toys/pending/ps.c - platform/external/toybox - Git at Google

 /* 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 to specify an alternate /etc/passwd (??!?)
  * 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.
  * 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.

 USE_PS(NEWTOY(ps, "aAdeflo*[!ol][+Ae]", TOYFLAG_USR|TOYFLAG_BIN))

 config PS
   bool "ps"
   default n
   help
     usage: ps [-Aade] [-fl] [-gG GROUP] [-o FIELD] [-p PID] [-t TTY] [-u USER]

     List processes.

     -A	All processes
     -a	Processes with terminals, except session leaders
     -d	Processes that aren't session leaders
     -e	Same as -A
     -f	Full listing
     -l	Long listing

     -g  Processes belonging to these session leaders
     -G	Processes with these real group IDs
     -o	Show FIELDS for each process
     -p	select by PID
     -t	select by TTY
     -u	select by USER
     -U	select by USER

      GROUP, FIELD, PID, TTY, and USER are comma separated lists.

     OUTPUT (-o) FIELDS:

       "UID", "PID", "PPID", "C", "PRI", "NI", "ADDR", "SZ",
       "WCHAN", "STIME", "TTY", "TIME", "CMD", "COMMAND", "ELAPSED", "GROUP",
       "%CPU", "PGID", "RGROUP", "RUSER", "USER", "VSZ"

       C    Processor utilization for scheduling
       F    Process flags (PF_*) from linux source file include/sched.h
            (in octal rather than hex because posix)
       S    Process state:
            R (running) S (sleeping) D (disk sleep) T (stopped)  t (tracing stop)
            Z (zombie)  X (dead)     x (dead)       K (wakekill) W (waking)
       PID  Process id
       PPID Parent process id
       PRI  Priority
       UID  User id of process owner

     Default output is -o PID,TTY,TIME,CMD
     With -f USER=UID,PID,PPID,C,STIME,TTY,TIME,CMD
     With -l F,S,UID,PID,PPID,C,PRI,NI,ADDR,SZ,WCHAN,TTY,TIME,CMD
 */

 #define FOR_ps
 #include "toys.h"

 GLOBALS(
   struct arg_list *o;

   unsigned width;
   dev_t tty;
   void *fields;
   long uptime;
 )

 /*
   l l fl  a   fl   fl l  l  l    l  l     f     a   a    a
   F S UID PID PPID C PRI NI ADDR SZ WCHAN STIME TTY TIME CMD
   ruser user rgroup group pid ppid pgid pcpu vsz nice etime time tty comm args

   todo: thread support /proc/$d/task/%d/stat
     man page: F flags mean...
 */

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

 // dirtree callback.
 // toybuf used as: 1024 /proc/$PID/stat, 1024 slot[], 2048 /proc/$PID/cmdline
 static int do_ps(struct dirtree *new)
 {
   struct strawberry *field;
   long long *slot = (void *)(toybuf+1024);
   char *name, *s, state;
   int nlen, i, fd, len, width = TT.width;

   if (!new->parent) return DIRTREE_RECURSE;
   if (!(*slot = atol(new->name))) return 0;

   // name field limited to 256 bytes by VFS, plus 40 fields * max 20 chars:
   // 1000-ish total, but some forced zero so actually there's headroom.
   sprintf(toybuf, "%lld/stat", *slot);
   if (!readfileat(dirtree_parentfd(new), toybuf, toybuf, 1024)) return 0;

   // parse oddball fields (name and state)
   if (!(s = strchr(toybuf, '('))) return 0;
   for (name = ++s; *s != ')'; s++) if (!*s) return 0;
   nlen = s++-name;
   if (1>sscanf(++s, " %c%n", &state, &i)) return 0;

   // parse numeric fields
   for (len = 1; len<100; len++)
     if (1>sscanf(s += i, " %lld%n", slot+len, &i)) break;

   // skip entries we don't care about.
   if ((toys.optflags&(FLAG_a|FLAG_d)) && getsid(*slot)==*slot) return 0;
   if ((toys.optflags&FLAG_a) && !slot[4]) return 0;
   if (!(toys.optflags&(FLAG_a|FLAG_d|FLAG_A|FLAG_e)) && TT.tty!=slot[4])
     return 0;

   for (field = TT.fields; field; field = field->next) {
     char *out = toybuf+2048;

