/* ps.c - show process list
 *
 * Copyright 2015 Rob Landley <rob@landley.net>
 *
 * See http://pubs.opengroup.org/onlinepubs/9699919799/utilities/ps.html
 * And http://kernel.org/doc/Documentation/filesystems/proc.txt Table 1-4
 * And linux kernel source fs/proc/array.c function do_task_stat()
 *
 * Deviations from posix: no -n because /proc/self/wchan exists; we use -n to
 * mean "show numeric users and groups" instead.
 * Posix says default output should have field named "TTY" but if you "-o tty"
 * the same field should be called "TT" which is _INSANE_ and I'm not doing it.
 * Similarly -f outputs USER but calls it UID (we call it USER).
 * It also says that -o "args" and "comm" should behave differently but use
 * the same title, which is not the same title as the default output. (No.)
 * Select by session id is -s not -g. Posix doesn't say truncated fields
 * should end with "+" but it's pretty common behavior.
 *
 * Posix defines -o ADDR as "The address of the process" but the process
 * start address is a constant on any elf system with mmu. The procps ADDR
 * field always prints "-" with an alignment of 1, which is why it has 11
 * characters left for "cmd" in in 80 column "ps -l" mode. On x86-64 you
 * need 12 chars, leaving nothing for cmd: I.E. posix 2008 ps -l mode can't
 * be sanely implemented on 64 bit Linux systems. In procps there's ps -y
 * which changes -l by removing the "F" column and swapping RSS for ADDR,
 * leaving 9 chars for cmd, so we're using that as our -l output.
 *
 * Added a bunch of new -o fields posix doesn't mention, and we don't
 * label "ps -o command,args,comm" as "COMMAND COMMAND COMMAND". We don't
 * output argv[0] unmodified for -o comm or -o args (but procps violates
 * posix for -o comm anyway, it's stat[2] not argv[0]).
 *
 * Note: iotop is STAYROOT so it can read other process's /proc/$PID/io
 *       files (why they're not globally readable when the rest of proc
 *       data is...?) and get a global I/O picture. Normal top is NOT,
 *       even though you can -o AIO there, to give sysadmins the option
 *       to reduce security exposure.)
 *
 * TODO: ps aux (att & bsd style "ps -ax" vs "ps ax" behavior difference)
 * TODO: switch -fl to -y
 * TODO: thread support /proc/$d/task/%d/stat (and -o stat has "l")
 * TODO: iotop: Window size change: respond immediately. Why not padding
 *       at right edge? (Not adjusting to screen size at all? Header wraps?)
 * TODO: top: thread support and SMP
 * TODO: pgrep -f only searches the amount of cmdline that fits in toybuf.

USE_PS(NEWTOY(ps, "k(sort)*P(ppid)*aAdeflMno*O*p(pid)*s*t*Tu*U*g*G*wZ[!ol][+Ae][!oO]", TOYFLAG_USR|TOYFLAG_BIN|TOYFLAG_LOCALE))
// stayroot because iotop needs root to read other process' proc/$$/io
// TOP and IOTOP have a large common option block used for common processing,
// the default values are different but the flags are in the same order.
USE_TOP(NEWTOY(top, ">0O*" "Hk*o*p*u*s#<1d:m#n#<1bq[!oO]", TOYFLAG_USR|TOYFLAG_BIN|TOYFLAG_LOCALE))
USE_IOTOP(NEWTOY(iotop, ">0AaKO" "Hk*o*p*u*s#<1=7d:m#n#<1bq", TOYFLAG_USR|TOYFLAG_BIN|TOYFLAG_STAYROOT|TOYFLAG_LOCALE))
USE_PGREP(NEWTOY(pgrep, "?cld:u*U*t*s*P*g*G*fnovxL:[-no]", TOYFLAG_USR|TOYFLAG_BIN))
USE_PKILL(NEWTOY(pkill,    "?Vu*U*t*s*P*g*G*fnovxl:[-no]", TOYFLAG_USR|TOYFLAG_BIN))

config PS
  bool "ps"
  default y
  help
    usage: ps [-AadefLlnwZ] [-gG GROUP,] [-k FIELD,] [-o FIELD,] [-p PID,] [-t TTY,] [-uU USER,]

    List processes.

    Which processes to show (-gGuUpPt selections may be comma separated lists):

    -A  all					-a  has terminal not session leader
    -d  All but session leaders		-e  synonym for -A
    -g  in GROUPs				-G  in real GROUPs (before sgid)
    -p  PIDs (--pid)			-P  Parent PIDs (--ppid)
    -s  In session IDs			-t  Attached to selected TTYs
    -T  Show threads also			-u  Owned by selected USERs
    -U  real USERs (before suid)

    Output modifiers:

    -k  Sort FIELDs (-FIELD to reverse)	-M  Measure/pad future field widths
    -n  Show numeric USER and GROUP		-w  Wide output (don't truncate fields)

    Which FIELDs to show. (Default = -o PID,TTY,TIME,CMD)

    -f  Full listing (-o USER:12=UID,PID,PPID,C,STIME,TTY,TIME,ARGS=CMD)
    -l  Long listing (-o F,S,UID,PID,PPID,C,PRI,NI,ADDR,SZ,WCHAN,TTY,TIME,CMD)
    -o  Output FIELDs instead of defaults, each with optional :size and =title
    -O  Add FIELDS to defaults
    -Z  Include LABEL

    Command line -o fields:

      ARGS     CMDLINE minus initial path     CMD  Command (thread) name (stat[2])
      CMDLINE  Command line (argv[])          COMM Command filename (/proc/$PID/exe)
      COMMAND  Command file (/proc/$PID/exe)  NAME Process name (argv[0] of $PID)

    Process attribute -o FIELDs:

      ADDR  Instruction pointer               BIT   Is this process 32 or 64 bits
      CPU   Which processor running on        ETIME   Elapsed time since PID start
      F     Flags (1=FORKNOEXEC 4=SUPERPRIV)  GID     Group id
      GROUP Group name                        LABEL   Security label
      MAJFL Major page faults                 MINFL   Minor page faults
      NI    Niceness (lower is faster)
      PCPU  Percentage of CPU time used       PCY     Android scheduling policy
      PGID  Process Group ID
      PID   Process ID                        PPID    Parent Process ID
      PRI   Priority (higher is faster)       PSR     Processor last executed on
      RGID  Real (before sgid) group ID       RGROUP  Real (before sgid) group name
      RSS   Resident Set Size (pages in use)  RTPRIO  Realtime priority
      RUID  Real (before suid) user ID        RUSER   Real (before suid) user name
      S     Process state:
            R (running) S (sleeping) D (device I/O) T (stopped)  t (traced)
            Z (zombie)  X (deader)   x (dead)       K (wakekill) W (waking)
      SCHED Scheduling policy (0=other, 1=fifo, 2=rr, 3=batch, 4=iso, 5=idle)
      STAT  Process state (S) plus:
            < high priority          N low priority L locked memory
            s session leader         + foreground   l multithreaded
      STIME Start time of process in hh:mm (size :19 shows yyyy-mm-dd hh:mm:ss)
      SZ    Memory Size (4k pages needed to completely swap out process)
      TCNT  Thread count                      TID     Thread ID
      TIME  CPU time consumed                 TTY     Controlling terminal
      UID   User id                           USER    User name
      VSZ   Virtual memory size (1k units)    %VSZ    VSZ as % of physical memory
      WCHAN Wait location in kernel

config TOP
  bool "top"
  default y
  help
    usage: top [-Hbq] [-k FIELD,] [-o FIELD,] [-s SORT] [-n NUMBER] [-m LINES] [-d SECONDS] [-p PID,] [-u USER,]

    Show process activity in real time.

    -H	Show threads
    -k	Fallback sort FIELDS (default -S,-%CPU,-ETIME,-PID)
    -o	Show FIELDS (def PID,USER,PR,NI,VIRT,RES,SHR,S,%CPU,%MEM,TIME+,CMDLINE)
    -O	Add FIELDS (replacing PR,NI,VIRT,RES,SHR,S from default)
    -s	Sort by field number (1-X, default 9)
    -b	Batch mode (no tty)
    -d	Delay SECONDS between each cycle (default 3)
    -m	Maximum number of tasks to show
    -n	Exit after NUMBER iterations
    -p	Show these PIDs
    -u	Show these USERs
    -q	Quiet (no header lines)

    Cursor LEFT/RIGHT to change sort, UP/DOWN move list, space to force
    update, R to reverse sort, Q to exit.

# Requires CONFIG_IRQ_TIME_ACCOUNTING in the kernel for /proc/$$/io
config IOTOP
  bool "iotop"
  default y
  help
    usage: iotop [-AaKObq] [-n NUMBER] [-d SECONDS] [-p PID,] [-u USER,]

    Rank processes by I/O.

    -A	All I/O, not just disk
    -a	Accumulated I/O (not percentage)
    -H	Show threads
    -K	Kilobytes
    -k	Fallback sort FIELDS (default -[D]IO,-ETIME,-PID)
    -m	Maximum number of tasks to show
    -O	Only show processes doing I/O
    -o	Show FIELDS (default PID,PR,USER,[D]READ,[D]WRITE,SWAP,[D]IO,COMM)
    -s	Sort by field number (0-X, default 6)
    -b	Batch mode (no tty)
    -d	Delay SECONDS between each cycle (default 3)
    -n	Exit after NUMBER iterations
    -p	Show these PIDs
    -u	Show these USERs
    -q	Quiet (no header lines)

    Cursor LEFT/RIGHT to change sort, UP/DOWN move list, space to force
    update, R to reverse sort, Q to exit.

config PGREP
  bool "pgrep"
  default y
  help
    usage: pgrep [-clfnovx] [-d DELIM] [-L SIGNAL] [PATTERN] [-G GID,] [-g PGRP,] [-P PPID,] [-s SID,] [-t TERM,] [-U UID,] [-u EUID,]

    Search for process(es). PATTERN is an extended regular expression checked
    against command names.

