/*
 * w - show what logged in users are doing.
 *
 * Almost entirely rewritten from scratch by Charles Blake circa
 * June 1996. Some vestigal traces of the original may exist.
 * That was done in 1993 by Larry Greenfield with some fixes by
 * Michael K. Johnson.
 *
 * Changes by Albert Cahalan, 2002.
 */

#include "c.h"
#include "nls.h"
#include "proc/devname.h"
#include "proc/escape.h"
#include "proc/procps.h"
#include "proc/readproc.h"
#include "proc/sysinfo.h"
#include "proc/version.h"
#include "proc/whattime.h"

#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <limits.h>
#include <locale.h>
#include <locale.h>
#include <pwd.h>
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <termios.h>
#include <time.h>
#include <unistd.h>
#include <utmp.h>

static int ignoreuser = 0;	/* for '-u' */
static int oldstyle = 0;	/* for '-o' */
static proc_t **procs;		/* our snapshot of the process table */

typedef struct utmp utmp_t;

#ifdef W_SHOWFROM
# define FROM_STRING "on"
#else
# define FROM_STRING "off"
#endif

/* Uh... same thing as UT_NAMESIZE */
#define USERSZ (sizeof u->ut_user)

/* Arbitary setting, not too big for the screen, max host size */
#define HOSTSZ 40


/*
 * This routine is careful since some programs leave utmp strings
 * unprintable. Always outputs at least 16 chars padded with
 * spaces on the right if necessary.
 */
static void print_host(const char *restrict host, int len, const int fromlen)
{
	const char *last;
	int width = 0;

	if (len > fromlen)
		len = fromlen;
	last = host + len;
	for (; host < last; host++) {
		if (isprint(*host) && *host != ' ') {
			fputc(*host, stdout);
			++width;
		} else {
			fputc('-', stdout);
			++width;
			break;
		}
	}

	/*
	 * space-fill, and a '-' too if needed to ensure the
	 * column exists
	 */
	while (width++ < fromlen)
		fputc(' ', stdout);
}

/* compact 7 char format for time intervals (belongs in libproc?) */
static void print_time_ival7(time_t t, int centi_sec, FILE * fout)
{
	if ((long)t < (long)0) {
		/* system clock changed? */
		printf("   ?   ");
		return;
	}
	if (oldstyle) {
		if (t >= 48 * 60 * 60)
			/* > 2 days */
			fprintf(fout, _(" %2ludays"), t / (24 * 60 * 60));
		else if (t >= 60 * 60)
			/* > 1 hour */
			fprintf(fout, " %2lu:%02u ", t / (60 * 60),
				(unsigned)((t / 60) % 60));
		else if (t > 60)
			/* > 1 minute */
			fprintf(fout, _(" %2lu:%02um"), t / 60, (unsigned)t % 60);
		else
			fprintf(fout, "       ");
	} else {
		if (t >= 48 * 60 * 60)
			/* 2 days or more */
			fprintf(fout, _(" %2ludays"), t / (24 * 60 * 60));
		else if (t >= 60 * 60)
			/* 1 hour or more */
			fprintf(fout, _(" %2lu:%02um"), t / (60 * 60),
				(unsigned)((t / 60) % 60));
		else if (t > 60)
			/* 1 minute or more */
			fprintf(fout, " %2lu:%02u ", t / 60, (unsigned)t % 60);
		else
			fprintf(fout, _(" %2lu.%02us"), t, centi_sec);
	}
}

/* stat the device file to get an idle time */
static time_t idletime(const char *restrict const tty)
{
	struct stat sbuf;
	if (stat(tty, &sbuf) != 0)
		return 0;
	return time(NULL) - sbuf.st_atime;
}

/* 7 character formatted login time */

static void print_logintime(time_t logt, FILE * fout)
{
        /* FIXME: make use of locale, remember strftime() */
	char weekday[][4] = {
		"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
	};
	char month[][4] = {
		"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug",
		"Sep", "Oct", "Nov", "Dec"
	};
	time_t curt;
	struct tm *logtm, *curtm;
	int today;

	curt = time(NULL);
	curtm = localtime(&curt);
	/* localtime returns a pointer to static memory */
	today = curtm->tm_yday;
	logtm = localtime(&logt);
	if (curt - logt > 12 * 60 * 60 && logtm->tm_yday != today) {
		if (curt - logt > 6 * 24 * 60 * 60)
			fprintf(fout, " %02d%3s%02d", logtm->tm_mday,
				month[logtm->tm_mon], logtm->tm_year % 100);
		else
			fprintf(fout, " %3s%02d  ", weekday[logtm->tm_wday],
				logtm->tm_hour);
	} else {
		fprintf(fout, " %02d:%02d  ", logtm->tm_hour, logtm->tm_min);
	}
}

