xref: /src/usr.bin/pkill/pkill.c

/*	$NetBSD: pkill.c,v 1.34 2024/10/07 06:14:05 roy Exp $	*/

/*-
 * Copyright (c) 2002, 2022 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Andrew Doran.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: pkill.c,v 1.34 2024/10/07 06:14:05 roy Exp $");
#endif /* !lint */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/sysctl.h>
#include <sys/proc.h>
#include <sys/queue.h>
#include <sys/resource.h>
#include <sys/stat.h>

#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <regex.h>
#include <ctype.h>
#include <kvm.h>
#include <err.h>
#include <fcntl.h>
#include <pwd.h>
#include <grp.h>
#include <errno.h>
#include <paths.h>

#define	STATUS_MATCH	0
#define	STATUS_NOMATCH	1
#define	STATUS_BADUSAGE	2
#define	STATUS_ERROR	3

#define	MIN_PID		5
#define	MAX_PID		30000 // XXX PID_MAX from sys/proc.h?

enum listtype {
	LT_GENERIC,
	LT_USER,
	LT_GROUP,
	LT_TTY,
	LT_PGRP,
	LT_SID
};

struct list {
	SLIST_ENTRY(list) li_chain;
	long	li_number;
};

SLIST_HEAD(listhead, list);

static struct kinfo_proc2	*plist;
static char	*selected;
static const char *delim = "\n";
static int	nproc;
static int	pgrep;
static int	prenice;
static int	signum = SIGTERM;
static int	nicenum;
static int	newest;
static int	quiet;
static int	inverse;
static int	longfmt;
static int	matchargs;
static int	fullmatch;
static int	cflags = REG_EXTENDED;
static kvm_t	*kd;
static pid_t	mypid;

static struct listhead euidlist = SLIST_HEAD_INITIALIZER(list);
static struct listhead ruidlist = SLIST_HEAD_INITIALIZER(list);
static struct listhead rgidlist = SLIST_HEAD_INITIALIZER(list);
static struct listhead pgrplist = SLIST_HEAD_INITIALIZER(list);
static struct listhead ppidlist = SLIST_HEAD_INITIALIZER(list);
static struct listhead tdevlist = SLIST_HEAD_INITIALIZER(list);
static struct listhead sidlist = SLIST_HEAD_INITIALIZER(list);

static void	usage(void) __dead;
static int	killact(const struct kinfo_proc2 *);
static int	reniceact(const struct kinfo_proc2 *);
static int	grepact(const struct kinfo_proc2 *);
static void	makelist(struct listhead *, enum listtype, char *);
static int	takepid(const char *, int);

int
main(int argc, char **argv)
{
  	char buf[_POSIX2_LINE_MAX], **pargv, *q, *pidfile = NULL;
	int i, j, ch, bestidx, rv, criteria, pidfromfile, pidfilelock = 0;
	int (*action)(const struct kinfo_proc2 *);
	const struct kinfo_proc2 *kp;
	struct list *li;
	const char *p;
	u_int32_t bestsec, bestusec;
	regex_t reg;
	regmatch_t regmatch;

	setprogname(argv[0]);

	if (strcmp(getprogname(), "pgrep") == 0) {
		action = grepact;
		pgrep = 1;
	} else if (strcmp(getprogname(), "prenice") == 0) {
		action = reniceact;
		prenice = 1;
	} else {
		action = killact;
		p = argv[1];

		if (argc > 1 && p[0] == '-') {
			p++;
			i = (int)strtol(p, &q, 10);
			if (*q == '\0') {
				signum = i;
				argv++;
				argc--;
			} else {
				if (strncasecmp(p, "sig", 3) == 0)
					p += 3;
				for (i = 1; i < NSIG; i++)
					if (strcasecmp(sys_signame[i], p) == 0)
						break;
				if (i != NSIG) {
					signum = i;
					argv++;
					argc--;
				}
			}
		}
	}

	criteria = 0;

