/*
 * Copyright 1998-2002 by Albert Cahalan; all rights resered.
 * This file may be used subject to the terms and conditions of the
 * GNU Library General Public License Version 2, or any later version
 * at your option, as published by the Free Software Foundation.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Library General Public License for more details.
 */
#include <fcntl.h>
#include <pwd.h>
#include <dirent.h>
#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>

#include "c.h"
#include "nls.h"
#include "xalloc.h"
#include "proc/pwcache.h"
#include "proc/sig.h"
#include "proc/devname.h"
#include "proc/procps.h"	/* char *user_from_uid(uid_t uid) */
#include "proc/version.h"	/* procps_version */

struct run_time_conf_t {
	int fast;
	int interactive;
	int verbose;
	int warnings;
	int noaction;
	int debugging;
};
static int tty_count, uid_count, cmd_count, pid_count;
static int *ttys;
static uid_t *uids;
static const char **cmds;
static int *pids;

#define ENLIST(thing,addme) do{ \
if(!thing##s) thing##s = xmalloc(sizeof(*thing##s)*saved_argc); \
thing##s[thing##_count++] = addme; \
}while(0)

static int my_pid;
static int saved_argc;

static int sig_or_pri;

enum {
	PROG_UNKNOWN,
	PROG_KILL,
	PROG_SKILL,
	PROG_SNICE
};
static int program = PROG_UNKNOWN;

static void display_kill_version(void)
{
	fprintf(stdout, PROCPS_NG_VERSION);
}

/* kill or nice a process */
static void hurt_proc(int tty, int uid, int pid, const char *restrict const cmd,
		      struct run_time_conf_t *run_time)
{
	int failed;
	int saved_errno;
	char dn_buf[1000];
	dev_to_tty(dn_buf, 999, tty, pid, ABBREV_DEV);
	if (run_time->interactive) {
		char buf[8];
		fprintf(stderr, "%-8s %-8s %5d %-16.16s   ? ",
			(char *)dn_buf, user_from_uid(uid), pid, cmd);
		if (!fgets(buf, 7, stdin)) {
			printf("\n");
			exit(0);
		}
		if (*buf != 'y' && *buf != 'Y')
			return;
	}
	/* do the actual work */
	if (program == PROG_SKILL)
		failed = kill(pid, sig_or_pri);
	else
		failed = setpriority(PRIO_PROCESS, pid, sig_or_pri);
	saved_errno = errno;
	if (run_time->warnings && failed) {
		fprintf(stderr, "%-8s %-8s %5d %-16.16s   ",
			(char *)dn_buf, user_from_uid(uid), pid, cmd);
		errno = saved_errno;
		perror("");
		return;
	}
	if (run_time->interactive)
		return;
	if (run_time->verbose) {
		printf("%-8s %-8s %5d %-16.16s\n",
		       (char *)dn_buf, user_from_uid(uid), pid, cmd);
		return;
	}
	if (run_time->noaction) {
		printf("%d\n", pid);
		return;
	}
}

/* check one process */
static void check_proc(int pid, struct run_time_conf_t *run_time)
{
	char buf[128];
	struct stat statbuf;
	char *tmp;
	int tty;
	int fd;
	int i;
	if (pid == my_pid)
		return;
	/* pid (cmd) state ppid pgrp session tty */
	sprintf(buf, "/proc/%d/stat", pid);
	fd = open(buf, O_RDONLY);
	if (fd == -1) {
		/* process exited maybe */
		if (pids && run_time->warnings)
			printf(_("WARNING: process %d could not be found.\n"),
			       pid);
		return;
	}
	fstat(fd, &statbuf);
	if (uids) {
		/* check the EUID */
		i = uid_count;
		while (i--)
			if (uids[i] == statbuf.st_uid)
				break;
		if (i == -1)
			goto closure;
	}
	read(fd, buf, 128);
	buf[127] = '\0';
	tmp = strrchr(buf, ')');
	*tmp++ = '\0';
	i = 5;
	while (i--)
		while (*tmp++ != ' ')
			/* scan to find tty */ ;
	tty = atoi(tmp);
	if (ttys) {
		i = tty_count;
		while (i--)
			if (ttys[i] == tty)
				break;
		if (i == -1)
			goto closure;
	}
	tmp = strchr(buf, '(') + 1;
	if (cmds) {
		i = cmd_count;
		/* fast comparison trick -- useful? */
		while (i--)
			if (cmds[i][0] == *tmp && !strcmp(cmds[i], tmp))
				break;
		if (i == -1)
			goto closure;
	}
	/* This is where we kill/nice something. */
	/* for debugging purposes?
	fprintf(stderr, "PID %d, UID %d, TTY %d,%d, COMM %s\n",
		pid, statbuf.st_uid, tty >> 8, tty & 0xf, tmp);
	*/
	hurt_proc(tty, statbuf.st_uid, pid, tmp, run_time);
 closure:
	/* kill/nice _first_ to avoid PID reuse */
	close(fd);
}