    -c	Show only count of matches
    -d	Use DELIM instead of newline
    -L	Send SIGNAL instead of printing name
    -l	Show command name
    -f	Check full command line for PATTERN
    -G	Match real Group ID(s)
    -g	Match Process Group(s) (0 is current user)
    -n	Newest match only
    -o	Oldest match only
    -P	Match Parent Process ID(s)
    -s	Match Session ID(s) (0 for current)
    -t	Match Terminal(s)
    -U	Match real User ID(s)
    -u	Match effective User ID(s)
    -v	Negate the match
    -x	Match whole command (not substring)

config PKILL
  bool "pkill"
  default y
  help
    usage: pkill [-fnovx] [-SIGNAL|-l SIGNAL] [PATTERN] [-G GID,] [-g PGRP,] [-P PPID,] [-s SID,] [-t TERM,] [-U UID,] [-u EUID,]

    -l	Send SIGNAL (default SIGTERM)
    -V	verbose
    -f	Check full command line for PATTERN
    -G	Match real Group ID(s)
    -g	Match Process Group(s) (0 is current user)
    -n	Newest match only
    -o	Oldest match only
    -P	Match Parent Process ID(s)
    -s	Match Session ID(s) (0 for current)
    -t	Match Terminal(s)
    -U	Match real User ID(s)
    -u	Match effective User ID(s)
    -v	Negate the match
    -x	Match whole command (not substring)
*/

#define FOR_ps
#include "toys.h"

GLOBALS(
  union {
    struct {
      struct arg_list *G;
      struct arg_list *g;
      struct arg_list *U;
      struct arg_list *u;
      struct arg_list *t;
      struct arg_list *s;
      struct arg_list *p;
      struct arg_list *O;
      struct arg_list *o;
      struct arg_list *P;
      struct arg_list *k;
    } ps;
    struct {
      long n;
      long m;
      char *d;
      long s;
      struct arg_list *u;
      struct arg_list *p;
      struct arg_list *o;
      struct arg_list *k;
      struct arg_list *O;

      long d_ms;
    } top;
    struct {
      char *L;
      struct arg_list *G;
      struct arg_list *g;
      struct arg_list *P;
      struct arg_list *s;
      struct arg_list *t;
      struct arg_list *U;
      struct arg_list *u;
      char *d;

      void *regexes, *snapshot;
      int signal;
      pid_t self, match;
    } pgrep;
  };

  struct sysinfo si;
  struct ptr_len gg, GG, pp, PP, ss, tt, uu, UU;
  struct dirtree *threadparent;
  unsigned width, height;
  dev_t tty;
  void *fields, *kfields;
  long long ticks, bits, time;
  int kcount, forcek, sortpos;
  int (*match_process)(long long *slot);
  void (*show_process)(void *tb);
)

// Linked list of -o fields selected for display, in order, with :len and =title

struct ofields {
  struct ofields *next, *prev;
  short which, len, reverse;
  char *title;
};

/* The function get_ps() reads all the data about one process, saving it in
 * toybox as a struct procpid. Simple ps calls then pass toybuf directly to
 * show_ps(), but features like sorting append a copy to a linked list
 * for further processing once all processes have been read.
 *
 * struct procpid contains a slot[] array of 64 bit values, with the following
 * data at each position in the array. Most is read from /proc/$PID/stat (see
 * https://kernel.org/doc/Documentation/filesystems/proc.txt table 1-4) but
 * we we replace several fields with don't use with other data. */

enum {
 SLOT_pid,      /*process id*/            SLOT_ppid,      // parent process id
 SLOT_pgrp,     /*process group*/         SLOT_sid,       // session id
 SLOT_ttynr,    /*tty the process uses*/  SLOT_ttypgrp,   // pgrp of the tty
 SLOT_flags,    /*task flags*/            SLOT_minflt,    // minor faults
 SLOT_cminflt,  /*minor faults+child*/    SLOT_majflt,    // major faults
 SLOT_cmajflt,  /*major faults+child*/    SLOT_utime,     // user+kernel jiffies
 SLOT_stime,    /*kernel mode jiffies*/   SLOT_cutime,    // utime+child utime
 SLOT_cstime,   /*stime+child*/           SLOT_priority,  // priority level
 SLOT_nice,     /*nice level*/            SLOT_numthreads,// thread count
 SLOT_vmlck,    /*locked memory*/         SLOT_starttime, // jiffies after boot
 SLOT_vsize,    /*virtual memory size*/   SLOT_rss,       // resident set size
 SLOT_rsslim,   /*limit in bytes on rss*/ SLOT_startcode, // code segment addr
 SLOT_endcode,  /*code segment address*/  SLOT_startstack,// stack address
 SLOT_esp,      /*task stack pointer*/    SLOT_eip,       // instruction pointer
 SLOT_iobytes,  /*All I/O bytes*/         SLOT_diobytes,  // disk I/O bytes
 SLOT_utime2,   /*relative utime (top)*/  SLOT_uid,       // user id
 SLOT_ruid,     /*real user id*/          SLOT_gid,       // group id
 SLOT_rgid,     /*real group id*/         SLOT_exitsig,   // sent to parent
 SLOT_taskcpu,  /*CPU running on*/        SLOT_rtprio,    // realtime priority
 SLOT_policy,   /*man sched_setscheduler*/SLOT_blkioticks,// IO wait time
 SLOT_gtime,    /*guest jiffies of task*/ SLOT_cgtime,    // gtime+child
 SLOT_startbss, /*data/bss address*/      SLOT_endbss,    // end addr data+bss
 SLOT_upticks,  /*uptime-starttime*/      SLOT_argv0len,  // argv[0] length
 SLOT_uptime,   /*si.uptime @read time*/  SLOT_vsz,       // Virtual mem Size
 SLOT_rss2,     /*Resident Set Size*/     SLOT_shr,       // Shared memory
 SLOT_rchar,    /*All bytes read*/        SLOT_wchar,     // All bytes written
 SLOT_rbytes,   /*Disk bytes read*/       SLOT_wbytes,    // Disk bytes written
 SLOT_swap,     /*Swap pages used*/       SLOT_bits,      // 32 or 64
 SLOT_tid,      /*Thread ID*/             SLOT_tcount,    // Thread count
 SLOT_pcy,      /*Android sched policy*/

 SLOT_count /* Size of array */
};

/* In addition to slot[], carevup contains 6 string fields to display
   command name, tty device, selinux label... They're stored one after the
   other in str[] (separated by null terminators), and offset[] contains the
   starting position of each string after the first (which is always 0). */

// Data layout in toybuf
struct procpid {
  long long slot[SLOT_count]; // data (see enum above)
  unsigned short offset[6];   // offset of fields in str[] (skip CMD, always 0)
  char state;
  char str[];                 // CMD, TTY, WCHAN, LABEL, COMM, ARGS, NAME
};

/* The typos[] array lists all the types understood by "ps -o", I.E all the
 * columns ps and top know how to display. Each entry has:
 *
 * name: the column name, displayed at top and used to select column with -o
 *
 * width: the display width. Fields are padded to this width when displaying
 *        to a terminal (negative means right justified). Strings are truncated
 *        to fit, numerical fields are padded but not truncated (although
 *        the display code reclaims unused padding from later fields to try to
 *        get the overflow back).
 *
 * slot: which slot[] out of procpid. Negative means it's a string field.
 *       Setting bit |64 requests extra display/sort processing.
 *
 * The TAGGED_ARRAY plumbing produces an enum of indexes, the "tag" is the
 * first string argument and the prefix is the first argument to TAGGED_ARRAY
 * so in this case "NAME" becomes PS_NAME which is the offset into typos[]
 * for that entry, and also _PS_NAME (the bit position, 1<<PS_NAME).
 * We record active columns in TT.bits, ala:
 *
 *   if (TT.bits & _PS_NAME) printf("-o included PS_NAME");
 */

// TODO: Android uses -30 for LABEL, but ideally it would auto-size.
// 64|slot means compare as string when sorting
struct typography {
  char *name;
  signed char width, slot;
} static const typos[] = TAGGED_ARRAY(PS,
  // Numbers. (What's in slot[] is what's displayed, sorted numerically.)
  {"PID", 5, SLOT_pid}, {"PPID", 5, SLOT_ppid}, {"PRI", 3, SLOT_priority},
  {"NI", 3, SLOT_nice}, {"ADDR", 4+sizeof(long), SLOT_eip},
  {"SZ", 5, SLOT_vsize}, {"RSS", 6, SLOT_rss}, {"PGID", 5, SLOT_pgrp},
  {"VSZ", 7, SLOT_vsize}, {"MAJFL", 6, SLOT_majflt}, {"MINFL", 6, SLOT_minflt},
  {"PR", 2, SLOT_priority}, {"PSR", 3, SLOT_taskcpu},
  {"RTPRIO", 6, SLOT_rtprio}, {"SCH", 3, SLOT_policy}, {"CPU", 3, SLOT_taskcpu},
  {"TID", 5, SLOT_tid}, {"TCNT", 4, SLOT_tcount}, {"BIT", 3, SLOT_bits},