	if (prenice) {
		if (argc < 2)
			usage();

		if (strcmp(argv[1], "-l") == 0) {
			longfmt = 1;
			argv++;
			argc--;
		}

		if (argc < 2)
			usage();

		p = argv[1];

		i = (int)strtol(p, &q, 10);
		if (*q == '\0') {
			nicenum = i;
			argv++;
			argc--;
		} else
			usage();
	} else {
		while ((ch = getopt(argc, argv, "F:G:LP:U:d:fg:ilnqs:t:u:vx")) != -1)
			switch (ch) {
			case 'F':
				pidfile = optarg;
				criteria = 1;
				break;
			case 'G':
				makelist(&rgidlist, LT_GROUP, optarg);
				criteria = 1;
				break;
			case 'L':
				pidfilelock = 1;
				break;
			case 'P':
				makelist(&ppidlist, LT_GENERIC, optarg);
				criteria = 1;
				break;
			case 'U':
				makelist(&ruidlist, LT_USER, optarg);
				criteria = 1;
				break;
			case 'd':
				if (!pgrep)
					usage();
				delim = optarg;
				break;
			case 'f':
				matchargs = 1;
				break;
			case 'g':
				makelist(&pgrplist, LT_PGRP, optarg);
				criteria = 1;
				break;
			case 'i':
				cflags |= REG_ICASE;
				break;
			case 'l':
				longfmt = 1;
				break;
			case 'n':
				newest = 1;
				criteria = 1;
				break;
			case 'q':
				if (!pgrep)
					usage();
				quiet = 1;
				break;
			case 's':
				makelist(&sidlist, LT_SID, optarg);
				criteria = 1;
				break;
			case 't':
				makelist(&tdevlist, LT_TTY, optarg);
				criteria = 1;
				break;
			case 'u':
				makelist(&euidlist, LT_USER, optarg);
				criteria = 1;
				break;
			case 'v':
				inverse = 1;
				break;
			case 'x':
				fullmatch = 1;
				break;
			default:
				usage();
				/* NOTREACHED */
			}
		argc -= optind;
		argv += optind;
	}

	if (argc != 0)
		criteria = 1;
	if (!criteria)
		usage();
	if (pidfile != NULL)
		pidfromfile = takepid(pidfile, pidfilelock);
	else {
		if (pidfilelock) {
			errx(STATUS_ERROR,
			    "Option -L doesn't make sense without -F");
		}
		pidfromfile = -1;
	}

	mypid = getpid();

	/*
	 * Retrieve the list of running processes from the kernel.
	 */
	kd = kvm_openfiles(NULL, NULL, NULL, KVM_NO_FILES, buf);
	if (kd == NULL)
		errx(STATUS_ERROR, "Cannot open kernel files (%s)", buf);

	plist = kvm_getproc2(kd, KERN_PROC_ALL, 0, sizeof(*plist), &nproc);
	if (plist == NULL)
		errx(STATUS_ERROR, "Cannot get process list (%s)",
		    kvm_geterr(kd));

	/*
	 * Allocate memory which will be used to keep track of the
	 * selection.
	 */
	if ((selected = calloc(sizeof(*selected), (size_t)nproc)) == NULL)
		err(STATUS_ERROR, "Cannot allocate memory for %d processes",
		    nproc);

	/*
	 * Refine the selection.
	 */
	for (; *argv != NULL; argv++) {
		if ((rv = regcomp(&reg, *argv, cflags)) != 0) {
			(void)regerror(rv, &reg, buf, sizeof(buf));
			errx(STATUS_BADUSAGE,
			    "Cannot compile regular expression `%s' (%s)",
			    *argv, buf);
		}

		for (i = 0, kp = plist; i < nproc; i++, kp++) {
			if ((kp->p_flag & P_SYSTEM) != 0 || kp->p_pid == mypid)
				continue;

