Import macOS userland

adv_cmds-176
basic_cmds-55
bootstrap_cmds-116.100.1
developer_cmds-66
diskdev_cmds-667.40.1
doc_cmds-53.60.1
file_cmds-321.40.3
mail_cmds-35
misc_cmds-34
network_cmds-606.40.1
patch_cmds-17
remote_cmds-63
shell_cmds-216.60.1
system_cmds-880.60.2
text_cmds-106

1 files changed, 840 insertions, 0 deletions

diff --git a/shell_cmds/xargs/xargs.c b/shell_cmds/xargs/xargs.c
new file mode 100644
index 0000000..a1ee480
--- /dev/null
+++ b/shell_cmds/xargs/xargs.c
@@ -0,0 +1,840 @@
+/*-
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ * Copyright (c) 1990, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * John B. Roll Jr.
+ *
+ * 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.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
+ *
+ * $xMach: xargs.c,v 1.6 2002/02/23 05:27:47 tim Exp $
+ */
+
+#if 0
+#ifndef lint
+static const char copyright[] =
+"@(#) Copyright (c) 1990, 1993\n\
+	The Regents of the University of California.  All rights reserved.\n";
+#endif /* not lint */
+
+#ifndef lint
+static char sccsid[] = "@(#)xargs.c	8.1 (Berkeley) 6/6/93";
+#endif /* not lint */
+#endif
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/time.h>
+#include <sys/param.h>
+#include <sys/resource.h>
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <langinfo.h>
+#include <locale.h>
+#include <paths.h>
+#include <regex.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "pathnames.h"
+
+#ifdef __APPLE__
+#include <get_compat.h>
+#else
+#define COMPAT_MODE(a,b) (1)
+#endif /* __APPLE__ */
+
+static void	parse_input(int, char *[]);
+static void	prerun(int, char *[]);
+static int	prompt(void);
+static void	run(char **);
+static void	usage(void);
+void		strnsubst(char **, const char *, const char *, size_t);
+static pid_t  xwait(int block, int *status);
+static void   xexit(const char *, const int);
+static void	waitchildren(const char *, int);
+static void   pids_init(void);
+static int    pids_empty(void);
+static int    pids_full(void);
+static void   pids_add(pid_t pid);
+static int    pids_remove(pid_t pid);
+static int    findslot(pid_t pid);
+static int    findfreeslot(void);
+static void   clearslot(int slot);
+
+static int last_was_newline = 1;
+static int last_was_blank = 0;
+
+static char echo[] = _PATH_ECHO;
+static char **av, **bxp, **ep, **endxp, **xp;
+static char *argp, *bbp, *ebp, *inpline, *p, *replstr;
+static const char *eofstr;
+static int count, insingle, indouble, oflag, pflag, tflag, Rflag, rval, zflag;
+static int cnt, Iflag, jfound, Lflag, Sflag, wasquoted, xflag;
+static int curprocs, maxprocs;
+static size_t pad9314053;
+static pid_t *childpids;
+
+static volatile int childerr;
+
+extern char **environ;
+
+int
+main(int argc, char *argv[])
+{
+	long arg_max;
+	int ch, Jflag, nflag, nline;
+	size_t nargs;
+	size_t linelen;
+	struct rlimit rl;
+	char *endptr;
+	const char *errstr;
+
+	inpline = replstr = NULL;
+	ep = environ;
+	eofstr = "";
+	Jflag = nflag = 0;
+
+	(void)setlocale(LC_ALL, "");
+
+	/*
+	 * POSIX.2 limits the exec line length to ARG_MAX - 2K.  Running that
+	 * caused some E2BIG errors, so it was changed to ARG_MAX - 4K.  Given
+	 * that the smallest argument is 2 bytes in length, this means that
+	 * the number of arguments is limited to:
+	 *
+	 *	 (ARG_MAX - 4K - LENGTH(utility + arguments)) / 2.