     // Default: unsupported (5 "C")
     sprintf(out, "-");

     // PID, PPID, PRI, NI, ADDR, SZ
     if (-1 != (i = stridx((char[]){3,4,6,7,8,9,0}, field->which)))
       sprintf(out, ((1<<i)&0x10) ? "%llx" : "%lld",
               slot[((char[]){0,2,16,17,22})[i]]>>(((1<<i)&0x20) ? 12 : 0));
     // F
     else if (!(i = field->which)) sprintf(out, "%llo", slot[7]);
     // S
     else if (i == 1)
       sprintf(out, "%c", state);
     // UID and USER
     else if (i == 2 || i == 22) {
       sprintf(out, "%d", new->st.st_uid);
       if (i == 22) {
         struct passwd *pw = getpwuid(new->st.st_uid);

         if (pw) out = pw->pw_name;
       }
     // WCHAN
     } else if (i==10) {
       sprintf(toybuf+512, "%lld/wchan", *slot);
       readfileat(dirtree_parentfd(new), toybuf+512, out, 2047);

     // STIME
     // TTY
     } else if (i==12) {

       // Can we readlink() our way to a name?
       for (i=0; i<3; i++) {
         struct stat st;

         sprintf(toybuf+512, "%lld/fd/%i", *slot, i);
         fd = dirtree_parentfd(new);
         if (!fstatat(fd, toybuf+512, &st, 0) && S_ISCHR(st.st_mode)
           && st.st_rdev == slot[4]
           && 0<(len = readlinkat(fd, toybuf+512, out, 2047)))
         {
           out[len] = 0;
           if (!strncmp(out, "/dev/", 5)) out += 5;

           break;
         }
       }

       // Couldn't find it, show major:minor
       if (i==3) {
         i = slot[4];
         sprintf(out, "%d:%d", (i>>8)&0xfff, ((i>>12)&0xfff00)|(i&0xff));
       }

     // TIME ELAPSED
     } else if (i==13 || i==16) {
       long seconds = (i==16) ? slot[20] : slot[11]+slot[12], ll = 60*60*24;

       seconds /= sysconf(_SC_CLK_TCK);
       if (i==16) seconds = TT.uptime-seconds;
       for (s = out, i = 0; i<4; i++) {
         if (i>1 || seconds > ll)
           s += sprintf(s, (i==3) ? "%02ld" : "%ld%c", seconds/ll, "-::"[i]);
         seconds %= ll;
         ll /= i ? 60 : 24;
       }

 //16 "ELAPSED", "GROUP", "%CPU", "PGID", "RGROUP",
 //21 "RUSER", -, "VSZ"

     // Command line limited to 2k displayable. 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. :)
     } else if (i == 14 || i == 15) {
       int fd;

       len = 0;
       sprintf(out, "%lld/cmdline", *slot);
       fd = openat(dirtree_parentfd(new), out, O_RDONLY);

       if (fd != -1) {
         if (0<(len = read(fd, out, 2047))) {
           if (!out[len-1]) len--;
           else out[len] = 0;
           for (i = 0; i<len; i++) if (out[i] < ' ') out[i] = ' ';
         }
         close(fd);
       }
       if (len<1) sprintf(out, "[%.*s]", nlen, name);
     }

     i = width<field->len ? width : field->len;
     width -= printf(" %*.*s", i, field->next ? i : width, out);
   }
   xputc('\n');

   return 0;
 }

 void ps_main(void)
 {
   struct strawberry *field;
   // Octal output code followed by header name
   char widths[] = {1,1,5,5,5,2,3,3,4,5,6,5,8,8,27,27,11,8,4,5,8,8,8,6},
        *typos[] = {
          "F", "S", "UID", "PID", "PPID", "C", "PRI", "NI", "ADDR", "SZ",
          "WCHAN", "STIME", "TTY", "TIME", "CMD", "COMMAND", "ELAPSED", "GROUP",
          "%CPU", "PGID", "RGROUP", "RUSER", "USER", "VSZ"
        };
   int i, fd = -1;