			if ((pargv = kvm_getargv2(kd, kp, 0)) == NULL)
				continue;
			if (matchargs) {

				j = 0;
				while (j < (int)sizeof(buf) && *pargv != NULL) {
					j += snprintf(buf + j, sizeof(buf) - j,
					    pargv[1] != NULL ? "%s " : "%s",
					    pargv[0]);
					pargv++;
				}
			} else if (pargv[0] != NULL)
				strlcpy(buf, pargv[0], sizeof(buf));
			else
				strlcpy(buf, kp->p_comm, sizeof(buf));

			rv = regexec(&reg, buf, 1, &regmatch, 0);
			if (rv == 0) {
				if (fullmatch) {
					if (regmatch.rm_so == 0 &&
					    regmatch.rm_eo ==
					    (regoff_t)strlen(buf))
						selected[i] = 1;
				} else
					selected[i] = 1;
			} else if (rv != REG_NOMATCH) {
				(void)regerror(rv, &reg, buf, sizeof(buf));
				errx(STATUS_ERROR,
				    "Regular expression evaluation error (%s)",
				    buf);
			}
		}

		regfree(&reg);
	}

	for (i = 0, kp = plist; i < nproc; i++, kp++) {
		if ((kp->p_flag & P_SYSTEM) != 0)
			continue;

		if (pidfromfile >= 0 && kp->p_pid != pidfromfile) {
			selected[i] = 0;
			continue;
		}

		SLIST_FOREACH(li, &ruidlist, li_chain)
			if (kp->p_ruid == (uid_t)li->li_number)
				break;
		if (SLIST_FIRST(&ruidlist) != NULL && li == NULL) {
			selected[i] = 0;
			continue;
		}

		SLIST_FOREACH(li, &rgidlist, li_chain)
			if (kp->p_rgid == (gid_t)li->li_number)
				break;
		if (SLIST_FIRST(&rgidlist) != NULL && li == NULL) {
			selected[i] = 0;
			continue;
		}

		SLIST_FOREACH(li, &euidlist, li_chain)
			if (kp->p_uid == (uid_t)li->li_number)
				break;
		if (SLIST_FIRST(&euidlist) != NULL && li == NULL) {
			selected[i] = 0;
			continue;
		}

		SLIST_FOREACH(li, &ppidlist, li_chain)
			if ((uid_t)kp->p_ppid == (uid_t)li->li_number)
				break;
		if (SLIST_FIRST(&ppidlist) != NULL && li == NULL) {
			selected[i] = 0;
			continue;
		}

		SLIST_FOREACH(li, &pgrplist, li_chain)
			if (kp->p__pgid == (pid_t)li->li_number)
				break;
		if (SLIST_FIRST(&pgrplist) != NULL && li == NULL) {
			selected[i] = 0;
			continue;
		}

		SLIST_FOREACH(li, &tdevlist, li_chain) {
			if (li->li_number == -1 &&
			    (kp->p_flag & P_CONTROLT) == 0)
				break;
			if (kp->p_tdev == (uid_t)li->li_number)
				break;
		}
		if (SLIST_FIRST(&tdevlist) != NULL && li == NULL) {
			selected[i] = 0;
			continue;
		}

		SLIST_FOREACH(li, &sidlist, li_chain)
			if (kp->p_sid == (pid_t)li->li_number)
				break;
		if (SLIST_FIRST(&sidlist) != NULL && li == NULL) {
			selected[i] = 0;
			continue;
		}

		if (argc == 0)
			selected[i] = 1;
	}

	if (newest) {
		bestsec = 0;
		bestusec = 0;
		bestidx = -1;

		for (i = 0, kp = plist; i < nproc; i++, kp++) {
			if (!selected[i])
				continue;

			if (kp->p_ustart_sec > bestsec ||
			    (kp->p_ustart_sec == bestsec
			    && kp->p_ustart_usec > bestusec)) {
			    	bestsec = kp->p_ustart_sec;
			    	bestusec = kp->p_ustart_usec;
				bestidx = i;
			}
		}