  // String fields (-1 is procpid->str, rest are str+offset[1-slot])
  {"TTY", -8, -2}, {"WCHAN", -6, -3}, {"LABEL", -30, -4}, {"COMM", -27, -5},
  {"NAME", -27, -7}, {"COMMAND", -27, -5}, {"CMDLINE", -27, -6},
  {"ARGS", -27, -6}, {"CMD", -15, -1},

  // user/group (may call getpwuid() or similar)
  {"UID", 5, SLOT_uid}, {"USER", -12, 64|SLOT_uid}, {"RUID", 4, SLOT_ruid},
  {"RUSER", -8, 64|SLOT_ruid}, {"GID", 8, SLOT_gid}, {"GROUP", -8, 64|SLOT_gid},
  {"RGID", 4, SLOT_rgid}, {"RGROUP", -8, 64|SLOT_rgid},

  // clock displays (00:00:00)
  {"TIME", 8, SLOT_utime}, {"ELAPSED", 11, SLOT_starttime},
  {"TIME+", 9, SLOT_utime},

  // Percentage displays (fixed point, one decimal digit. 123 -> 12.3)
  {"C", 1, SLOT_utime2}, {"%VSZ", 5, SLOT_vsize}, {"%MEM", 5, SLOT_rss},
  {"%CPU", 4, SLOT_utime2},

  // human_readable (function human_readable() in lib, 1.23M, 1.4G, etc)
  {"VIRT", 4, SLOT_vsz}, {"RES", 4, SLOT_rss2},
  {"SHR", 4, SLOT_shr}, {"READ", 6, SLOT_rchar}, {"WRITE", 6, SLOT_wchar},
  {"IO", 6, SLOT_iobytes}, {"DREAD", 6, SLOT_rbytes},
  {"DWRITE", 6, SLOT_wbytes}, {"SWAP", 6, SLOT_swap}, {"DIO", 6, SLOT_diobytes},

  // Misc (special cases)
  {"STIME", 5, SLOT_starttime}, {"F", 1, 64|SLOT_flags}, {"S", -1, 64},
  {"STAT", -5, 64}, {"PCY", 3, 64|SLOT_pcy},
);

// Return 0 to discard, nonzero to keep
static int shared_match_process(long long *slot)
{
  struct ptr_len match[] = {
    {&TT.gg, SLOT_gid}, {&TT.GG, SLOT_rgid}, {&TT.pp, SLOT_pid},
    {&TT.PP, SLOT_ppid}, {&TT.ss, SLOT_sid}, {&TT.tt, SLOT_ttynr},
    {&TT.uu, SLOT_uid}, {&TT.UU, SLOT_ruid}
  };
  int i, j;
  long *ll = 0;

  // Do we have -g -G -p -P -s -t -u -U options selecting processes?
  for (i = 0; i < ARRAY_LEN(match); i++) {
    struct ptr_len *mm = match[i].ptr;

    if (mm->len) {
      ll = mm->ptr;
      for (j = 0; j<mm->len; j++) if (ll[j] == slot[match[i].len]) return 1;
    }
  }

  return ll ? 0 : -1;
}


// Return 0 to discard, nonzero to keep
static int ps_match_process(long long *slot)
{
  int i = shared_match_process(slot);

  if (i>0) return 1;
  // If we had selections and didn't match them, don't display
  if (!i) return 0;

  // Filter implicit categories for other display types
  if ((toys.optflags&(FLAG_a|FLAG_d)) && slot[SLOT_sid]==*slot) return 0;
  if ((toys.optflags&FLAG_a) && !slot[SLOT_ttynr]) return 0;
  if (!(toys.optflags&(FLAG_a|FLAG_d|FLAG_A|FLAG_e))
      && TT.tty!=slot[SLOT_ttynr]) return 0;

  return 1;
}

// Convert field to string representation
static char *string_field(struct procpid *tb, struct ofields *field)
{
  char *buf = toybuf+sizeof(toybuf)-260, *out = buf, *s;
  int which = field->which, sl = typos[which].slot;
  long long *slot = tb->slot, ll = (sl >= 0) ? slot[sl&63] : 0;

  // numbers, mostly from /proc/$PID/stat
  if (which <= PS_BIT) {
    char *fmt = "%lld";

    if (which==PS_PRI) ll = 39-ll;
    if (which==PS_ADDR) fmt = "%llx";
    else if (which==PS_SZ) ll >>= 12;
    else if (which==PS_RSS) ll <<= 2;
    else if (which==PS_VSZ) ll >>= 10;
    else if (which==PS_PR && ll<-9) fmt="RT";
    else if ((which==PS_RTPRIO || which==PS_BIT) && ll == 0) fmt="-";
    sprintf(out, fmt, ll);

  // String fields
  } else if (sl < 0) {
    out = tb->str;
    sl *= -1;
    // First string slot has offset 0, others are offset[-slot-2]
    if (--sl) out += tb->offset[--sl];
    if (which==PS_ARGS || which==PS_COMM) {
      int i;

      s = out;
      for (i = 0; (which==PS_ARGS) ? i < slot[SLOT_argv0len] : out[i]; i++)
        if (out[i] == '/') s = out+i+1;
      out = s;
    }
    if (which>=PS_COMM && !*out) sprintf(out = buf, "[%s]", tb->str);

  // user/group
  } else if (which <= PS_RGROUP) {
    sprintf(out, "%lld", ll);
    if (sl&64) {
      if (which > PS_RUSER) {
        struct group *gr = bufgetgrgid(ll);

        if (gr) out = gr->gr_name;
      } else {
        struct passwd *pw = bufgetpwuid(ll);

        if (pw) out = pw->pw_name;
      }
    }

  // Clock displays
  } else if (which <= PS_TIME_) {
    int unit = 60, pad = 2, j = TT.ticks; 
    time_t seconds;

    if (which!=PS_TIME_) unit *= 60*24;
    else pad = 0;
    // top adjusts slot[SLOT_upticks], we want original meaning.
    if (which==PS_ELAPSED) ll = (slot[SLOT_uptime]*j)-slot[SLOT_starttime];
    seconds = ll/j;

    // Output days-hours:mins:secs, skipping non-required fields with zero
    // TIME has 3 required fields, ETIME has 2. (Posix!) TIME+ is from top
    for (s = 0, j = 2*(which==PS_TIME_); j<4; j++) {
      if (!s && (seconds>unit || j == 1+(which!=PS_TIME))) s = out;
      if (s) {
        s += sprintf(s, j ? "%0*ld": "%*ld", pad, (long)(seconds/unit));
        pad = 2;
        if ((*s = "-::"[j])) s++;
      }
      seconds %= unit;
      unit /= j ? 60 : 24;
    }
    if (which==PS_TIME_ && s-out<8)
      sprintf(s, ".%02lld", (100*(ll%TT.ticks))/TT.ticks);

  // Percentage displays
  } else if (which <= PS__CPU) {
    ll = slot[sl&63]*1000;
    if (which==PS__VSZ || which==PS__MEM)
      ll /= TT.si.totalram/((which==PS__VSZ) ? 1024 : 4096);
    else if (slot[SLOT_upticks]) ll /= slot[SLOT_upticks];
    sl = ll;
    if (which==PS_C) sl += 5;
    sprintf(out, "%d", sl/10);
    if (which!=PS_C && sl<1000) sprintf(out+strlen(out), ".%d", sl%10);

  // Human readable
  } else if (which <= PS_DIO) {
    ll = slot[typos[which].slot];
    if (which <= PS_SHR) ll *= sysconf(_SC_PAGESIZE);
    if (TT.forcek) sprintf(out, "%lldk", ll/1024);
    else human_readable(out, ll, 0);

  // Posix doesn't specify what flags should say. Man page says
  // 1 for PF_FORKNOEXEC and 4 for PF_SUPERPRIV from linux/sched.h
  } else if (which==PS_F) sprintf(out, "%llo", (slot[SLOT_flags]>>6)&5);
  else if (which==PS_S || which==PS_STAT) {
    s = out;
    *s++ = tb->state;
    if (which==PS_STAT) {
      // TODO l = multithreaded
      if (slot[SLOT_nice]<0) *s++ = '<';
      else if (slot[SLOT_nice]>0) *s++ = 'N';
      if (slot[SLOT_sid]==*slot) *s++ = 's';
      if (slot[SLOT_vmlck]) *s++ = 'L';
      if (slot[SLOT_ttypgrp]==*slot) *s++ = '+';
    } 
    *s = 0;
  } else if (which==PS_STIME) {
    time_t t = time(0)-slot[SLOT_uptime]+slot[SLOT_starttime]/TT.ticks;

    // Padding behavior's a bit odd: default field size is just hh:mm.
    // Increasing stime:size reveals more data at left until full,
    // so move start address so yyyy-mm-dd hh:mm revealed on left at :16,
    // then add :ss on right for :19.
    strftime(out, 260, "%F %T", localtime(&t));
    out = out+strlen(out)-3-abs(field->len);
    if (out<buf) out = buf;