/*
 * This function scans the process table accumulating total cpu
 * times for any processes "associated" with this login session.
 * It also searches for the "best" process to report as "(w)hat"
 * the user for that login session is doing currently. This the
 * essential core of 'w'.
 */
static const proc_t *getproc(const utmp_t * restrict const u,
			     const char *restrict const tty,
			     unsigned long long *restrict const jcpu,
			     int *restrict const found_utpid)
{
	int line;
	proc_t **pptr = procs;
	const proc_t *best = NULL;
	const proc_t *secondbest = NULL;
	unsigned uid = ~0U;

	*found_utpid = 0;
	if (!ignoreuser) {
		char buf[UT_NAMESIZE + 1];
		/* pointer to static data */
		struct passwd *passwd_data;
		strncpy(buf, u->ut_user, UT_NAMESIZE);
		buf[UT_NAMESIZE] = '\0';
		passwd_data = getpwnam(buf);
		if (!passwd_data)
			return NULL;
		uid = passwd_data->pw_uid;
		/* OK to have passwd_data go out of scope here */
	}
	line = tty_to_dev(tty);
	*jcpu = 0;
	for (; *pptr; pptr++) {
		const proc_t *restrict const tmp = *pptr;
		if (unlikely(tmp->tgid == u->ut_pid)) {
			*found_utpid = 1;
			best = tmp;
		}
		if (tmp->tty != line)
			continue;
		(*jcpu) += tmp->utime + tmp->stime;
		secondbest = tmp;
		/* same time-logic here as for "best" below */
		if (!(secondbest && tmp->start_time <= secondbest->start_time)) {
			secondbest = tmp;
		}
		if (!ignoreuser && uid != tmp->euid && uid != tmp->ruid)
			continue;
		if (tmp->pgrp != tmp->tpgid)
			continue;
		if (best && tmp->start_time <= best->start_time)
			continue;
		best = tmp;
	}
	return best ? best : secondbest;
}

static void showinfo(utmp_t * u, int formtype, int maxcmd, int from,
		     const int userlen, const int fromlen)
{
	unsigned long long jcpu;
	int ut_pid_found;
	unsigned i;
	char uname[USERSZ + 1] = "", tty[5 + sizeof u->ut_line + 1] = "/dev/";
	const proc_t *best;

	for (i = 0; i < sizeof(u->ut_line); i++)
		/* clean up tty if garbled */
		if (isalnum(u->ut_line[i]) || (u->ut_line[i] == '/'))
			tty[i + 5] = u->ut_line[i];
		else
			tty[i + 5] = '\0';

	best = getproc(u, tty + 5, &jcpu, &ut_pid_found);

	/*
	 * just skip if stale utmp entry (i.e. login proc doesn't
	 * exist). If there is a desire a cmdline flag could be
	 * added to optionally show it with a prefix of (stale)
	 * in front of cmd or something like that.
	 */
	if (!ut_pid_found)
		return;

	/* force NUL term for printf */
	strncpy(uname, u->ut_user, USERSZ);

	if (formtype) {
		printf("%-*.*s%-9.8s", userlen + 1, userlen, uname, u->ut_line);
		if (from)
			print_host(u->ut_host, sizeof u->ut_host, fromlen);
		print_logintime(u->ut_time, stdout);
		if (*u->ut_line == ':')
			/* idle unknown for xdm logins */
			printf(" ?xdm? ");
		else
			print_time_ival7(idletime(tty), 0, stdout);
		print_time_ival7(jcpu / Hertz, (jcpu % Hertz) * (100. / Hertz),
				 stdout);
		if (best) {
			unsigned long long pcpu = best->utime + best->stime;
			print_time_ival7(pcpu / Hertz,
					 (pcpu % Hertz) * (100. / Hertz),
					 stdout);
		} else
			printf("   ?   ");
	} else {
		printf("%-*.*s%-9.8s", userlen + 1, userlen, u->ut_user,
		       u->ut_line);
		if (from)
			print_host(u->ut_host, sizeof u->ut_host, fromlen);
		if (*u->ut_line == ':')
			/* idle unknown for xdm logins */
			printf(" ?xdm? ");
		else
			print_time_ival7(idletime(tty), 0, stdout);
	}
	fputs(" ", stdout);
	if (likely(best)) {
		char cmdbuf[512];
		escape_command(cmdbuf, best, sizeof cmdbuf, &maxcmd, ESC_ARGS);
		fputs(cmdbuf, stdout);
	} else {
		printf("-");
	}
	fputc('\n', stdout);
}