/* debug function */
static void show_lists(void)
{
	int i;

	fprintf(stderr, _("%d TTY: "), tty_count);
	if (ttys) {
		i = tty_count;
		while (i--) {
			fprintf(stderr, "%d,%d%c", (ttys[i] >> 8) & 0xff,
				ttys[i] & 0xff, i ? ' ' : '\n');
		}
	} else
		fprintf(stderr, "\n");

	fprintf(stderr, _("%d UID: "), uid_count);
	if (uids) {
		i = uid_count;
		while (i--)
			fprintf(stderr, "%d%c", uids[i], i ? ' ' : '\n');
	} else
		fprintf(stderr, "\n");

	fprintf(stderr, _("%d PID: "), pid_count);
	if (pids) {
		i = pid_count;
		while (i--)
			fprintf(stderr, "%d%c", pids[i], i ? ' ' : '\n');
	} else
		fprintf(stderr, "\n");

	fprintf(stderr, _("%d CMD: "), cmd_count);
	if (cmds) {
		i = cmd_count;
		while (i--)
			fprintf(stderr, "%s%c", cmds[i], i ? ' ' : '\n');
	} else
		fprintf(stderr, "\n");
}

/* iterate over all PIDs */
static void iterate(struct run_time_conf_t *run_time)
{
	int pid;
	DIR *d;
	struct dirent *de;
	if (pids) {
		pid = pid_count;
		while (pid--)
			check_proc(pids[pid], run_time);
		return;
	}
#if 0
	/* could setuid() and kill -1 to have the kernel wipe out a user */
	if (!ttys && !cmds && !pids && !run_time->interactive) {
	}
#endif
	d = opendir("/proc");
	if (!d) {
		perror("/proc");
		exit(1);
	}
	while ((de = readdir(d))) {
		if (de->d_name[0] > '9')
			continue;
		if (de->d_name[0] < '1')
			continue;
		pid = atoi(de->d_name);
		if (pid)
			check_proc(pid, run_time);
	}
	closedir(d);
}

/* kill help */
static void __attribute__ ((__noreturn__)) kill_usage(void)
{
	fputs(USAGE_HEADER, stderr);
	fprintf(stderr,
		" %s [options] <pid> [...]\n", program_invocation_short_name);
	fputs(USAGE_OPTIONS, stderr);
	fputs(_("  <pid> [...]    send SIGTERM to every <pid> listed\n"), stderr);
	fputs(_("  -<signal>      specify the <signal> to be sent\n"), stderr);
	fputs(_("  -s <signal>    specify the <signal> to be sent\n"), stderr);
	fputs(_("  -l             list all signal names\n"), stderr);
	fputs(_("  -L             list all signal names in a nice table\n"), stderr);
	fputs(_("  -l <signal>    convert between signal numbers and names\n"), stderr);
	fputs(USAGE_SEPARATOR, stderr);
	fprintf(stderr, USAGE_MAN_TAIL("skill(1)"));
	exit(1);
}