  } else if (which==PS_PCY) sprintf(out, "%.2s", get_sched_policy_name(ll));
  else if (CFG_TOYBOX_DEBUG) error_exit("bad which %d", which);

  return out;
}

// Display process data that get_ps() read from /proc, formatting with TT.fields
static void show_ps(void *p)
{
  struct procpid *tb = p;
  struct ofields *field;
  int pad, len, width = TT.width, abslen, sign, olen, extra = 0;

  // Loop through fields to display
  for (field = TT.fields; field; field = field->next) {
    char *out = string_field(tb, field);

    // Output the field, appropriately padded

    // Minimum one space between each field
    if (width<2) break;
    if (field != TT.fields) {
      putchar(' ');
      width--;
    }

    // Don't truncate number fields, but try to reclaim extra offset from later
    // fields that can naturally be shorter
    abslen = abs(field->len);
    sign = field->len<0 ? -1 : 1;
    olen = (TT.tty) ? utf8len(out) : strlen(out);
    if ((field->which<=PS_BIT || (toys.optflags&FLAG_w)) && olen>abslen) {
      // overflow but remember by how much
      extra += olen-abslen;
      abslen = olen;
    } else if (extra && olen<abslen) {
      int unused = abslen-olen;

      // If later fields have slack space, take back overflow
      if (unused>extra) unused = extra;
      abslen -= unused;
      extra -= unused;
    }
    if (abslen>width) abslen = width;
    len = pad = abslen;
    pad *= sign;

    // If last field is left justified, no trailing spaces.
    if (!field->next && sign<0) {
      pad = -1;
      len = width;
    }

    // If we truncated a left-justified field, show + instead of last char
    if (olen>len && len>1 && sign<0) {
      width--;
      len--;
      if (field->next) pad++;
      abslen = 0;
    }

    if (TT.tty) width -= draw_trim(out, pad, len);
    else width -= printf("%*.*s", pad, len, out);
    if (!abslen) putchar('+');
    if (!width) break;
  }
  putchar(TT.time ? '\r' : '\n');
}

// dirtree callback: read data about process to display, store, or discard it.
// Fills toybuf with struct procpid and either DIRTREE_SAVEs a copy to ->extra
// (in -k mode) or calls show_ps on toybuf (no malloc/copy/free there).
static int get_ps(struct dirtree *new)
{
  struct {
    char *name;     // Path under /proc/$PID directory
    long long bits; // Only fetch extra data if an -o field is displaying it
  } fetch[] = {
    // sources for procpid->offset[] data
    {"fd/", _PS_TTY}, {"wchan", _PS_WCHAN}, {"attr/current", _PS_LABEL},
    {"exe", _PS_COMMAND|_PS_COMM}, {"cmdline", _PS_CMDLINE|_PS_ARGS|_PS_NAME},
    {"", _PS_NAME}
  };
  struct procpid *tb = (void *)toybuf;
  long long *slot = tb->slot;
  char *name, *s, *buf = tb->str, *end = 0;
  int i, j, fd;
  off_t len;

  // Recurse one level into /proc children, skip non-numeric entries
  if (!new->parent)
    return DIRTREE_RECURSE|DIRTREE_SHUTUP|DIRTREE_PROC
      |(DIRTREE_SAVE*(TT.threadparent||!TT.show_process));

  memset(slot, 0, sizeof(tb->slot));
  slot[SLOT_tid] = *slot = atol(new->name);
  if (TT.threadparent && TT.threadparent->extra) {
    *slot = *(((struct procpid *)TT.threadparent->extra)->slot);
    // Parent also shows up as a thread, discard duplicate
    if (*slot == slot[SLOT_tid]) return 0;
  }
  fd = dirtree_parentfd(new);

  len = 2048;
  sprintf(buf, "%lld/stat", slot[SLOT_tid]);
  if (!readfileat(fd, buf, buf, &len)) return 0;

  // parse oddball fields (name and state). Name can have embedded ')' so match
  // _last_ ')' in stat (although VFS limits filenames to 255 bytes max).
  // All remaining fields should be numeric.
  if (!(name = strchr(buf, '('))) return 0;
  for (s = ++name; *s; s++) if (*s == ')') end = s;
  if (!end || end-name>255) return 0;

  // Parse numeric fields (starting at 4th field in slot[SLOT_ppid])
  if (1>sscanf(s = end, ") %c%n", &tb->state, &i)) return 0;
  for (j = 1; j<SLOT_count; j++)
    if (1>sscanf(s += i, " %lld%n", slot+j, &i)) break;

  // Now we've read the data, move status and name right after slot[] array,
  // and convert low chars to ? for non-tty display while we're at it.
  for (i = 0; i<end-name; i++)
    if ((tb->str[i] = name[i]) < ' ')
      if (!TT.tty) tb->str[i] = '?';
  buf = tb->str+i;
  *buf++ = 0;
  len = sizeof(toybuf)-(buf-toybuf);

  // save uid, ruid, gid, gid, and rgid int slots 31-34 (we don't use sigcatch
  // or numeric wchan, and the remaining two are always zero), and vmlck into
  // 18 (which is "obsolete, always 0" from stat)
  slot[SLOT_uid] = new->st.st_uid;
  slot[SLOT_gid] = new->st.st_gid;

  // TIME and TIME+ use combined value, ksort needs 'em added.
  slot[SLOT_utime] += slot[SLOT_stime];
  slot[SLOT_utime2] = slot[SLOT_utime];

  // If RGROUP RUSER STAT RUID RGID SWAP happening, or -G or -U, parse "status"
  // and save ruid, rgid, and vmlck.
  if ((TT.bits&(_PS_RGROUP|_PS_RUSER|_PS_STAT|_PS_RUID|_PS_RGID|_PS_SWAP
               |_PS_IO|_PS_DIO)) || TT.GG.len || TT.UU.len)
  {
    off_t temp = len;

    sprintf(buf, "%lld/status", slot[SLOT_tid]);
    if (!readfileat(fd, buf, buf, &temp)) *buf = 0;
    s = strafter(buf, "\nUid:");
    slot[SLOT_ruid] = s ? atol(s) : new->st.st_uid;
    s = strafter(buf, "\nGid:");
    slot[SLOT_rgid] = s ? atol(s) : new->st.st_gid;
    if ((s = strafter(buf, "\nVmLck:"))) slot[SLOT_vmlck] = atoll(s);
    if ((s = strafter(buf, "\nVmSwap:"))) slot[SLOT_swap] = atoll(s);
  }

  // Do we need to read "io"?
  if (TT.bits&(_PS_READ|_PS_WRITE|_PS_DREAD|_PS_DWRITE|_PS_IO|_PS_DIO)) {
    off_t temp = len;

    sprintf(buf, "%lld/io", slot[SLOT_tid]);
    if (!readfileat(fd, buf, buf, &temp)) *buf = 0;
    if ((s = strafter(buf, "rchar:"))) slot[SLOT_rchar] = atoll(s);
    if ((s = strafter(buf, "wchar:"))) slot[SLOT_wchar] = atoll(s);
    if ((s = strafter(buf, "read_bytes:"))) slot[SLOT_rbytes] = atoll(s);
    if ((s = strafter(buf, "write_bytes:"))) slot[SLOT_wbytes] = atoll(s);
    slot[SLOT_iobytes] = slot[SLOT_rchar]+slot[SLOT_wchar]+slot[SLOT_swap];
    slot[SLOT_diobytes] = slot[SLOT_rbytes]+slot[SLOT_wbytes]+slot[SLOT_swap];
  }

  // We now know enough to skip processes we don't care about.
  if (TT.match_process && !TT.match_process(slot)) return 0;

  // /proc data is generated as it's read, so for maximum accuracy on slow
  // systems (or ps | more) we re-fetch uptime as we fetch each /proc line.
  sysinfo(&TT.si);
  slot[SLOT_uptime] = TT.si.uptime;
  slot[SLOT_upticks] = slot[SLOT_uptime]*TT.ticks - slot[SLOT_starttime];

  // Do we need to read "statm"?
  if (TT.bits&(_PS_VIRT|_PS_RES|_PS_SHR)) {
    off_t temp = len;

    sprintf(buf, "%lld/statm", slot[SLOT_tid]);
    if (!readfileat(fd, buf, buf, &temp)) *buf = 0;
    
    for (s = buf, i=0; i<3; i++)
      if (!sscanf(s, " %lld%n", slot+SLOT_vsz+i, &j)) slot[SLOT_vsz+i] = 0;
      else s += j;
  }

  // Do we need to read "exe"?
  if (TT.bits&_PS_BIT) {
    off_t temp = 6;

    sprintf(buf, "%lld/exe", slot[SLOT_tid]);
    if (readfileat(fd, buf, buf, &temp) && !memcmp(buf, "\177ELF", 4)) {
      if (buf[4] == 1) slot[SLOT_bits] = 32;
      else if (buf[4] == 2) slot[SLOT_bits] = 64;
    }
  }

  // Do we need Android scheduling policy?
  if (TT.bits&_PS_PCY)
    get_sched_policy(slot[SLOT_tid], (void *)&slot[SLOT_pcy]);

  // Fetch string data while parentfd still available, appending to buf.
  // (There's well over 3k of toybuf left. We could dynamically malloc, but
  // it'd almost never get used, querying length of a proc file is awkward,
  // fixed buffer is nommu friendly... Wait for somebody to complain. :)
  slot[SLOT_argv0len] = 0;
  for (j = 0; j<ARRAY_LEN(fetch); j++) {
    tb->offset[j] = buf-(tb->str);
    if (!(TT.bits&fetch[j].bits)) {
      *buf++ = 0;
      continue;
    }