static void __attribute__ ((__noreturn__))
    usage(FILE * out)
{
	fputs(USAGE_HEADER, out);
	fprintf(out,
              _(" %s [options]\n"), program_invocation_short_name);
	fputs(USAGE_OPTIONS, out);
	fputs(_(" -h, --no-header     do not print header\n"
		" -u, --no-current    ignore current process username\n"
		" -s, --short         short format\n"
		" -f, --from          show remote hostname field\n"
		" -o, --old-style     old style output\n"), out);
	fputs(USAGE_SEPARATOR, out);
	fputs(_("     --help     display this help and exit\n"), out);
	fputs(USAGE_VERSION, out);
	fprintf(out, USAGE_MAN_TAIL("w(1)"));

	exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
}

int main(int argc, char **argv)
{
	char *user = NULL, *p;
	utmp_t *u;
	struct winsize win;
	int header = 1, longform = 1, from = 1, args, maxcmd = 80, ch;
	int userlen = 8;
	int fromlen = 16;
	char *env_var;

	enum {
		HELP_OPTION = CHAR_MAX + 1
	};

	static const struct option longopts[] = {
		{"no-header", no_argument, NULL, 'h'},
		{"no-current", no_argument, NULL, 'u'},
		{"sort", no_argument, NULL, 's'},
		{"from", no_argument, NULL, 'f'},
		{"old-style", no_argument, NULL, 'o'},
		{"help", no_argument, NULL, HELP_OPTION},
		{"version", no_argument, NULL, 'V'},
		{NULL, 0, NULL, 0}
	};

	program_invocation_name = program_invocation_short_name;
	setlocale (LC_ALL, "");
	bindtextdomain(PACKAGE, LOCALEDIR);
	textdomain(PACKAGE);

#ifndef W_SHOWFROM
	from = 0;
#endif

	while ((ch =
		getopt_long(argc, argv, "husfoV", longopts, NULL)) != -1)
		switch (ch) {
		case 'h':
			header = 0;
			break;
		case 'l':
			longform = 1;
			break;
		case 's':
			longform = 0;
			break;
		case 'f':
			from = !from;
			break;
		case 'V':
			printf(PROCPS_NG_VERSION);
			exit(0);
		case 'u':
			ignoreuser = 1;
			break;
		case 'o':
			oldstyle = 1;
			break;
		case HELP_OPTION:
			usage(stdout);
		default:
			usage(stderr);
		}

	if ((argv[optind]))
		user = (argv[optind]);

	/* Get user field length from environment */
	if ((env_var = getenv("PROCPS_USERLEN")) != NULL) {
		userlen = atoi(env_var);
		if (userlen < 8 || userlen > USERSZ) {
			xwarnx
			    (_("user length environment PROCPS_USERLEN must be between 8 and %d, ignoring\n"),
			     USERSZ);
			userlen = 8;
		}
	}
	/* Get from field length from environment */
	if ((env_var = getenv("PROCPS_FROMLEN")) != NULL) {
		fromlen = atoi(env_var);
		if (fromlen < 8 || fromlen > HOSTSZ) {
			xwarnx
			    (_("from length environment PROCPS_FROMLEN must be between 8 and %d, ignoring\n"),
			     HOSTSZ);
			fromlen = 16;
		}
	}
	if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &win) != -1 && win.ws_col > 0)
		maxcmd = win.ws_col;
	else if (p = getenv("COLUMNS"))
		maxcmd = atoi(p);
	else
		maxcmd = 80;
	if (maxcmd < 71)
		xerrx(EXIT_FAILURE, _("%d column window is too narrow"), maxcmd);

	maxcmd -= 21 + userlen + (from ? fromlen : 0) + (longform ? 20 : 0);
	if (maxcmd < 3)
		xwarnx(_("warning: screen width %d suboptimal"), win.ws_col);

	procs = readproctab(PROC_FILLCOM | PROC_FILLUSR | PROC_FILLSTAT);

	if (header) {
		/* print uptime and headers */
		print_uptime(0);
		/* Translation Hint: Following five uppercase messages are
		 * headers. Try to keep alignment intact.  */
		printf(_("%-*s TTY      "), userlen, _("USER"));
		if (from)
			printf(_("FROM            "));
		if (longform)
			printf(_("  LOGIN@   IDLE   JCPU   PCPU WHAT\n"));
		else
			printf(_("   IDLE WHAT\n"));
	}

	utmpname(UTMP_FILE);
	setutent();
	if (user) {
		for (;;) {
			u = getutent();
			if (unlikely(!u))
				break;
			if (u->ut_type != USER_PROCESS)
				continue;
			if (!strncmp(u->ut_user, user, USERSZ))
				showinfo(u, longform, maxcmd, from, userlen,
					 fromlen);
		}
	} else {
		for (;;) {
			u = getutent();
			if (unlikely(!u))
				break;
			if (u->ut_type != USER_PROCESS)
				continue;
			if (*u->ut_user)
				showinfo(u, longform, maxcmd, from, userlen,
					 fromlen);
		}
	}
	endutent();

	return EXIT_SUCCESS;
}