/* skill and snice help */
static void __attribute__ ((__noreturn__)) skillsnice_usage(void)
{
	fputs(USAGE_HEADER, stderr);

	if (program == PROG_SKILL) {
		fprintf(stderr,
			" %s [signal] [options] <expression>\n",
			program_invocation_short_name);
	} else {
		fprintf(stderr,
			" %s [new priority] [options] <expression>\n",
			program_invocation_short_name);
	}
	fputs(USAGE_OPTIONS, stderr);
	fputs(_(" -f             fast mode (not implemented)\n"), stderr);
	fputs(_(" -i             interactive\n"), stderr);
	fputs(_(" -l             list all signal names\n"), stderr);
	fputs(_(" -L             list all signal names in a nice table\n"),
	      stderr);
	fputs(_(" -n             no action\n"), stderr);
	fputs(_(" -v             explain what is being done\n"), stderr);
	fputs(_(" -w             enable warnings (not implemented)\n"), stderr);
	fputs(USAGE_VERSION, stderr);
	fputs(_("\n"), stderr);
	fputs(_("Expression can be: terminal, user, pid, command.\n"), stderr);
	fputs(_("The options below may be used to ensure correct interpretation.\n"), stderr);
	fputs(_(" -c <command>   expression is a command name\n"), stderr);
	fputs(_(" -p <pid>       expression is a process id number\n"), stderr);
	fputs(_(" -t <tty>       expression is a terminal\n"), stderr);
	fputs(_(" -u <username>  expression is a username\n"), stderr);
	if (program == PROG_SKILL) {
		fprintf(stderr,
			_("\n"
			  "The default signal is TERM. Use -l or -L to list available signals.\n"
			  "Particularly useful signals include HUP, INT, KILL, STOP, CONT, and 0.\n"
			  "Alternate signals may be specified in three ways: -SIGKILL -KILL -9\n"));
		fprintf(stderr, USAGE_MAN_TAIL("skill(1)"));
	} else {
		fprintf(stderr,
			_("\n"
			  "The default priority is +4. (snice +4 ...)\n"
			  "Priority numbers range from +20 (slowest) to -20 (fastest).\n"
			  "Negative priority numbers are restricted to administrative users.\n"));
		fprintf(stderr, USAGE_MAN_TAIL("snice(1)"));
	}
	exit(1);
}

/* kill */
static void __attribute__ ((__noreturn__))
kill_main(int argc,  const char *restrict const *restrict argv,
          struct run_time_conf_t *run_time)
{
	const char *sigptr;
	int signo = SIGTERM;
	int exitvalue = 0;
	if (argc < 2)
		kill_usage();
	if (!strcmp(argv[1], "-V") || !strcmp(argv[1], "--version")) {
		display_kill_version();
		exit(0);
	}
	if (argv[1][0] != '-') {
		argv++;
		argc--;
		goto no_more_args;
	}

	/* The -l option prints out signal names. */
	if (argv[1][1] == 'l' && argv[1][2] == '\0') {
		if (argc == 2) {
			unix_print_signals();
			exit(0);
		}
		/* at this point, argc must be 3 or more */
		if (argc > 128 || argv[2][0] == '-')
			kill_usage();
		exit(print_given_signals(argc - 2, argv + 2, 80));
	}

	/* The -L option prints out signal names in a nice table. */
	if (argv[1][1] == 'L' && argv[1][2] == '\0') {
		if (argc == 2) {
			pretty_print_signals();
			exit(0);
		}
		kill_usage();
	}
	if (argv[1][1] == '-' && argv[1][2] == '\0') {
		argv += 2;
		argc -= 2;
		goto no_more_args;
	}
	if (argv[1][1] == '-')
		kill_usage();	/* likely --help */
	// FIXME: "kill -sWINCH $$" not handled
	if (argv[1][2] == '\0' && (argv[1][1] == 's' || argv[1][1] == 'n')) {
		sigptr = argv[2];
		argv += 3;
		argc -= 3;
	} else {
		sigptr = argv[1] + 1;
		argv += 2;
		argc -= 2;
	}
	signo = signal_name_to_number(sigptr);
	if (signo < 0) {
		fprintf(stderr, _("ERROR: unknown signal name \"%s\".\n"),
			sigptr);
		kill_usage();
	}
 no_more_args:
	if (!argc)
		kill_usage();	/* nothing to kill? */
	while (argc--) {
		long pid;
		char *endp;
		pid = strtol(argv[argc], &endp, 10);
		if (!*endp && (endp != argv[argc])) {
			if (!kill((pid_t) pid, signo))
				continue;
			/*
			 * The UNIX standard contradicts itself. If at least
			 * one process is matched for each PID (as if
			 * processes could share PID!) and "the specified
			 * signal was successfully processed" (the systcall
			 * returned zero?) for at least one of those
			 * processes, then we must exit with zero.  Note that
			 * an error might have also occured.  The standard
			 * says we return non-zero if an error occurs.  Thus
			 * if killing two processes gives 0 for one and EPERM
			 * for the other, we are required to return both zero
			 * and non-zero.  Quantum kill???
			 */
			perror("kill");
			exitvalue = 1;
			continue;
		}
		fprintf(stderr, _("ERROR: garbage process ID \"%s\".\n"),
			argv[argc]);
		kill_usage();
	}
	exit(exitvalue);
}
#if 0
static void _skillsnice_usage(int line)
{
	fprintf(stderr, _("Something at line %d.\n"), line);
	skillsnice_usage();
}