   TT.width = 80;
   terminal_size(&TT.width, 0);
   TT.width--;

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

     if (i != 3 || -1 != (i = fd = open("/dev/tty", O_RDONLY))) {
       if (isatty(i) && !fstat(i, &st)) {
         TT.tty = st.st_rdev;
         break;
       }
     }
   }
   if (fd != -1) close(fd);

   sysinfo((void *)toybuf);
   // Because "TT.uptime = *(long *)toybuf;" triggers a bug in gcc.
   {
     long *sigh = (long *)toybuf;
     TT.uptime = *sigh;
   }

   // Manual field selection via -o
   if (toys.optflags&FLAG_o) {
     struct arg_list *ol;
     int length;

     for (ol = TT.o; ol; ol = ol->next) {
       char *width, *type, *title, *end, *arg = ol->arg;

       // Set title, length of title, type, end of type, and display width
       while ((type = comma_iterate(&arg, &length))) {
         if ((end = strchr(type, '=')) && length<(end-type)) {
           title = end+1;
           length = (end-type)-1;
         } else {
           end = type+length;
           title = 0;
         }

         // If changing display width, trim title at the :
         if ((width = strchr(type, ':')) && width<end) {
           if (!title) length = width-type;
         } else width = 0;

         // Allocate structure, copy title
         field = xmalloc(sizeof(struct strawberry)+length+1);
         if (title) {
           memcpy(field->title, title, length);
           field->title[length] = 0;
         }
         field->len = length;

         if (width) {
           field->len = strtol(++width, &title, 10);
           if (!isdigit(*width) || title != end)
             error_exit("bad : in -o %s@%ld", ol->arg, title-ol->arg);
           end = width;
         }

         // Find type (reuse width as temp because we're done with it)
         for (i = 0; i<ARRAY_LEN(typos) && !field->which; i++) {
           int j, k;
           char *s;

           field->which = i;
           for (j = 0; j < 2; j++) {
             if (!j) s = typos[i];
             // posix requires alternate names for some fields
             else if (-1 == (k = stridx((char []){7, 14, 15, 16}, i))) break;
             else s = ((char *[]){"nice", "args", "comm", "etime"})[k];

             if (!strncasecmp(type, s, end-type) && strlen(s)==end-type) break;
           }
           if (j!=2) break;
         }
         if (i == ARRAY_LEN(typos)) error_exit("bad -o %.*s", end-type, type);
         if (!field->title) strcpy(field->title, typos[field->which]);
         dlist_add_nomalloc((void *)&TT.fields, (void *)field);
       }
     }

   // Default fields (also with -f and -l)
   } else {
     unsigned short def = 0x7008;

     if (toys.optflags&FLAG_f) def = 0x783c;
     if (toys.optflags&FLAG_l) def = 0x77ff;

     // order of fields[] matches posix STDOUT section, so add enabled XSI
     // defaults according to bitmask

     for (i=0; def>>i; i++) {
       if (!((def>>i)&1)) continue;

       field = xmalloc(sizeof(struct strawberry)+strlen(typos[i])+1);
       field->which = i;
       field->len = widths[i];
       strcpy(field->title, typos[i]);
       dlist_add_nomalloc((void *)&TT.fields, (void *)field);
     }
   }
   dlist_terminate(TT.fields);

   // Print padded headers. (Numbers are right justified, everyting else left.
   // time and pcpu count as numbers, tty does not)
   for (field = TT.fields; field; field = field->next) {

     // right justify F, UID, PID, PPID, PRI, NI, ADDR SZ, TIME, ELAPSED, %CPU
     // todo: STIME? C?
     if (!((1<<field->which)&0x523dd)) field->len *= -1;
     printf(" %*s", field->len, field->title);

     // -f prints USER but calls it UID (but "ps -o uid -f" is numeric...?)
     if ((toys.optflags&(FLAG_f|FLAG_o))==FLAG_f && field->which==2)
       field->which = 22;
   }
   xputc('\n');

   dirtree_read("/proc", do_ps);
 }
	/* 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 to specify an alternate /etc/passwd (??!?)
	* 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.
	* 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.

