/* 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 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
USE_TOP(NEWTOY(top, ">0m" "O*Hk*o*p*u*s#<1d#=3<1n#<1bq[!oO]", TOYFLAG_USR|TOYFLAG_BIN|TOYFLAG_LOCALE))
USE_IOTOP(NEWTOY(iotop, ">0AaKO" "k*o*p*u*s#<1=7d#=3<1n#<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 (selections may be comma separated lists):

    -A	All processes
    -a	Processes with terminals that aren't session leaders
    -d	All processes that aren't session leaders
    -e	Same as -A
    -g	Belonging to GROUPs
    -G	Belonging to real GROUPs (before sgid)
    -p	PIDs (--pid)
    -P	Parent PIDs (--ppid)
    -s	In session IDs
    -t	Attached to selected TTYs
    -T	Show threads
    -u	Owned by USERs
    -U	Owned by real USERs (before suid)

    Output modifiers:

    -k	Sort FIELDs in +increasing or -decreasting order (--sort)
    -M	Measure field widths (expanding as necessary)
    -n	Show numeric USER and GROUP
    -w	Wide output (don't truncate at terminal width)

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

    -f	Full listing (-o USER:8=UID,PID,PPID,C,STIME,TTY,TIME,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     Command line (argv[] -path)    CMD   COMM, or ARGS with -f
      CMDLINE  Command line (argv[])          COMM  Original command name (stat[2])
      COMMAND  Command name (argv[0])         NAME  Command name (argv[0] -path)

    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 What are we waiting in kernel for

config TOP
  bool "top"
  depends on TOP_COMMON
  default y
  help
    usage: top [-H] [-k FIELD,] [-o FIELD,] [-s SORT]

    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)

# Requires CONFIG_IRQ_TIME_ACCOUNTING in the kernel for /proc/$$/io
config IOTOP
  bool "iotop"
  depends on TOP_COMMON
  default y
  help
    usage: iotop [-AaKO]

    Rank processes by I/O.

    -A	All I/O, not just disk
    -a	Accumulated I/O (not percentage)
    -K	Kilobytes
    -k	Fallback sort FIELDS (default -[D]IO,-ETIME,-PID)
    -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)

config TOP_COMMON
  bool
  default y
  help
    usage: * [-bq] [-n NUMBER] [-d SECONDS] [-p PID,] [-u USER,]

    -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
  depends on PGKILL_COMMON
  help
    usage: pgrep [-cL] [-d DELIM] [-L SIGNAL] [PATTERN]

    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

config PKILL
  bool "pkill"
  default y
  depends on PGKILL_COMMON
  help
    usage: pkill [-l SIGNAL] [PATTERN]

    -l	SIGNAL to send
    -V	verbose

config PGKILL_COMMON
  bool
  default y
  help
    usage: * [-fnovx] [-G GID,] [-g PGRP,] [-P PPID,] [-s SID,] [-t TERM,] [-U UID,] [-u EUID,]

    -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 d;
      long s;
      struct arg_list *u;
      struct arg_list *p;
      struct arg_list *o;
      struct arg_list *k;
      struct arg_list *O;
    } 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);
)

struct strawberry {
  struct strawberry *next, *prev;
  short which, len, reverse;
  char *title;
  char forever[];
};

/* The slot[] array is mostly populated from /proc/$PID/stat (kernel proc.txt
 * table 1-4) but we shift and repurpose fields, with the result being: */

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
 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,  /*46-19 (divisor for %)*/ 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
};

// Data layout in toybuf
struct carveup {
  long long slot[SLOT_count]; // data (see enum above)
  unsigned short offset[5];   // offset of fields in str[] (skip name, always 0)
  char state;
  char str[];                 // name, tty, command, wchan, attr, cmdline
};

// 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
  {"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", 5, SLOT_rss}, {"PGID", 5, SLOT_pgrp},
  {"VSZ", 6, 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
  {"COMM", -15, -1}, {"TTY", -8, -2}, {"WCHAN", -6, -3}, {"LABEL", -30, -4},
  {"COMMAND", -27, -5}, {"CMDLINE", -27, -6}, {"ARGS", -27, -6},
  {"NAME", -15, -6}, {"CMD", -27, -1},

  // user/group
  {"UID", 5, SLOT_uid}, {"USER", -8, 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
  {"TIME", 8, SLOT_utime}, {"ELAPSED", 11, SLOT_starttime},
  {"TIME+", 9, SLOT_utime},

  // Percentage displays
  {"C", 1, SLOT_utime2}, {"%VSZ", 5, SLOT_vsize}, {"%MEM", 5, SLOT_rss},
  {"%CPU", 4, SLOT_utime2},