+	 *
+	 * We arbitrarily limit the number of arguments to 5000.  This is
+	 * allowed by POSIX.2 as long as the resulting minimum exec line is
+	 * at least LINE_MAX.  Realloc'ing as necessary is possible, but
+	 * probably not worthwhile.
+	 */
+	nargs = 5000;
+	if ((arg_max = sysconf(_SC_ARG_MAX)) == -1)
+		errx(1, "sysconf(_SC_ARG_MAX) failed");
+	nline = arg_max - MAXPATHLEN; /* for argv[0] from execvp() */
+	pad9314053 = sizeof(char *); /* reserve for string area rounding */
+	while (*ep != NULL) {
+		/* 1 byte for each '\0' */
+		nline -= strlen(*ep++) + 1 + sizeof(*ep);
+	}
+	nline -= pad9314053;
+	maxprocs = 1;
+	while ((ch = getopt(argc, argv, "0E:I:J:L:n:oP:pR:S:s:rtx")) != -1)
+		switch (ch) {
+		case 'E':
+			eofstr = optarg;
+			break;
+		case 'I':
+			Jflag = 0;
+			Iflag = 1;
+			Lflag = 1;
+			replstr = optarg;
+			break;
+		case 'J':
+			Iflag = 0;
+			Jflag = 1;
+			replstr = optarg;
+			break;
+		case 'L':
+			Lflag = strtonum(optarg, 0, INT_MAX, &errstr);
+			if (errstr)
+				errx(1, "-L %s: %s", optarg, errstr);
+			if (COMPAT_MODE("bin/xargs", "Unix2003")) {
+				nflag = 0; /* Override */
+				nargs = 5000;
+			}
+			break;
+		case 'n':
+			nflag = 1;
+			if ((nargs = strtol(optarg, NULL, 10)) <= 0)
+				errx(1, "illegal argument count");
+			if (COMPAT_MODE("bin/xargs", "Unix2003")) {
+				Lflag = 0; /* Override */
+			}
+			break;
+		case 'o':
+			oflag = 1;
+			break;
+		case 'P':
+			maxprocs = strtonum(optarg, 0, INT_MAX, &errstr);
+			if (errstr)
+				errx(1, "-P %s: %s", optarg, errstr);
+			if (getrlimit(RLIMIT_NPROC, &rl) != 0)
+				errx(1, "getrlimit failed");
+			if (maxprocs == 0 || maxprocs > rl.rlim_cur)
+				maxprocs = rl.rlim_cur;
+			break;
+		case 'p':
+			pflag = 1;
+			break;
+		case 'R':
+			Rflag = strtol(optarg, &endptr, 10);
+			if (*endptr != '\0')
+				errx(1, "replacements must be a number");
+			break;
+		case 'r':
+			/* GNU compatibility */
+			break;
+		case 'S':
+			Sflag = strtoul(optarg, &endptr, 10);
+			if (*endptr != '\0')
+				errx(1, "replsize must be a number");
+			break;
+		case 's':
+			nline = strtonum(optarg, 0, INT_MAX, &errstr);
+			if (errstr)
+				errx(1, "-s %s: %s", optarg, errstr);
+			pad9314053 = 0; /* assume the -s value is valid */
+			break;
+		case 't':
+			tflag = 1;
+			break;
+		case 'x':
+			xflag = 1;
+			break;
+		case '0':
+			zflag = 1;
+			break;
+		case '?':
+		default:
+			usage();
+	}
+	argc -= optind;
+	argv += optind;
+
+	if (!Iflag && Rflag)
+		usage();
+	if (!Iflag && Sflag)
+		usage();
+	if (Iflag && !Rflag)
+		Rflag = 5;
+	if (Iflag && !Sflag)
+		Sflag = 255;
+	if (xflag && !nflag)
+		usage();
+	if (Iflag || Lflag)
+		xflag = 1;
+	if (replstr != NULL && *replstr == '\0')
+		errx(1, "replstr may not be empty");
+
+	pids_init();
+
+	/*
+	 * Allocate pointers for the utility name, the utility arguments,
+	 * the maximum arguments to be read from stdin and the trailing
+	 * NULL.
