {
                                /* Prepare for xrealloc() */
                                cpu_jif = cpu_prev_jif = NULL;
                        }
                        num_cpus = 0;
                        smp_cpu_info = !smp_cpu_info;
                        get_jiffy_counts();
                        continue;
                }
#  endif
# endif
                break; /* unknown key -> force refresh */
        }

        return scan_mask;
}
#endif

//usage:#if ENABLE_FEATURE_SHOW_THREADS || ENABLE_FEATURE_TOP_SMP_CPU
//usage:# define IF_SHOW_THREADS_OR_TOP_SMP(...) __VA_ARGS__
//usage:#else
//usage:# define IF_SHOW_THREADS_OR_TOP_SMP(...)
//usage:#endif
//usage:#define top_trivial_usage
//usage:       "[-b"IF_FEATURE_TOPMEM("m")IF_FEATURE_SHOW_THREADS("H")"]"
//usage:       " [-n COUNT] [-d SECONDS]"
//usage:#define top_full_usage "\n\n"
//usage:       "Show a view of process activity in real time."
//usage:   "\n""Read the status of all processes from /proc each SECONDS"
//usage:   "\n""and show a screenful of them."
//usage:   "\n"
//usage:        IF_FEATURE_TOP_INTERACTIVE(
//usage:       "Keys:"
//usage:   "\n""        N/M"
//usage:                IF_FEATURE_TOP_CPU_USAGE_PERCENTAGE("/P")
//usage:                IF_FEATURE_TOP_CPU_USAGE_PERCENTAGE("/T")
//usage:           ": " IF_FEATURE_TOPMEM("show CPU usage, ") "sort by pid/mem"
//usage:                IF_FEATURE_TOP_CPU_USAGE_PERCENTAGE("/cpu")
//usage:                IF_FEATURE_TOP_CPU_USAGE_PERCENTAGE("/time")
//usage:        IF_FEATURE_TOPMEM(
//usage:   "\n""        S: show memory"
//usage:        )
//usage:   "\n""        R: reverse sort"
//usage:        IF_SHOW_THREADS_OR_TOP_SMP(
//usage:   "\n""        "
//usage:                IF_FEATURE_SHOW_THREADS("H: toggle threads")
//usage:                IF_FEATURE_SHOW_THREADS(IF_FEATURE_TOP_SMP_CPU(", "))
//usage:                IF_FEATURE_TOP_SMP_CPU("1: toggle SMP")
//usage:        )
//usage:   "\n""        Q,^C: exit"
//usage:   "\n""Options:"
//usage:        )
//usage:   "\n""        -b      Batch mode"
//usage:   "\n""        -n N    Exit after N iterations"
//usage:   "\n""        -d SEC  Delay between updates"
//usage:        IF_FEATURE_TOPMEM(
//usage:   "\n""        -m      Same as 's' key"
//usage:        )
//usage:        IF_FEATURE_SHOW_THREADS(
//usage:   "\n""        -H      Show threads"
//usage:        )

/* Interactive testing:
 * echo sss | ./busybox top
 * - shows memory screen
 * echo sss | ./busybox top -bn1 >mem
 * - saves memory screen - the *whole* list, not first NROWS processes!
 * echo .m.s.s.s.s.s.s.q | ./busybox top -b >z
 * - saves several different screens, and exits
 *
 * TODO: -i STRING param as a better alternative?
 */

int top_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int top_main(int argc UNUSED_PARAM, char **argv)
{
        duration_t interval;
        int iterations;
        unsigned col;
        char *str_interval, *str_iterations;
        unsigned scan_mask = TOP_MASK;

        INIT_G();

        interval = 5; /* default update interval is 5 seconds */
        iterations = 0; /* infinite */
#if ENABLE_FEATURE_TOP_SMP_CPU
        /*num_cpus = 0;*/
        /*smp_cpu_info = 0;*/  /* to start with show aggregate */
        cpu_jif = &cur_jif;
        cpu_prev_jif = &prev_jif;
#endif

        /* all args are options; -n NUM */
        make_all_argv_opts(argv); /* options can be specified w/o dash */
        col = getopt32(argv, "d:n:bHm", &str_interval, &str_iterations);
        /* NB: -m and -H are accepted even if not configured */
#if ENABLE_FEATURE_TOPMEM
        if (col & OPT_m) /* -m (busybox specific) */
                scan_mask = TOPMEM_MASK;
#endif
        if (col & OPT_d) {
                /* work around for "-d 1" -> "-d -1" done by make_all_argv_opts() */
                if (str_interval[0] == '-')
                        str_interval++;
                interval = parse_duration_str(str_interval);
                /* Need to limit it to not overflow poll timeout */
                if (interval > INT_MAX / 1000)
                        interval = INT_MAX / 1000;
        }
        if (col & OPT_n) {
                if (str_iterations[0] == '-')
                        str_iterations++;
                iterations = xatou(str_iterations);
        }
#if ENABLE_FEATURE_SHOW_THREADS
        if (col & OPT_H) {
                scan_mask |= PSSCAN_TASKS;
        }
#endif

        /* change to /proc */
        xchdir("/proc");