	USE_PS(NEWTOY(ps, "aAdeflo*[!ol][+Ae]", TOYFLAG_USR\|TOYFLAG_BIN))

	config PS
	bool "ps"
	default n
	help
	usage: ps [-Aade] [-fl] [-gG GROUP] [-o FIELD] [-p PID] [-t TTY] [-u USER]

	List processes.

	-A All processes
	-a Processes with terminals, except session leaders
	-d Processes that aren't session leaders
	-e Same as -A
	-f Full listing
	-l Long listing

	-g Processes belonging to these session leaders
	-G Processes with these real group IDs
	-o Show FIELDS for each process
	-p select by PID
	-t select by TTY
	-u select by USER
	-U select by USER

	GROUP, FIELD, PID, TTY, and USER are comma separated lists.

	OUTPUT (-o) FIELDS:

	"UID", "PID", "PPID", "C", "PRI", "NI", "ADDR", "SZ",
	"WCHAN", "STIME", "TTY", "TIME", "CMD", "COMMAND", "ELAPSED", "GROUP",
	"%CPU", "PGID", "RGROUP", "RUSER", "USER", "VSZ"

	C Processor utilization for scheduling
	F Process flags (PF_*) from linux source file include/sched.h
	(in octal rather than hex because posix)
	S Process state:
	R (running) S (sleeping) D (disk sleep) T (stopped) t (tracing stop)
	Z (zombie) X (dead) x (dead) K (wakekill) W (waking)
	PID Process id
	PPID Parent process id
	PRI Priority
	UID User id of process owner

	Default output is -o PID,TTY,TIME,CMD
	With -f USER=UID,PID,PPID,C,STIME,TTY,TIME,CMD
	With -l F,S,UID,PID,PPID,C,PRI,NI,ADDR,SZ,WCHAN,TTY,TIME,CMD
	*/

	#define FOR_ps
	#include "toys.h"

	GLOBALS(
	struct arg_list *o;

	unsigned width;
	dev_t tty;
	void *fields;
	long uptime;
	)

	/*
	l l fl a fl fl l l l l l f a a a
	F S UID PID PPID C PRI NI ADDR SZ WCHAN STIME TTY TIME CMD
	ruser user rgroup group pid ppid pgid pcpu vsz nice etime time tty comm args

	todo: thread support /proc/$d/task/%d/stat
	man page: F flags mean...
	*/

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

	// dirtree callback.
	// toybuf used as: 1024 /proc/$PID/stat, 1024 slot[], 2048 /proc/$PID/cmdline
	static int do_ps(struct dirtree *new)
	{
	struct strawberry *field;
	long long slot = (void )(toybuf+1024);
	char name, s, state;
	int nlen, i, fd, len, width = TT.width;

	if (!new->parent) return DIRTREE_RECURSE;
	if (!(*slot = atol(new->name))) return 0;

	// name field limited to 256 bytes by VFS, plus 40 fields * max 20 chars:
	// 1000-ish total, but some forced zero so actually there's headroom.
	sprintf(toybuf, "%lld/stat", *slot);
	if (!readfileat(dirtree_parentfd(new), toybuf, toybuf, 1024)) return 0;

	// parse oddball fields (name and state)
	if (!(s = strchr(toybuf, '('))) return 0;
	for (name = ++s; s != ')'; s++) if (!s) return 0;
	nlen = s++-name;
	if (1>sscanf(++s, " %c%n", &state, &i)) return 0;

	// parse numeric fields
	for (len = 1; len<100; len++)
	if (1>sscanf(s += i, " %lld%n", slot+len, &i)) break;

	// skip entries we don't care about.
	if ((toys.optflags&(FLAG_a\|FLAG_d)) && getsid(slot)==slot) return 0;
	if ((toys.optflags&FLAG_a) && !slot[4]) return 0;
	if (!(toys.optflags&(FLAG_a\|FLAG_d\|FLAG_A\|FLAG_e)) && TT.tty!=slot[4])
	return 0;

	for (field = TT.fields; field; field = field->next) {
	char *out = toybuf+2048;