+	 */
+	linelen = 1 + argc + nargs + 1;
+	if ((av = bxp = malloc(linelen * sizeof(char *))) == NULL)
+		errx(1, "malloc failed");
+
+	/*
+	 * Use the user's name for the utility as argv[0], just like the
+	 * shell.  Echo is the default.  Set up pointers for the user's
+	 * arguments.
+	 */
+	if (*argv == NULL)
+		cnt = strlen(*bxp++ = echo) + pad9314053;
+	else {
+		do {
+			if (Jflag && strcmp(*argv, replstr) == 0) {
+				char **avj;
+				jfound = 1;
+				argv++;
+				for (avj = argv; *avj; avj++)
+					cnt += strlen(*avj) + 1 + pad9314053;
+				break;
+			}
+			cnt += strlen(*bxp++ = *argv) + 1 + pad9314053;
+		} while (*++argv != NULL);
+	}
+
+	/*
+	 * Set up begin/end/traversing pointers into the array.  The -n
+	 * count doesn't include the trailing NULL pointer, so the malloc
+	 * added in an extra slot.
+	 */
+	endxp = (xp = bxp) + nargs;
+
+	/*
+	 * Allocate buffer space for the arguments read from stdin and the
+	 * trailing NULL.  Buffer space is defined as the default or specified
+	 * space, minus the length of the utility name and arguments.  Set up
+	 * begin/end/traversing pointers into the array.  The -s count does
+	 * include the trailing NULL, so the malloc didn't add in an extra
+	 * slot.
+	 */
+	nline -= cnt;
+	if (nline <= 0)
+		errx(1, "insufficient space for command");
+
+	if ((bbp = malloc((size_t)(nline + 1))) == NULL)
+		errx(1, "malloc failed");
+	ebp = (argp = p = bbp) + nline - 1;
+	for (;;)
+		parse_input(argc, argv);
+}
+
+static void
+parse_input(int argc, char *argv[])
+{
+	int ch, foundeof;
+	char **avj;
+	int last_was_backslashed = 0;
+
+	foundeof = 0;
+
+	switch (ch = getchar()) {
+	case EOF:
+		/* No arguments since last exec. */
+		if (p == bbp)
+			xexit(*av, rval);
+		goto arg1;
+	case ' ':
+		last_was_blank = 1;
+	case '\t':
+		/* Quotes escape tabs and spaces. */
+		if (insingle || indouble || zflag)
+			goto addch;
+		goto arg2;
+	case '\0':
+		if (zflag) {
+			/*
+			 * Increment 'count', so that nulls will be treated
+			 * as end-of-line, as well as end-of-argument.  This
+			 * is needed so -0 works properly with -I and -L.
+			 */
+			count++;
+			goto arg2;
+		}
+		goto addch;
+	case '\n':
+		if (zflag)
+			goto addch;
+		if (COMPAT_MODE("bin/xargs", "Unix2003")) {
+			if (last_was_newline) {
+				/* don't count empty line */
+				break;
+			}
+			if (!last_was_blank ) {
+				/* only count if NOT continuation line */
+				count++;
+			} 
+		} else {
+			count++;
+		}
+		last_was_newline = 1;
+
+		/* Quotes do not escape newlines. */
+arg1:		if (insingle || indouble) {
+			warnx("unterminated quote");
+			xexit(*av, 1);
+		}
+arg2:
+		foundeof = *eofstr != '\0' &&
+		    strncmp(argp, eofstr, p - argp) == 0;
+
+#ifdef __APPLE__
+		/* 6591323: -I specifies that it processes the entire line,
+		 * so only recognize eofstr at the end of a line. */
+		if (Iflag && !last_was_newline)
+			foundeof = 0;
+
+		/* 6591323: Essentially the same as the EOF handling above. */
+		if (foundeof && (p - strlen(eofstr) == bbp)) {
+			waitchildren(*argv, 1);
+			exit(rval);
+		}
+#endif
+
+		/* Do not make empty args unless they are quoted */
+		if ((argp != p || wasquoted) && !foundeof) {
+			*p++ = '\0';
+			*xp++ = argp;
+			if (Iflag) {
+				size_t curlen;
+
+				if (inpline == NULL)
+					curlen = 0;
+				else {
+					/*
+					 * If this string is not zero
+					 * length, append a space for
+					 * separation before the next
+					 * argument.