		(void)memset(selected, 0, (size_t)nproc);
		if (bestidx != -1)
			selected[bestidx] = 1;
	}

	/*
	 * Take the appropriate action for each matched process, if any.
	 */
	for (i = 0, rv = 0, kp = plist; i < nproc; i++, kp++) {
		if (kp->p_pid == mypid)
			continue;
		if (selected[i]) {
			if (inverse)
				continue;
		} else if (!inverse)
			continue;

		if ((kp->p_flag & P_SYSTEM) != 0)
			continue;

		rv |= (*action)(kp);
	}

	return rv ? STATUS_MATCH : STATUS_NOMATCH;
}

static void
usage(void)
{
	const char *ustr;

	if (prenice)
		fprintf(stderr, "Usage: %s [-l] priority pattern ...\n",
		    getprogname());
	else {
		if (pgrep)
			ustr = "[-Lfilnqvx] [-d delim]";
		else
			ustr = "[-signal] [-Lfilnvx]";

		(void)fprintf(stderr,
		    "Usage: %s %s [-F pidfile] [-G gid] [-g pgrp] [-P ppid] [-s sid] "
			   "[-t tty]\n"
		    "             [-U uid] [-u euid] pattern ...\n",
			      getprogname(), ustr);
	}

	exit(STATUS_BADUSAGE);
}

static int
killact(const struct kinfo_proc2 *kp)
{
	if (longfmt)
		grepact(kp);
	if (kill(kp->p_pid, signum) == -1) {

		/*
		 * Check for ESRCH, which indicates that the process
		 * disappeared between us matching it and us
		 * signalling it; don't issue a warning about it.
		 */
		if (errno != ESRCH)
			warn("signalling pid %d", (int)kp->p_pid);

		/*
		 * Return 0 to indicate that the process should not be
		 * considered a match, since we didn't actually get to
		 * signal it.
		 */
		return 0;
	}

	return 1;
}

static int
reniceact(const struct kinfo_proc2 *kp)
{
	int oldprio;

	if (longfmt)
		grepact(kp);

	errno = 0;
	if ((oldprio = getpriority(PRIO_PROCESS, kp->p_pid)) == -1 &&
	    errno != 0) {
		warn("%d: getpriority", kp->p_pid);
		return 0;
	}

	if (setpriority(PRIO_PROCESS, kp->p_pid, nicenum) == -1) {
		warn("%d: setpriority", kp->p_pid);
		return 0;
	}

	(void)printf("%d: old priority %d, new priority %d\n",
	    kp->p_pid, oldprio, nicenum);

	return 1;
}

static int
grepact(const struct kinfo_proc2 *kp)
{
	char **argv;

	if (quiet)
		return 1;

	if (longfmt && matchargs) {

		/*
		 * If kvm_getargv2() failed the process has probably
		 * disappeared.  Return 0 to indicate that the process
		 * should not be considered a match, since we are no
		 * longer in a position to output it as a match.
		 */
		if ((argv = kvm_getargv2(kd, kp, 0)) == NULL)
			return 0;

		(void)printf("%d ", (int)kp->p_pid);
		for (; *argv != NULL; argv++) {
			(void)printf("%s", *argv);
			if (argv[1] != NULL)
				(void)putchar(' ');
		}
	} else if (longfmt)
		(void)printf("%d %s", (int)kp->p_pid, kp->p_comm);
	else
		(void)printf("%d", (int)kp->p_pid);