  // human_readable
  {"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
  {"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 carveup *tb, struct strawberry *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) {
    // If there's data after argv[0], insert null or space as appropriate
    if (slot[SLOT_argv0len])
      tb->str[tb->offset[4]+slot[SLOT_argv0len]] = (which==PS_NAME) ? 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)
      for (s = out; *s && *s != ' '; s++) if (*s == '/') out = s+1;
    if (which>PS_COMMAND && (!*out || *slot != slot[SLOT_tid]))
      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(struct carveup *tb)
{
  struct strawberry *field;
  int pad, len, width = TT.width;

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

    // Output the field, appropriately padded
    if (field != TT.fields) {
      putchar(' ');
      width--;
    }
    len = width;
    pad = 0;
    if (field->next || field->len>0)
      len = abs(pad = width<abs(field->len) ? width : field->len);

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

// dirtree callback: read data about process to display, store, or discard it.
// Fills toybuf with struct carveup 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;
    long long bits;
  } fetch[] = {
    // sources for carveup->offset[] data
    {"fd/", _PS_TTY}, {"wchan", _PS_WCHAN}, {"attr/current", _PS_LABEL},
    {"exe", _PS_COMMAND}, {"cmdline", _PS_CMDLINE|_PS_ARGS|_PS_NAME}
  };
  struct carveup *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_SAVE*(TT.threadparent||!TT.show_process));

  memset(slot, 0, sizeof(tb->slot));
  if (!(tb->slot[SLOT_tid] = *slot = atol(new->name))) return 0;
  if (TT.threadparent && TT.threadparent->extra)
    if (*slot == *(((struct carveup *)TT.threadparent->extra)->slot)) return 0;
  fd = dirtree_parentfd(new);

  len = 2048;
  sprintf(buf, "%lld/stat", *slot);
  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<50; 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);
    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);
    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);
    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);
    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, (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, fetch[j].name);

    // For exe we readlink instead of read contents
    if (j==3) {
      // Thread doesn't have exe, so use parent's
      if (TT.threadparent && TT.threadparent->extra) {
        struct carveup *ptb = (void *)TT.threadparent->extra;
        i = strlen(s = ptb->str+ptb->offset[3]);
        if (i<len) len = i;
        memcpy(buf, s, i);
        buf[len] = 0;
      } else if ((len = readlinkat(fd, buf, buf, len))>0) buf[len] = 0;
      else *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, i);
          if (!fstatat(fd, buf, &st, 0) && S_ISCHR(st.st_mode)
            && st.st_rdev == rdev && 0<(len = readlinkat(fd, buf, buf, len)))
          {
            buf[len] = 0;
            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 -= 5);
      }

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

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

        if (buf[len-1]=='\n') buf[--len] = 0;

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

    // 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 carveup *tb;
  unsigned pid, kcount;

  if (!new->parent) return get_ps(new);

  if (!(pid = atol(new->name))) return 0;

  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, get_ps);
  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);
  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 strawberry *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, copy title
  field = xzalloc(sizeof(struct strawberry)+(length+1)*!!title);
  if (title) {
    memcpy(field->title = field->forever, 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;
}

long long get_headers(struct strawberry *fields, char *buf, int blen)
{
  long long bits = 0;
  int len = 0;

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

  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 strawberry *field;
  struct carveup *ta = *(struct carveup **)aa, *tb = *(struct carveup **)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 carveup **collate_leaves(struct carveup **tb, struct dirtree *dt) 
{
  while (dt) {
    struct dirtree *next = dt->next;

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

  return tb;
}

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

  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);
}

static void shared_main(void)
{
  int i;

  TT.ticks = sysconf(_SC_CLK_TCK);
  if (!TT.width) {
    TT.width = (toys.which->name[1] == 's') ? 99999 : 80;
    TT.height = 25;
    terminal_size(&TT.width, &TT.height);
  }

  // find controlling tty, falling back to /dev/tty if none
  for (i = 0; !TT.tty && i<4; i++) {
    struct stat st;
    int fd = i;

    if (i==3 && -1==(fd = open("/dev/tty", O_RDONLY))) break;

    if (isatty(fd) && !fstat(fd, &st)) TT.tty = st.st_rdev;
    if (i==3) close(fd);
  }
}

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

  if (toys.optflags&FLAG_w) TT.width = 99999;
  shared_main();

  // 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);

  // Figure out which fields to display
  not_o = "%sTTY,TIME,CMD";
  if (toys.optflags&FLAG_f)
    sprintf(not_o = toybuf+128, "USER:8=UID,%%sPPID,%s,STIME,TTY,TIME,CMD",
      (toys.optflags&FLAG_T) ? "TCNT" : "C");
  else if (toys.optflags&FLAG_l)
    not_o = "F,S,UID,%sPPID,C,PRI,NI,ADDR,SZ,WCHAN,TTY,TIME,CMD";
  else if (CFG_TOYBOX_ON_ANDROID)
    not_o = "USER,%sPPID,VSIZE,RSS,WCHAN:10,ADDR:10=PC,S,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 strawberry *)TT.fields)->prev;
    comma_args(TT.ps.O, &TT.fields, "bad -O", parse_ko);
    if (TT.fields) TT.fields = ((struct strawberry *)TT.fields)->next;
  }
  dlist_terminate(TT.fields);