+					 */
+					if ((curlen = strlen(inpline)))
+						strcat(inpline, " ");
+				}
+				curlen++;
+				/*
+				 * Allocate enough to hold what we will
+				 * be holding in a second, and to append
+				 * a space next time through, if we have
+				 * to.
+				 */
+				inpline = realloc(inpline, curlen + 2 +
+				    strlen(argp));
+				if (inpline == NULL) {
+					warnx("realloc failed");
+					xexit(*av, 1);
+				}
+				if (curlen == 1)
+					strcpy(inpline, argp);
+				else
+					strcat(inpline, argp);
+			}
+		}
+
+		/*
+		 * If max'd out on args or buffer, or reached EOF,
+		 * run the command.  If xflag and max'd out on buffer
+		 * but not on args, object.  Having reached the limit
+		 * of input lines, as specified by -L is the same as
+		 * maxing out on arguments.
+		 */
+		if (xp == endxp || p + (count * pad9314053) > ebp || ch == EOF ||
+		    (Lflag <= count && xflag) || foundeof) {
+			if (xflag && xp != endxp && p + (count * pad9314053) > ebp) {
+				warnx("insufficient space for arguments");
+				xexit(*av, 1);
+			}
+			if (jfound) {
+				for (avj = argv; *avj; avj++)
+					*xp++ = *avj;
+			}
+			prerun(argc, av);
+			if (ch == EOF || foundeof)
+				xexit(*av, rval);
+			p = bbp;
+			xp = bxp;
+			count = 0;
+		}
+		argp = p;
+		wasquoted = 0;
+		break;
+	case '\'':
+		if (indouble || zflag)
+			goto addch;
+		insingle = !insingle;
+		wasquoted = 1;
+		break;
+	case '"':
+		if (insingle || zflag)
+			goto addch;
+		indouble = !indouble;
+		wasquoted = 1;
+		break;
+	case '\\':
+		last_was_backslashed = 1;
+		if (zflag)
+			goto addch;
+		/* Backslash escapes anything, is escaped by quotes. */
+		if (!insingle && !indouble && (ch = getchar()) == EOF) {
+			warnx("backslash at EOF");
+			xexit(*av, 1);
+		}
+		/* FALLTHROUGH */
+	default:
+addch:		if (p < ebp) {
+			*p++ = ch;
+			break;
+		}
+
+		/* If only one argument, not enough buffer space. */
+		if (bxp == xp) {
+			warnx("insufficient space for argument");
+			xexit(*av, 1);
+		}
+		/* Didn't hit argument limit, so if xflag object. */
+		if (xflag) {
+			warnx("insufficient space for arguments");
+			xexit(*av, 1);
+		}
+
+		if (jfound) {
+			for (avj = argv; *avj; avj++)
+				*xp++ = *avj;
+		}
+		prerun(argc, av);
+		xp = bxp;
+		cnt = ebp - argp;
+		memcpy(bbp, argp, (size_t)cnt);
+		p = (argp = bbp) + cnt;
+		*p++ = ch;
+		break;
+	}
+	if (ch != ' ')
+		last_was_blank = 0;
+	if (ch != '\n' || last_was_backslashed)
+		last_was_newline = 0;
+}
+
+/*
+ * Do things necessary before run()'ing, such as -I substitution,
+ * and then call run().
+ */
+static void
+prerun(int argc, char *argv[])
+{
+	char **tmp, **tmp2, **avj;
+	int repls;
+
+	repls = Rflag;
+
+	if (argc == 0 || repls == 0) {
+		*xp = NULL;
+		run(argv);
+		return;
+	}
+
+	avj = argv;
+
+	/*
+	 * Allocate memory to hold the argument list, and
+	 * a NULL at the tail.