    // Determine remaining space, reserving minimum of 256 bytes/field and
    // 260 bytes scratch space at the end (for output conversion later).
    len = sizeof(toybuf)-(buf-toybuf)-260-256*(ARRAY_LEN(fetch)-j);
    sprintf(buf, "%lld/%s", slot[SLOT_tid], fetch[j].name);

    // For exe we readlink instead of read contents
    if (j==3 || j==5) {
      struct procpid *ptb = 0;
      int k;

      // Thread doesn't have exe or argv[0], so use parent's
      if (TT.threadparent && TT.threadparent->extra)
        ptb = (void *)TT.threadparent->extra;

      if (j==3 && !ptb) len = readlinkat0(fd, buf, buf, len);
      else {
        if (j==3) i = strlen(s = ptb->str+ptb->offset[3]);
        else {
          if (!ptb || slot[SLOT_argv0len]) ptb = tb;
          i = ptb->slot[SLOT_argv0len];
          s = ptb->str+ptb->offset[4];
          while (-1!=(k = stridx(s, '/')) && k<i) {
            s += k+1;
            i -= k+1;
          }
        }
        if (i<len) len = i;
        memcpy(buf, s, len);
        buf[len] = 0;
      }

    // If it's not the TTY field, data we want is in a file.
    // Last length saved in slot[] is command line (which has embedded NULs)
    } else if (!j) {
      int rdev = slot[SLOT_ttynr];
      struct stat st;

      // Call no tty "?" rather than "0:0".
      strcpy(buf, "?");
      if (rdev) {
        // Can we readlink() our way to a name?
        for (i = 0; i<3; i++) {
          sprintf(buf, "%lld/fd/%i", slot[SLOT_tid], i);
          if (!fstatat(fd, buf, &st, 0) && S_ISCHR(st.st_mode)
            && st.st_rdev == rdev && (len = readlinkat0(fd, buf, buf, len)))
              break;
        }

        // Couldn't find it, try all the tty drivers.
        if (i == 3) {
          FILE *fp = fopen("/proc/tty/drivers", "r");
          int tty_major = 0, maj = dev_major(rdev), min = dev_minor(rdev);

          if (fp) {
            while (fscanf(fp, "%*s %256s %d %*s %*s", buf, &tty_major) == 2) {
              // TODO: we could parse the minor range too.
              if (tty_major == maj) {
                len = strlen(buf);
                len += sprintf(buf+len, "%d", min);
                if (!stat(buf, &st) && S_ISCHR(st.st_mode) && st.st_rdev==rdev)
                  break;
              }
              tty_major = 0;
            }
            fclose(fp);
          }

          // Really couldn't find it, so just show major:minor.
          if (!tty_major) len = sprintf(buf, "%d:%d", maj, min);
        }

        s = buf;
        if (strstart(&s, "/dev/")) memmove(buf, s, len -= 4);
      }

    // Data we want is in a file.
    // Last length saved in slot[] is command line (which has embedded NULs)
    } else {
      int temp = 0;

      // When command has no arguments, don't space over the NUL
      if (readfileat(fd, buf, buf, &len) && len>0) {

        // Trim trailing whitespace and NUL bytes
        while (len)
          if (!buf[len-1] || isspace(buf[len-1])) buf[--len] = 0;
          else break;

        // Turn NUL to space, other low ascii to ? (in non-tty mode)
        // cmdline has a trailing NUL that we don't want to turn to space.
        for (i=0; i<len-1; i++) {
          char c = buf[i];

          if (!c) {
            if (!temp) temp = i;
            c = ' ';
          } else if (!TT.tty && c<' ') c = '?';
          buf[i] = c;
        }
      } else *buf = len = 0;

      // Store end of argv[0] so ARGS and CMDLINE can differ.
      // We do it for each file string slot but last is cmdline, which sticks.
      slot[SLOT_argv0len] = temp ? temp : len;  // Position of _first_ NUL
    }

    // Above calculated/retained len, so we don't need to re-strlen.
    buf += len+1;
  }

  TT.kcount++;
  if (TT.show_process && !TT.threadparent) {
    TT.show_process(tb);

    return 0;
  }

  // If we need to sort the output, add it to the list and return.
  s = xmalloc(buf-toybuf);
  new->extra = (long)s;
  memcpy(s, toybuf, buf-toybuf);

  return DIRTREE_SAVE;
}

static int get_threads(struct dirtree *new)
{
  struct dirtree *dt;
  struct procpid *tb;
  unsigned pid, kcount;

  if (!new->parent) return get_ps(new);
  pid = atol(new->name);

  TT.threadparent = new;
  if (!get_ps(new)) {
    TT.threadparent = 0;

    return 0;
  }

  // Recurse down into tasks, retaining thread groups.
  // Disable show_process at least until we can calculate tcount
  kcount = TT.kcount;
  sprintf(toybuf, "/proc/%u/task", pid);
  new->child = dirtree_flagread(toybuf, DIRTREE_SHUTUP|DIRTREE_PROC, get_ps);
  if (new->child == DIRTREE_ABORTVAL) new->child = 0;
  TT.threadparent = 0;
  kcount = TT.kcount-kcount+1;
  tb = (void *)new->extra;
  tb->slot[SLOT_tcount] = kcount;

  // Fill out tid and thread count for each entry in group
  if (new->child) for (dt = new->child->child; dt; dt = dt->next) {
    tb = (void *)dt->extra;
    tb->slot[SLOT_pid] = pid;
    tb->slot[SLOT_tcount] = kcount;
  }

  // Save or display
  if (!TT.show_process) return DIRTREE_SAVE;
  TT.show_process((void *)new->extra);
  if ((dt = new->child)) {
    new->child = 0;
    while (dt->child) {
      new = dt->child->next;
      TT.show_process((void *)dt->child->extra);
      free(dt->child);
      dt->child = new;
    }
    free(dt);
  }

  return 0;
}

static char *parse_ko(void *data, char *type, int length)
{
  struct ofields *field;
  char *width, *title, *end, *s;
  int i, j, k;

  // Get title, length of title, type, end of type, and display width

  // Chip off =name to display
  if ((end = strchr(type, '=')) && length>(end-type)) {
    title = end+1;
    length -= (end-type)+1;
  } else {
    end = type+length;
    title = 0;
  }

  // Chip off :width to display
  if ((width = strchr(type, ':')) && width<end) {
    if (!title) length = width-type;
  } else width = 0;

  // Allocate structure plus extra space to append a copy of title data
  // (this way it's same lifetime, freeing struct automatically frees title)
  field = xzalloc(sizeof(struct ofields)+(length+1)*!!title);
  if (title) {
    memcpy(field->title = (char *)(field+1), title, length);
    field->title[field->len = length] = 0;
  }

  if (width) {
    field->len = strtol(++width, &title, 10);
    if (!isdigit(*width) || title != end) return title;
    end = --width;
  }

  // Find type
  field->reverse = 1;
  if (*type == '-') field->reverse = -1;
  else if (*type != '+') type--;
  type++;
  for (i = 0; i<ARRAY_LEN(typos); i++) {
    field->which = i;
    for (j = 0; j<2; j++) {
      if (!j) s = typos[i].name;
      // posix requires alternate names for some fields
      else if (-1==(k = stridx((char []){PS_NI, PS_SCH, PS_ELAPSED, PS__CPU,
        PS_VSZ, PS_USER, 0}, i))) continue;
      else
        s = ((char *[]){"NICE", "SCHED", "ETIME", "PCPU", "VSIZE", "UNAME"})[k];

      if (!strncasecmp(type, s, end-type) && strlen(s)==end-type) break;
    }
    if (j!=2) break;
  }
  if (i==ARRAY_LEN(typos)) return type;
  if (!field->title) field->title = typos[field->which].name;
  if (!field->len) field->len = typos[field->which].width;
  else if (typos[field->which].width<0) field->len *= -1;
  dlist_add_nomalloc(data, (void *)field);

  return 0;
}

static long long get_headers(struct ofields *field, char *buf, int blen)
{
  long long bits = 0;
  int len = 0;

  for (; field; field = field->next) {
    len += snprintf(buf+len, blen-len, " %*s"+!bits, field->len,
      field->title);
    bits |= 1LL<<field->which;
  }

  return bits;
}

// Parse -p -s -t -u -U -g -G
static char *parse_rest(void *data, char *str, int len)
{
  struct ptr_len *pl = (struct ptr_len *)data;
  long *ll = pl->ptr;
  char *end;
  int num = 0;

  // Allocate next chunk of data
  if (!(15&pl->len))
    ll = pl->ptr = xrealloc(pl->ptr, sizeof(long)*(pl->len+16));