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

    for (ever = TT.fields; ever; ever = ever->next) {
      if ((toys.optflags&FLAG_f) && ever->which==PS_CMD) ever->which = PS_ARGS;
      if ((toys.optflags&FLAG_n) && ever->which>=PS_UID
        && ever->which<=PS_RGROUP && (typos[ever->which].slot&64))
          ever->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 = (void *)show_ps;
  TT.match_process = ps_match_process;
  dt = dirtree_read("/proc",
    ((toys.optflags&FLAG_T) || (TT.bits&(_PS_TID|_PS_TCNT)))
      ? get_threads : get_ps);

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

    if (toys.optflags&FLAG_M) {
      for (i = 0; i<TT.kcount; i++) {
        struct strawberry *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 carveup *), (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 strawberry *field, *going2;
  int i = 0;

  if (pos<0) pos = 0;

  for (field = TT.fields; field; field = field->next) {
    if ((TT.sortpos = i++)<pos && field->next) continue;
    going2 = TT.kfields;
    going2->which = field->which;
    going2->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\r\n", rev ? "\033[7m" : "",
    (toys.optflags&FLAG_b) ? 0 : -TT.width, TT.width, toybuf,
    rev ? "\033[0m" : "");

  return line-1;
}

static long long millitime(void)
{
  struct timespec ts;

  clock_gettime(CLOCK_MONOTONIC, &ts);
  return ts.tv_sec*1000+ts.tv_nsec/1000000;
}

static void top_common(
  int (*filter)(long long *oslot, long long *nslot, int milis))
{
  long long timeout = 0, now, stats[16];
  struct proclist {
    struct carveup **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;

  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_read("/proc",
      ((toys.optflags&FLAG_H) || (TT.bits&(_PS_TID|_PS_TCNT)))
        ? get_threads : get_ps);
    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 carveup));
    mix.count = 0;

    while (old.count || new.count) {
      struct carveup *otb = *old.tb, *ntb = *new.tb;

      // 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 carveup *), (void *)ksort);
        if (!(toys.optflags&FLAG_b)) {
          printf("\033[H\033[J");
          if (toys.signal) {
            toys.signal = 0;
            terminal_probesize(&TT.width, &TT.height);
          }
        }
        lines = TT.height;
      }
      if (recalc && !(toys.optflags&FLAG_q)) {
        // Display "top" header.
        if (*toys.which->name == 't') {
          struct strawberry alluc;
          long long ll, up = 0;
          long run[6];
          int j;

          // Count running, sleeping, stopped, zombie processes.
          alluc.which = PS_S;
          memset(run, 0, sizeof(run));
          for (i = 0; i<mix.count; i++)
            run[1+stridx("RSTZ", *string_field(mix.tb[i], &alluc))]++;
          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 strawberry *fields;
          struct carveup tb;

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

            if (fields->which<PS_C || fields->which>PS_DIO) continue;
            ll = 1LL<<fields->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[fields->which].name,
              fields->len, string_field(&tb, fields));
          }
          *--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++) {
        if (!(toys.optflags&FLAG_b) && i) xputc('\n');
        show_ps(mix.tb[i+topoff]);
      }

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

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

      // 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;
      }

      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;

      // 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 strawberry *)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)
{
  TT.top.d *= 1000;
  if (toys.optflags&FLAG_b) TT.width = TT.height = 99999;
  else {
    TT.time = millitime();
    set_terminal(0, 1, 0);
    sigatexit(tty_sigreset);
    xsignal(SIGWINCH, generic_signal);
    printf("\033[?25l\033[0m");
  }
  shared_main();

  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)
{
  // usage: [-h HEADER] -o OUTPUT -k SORT

  sprintf(toybuf, "PID,USER,%s%%CPU,%%MEM,TIME+,ARGS",
    TT.top.O ? "" : "PR,NI,VIRT,RES,SHR,S,");
  if (!TT.top.s) TT.top.s = TT.top.O ? 3 : 9;
  top_setup(toybuf, "-%CPU,-ETIME,-PID");
  if (TT.top.O) {
    struct strawberry *fields = TT.fields;

    fields = fields->next->next;
    comma_args(TT.top.O, &fields, "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 carveup *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(struct carveup *tb)
{
  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;
  }

  // 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: " parsing.
  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 = (void *)match_pgrep;

  dirtree_read("/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)
{
  if (!TT.pgrep.L) TT.pgrep.signal = SIGTERM;
  if (toys.optflags & FLAG_V) TT.tty = 1;
  pgrep_main();
}