+	 */
+	tmp = malloc((argc + 1) * sizeof(char *));
+	if (tmp == NULL) {
+		warnx("malloc failed");
+		xexit(*argv, 1);
+	}
+	tmp2 = tmp;
+
+	/*
+	 * Save the first argument and iterate over it, we
+	 * cannot do strnsubst() to it.
+	 */
+	if ((*tmp++ = strdup(*avj++)) == NULL) {
+		warnx("strdup failed");
+		xexit(*argv, 1);
+	}
+
+	/*
+	 * For each argument to utility, if we have not used up
+	 * the number of replacements we are allowed to do, and
+	 * if the argument contains at least one occurrence of
+	 * replstr, call strnsubst(), else just save the string.
+	 * Iterations over elements of avj and tmp are done
+	 * where appropriate.
+	 */
+	while (--argc) {
+		*tmp = *avj++;
+		if (repls && strstr(*tmp, replstr) != NULL) {
+			strnsubst(tmp++, replstr, inpline, (size_t)Sflag);
+			if (repls > 0)
+				repls--;
+		} else {
+			if ((*tmp = strdup(*tmp)) == NULL) {
+				warnx("strdup failed");
+				xexit(*argv, 1);
+			}
+			tmp++;
+		}
+	}
+
+	/*
+	 * Run it.
+	 */
+	*tmp = NULL;
+	run(tmp2);
+
+	/*
+	 * Walk from the tail to the head, free along the way.
+	 */
+	for (; tmp2 != tmp; tmp--)
+		free(*tmp);
+	/*
+	 * Now free the list itself.
+	 */
+	free(tmp2);
+
+	/*
+	 * Free the input line buffer, if we have one.
+	 */
+	if (inpline != NULL) {
+		free(inpline);
+		inpline = NULL;
+	}
+}
+
+static void
+run(char **argv)
+{
+	pid_t pid;
+	int fd;
+	char **avec;
+
+	/*
+	 * If the user wants to be notified of each command before it is
+	 * executed, notify them.  If they want the notification to be
+	 * followed by a prompt, then prompt them.
+	 */
+	if (tflag || pflag) {
+		(void)fprintf(stderr, "%s", *argv);
+		for (avec = argv + 1; *avec != NULL; ++avec)
+			(void)fprintf(stderr, " %s", *avec);
+		/*
+		 * If the user has asked to be prompted, do so.
+		 */
+		if (pflag)
+			/*
+			 * If they asked not to exec, return without execution
+			 * but if they asked to, go to the execution.  If we
+			 * could not open their tty, break the switch and drop
+			 * back to -t behaviour.
+			 */
+			switch (prompt()) {
+			case 0:
+				return;
+			case 1:
+				goto exec;
+			case 2:
+				break;
+			}
+		(void)fprintf(stderr, "\n");
+		(void)fflush(stderr);
+	}
+exec:
+	childerr = 0;
+	switch (pid = vfork()) {
+	case -1:
+		warn("vfork");
+		xexit(*argv, 1);
+	case 0:
+		if (oflag) {
+			if ((fd = open(_PATH_TTY, O_RDONLY)) == -1)
+				err(1, "can't open /dev/tty");
+		} else {
+			fd = open(_PATH_DEVNULL, O_RDONLY);
+		}
+		if (fd > STDIN_FILENO) {
+			if (dup2(fd, STDIN_FILENO) != 0)
+				err(1, "can't dup2 to stdin");
+			close(fd);
+		}
+		execvp(argv[0], argv);
+		childerr = errno;
+		_exit(1);
+	}
+	pids_add(pid);
+	waitchildren(*argv, 0);
+}
+
+/*
+ * Wait for a tracked child to exit and return its pid and exit status.
+ *
+ * Ignores (discards) all untracked child processes.
+ * Returns -1 and sets errno to ECHILD if no tracked children exist.
+ * If block is set, waits indefinitely for a child process to exit.
+ * If block is not set and no children have exited, returns 0 immediately.