#define skillsnice_usage() _skillsnice_usage(__LINE__)
#endif

#define NEXTARG (argc?( argc--, ((argptr=*++argv)) ):NULL)

/* common skill/snice argument parsing code */

#define NO_PRI_VAL ((int)0xdeafbeef)
static void skillsnice_parse(int argc,
			     const char *restrict const *restrict argv,
			     struct run_time_conf_t *run_time)
{
	int signo = -1;
	int prino = NO_PRI_VAL;
	int force = 0;
	int num_found = 0;
	const char *restrict argptr;
	if (argc < 2)
		skillsnice_usage();
	if (argc == 2 && argv[1][0] == '-') {
		if (!strcmp(argv[1], "-L")) {
			pretty_print_signals();
			exit(0);
		}
		if (!strcmp(argv[1], "-l")) {
			unix_print_signals();
			exit(0);
		}
		if (!strcmp(argv[1], "-V") || !strcmp(argv[1], "--version")) {
			display_kill_version();
			exit(0);
		}
		skillsnice_usage();
	}
	NEXTARG;
	/* Time for serious parsing. What does "skill -int 123 456" mean? */
	while (argc) {
		if (force && !num_found) {
			/* if forced, _must_ find something */
			fprintf(stderr, _("ERROR: -%c used with bad data.\n"),
				force);
			skillsnice_usage();
		}
		force = 0;
		if (program == PROG_SKILL && signo < 0 && *argptr == '-') {
			signo = signal_name_to_number(argptr + 1);
			if (signo >= 0) {
				/* found a signal */
				if (!NEXTARG)
					break;
				continue;
			}
		}
		if (program == PROG_SNICE && prino == NO_PRI_VAL
		    && (*argptr == '+' || *argptr == '-') && argptr[1]) {
			long val;
			char *endp;
			val = strtol(argptr, &endp, 10);
			if (!*endp && val <= 999 && val >= -999) {
				prino = val;
				if (!NEXTARG)
					break;
				continue;
			}
		}
		/* If '-' found, collect any flags. (but lone "-" is a tty) */
		if (*argptr == '-' && argptr[1]) {
			argptr++;
			do {
				switch ((force = *argptr++)) {
				default:
					skillsnice_usage();
				case 't':
				case 'u':
				case 'p':
				case 'c':
					if (!*argptr) {
						/* nothing left here, *argptr is '\0' */
						if (!NEXTARG) {
							fprintf(stderr,
								_
								("ERROR: -%c with nothing after it.\n"),
								force);
							skillsnice_usage();
						}
					}
					goto selection_collection;
				case 'f':
					run_time->fast++;
					break;
				case 'i':
					run_time->interactive++;
					break;
				case 'v':
					run_time->verbose++;
					break;
				case 'w':
					run_time->warnings++;
					break;
				case 'n':
					run_time->noaction++;
					break;
				case 0:
					NEXTARG;
					/*
					 * If no more arguments, all the
					 * "if(argc)..." tests will fail and
					 * the big loop will exit.
					 */
				} /* END OF SWITCH */
			} while (force);
		} /* END OF IF */
 selection_collection:
		num_found = 0;	/* we should find at least one thing */
		switch (force) {
		/* fall through each data type */
		default:
			skillsnice_usage();
		case 0:		/* not forced */
			if (argptr && argptr[0] == '-')
				/* its the next argument not a parameter */
				continue;
		case 't':
			if (argc) {
				struct stat sbuf;
				char path[32];
				if (!argptr)
					/* Huh? Maybe "skill -t ''". */
					skillsnice_usage();
				snprintf(path, 32, "/dev/%s", argptr);
				if (stat(path, &sbuf) >= 0
				    && S_ISCHR(sbuf.st_mode)) {
					num_found++;
					ENLIST(tty, sbuf.st_rdev);
					if (!NEXTARG)
						break;
				} else if (!(argptr[1])) {
					/* if only 1 character */
					switch (*argptr) {
					default:
						if (stat(argptr, &sbuf) < 0)
							/* the shell eats '?' */
							break;
					case '-':
					case '?':
						num_found++;
						ENLIST(tty, 0);
						if (!NEXTARG)
							break;
					}
				}
			}
			if (force)
				continue;
		case 'u':
			if (argc) {
				struct passwd *passwd_data;
				passwd_data = getpwnam(argptr);
				if (passwd_data) {
					num_found++;
					ENLIST(uid, passwd_data->pw_uid);
					if (!NEXTARG)
						break;
				}
			}
			if (force)
				continue;
		case 'p':
			if (argc && *argptr >= '0' && *argptr <= '9') {
				char *endp;
				int num;
				num = strtol(argptr, &endp, 0);
				if (*endp == '\0') {
					num_found++;
					ENLIST(pid, num);
					if (!NEXTARG)
						break;
				}
			}
			if (force)
				continue;
			if (num_found)
				/* could still be an option */
				continue;
		case 'c':
			if (argc) {
				num_found++;
				ENLIST(cmd, argptr);
				if (!NEXTARG)
					break;
			}
		} /* END OF SWITCH */
	} /* END OF WHILE */
	/* No more arguments to process. Must sanity check. */
	if (!tty_count && !uid_count && !cmd_count && !pid_count) {
		fprintf(stderr, _("ERROR: no process selection criteria.\n"));
		skillsnice_usage();
	}
	if ((run_time->fast | run_time->interactive | run_time->verbose | run_time->warnings | run_time->noaction) & ~1) {
		fprintf(stderr,
			_("ERROR: general flags may not be repeated.\n"));
		skillsnice_usage();
	}
	if (run_time->interactive && (run_time->verbose | run_time->fast | run_time->noaction)) {
		fprintf(stderr,
			_("ERROR: -i makes no sense with -v, -f, and -n.\n"));
		skillsnice_usage();
	}
	if (run_time->verbose && (run_time->interactive | run_time->fast)) {
		fprintf(stderr,
			_("ERROR: -v makes no sense with -i and -f.\n"));
		skillsnice_usage();
	}
	/* OK, set up defaults */
	if (prino == NO_PRI_VAL)
		prino = 4;
	if (signo < 0)
		signo = SIGTERM;
	if (run_time->noaction) {
		program = PROG_SKILL;
		/* harmless */
		signo = 0;
	}
	if (program == PROG_SKILL)
		sig_or_pri = signo;
	else
		sig_or_pri = prino;
}