	// Default: unsupported (5 "C")
	sprintf(out, "-");

	// PID, PPID, PRI, NI, ADDR, SZ
	if (-1 != (i = stridx((char[]){3,4,6,7,8,9,0}, field->which)))
	sprintf(out, ((1<<i)&0x10) ? "%llx" : "%lld",
	slot[((char[]){0,2,16,17,22})[i]]>>(((1<<i)&0x20) ? 12 : 0));
	// F
	else if (!(i = field->which)) sprintf(out, "%llo", slot[7]);
	// S
	else if (i == 1)
	sprintf(out, "%c", state);
	// UID and USER
	else if (i == 2 \|\| i == 22) {
	sprintf(out, "%d", new->st.st_uid);
	if (i == 22) {
	struct passwd *pw = getpwuid(new->st.st_uid);

	if (pw) out = pw->pw_name;
	}
	// WCHAN
	} else if (i==10) {
	sprintf(toybuf+512, "%lld/wchan", *slot);
	readfileat(dirtree_parentfd(new), toybuf+512, out, 2047);

	// STIME
	// TTY
	} else if (i==12) {

	// Can we readlink() our way to a name?
	for (i=0; i<3; i++) {
	struct stat st;

	sprintf(toybuf+512, "%lld/fd/%i", *slot, i);
	fd = dirtree_parentfd(new);
	if (!fstatat(fd, toybuf+512, &st, 0) && S_ISCHR(st.st_mode)
	&& st.st_rdev == slot[4]
	&& 0<(len = readlinkat(fd, toybuf+512, out, 2047)))
	{
	out[len] = 0;
	if (!strncmp(out, "/dev/", 5)) out += 5;

	break;
	}
	}

	// Couldn't find it, show major:minor
	if (i==3) {
	i = slot[4];
	sprintf(out, "%d:%d", (i>>8)&0xfff, ((i>>12)&0xfff00)\|(i&0xff));
	}

	// TIME ELAPSED
	} else if (i==13 \|\| i==16) {
	long seconds = (i==16) ? slot[20] : slot[11]+slot[12], ll = 606024;

	seconds /= sysconf(_SC_CLK_TCK);
	if (i==16) seconds = TT.uptime-seconds;
	for (s = out, i = 0; i<4; i++) {
	if (i>1 \|\| seconds > ll)
	s += sprintf(s, (i==3) ? "%02ld" : "%ld%c", seconds/ll, "-::"[i]);
	seconds %= ll;
	ll /= i ? 60 : 24;
	}

	//16 "ELAPSED", "GROUP", "%CPU", "PGID", "RGROUP",
	//21 "RUSER", -, "VSZ"

	// Command line limited to 2k displayable. 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. :)
	} else if (i == 14 \|\| i == 15) {
	int fd;

	len = 0;
	sprintf(out, "%lld/cmdline", *slot);
	fd = openat(dirtree_parentfd(new), out, O_RDONLY);

	if (fd != -1) {
	if (0<(len = read(fd, out, 2047))) {
	if (!out[len-1]) len--;
	else out[len] = 0;
	for (i = 0; i<len; i++) if (out[i] < ' ') out[i] = ' ';
	}
	close(fd);
	}
	if (len<1) sprintf(out, "[%.*s]", nlen, name);
	}

	i = width<field->len ? width : field->len;
	width -= printf(" %.s", i, field->next ? i : width, out);
	}
	xputc('\n');

	return 0;
	}

	void ps_main(void)
	{
	struct strawberry *field;
	// Octal output code followed by header name
	char widths[] = {1,1,5,5,5,2,3,3,4,5,6,5,8,8,27,27,11,8,4,5,8,8,8,6},
	*typos[] = {
	"F", "S", "UID", "PID", "PPID", "C", "PRI", "NI", "ADDR", "SZ",
	"WCHAN", "STIME", "TTY", "TIME", "CMD", "COMMAND", "ELAPSED", "GROUP",
	"%CPU", "PGID", "RGROUP", "RUSER", "USER", "VSZ"
	};
	int i, fd = -1;