  // Parse numerical input
  if (isdigit(*str)) {
    ll[pl->len] = xstrtol(str, &end, 10);
    if (end==(len+str)) num++;
    // For pkill, -s 0 represents pkill's session id.
    if (pl==&TT.ss && ll[pl->len]==0) ll[pl->len] = getsid(0);
  }

  if (pl==&TT.pp || pl==&TT.ss) {
    if (num && ll[pl->len]>0) {
      pl->len++;

      return 0;
    }
  } else if (pl==&TT.tt) {
    // -t pts = 12,pts/12 tty = /dev/tty2,tty2,S0
    if (!num) {
      if (strstart(&str, strcpy(toybuf, "/dev/"))) len -= 5;
      if (strstart(&str, "pts/")) {
        len -= 4;
        num++;
      } else if (strstart(&str, "tty")) len -= 3;
    }
    if (len<256 && (!(end = strchr(str, '/')) || end-str>len)) {
      struct stat st;

      end = toybuf + sprintf(toybuf, "/dev/%s", num ? "pts/" : "tty");
      memcpy(end, str, len);
      end[len] = 0;
      xstat(toybuf, &st);
      ll[pl->len++] = st.st_rdev;

      return 0;
    }
  } else if (len<255) {
    char name[256];

    if (num) {
      pl->len++;

      return 0;
    }

    memcpy(name, str, len);
    name[len] = 0;
    if (pl==&TT.gg || pl==&TT.GG) {
      struct group *gr = getgrnam(name);
      if (gr) {
        ll[pl->len++] = gr->gr_gid;

        return 0;
      }
    } else if (pl==&TT.uu || pl==&TT.UU) {
      struct passwd *pw = getpwnam(name);
      if (pw) {
        ll[pl->len++] = pw->pw_uid;

        return 0;
      }
    }
  }

  // Return error
  return str;
}

// sort for -k
static int ksort(void *aa, void *bb)
{
  struct ofields *field;
  struct procpid *ta = *(struct procpid **)aa, *tb = *(struct procpid **)bb;
  int ret = 0, slot;

  for (field = TT.kfields; field && !ret; field = field->next) {
    slot = typos[field->which].slot;

    // Can we do numeric sort?
    if (!(slot&64)) {
      if (ta->slot[slot]<tb->slot[slot]) ret = -1;
      if (ta->slot[slot]>tb->slot[slot]) ret = 1;
    }

    // fallback to string sort
    if (!ret) {
      memccpy(toybuf, string_field(ta, field), 0, 2048);
      toybuf[2048] = 0;
      ret = strcmp(toybuf, string_field(tb, field));
    }
    ret *= field->reverse;
  }

  return ret;
}

static struct procpid **collate_leaves(struct procpid **tb, struct dirtree *dt) 
{
  while (dt) {
    struct dirtree *next = dt->next;

    if (dt->extra) *(tb++) = (void *)dt->extra;
    if (dt->child) tb = collate_leaves(tb, dt->child);
    free(dt);
    dt = next;
  }

  return tb;
}

static struct procpid **collate(int count, struct dirtree *dt)
{
  struct procpid **tbsort = xmalloc(count*sizeof(struct procpid *));

  collate_leaves(tbsort, dt);

  return tbsort;
} 

static void default_ko(char *s, void *fields, char *err, struct arg_list *arg)
{
  struct arg_list def;

  memset(&def, 0, sizeof(struct arg_list));
  def.arg = s;
  comma_args(arg ? arg : &def, fields, err, parse_ko);
}

void ps_main(void)
{
  char **arg;
  struct dirtree *dt;
  char *not_o;
  int i;

  TT.ticks = sysconf(_SC_CLK_TCK); // units for starttime/uptime

  if (-1 != (i = tty_fd())) {
    struct stat st;

    if (!fstat(i, &st)) TT.tty = st.st_rdev;
  }

  // If we can't query terminal size pad to 80 but do -w
  TT.width = 80;
  if (!isatty(1) || !terminal_size(&TT.width, 0))
    toys.optflags |= FLAG_w;
  if (toys.optflags&FLAG_w) TT.width = 99999;

  // parse command line options other than -o
  comma_args(TT.ps.P, &TT.PP, "bad -P", parse_rest);
  comma_args(TT.ps.p, &TT.pp, "bad -p", parse_rest);
  comma_args(TT.ps.t, &TT.tt, "bad -t", parse_rest);
  comma_args(TT.ps.s, &TT.ss, "bad -s", parse_rest);
  comma_args(TT.ps.u, &TT.uu, "bad -u", parse_rest);
  comma_args(TT.ps.U, &TT.UU, "bad -U", parse_rest);
  comma_args(TT.ps.g, &TT.gg, "bad -g", parse_rest);
  comma_args(TT.ps.G, &TT.GG, "bad -G", parse_rest);
  comma_args(TT.ps.k, &TT.kfields, "bad -k", parse_ko);
  dlist_terminate(TT.kfields);

  // It's undocumented, but traditionally extra arguments are extra -p args
  for (arg = toys.optargs; *arg; arg++)
    if (parse_rest(&TT.pp, *arg, strlen(*arg))) error_exit_raw(*arg);

  // Figure out which fields to display
  not_o = "%sTTY,TIME,CMD";
  if (toys.optflags&FLAG_f)
    sprintf(not_o = toybuf+128,
      "USER:12=UID,%%sPPID,%s,STIME,TTY,TIME,ARGS=CMD",
      (toys.optflags&FLAG_T) ? "TCNT" : "C");
  else if (toys.optflags&FLAG_l)
    not_o = "F,S,UID,%sPPID,C,PRI,NI,BIT,SZ,WCHAN,TTY,TIME,CMD";
  else if (CFG_TOYBOX_ON_ANDROID)
    sprintf(not_o = toybuf+128,
            "USER,%%sPPID,VSIZE,RSS,WCHAN:10,ADDR:10,S,%s",
            (toys.optflags&FLAG_T) ? "CMD" : "NAME");
  sprintf(toybuf, not_o, (toys.optflags & FLAG_T) ? "PID,TID," : "PID,");

  // Init TT.fields. This only uses toybuf if TT.ps.o is NULL
  if (toys.optflags&FLAG_Z) default_ko("LABEL", &TT.fields, 0, 0);
  default_ko(toybuf, &TT.fields, "bad -o", TT.ps.o);

  if (TT.ps.O) {
    if (TT.fields) TT.fields = ((struct ofields *)TT.fields)->prev;
    comma_args(TT.ps.O, &TT.fields, "bad -O", parse_ko);
    if (TT.fields) TT.fields = ((struct ofields *)TT.fields)->next;
  }
  dlist_terminate(TT.fields);

  // -f and -n change the meaning of some fields
  if (toys.optflags&(FLAG_f|FLAG_n)) {
    struct ofields *field;

    for (field = TT.fields; field; field = field->next) {
      if ((toys.optflags&FLAG_n) && field->which>=PS_UID
        && field->which<=PS_RGROUP && (typos[field->which].slot&64))
          field->which--;
    }
  }

  // Calculate seen fields bit array, and if we aren't deferring printing
  // print headers now (for low memory/nommu systems).
  TT.bits = get_headers(TT.fields, toybuf, sizeof(toybuf));
  if (!(toys.optflags&FLAG_M)) printf("%.*s\n", TT.width, toybuf);
  if (!(toys.optflags&(FLAG_k|FLAG_M))) TT.show_process = show_ps;
  TT.match_process = ps_match_process;
  dt = dirtree_flagread("/proc", DIRTREE_SHUTUP|DIRTREE_PROC,
    ((toys.optflags&FLAG_T) || (TT.bits&(_PS_TID|_PS_TCNT)))
      ? get_threads : get_ps);

  if ((dt != DIRTREE_ABORTVAL) && toys.optflags&(FLAG_k|FLAG_M)) {
    struct procpid **tbsort = collate(TT.kcount, dt);

    if (toys.optflags&FLAG_M) {
      for (i = 0; i<TT.kcount; i++) {
        struct ofields *field;

        for (field = TT.fields; field; field = field->next) {
          int len = strlen(string_field(tbsort[i], field));

          if (abs(field->len)<len) field->len = (field->len<0) ? -len : len;
        }
      }

      // Now that we've recalculated field widths, re-pad headers again
      get_headers(TT.fields, toybuf, sizeof(toybuf));
      printf("%.*s\n", TT.width, toybuf);
    }

    if (toys.optflags&FLAG_k)
      qsort(tbsort, TT.kcount, sizeof(struct procpid *), (void *)ksort);
    for (i = 0; i<TT.kcount; i++) {
      show_ps(tbsort[i]);
      free(tbsort[i]);
    }
    if (CFG_TOYBOX_FREE) free(tbsort);
  }

  if (CFG_TOYBOX_FREE) {
    free(TT.gg.ptr);
    free(TT.GG.ptr);
    free(TT.pp.ptr);
    free(TT.PP.ptr);
    free(TT.ss.ptr);
    free(TT.tt.ptr);
    free(TT.uu.ptr);
    free(TT.UU.ptr);
    llist_traverse(TT.fields, free);
  }
}

#define CLEANUP_ps
#define FOR_top
#include "generated/flags.h"

// select which of the -o fields to sort by
static void setsort(int pos)
{
  struct ofields *field, *field2;
  int i = 0;

  if (pos<0) pos = 0;

  for (field = TT.fields; field; field = field->next) {
    if ((TT.sortpos = i++)<pos && field->next) continue;
    field2 = TT.kfields;
    field2->which = field->which;
    field2->len = field->len;
    break;
  }
}