	(void)printf("%s", delim);

	return 1;
}

static void
makelist(struct listhead *head, enum listtype type, char *src)
{
	struct list *li;
	struct passwd *pw;
	struct group *gr;
	struct stat st;
	char *sp, *ep, buf[MAXPATHLEN];
	const char *p;
	int empty;
	const char *prefix = _PATH_DEV;

	empty = 1;

	while ((sp = strsep(&src, ",")) != NULL) {
		if (*sp == '\0')
			usage();

		if ((li = malloc(sizeof(*li))) == NULL)
			err(STATUS_ERROR, "Cannot allocate %zu bytes",
			    sizeof(*li));
		SLIST_INSERT_HEAD(head, li, li_chain);
		empty = 0;

		li->li_number = (uid_t)strtol(sp, &ep, 0);
		if (*ep == '\0' && type != LT_TTY) {
			switch (type) {
			case LT_PGRP:
				if (li->li_number == 0)
					li->li_number = getpgrp();
				break;
			case LT_SID:
				if (li->li_number == 0)
					li->li_number = getsid(mypid);
				break;
			default:
				break;
			}
			continue;
		}

		switch (type) {
		case LT_USER:
			if ((pw = getpwnam(sp)) == NULL)
				errx(STATUS_BADUSAGE, "Unknown user `%s'",
				    sp);
			li->li_number = pw->pw_uid;
			break;
		case LT_GROUP:
			if ((gr = getgrnam(sp)) == NULL)
				errx(STATUS_BADUSAGE, "Unknown group `%s'",
				    sp);
			li->li_number = gr->gr_gid;
			break;
		case LT_TTY:
			p = sp;
			if (*sp == '/')
				prefix = "";
			else if (strcmp(sp, "-") == 0) {
				li->li_number = -1;
				break;
			} else if (strcmp(sp, "co") == 0)
				p = "console";
			else if (strncmp(sp, "tty", 3) == 0)
				/* all set */;
			else if (strncmp(sp, "pts/", 4) == 0)
				/* all set */;
			else if (*ep != '\0' || (strlen(sp) == 2 && *sp == '0'))
				prefix = _PATH_TTY;
			else
				prefix = _PATH_DEV_PTS;

			(void)snprintf(buf, sizeof(buf), "%s%s", prefix, p);

			if (stat(buf, &st) == -1) {
				if (errno == ENOENT)
					errx(STATUS_BADUSAGE,
					    "No such tty: `%s'", buf);
				err(STATUS_ERROR, "Cannot access `%s'", buf);
			}

			if ((st.st_mode & S_IFCHR) == 0)
				errx(STATUS_BADUSAGE, "Not a tty: `%s'", buf);

			li->li_number = st.st_rdev;
			break;
		default:
			usage();
		}
	}

	if (empty)
		usage();
}

static int
takepid(const char *pidfile, int pidfilelock)
{
	char *endp, line[BUFSIZ];
	FILE *fh;
	long rval;

	fh = fopen(pidfile, "r");
	if (fh == NULL)
		err(STATUS_ERROR, "Cannot open pidfile `%s'", pidfile);

	if (pidfilelock) {
		/*
		 * If we can lock pidfile, this means that daemon is not
		 * running, so would be better not to kill some random process.
		 */
		if (flock(fileno(fh), LOCK_EX | LOCK_NB) == 0) {
			(void)fclose(fh);
			errx(STATUS_ERROR, "File '%s' can be locked", pidfile);
		} else {
			if (errno != EWOULDBLOCK) {
				errx(STATUS_ERROR,
				    "Error while locking file '%s'", pidfile);
			}
		}
	}

	if (fgets(line, sizeof(line), fh) == NULL) {
		if (feof(fh)) {
			(void)fclose(fh);
			errx(STATUS_ERROR, "Pidfile `%s' is empty", pidfile);
		}
		(void)fclose(fh);
		err(STATUS_ERROR, "Cannot read from pid file `%s'", pidfile);
	}
	(void)fclose(fh);

	rval = strtol(line, &endp, 10);
	if (*endp != '\0' && !isspace((unsigned char)*endp))
		errx(STATUS_ERROR, "Invalid pid in file `%s'", pidfile);
	else if (rval < MIN_PID || rval > MAX_PID)
		errx(STATUS_ERROR, "Invalid pid in file `%s'", pidfile);
	return (rval);
}