	TT.width = 80;
	terminal_size(&TT.width, 0);
	TT.width--;

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

	if (i != 3 \|\| -1 != (i = fd = open("/dev/tty", O_RDONLY))) {
	if (isatty(i) && !fstat(i, &st)) {
	TT.tty = st.st_rdev;
	break;
	}
	}
	}
	if (fd != -1) close(fd);

	sysinfo((void *)toybuf);
	// Because "TT.uptime = (long )toybuf;" triggers a bug in gcc.
	{
	long sigh = (long )toybuf;
	TT.uptime = *sigh;
	}

	// Manual field selection via -o
	if (toys.optflags&FLAG_o) {
	struct arg_list *ol;
	int length;

	for (ol = TT.o; ol; ol = ol->next) {
	char width, type, title, end, *arg = ol->arg;

	// Set title, length of title, type, end of type, and display width
	while ((type = comma_iterate(&arg, &length))) {
	if ((end = strchr(type, '=')) && length<(end-type)) {
	title = end+1;
	length = (end-type)-1;
	} else {
	end = type+length;
	title = 0;
	}

	// If changing display width, trim title at the :
	if ((width = strchr(type, ':')) && width<end) {
	if (!title) length = width-type;
	} else width = 0;

	// Allocate structure, copy title
	field = xmalloc(sizeof(struct strawberry)+length+1);
	if (title) {
	memcpy(field->title, title, length);
	field->title[length] = 0;
	}
	field->len = length;

	if (width) {
	field->len = strtol(++width, &title, 10);
	if (!isdigit(*width) \|\| title != end)
	error_exit("bad : in -o %s@%ld", ol->arg, title-ol->arg);
	end = width;
	}

	// Find type (reuse width as temp because we're done with it)
	for (i = 0; i<ARRAY_LEN(typos) && !field->which; i++) {
	int j, k;
	char *s;

	field->which = i;
	for (j = 0; j < 2; j++) {
	if (!j) s = typos[i];
	// posix requires alternate names for some fields
	else if (-1 == (k = stridx((char []){7, 14, 15, 16}, i))) break;
	else s = ((char *[]){"nice", "args", "comm", "etime"})[k];

	if (!strncasecmp(type, s, end-type) && strlen(s)==end-type) break;
	}
	if (j!=2) break;
	}
	if (i == ARRAY_LEN(typos)) error_exit("bad -o %.*s", end-type, type);
	if (!field->title) strcpy(field->title, typos[field->which]);
	dlist_add_nomalloc((void )&TT.fields, (void )field);
	}
	}

	// Default fields (also with -f and -l)
	} else {
	unsigned short def = 0x7008;

	if (toys.optflags&FLAG_f) def = 0x783c;
	if (toys.optflags&FLAG_l) def = 0x77ff;

	// order of fields[] matches posix STDOUT section, so add enabled XSI
	// defaults according to bitmask

	for (i=0; def>>i; i++) {
	if (!((def>>i)&1)) continue;

	field = xmalloc(sizeof(struct strawberry)+strlen(typos[i])+1);
	field->which = i;
	field->len = widths[i];
	strcpy(field->title, typos[i]);
	dlist_add_nomalloc((void )&TT.fields, (void )field);
	}
	}
	dlist_terminate(TT.fields);

	// Print padded headers. (Numbers are right justified, everyting else left.
	// time and pcpu count as numbers, tty does not)
	for (field = TT.fields; field; field = field->next) {

	// right justify F, UID, PID, PPID, PRI, NI, ADDR SZ, TIME, ELAPSED, %CPU
	// todo: STIME? C?
	if (!((1<<field->which)&0x523dd)) field->len *= -1;
	printf(" %*s", field->len, field->title);

	// -f prints USER but calls it UID (but "ps -o uid -f" is numeric...?)
	if ((toys.optflags&(FLAG_f\|FLAG_o))==FLAG_f && field->which==2)
	field->which = 22;
	}
	xputc('\n');

	dirtree_read("/proc", do_ps);
	}