// If we have both, adjust slot[deltas[]] to be relative to previous
// measurement rather than process start. Stomping old.data is fine
// because we free it after displaying.
static int merge_deltas(long long *oslot, long long *nslot, int milis)
{
  char deltas[] = {SLOT_utime2, SLOT_iobytes, SLOT_diobytes, SLOT_rchar,
                   SLOT_wchar, SLOT_rbytes, SLOT_wbytes, SLOT_swap};
  int i;

  for (i = 0; i<ARRAY_LEN(deltas); i++)
    oslot[deltas[i]] = nslot[deltas[i]] - oslot[deltas[i]];
  oslot[SLOT_upticks] = (milis*TT.ticks)/1000;

  return 1;
}

static int header_line(int line, int rev)
{
  if (!line) return 0;

  if (toys.optflags&FLAG_b) rev = 0;

  printf("%s%*.*s%s%s\n", rev ? "\033[7m" : "",
    (toys.optflags&FLAG_b) ? 0 : -TT.width, TT.width, toybuf,
    rev ? "\033[0m" : "", (toys.optflags&FLAG_b) ? "" : "\r");

  return line-1;
}

static void top_common(
  int (*filter)(long long *oslot, long long *nslot, int milis))
{
  long long timeout = 0, now, stats[16];
  struct proclist {
    struct procpid **tb;
    int count;
    long long whence;
  } plist[2], *plold, *plnew, old, new, mix;
  char scratch[16], *pos, *cpufields[] = {"user", "nice", "sys", "idle",
    "iow", "irq", "sirq", "host"};
 
  unsigned tock = 0;
  int i, lines, topoff = 0, done = 0;
  char stdout_buf[BUFSIZ];

  // Avoid flicker in interactive mode.
  if (!(toys.optflags&FLAG_b)) setbuf(stdout, stdout_buf);

  toys.signal = SIGWINCH;
  TT.bits = get_headers(TT.fields, toybuf, sizeof(toybuf));
  *scratch = 0;
  memset(plist, 0, sizeof(plist));
  memset(stats, 0, sizeof(stats));
  do {
    struct dirtree *dt;
    int recalc = 1;

    plold = plist+(tock++&1);
    plnew = plist+(tock&1);
    plnew->whence = millitime();
    dt = dirtree_flagread("/proc", DIRTREE_SHUTUP|DIRTREE_PROC,
      ((toys.optflags&FLAG_H) || (TT.bits&(_PS_TID|_PS_TCNT)))
        ? get_threads : get_ps);
    if (dt == DIRTREE_ABORTVAL) error_exit("no /proc");
    plnew->tb = collate(plnew->count = TT.kcount, dt);
    TT.kcount = 0;

    if (readfile("/proc/stat", pos = toybuf, sizeof(toybuf))) {
      long long *st = stats+8*(tock&1);

      // user nice system idle iowait irq softirq host
      sscanf(pos, "cpu %lld %lld %lld %lld %lld %lld %lld %lld",
        st, st+1, st+2, st+3, st+4, st+5, st+6, st+7);
    }

    // First time, wait a quarter of a second to collect a little delta data.
    if (!plold->tb) {
      msleep(250);
      continue;
    }

    // Collate old and new into "mix", depends on /proc read in pid sort order
    old = *plold;
    new = *plnew;
    mix.tb = xmalloc((old.count+new.count)*sizeof(struct procpid));
    mix.count = 0;

    while (old.count || new.count) {
      struct procpid *otb = old.count ? *old.tb : 0,
                     *ntb = new.count ? *new.tb : 0;

      // If we just have old for this process, it exited. Discard it.
      if (old.count && (!new.count || *otb->slot < *ntb->slot)) {
        old.tb++;
        old.count--;

        continue;
      }

      // If we just have new, use it verbatim
      if (!old.count || *otb->slot > *ntb->slot) mix.tb[mix.count] = ntb;
      else {
        // Keep or discard
        if (filter(otb->slot, ntb->slot, new.whence-old.whence)) {
          mix.tb[mix.count] = otb;
          mix.count++;
        }
        old.tb++;
        old.count--;
      }
      new.tb++;
      new.count--;
    }

    // Don't re-fetch data if it's not time yet, just re-display existing data.
    for (;;) {
      char was, is;

      if (recalc) {
        qsort(mix.tb, mix.count, sizeof(struct procpid *), (void *)ksort);
        if (!(toys.optflags&FLAG_b)) {
          printf("\033[H\033[J");
          if (toys.signal) {
            toys.signal = 0;
            terminal_probesize(&TT.width, &TT.height);
          }
        }
        if (TT.top.m) TT.height = TT.top.m+5;
        lines = TT.height;
      }
      if (recalc && !(toys.optflags&FLAG_q)) {
        // Display "top" header.
        if (*toys.which->name == 't') {
          struct ofields field;
          long long ll, up = 0;
          long run[6];
          int j;

          // Count running, sleeping, stopped, zombie processes.
          field.which = PS_S;
          memset(run, 0, sizeof(run));
          for (i = 0; i<mix.count; i++)
            run[1+stridx("RSTZ", *string_field(mix.tb[i], &field))]++;
          sprintf(toybuf,
            "Tasks: %d total,%4ld running,%4ld sleeping,%4ld stopped,"
            "%4ld zombie", mix.count, run[1], run[2], run[3], run[4]);
          lines = header_line(lines, 0);

          if (readfile("/proc/meminfo", toybuf, sizeof(toybuf))) {
            for (i=0; i<6; i++) {
              pos = strafter(toybuf, (char *[]){"MemTotal:","\nMemFree:",
                    "\nBuffers:","\nCached:","\nSwapTotal:","\nSwapFree:"}[i]);
              run[i] = pos ? atol(pos) : 0;
            }
            sprintf(toybuf,
             "Mem:%10ldk total,%9ldk used,%9ldk free,%9ldk buffers",
              run[0], run[0]-run[1], run[1], run[2]);
            lines = header_line(lines, 0);
            sprintf(toybuf,
              "Swap:%9ldk total,%9ldk used,%9ldk free,%9ldk cached",
              run[4], run[4]-run[5], run[5], run[3]);
            lines = header_line(lines, 0);
          }

          pos = toybuf;
          i = sysconf(_SC_NPROCESSORS_CONF);
          pos += sprintf(pos, "%d%%cpu", i*100);
          j = 4+(i>10);

          // If a processor goes idle it's powered down and its idle ticks don't
          // advance, so calculate idle time as potential time - used.
          if (mix.count) up = mix.tb[0]->slot[SLOT_upticks];
          if (!up) up = 1;
          now = up*i;
          ll = stats[3] = stats[11] = 0;
          for (i = 0; i<8; i++) ll += stats[i]-stats[i+8];
          stats[3] = now - llabs(ll);

          for (i = 0; i<8; i++) {
            ll = (llabs(stats[i]-stats[i+8])*1000)/up;
            pos += sprintf(pos, "% *lld%%%s", j, (ll+5)/10, cpufields[i]);
          }
          lines = header_line(lines, 0);
        } else {
          struct ofields *field;
          struct procpid tb;

          memset(&tb, 0, sizeof(struct procpid));
          pos = stpcpy(toybuf, "Totals:");
          for (field = TT.fields; field; field = field->next) {
            long long ll, bits = 0;
            int slot = typos[field->which].slot&63;

            if (field->which<PS_C || field->which>PS_DIO) continue;
            ll = 1LL<<field->which;
            if (bits&ll) continue;
            bits |= ll;
            for (i=0; i<mix.count; i++)
              tb.slot[slot] += mix.tb[i]->slot[slot];
            pos += snprintf(pos, sizeof(toybuf)/2-(pos-toybuf),
              " %s: %*s,", typos[field->which].name,
              field->len, string_field(&tb, field));
          }
          *--pos = 0;
          lines = header_line(lines, 0);
        }

        get_headers(TT.fields, pos = toybuf, sizeof(toybuf));
        for (i = 0, is = ' '; *pos; pos++) {
          was = is;
          is = *pos;
          if (isspace(was) && !isspace(is) && i++==TT.sortpos && pos!=toybuf)
            pos[-1] = '[';
          if (!isspace(was) && isspace(is) && i==TT.sortpos+1) *pos = ']';
        }
        *pos = 0;
        lines = header_line(lines, 1);
      }
      if (!recalc && !(toys.optflags&FLAG_b))
        printf("\033[%dH\033[J", 1+TT.height-lines);
      recalc = 1;

      for (i = 0; i<lines && i+topoff<mix.count; i++) {
        // Running processes are shown in bold.
        int bold = !(toys.optflags&FLAG_b) && mix.tb[i+topoff]->state == 'R';

        if (!(toys.optflags&FLAG_b) && i) putchar('\n');
        if (bold) printf("\033[1m");
        show_ps(mix.tb[i+topoff]);
        if (bold) printf("\033[m");
      }

      if (TT.top.n && !--TT.top.n) {
        done++;
        break;
      }

      now = millitime();
      if (timeout<=now) timeout = new.whence+TT.top.d_ms;
      if (timeout<=now || timeout>now+TT.top.d_ms) timeout = now+TT.top.d_ms;

      // In batch mode, we ignore the keyboard.
      if (toys.optflags&FLAG_b) {
        msleep(timeout-now);
        // Make an obvious gap between datasets.
        xputs("\n\n");
        continue;
      } else fflush(stdout);

      i = scan_key_getsize(scratch, timeout-now, &TT.width, &TT.height);
      if (i==-1 || i==3 || toupper(i)=='Q') {
        done++;
        break;
      }
      if (i==-2) break;
      if (i==-3) continue;