#if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
        sort_function[0] = pcpu_sort;
        sort_function[1] = mem_sort;
        sort_function[2] = time_sort;
#else
        sort_function[0] = mem_sort;
#endif

        if (OPT_BATCH_MODE) {
                option_mask32 |= OPT_EOF;
        }
#if ENABLE_FEATURE_TOP_INTERACTIVE
        else {
                /* Turn on unbuffered input; turn off echoing, ^C ^Z etc */
                set_termios_to_raw(STDIN_FILENO, &initial_settings, TERMIOS_CLEAR_ISIG);
                die_func = reset_term;
        }

        bb_signals(BB_FATAL_SIGS, sig_catcher);

        /* Eat initial input, if any */
        scan_mask = handle_input(scan_mask, 0);
#endif

        while (scan_mask != EXIT_MASK) {
                IF_FEATURE_TOP_INTERACTIVE(unsigned new_mask;)
                procps_status_t *p = NULL;

                if (OPT_BATCH_MODE) {
                        G.lines = INT_MAX;
                        col = LINE_BUF_SIZE - 2; /* +2 bytes for '\n', NUL */
                } else {
                        G.lines = 24; /* default */
                        col = 79;
                        /* We output to stdout, we need size of stdout (not stdin)! */
                        get_terminal_width_height(STDOUT_FILENO, &col, &G.lines);
                        if (G.lines < 5 || col < 10) {
                                sleep_for_duration(interval);
                                continue;
                        }
                        if (col > LINE_BUF_SIZE - 2)
                                col = LINE_BUF_SIZE - 2;
                }

                /* read process IDs & status for all the processes */
                ntop = 0;
                while ((p = procps_scan(p, scan_mask)) != NULL) {
                        int n;

                        IF_FEATURE_TOPMEM(if (scan_mask != TOPMEM_MASK)) {
                                n = ntop;
                                top = xrealloc_vector(top, 6, ntop++);
                                top[n].pid = p->pid;
                                top[n].ppid = p->ppid;
                                top[n].vsz = p->vsz;
#if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
                                top[n].ticks = p->stime + p->utime;
#endif
                                top[n].uid = p->uid;
                                strcpy(top[n].state, p->state);
                                strcpy(top[n].comm, p->comm);
#if ENABLE_FEATURE_TOP_SMP_PROCESS
                                top[n].last_seen_on_cpu = p->last_seen_on_cpu;
#endif
                        }
#if ENABLE_FEATURE_TOPMEM
                        else { /* TOPMEM */
                                if (!(p->smaps.mapped_ro | p->smaps.mapped_rw))
                                        continue; /* kernel threads are ignored */
                                n = ntop;
                                /* No bug here - top and topmem are the same */
                                top = xrealloc_vector(topmem, 6, ntop++);
                                strcpy(topmem[n].comm, p->comm);
                                topmem[n].pid      = p->pid;
                                topmem[n].vsz      = p->smaps.mapped_rw + p->smaps.mapped_ro;
                                topmem[n].vszrw    = p->smaps.mapped_rw;
                                topmem[n].rss_sh   = p->smaps.shared_clean + p->smaps.shared_dirty;
                                topmem[n].rss      = p->smaps.private_clean + p->smaps.private_dirty + topmem[n].rss_sh;
                                topmem[n].dirty    = p->smaps.private_dirty + p->smaps.shared_dirty;
                                topmem[n].dirty_sh = p->smaps.shared_dirty;
                                topmem[n].stack    = p->smaps.stack;
                        }
#endif
                } /* end of "while we read /proc" */
                if (ntop == 0) {
                        bb_simple_error_msg("no process info in /proc");
                        break;
                }

                IF_FEATURE_TOPMEM(if (scan_mask != TOPMEM_MASK)) {
#if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
                        if (!prev_hist_count) {
                                do_stats();
                                usleep(100000);
                                clearmems();
                                continue;
                        }
                        do_stats();
                        /* TODO: we don't need to sort all 10000 processes, we need to find top 24! */
                        qsort(top, ntop, sizeof(top_status_t), (void*)mult_lvl_cmp);
#else
                        qsort(top, ntop, sizeof(top_status_t), (void*)(sort_function[0]));
#endif
                }
#if ENABLE_FEATURE_TOPMEM
                else { /* TOPMEM */
                        qsort(topmem, ntop, sizeof(topmem_status_t), (void*)topmem_sort);
                }
#endif
 IF_FEATURE_TOP_INTERACTIVE(display:)
                IF_FEATURE_TOPMEM(if (scan_mask != TOPMEM_MASK)) {
                        display_process_list(G.lines, col);
                }
#if ENABLE_FEATURE_TOPMEM
                else { /* TOPMEM */
                        display_topmem_process_list(G.lines, col);
                }
#endif
                if (iterations >= 0 && !--iterations)
                        break;
#if !ENABLE_FEATURE_TOP_INTERACTIVE
                clearmems();
                sleep_for_duration(interval);
#else
                new_mask = handle_input(scan_mask, interval);
                if (new_mask == NO_RESCAN_MASK)
                        goto display;
                scan_mask = new_mask;
                clearmems();
#endif
        } /* end of "while (not Q)" */

        bb_putchar('\n');
#if ENABLE_FEATURE_TOP_INTERACTIVE
        reset_term();
#endif
        if (ENABLE_FEATURE_CLEAN_UP) {
                clearmems();
#if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
                free(prev_hist);
#endif
        }
        return EXIT_SUCCESS;
}