/* main body */
int main(int argc, const char *argv[])
{
	struct run_time_conf_t run_time;
	memset(&run_time, 0, sizeof(struct run_time_conf_t));
	my_pid = getpid();

	if (strcmp(program_invocation_short_name, "kill") == 0 ||
	    strcmp(program_invocation_short_name, "lt-kill") == 0)
		program = PROG_KILL;
	else if (strcmp(program_invocation_short_name, "skill") == 0 ||
		 strcmp(program_invocation_short_name, "lt-skill") == 0)
		program = PROG_SKILL;
	else if (strcmp(program_invocation_short_name, "snice") == 0 ||
		 strcmp(program_invocation_short_name, "lt-snice") == 0)
		program = PROG_SNICE;

	switch (program) {
	case PROG_SNICE:
	case PROG_SKILL:
		setpriority(PRIO_PROCESS, my_pid, -20);
		skillsnice_parse(argc, argv, &run_time);
		if (run_time.debugging)
			show_lists();
		iterate(&run_time);
		break;
	case PROG_KILL:
		kill_main(argc, argv, &run_time);
		break;
	default:
		fprintf(stderr, _("skill: \"%s\" is not support\n"),
			program_invocation_short_name);
		fprintf(stderr, USAGE_MAN_TAIL("skill(1)"));
		return 1;
	}
	return 0;
}