      // Flush unknown escape sequences.
      if (i==27) while (0<scan_key_getsize(scratch, 0, &TT.width, &TT.height));
      else if (i==' ') {
        timeout = 0;
        break;
      } else if (toupper(i)=='R')
        ((struct ofields *)TT.kfields)->reverse *= -1;
      else {
        i -= 256;
        if (i == KEY_LEFT) setsort(TT.sortpos-1);
        else if (i == KEY_RIGHT) setsort(TT.sortpos+1);
        // KEY_UP is 0, so at end of strchr
        else if (strchr((char []){KEY_DOWN,KEY_PGUP,KEY_PGDN,KEY_UP}, i)) {
          recalc = 0;

          if (i == KEY_UP) topoff--;
          else if (i == KEY_DOWN) topoff++;
          else if (i == KEY_PGDN) topoff += lines;
          else if (i == KEY_PGUP) topoff -= lines;
          if (topoff<0) topoff = 0; 
          if (topoff>mix.count) topoff = mix.count;
        }
      }
      continue;
    }

    free(mix.tb);
    for (i=0; i<plold->count; i++) free(plold->tb[i]);
    free(plold->tb);
  } while (!done);

  if (!(toys.optflags&FLAG_b)) tty_reset();
}

static void top_setup(char *defo, char *defk)
{
  if (TT.top.d) {
    long frac;

    TT.top.d_ms = xparsetime(TT.top.d, 1000, &frac) * 1000;
    TT.top.d_ms += frac;
  } else TT.top.d_ms = 3000;

  TT.ticks = sysconf(_SC_CLK_TCK); // units for starttime/uptime
  TT.tty = tty_fd() != -1;

  // Are we doing "batch" output or interactive?
  if (toys.optflags&FLAG_b) TT.width = TT.height = 99999;
  else {
    // Grab starting time, make terminal raw, switch off cursor,
    // set signal handler to put terminal/cursor back to normal at exit.
    TT.time = millitime();
    set_terminal(0, 1, 0);
    sigatexit(tty_sigreset);
    xsignal(SIGWINCH, generic_signal);
    printf("\033[?25l\033[0m");
    TT.width = 80;
    TT.height = 25;
  }

  comma_args(TT.top.u, &TT.uu, "bad -u", parse_rest);
  comma_args(TT.top.p, &TT.pp, "bad -p", parse_rest);
  TT.match_process = shared_match_process;

  default_ko(defo, &TT.fields, "bad -o", TT.top.o);
  dlist_terminate(TT.fields);

  // First (dummy) sort field is overwritten by setsort()
  default_ko("-S", &TT.kfields, 0, 0);
  default_ko(defk, &TT.kfields, "bad -k", TT.top.k);
  dlist_terminate(TT.kfields);
  setsort(TT.top.s-1);
}

void top_main(void)
{
  sprintf(toybuf, "PID,USER,%s%%CPU,%%MEM,TIME+,%s",
    TT.top.O ? "" : "PR,NI,VIRT,RES,SHR,S,",
    toys.optflags&FLAG_H ? "CMD:15=THREAD,NAME=PROCESS" : "ARGS");
  if (!TT.top.s) TT.top.s = TT.top.O ? 3 : 9;
  top_setup(toybuf, "-%CPU,-ETIME,-PID");
  if (TT.top.O) {
    struct ofields *field = TT.fields;

    field = field->next->next;
    comma_args(TT.top.O, &field, "bad -O", parse_ko);
  }

  top_common(merge_deltas);
}

#define CLEANUP_top
#define FOR_iotop
#include "generated/flags.h"

static int iotop_filter(long long *oslot, long long *nslot, int milis)
{
  if (!(toys.optflags&FLAG_a)) merge_deltas(oslot, nslot, milis);
  else oslot[SLOT_upticks] = ((millitime()-TT.time)*TT.ticks)/1000;

  return !(toys.optflags&FLAG_o)||oslot[SLOT_iobytes+!(toys.optflags&FLAG_A)];
}

void iotop_main(void)
{
  char *s1 = 0, *s2 = 0, *d = "D"+!!(toys.optflags&FLAG_A);

  if (toys.optflags&FLAG_K) TT.forcek++;

  top_setup(s1 = xmprintf("PID,PR,USER,%sREAD,%sWRITE,SWAP,%sIO,COMM",d,d,d),
    s2 = xmprintf("-%sIO,-ETIME,-PID",d));
  free(s1);
  free(s2);
  top_common(iotop_filter);
}

// pkill's plumbing wraps pgrep's and thus mostly takes place in pgrep's flag
// context, so force pgrep's flags on even when building pkill standalone.
// (All the pgrep/pkill functions drop out when building ps standalone.)
#define FORCE_FLAGS
#define CLEANUP_iotop
#define FOR_pgrep
#include "generated/flags.h"

struct regex_list {
  struct regex_list *next;
  regex_t reg;
};

static void do_pgk(struct procpid *tb)
{
  if (TT.pgrep.signal) {
    if (kill(*tb->slot, TT.pgrep.signal)) {
      char *s = num_to_sig(TT.pgrep.signal);

      if (!s) sprintf(s = toybuf, "%d", TT.pgrep.signal);
      perror_msg("%s->%lld", s, *tb->slot);
    }
  }
  if (!(toys.optflags&FLAG_c) && (!TT.pgrep.signal || TT.tty)) {
    printf("%lld", *tb->slot);
    if (toys.optflags&FLAG_l)
      printf(" %s", tb->str+tb->offset[4]*!!(toys.optflags&FLAG_f));
    
    printf("%s", TT.pgrep.d ? TT.pgrep.d : "\n");
  }
}

static void match_pgrep(void *p)
{
  struct procpid *tb = p;
  regmatch_t match;
  struct regex_list *reg;
  char *name = tb->str+tb->offset[4]*!!(toys.optflags&FLAG_f);;

  // Never match ourselves.
  if (TT.pgrep.self == *tb->slot) return;

  if (TT.pgrep.regexes) {
    for (reg = TT.pgrep.regexes; reg; reg = reg->next) {
      if (regexec(&reg->reg, name, 1, &match, 0)) continue;
      if (toys.optflags&FLAG_x)
        if (match.rm_so || match.rm_eo!=strlen(name)) continue;
      break;
    }
    if ((toys.optflags&FLAG_v) ? !!reg : !reg) return;
  }

  // pgrep should return success if there's a match.
  toys.exitval = 0;

  // Repurpose a field for -c count.
  TT.sortpos++;
  if (toys.optflags&(FLAG_n|FLAG_o)) {
    long long ll = tb->slot[SLOT_starttime];

    if (toys.optflags&FLAG_o) ll *= -1;
    if (TT.time && TT.time>ll) return;
    TT.time = ll;
    free(TT.pgrep.snapshot);
    TT.pgrep.snapshot = xmemdup(toybuf, (name+strlen(name)+1)-toybuf);
  } else do_pgk(tb);
}

static int pgrep_match_process(long long *slot)
{
  int match = shared_match_process(slot);

  return (toys.optflags&FLAG_v) ? !match : match;
}

void pgrep_main(void)
{
  char **arg;
  struct regex_list *reg;

  TT.pgrep.self = getpid();

  // No signal names start with "L", so no need for "L: " in optstr.
  if (TT.pgrep.L && 1>(TT.pgrep.signal = sig_to_num(TT.pgrep.L)))
    error_exit("bad -L '%s'", TT.pgrep.L);

  comma_args(TT.pgrep.G, &TT.GG, "bad -G", parse_rest);
  comma_args(TT.pgrep.g, &TT.gg, "bad -g", parse_rest);
  comma_args(TT.pgrep.P, &TT.PP, "bad -P", parse_rest);
  comma_args(TT.pgrep.s, &TT.ss, "bad -s", parse_rest);
  comma_args(TT.pgrep.t, &TT.tt, "bad -t", parse_rest);
  comma_args(TT.pgrep.U, &TT.UU, "bad -U", parse_rest);
  comma_args(TT.pgrep.u, &TT.uu, "bad -u", parse_rest);

  if ((toys.optflags&(FLAG_x|FLAG_f)) ||
      !(toys.optflags&(FLAG_G|FLAG_g|FLAG_P|FLAG_s|FLAG_t|FLAG_U|FLAG_u)))
    if (!toys.optc) help_exit("No PATTERN");

  if (toys.optflags&FLAG_f) TT.bits |= _PS_CMDLINE;
  for (arg = toys.optargs; *arg; arg++) {
    reg = xmalloc(sizeof(struct regex_list));
    xregcomp(&reg->reg, *arg, REG_EXTENDED);
    reg->next = TT.pgrep.regexes;
    TT.pgrep.regexes = reg;
  }
  TT.match_process = pgrep_match_process;
  TT.show_process = match_pgrep;

  // pgrep should return failure if there are no matches.
  toys.exitval = 1;

  dirtree_flagread("/proc", DIRTREE_SHUTUP|DIRTREE_PROC, get_ps);
  if (toys.optflags&FLAG_c) printf("%d\n", TT.sortpos);
  if (TT.pgrep.snapshot) {
    do_pgk(TT.pgrep.snapshot);
    if (CFG_TOYBOX_FREE) free(TT.pgrep.snapshot);
  }
  if (TT.pgrep.d) xputc('\n');
}

#define CLEANUP_pgrep
#define FOR_pkill
#include "generated/flags.h"

void pkill_main(void)
{
  char **args = toys.optargs;

  if (!(toys.optflags&FLAG_l) && *args && **args=='-') TT.pgrep.L = *(args++)+1;
  if (!TT.pgrep.L) TT.pgrep.signal = SIGTERM;
  if (toys.optflags & FLAG_V) TT.tty = 1;
  pgrep_main();
}