+ */
+static pid_t
+xwait(int block, int *status) {
+	pid_t pid;
+
+	if (pids_empty()) {
+		errno = ECHILD;
+		return (-1);
+	}
+
+	while ((pid = waitpid(-1, status, block ? 0 : WNOHANG)) > 0)
+		if (pids_remove(pid))
+			break;
+
+	return (pid);
+}
+
+static void
+xexit(const char *name, const int exit_code) {
+	waitchildren(name, 1);
+	exit(exit_code);
+}
+
+static void
+waitchildren(const char *name, int waitall)
+{
+	pid_t pid;
+	int status;
+	int cause_exit = 0;
+
+	while ((pid = xwait(waitall || pids_full(), &status)) > 0) {
+		/*
+		 * If we couldn't invoke the utility or if utility exited
+		 * because of a signal or with a value of 255, warn (per
+		 * POSIX), and then wait until all other children have
+		 * exited before exiting 1-125. POSIX requires us to stop
+		 * reading if child exits because of a signal or with 255,
+		 * but it does not require us to exit immediately; waiting
+		 * is preferable to orphaning.
+		 */
+		if (childerr != 0 && cause_exit == 0) {
+			errno = childerr;
+			waitall = 1;
+			cause_exit = errno == ENOENT ? 127 : 126;
+			warn("%s", name);
+		} else if (WIFSIGNALED(status)) {
+			waitall = cause_exit = 1;
+			warnx("%s: terminated with signal %d; aborting",
+			    name, WTERMSIG(status));
+		} else if (WEXITSTATUS(status) == 255) {
+			waitall = cause_exit = 1;
+			warnx("%s: exited with status 255; aborting", name);
+		} else if (WEXITSTATUS(status))
+ 			rval = 1;
+	}
+
+ 	if (cause_exit)
+		exit(cause_exit);
+	if (pid == -1 && errno != ECHILD)
+		err(1, "waitpid");
+}
+
+#define	NOPID	(0)
+
+static void
+pids_init(void)
+{
+	int i;
+
+	if ((childpids = malloc(maxprocs * sizeof(*childpids))) == NULL)
+		errx(1, "malloc failed");
+
+	for (i = 0; i < maxprocs; i++)
+		clearslot(i);
+}
+
+static int
+pids_empty(void)
+{
+
+	return (curprocs == 0);
+}
+
+static int
+pids_full(void)
+{
+
+	return (curprocs >= maxprocs);
+}
+
+static void
+pids_add(pid_t pid)
+{
+	int slot;
+
+	slot = findfreeslot();
+	childpids[slot] = pid;
+	curprocs++;
+}
+
+static int
+pids_remove(pid_t pid)
+{
+	int slot;
+
+	if ((slot = findslot(pid)) < 0)
+		return (0);
+
+	clearslot(slot);
+	curprocs--;
+	return (1);
+}
+
+static int
+findfreeslot(void)
+{
+	int slot;
+
+	if ((slot = findslot(NOPID)) < 0)
+		errx(1, "internal error: no free pid slot");
+	return (slot);
+}
+
+static int
+findslot(pid_t pid)
+{
+	int slot;
+
+	for (slot = 0; slot < maxprocs; slot++)
+		if (childpids[slot] == pid)
+			return (slot);
+	return (-1);
+}
+
+static void
+clearslot(int slot)
+{
+
+	childpids[slot] = NOPID;
+}
+
+/*
+ * Prompt the user about running a command.
+ */
+static int
+prompt(void)
+{
+	regex_t cre;
+	size_t rsize;
+	int match;
+	char *response;
+	FILE *ttyfp;
+
+	if ((ttyfp = fopen(_PATH_TTY, "r")) == NULL)
+		return (2);	/* Indicate that the TTY failed to open. */
+	(void)fprintf(stderr, "?...");
+	(void)fflush(stderr);
+	if ((response = fgetln(ttyfp, &rsize)) == NULL ||
+	    regcomp(&cre, nl_langinfo(YESEXPR), REG_BASIC) != 0) {
+		(void)fclose(ttyfp);
+		return (0);
+	}
+	response[rsize - 1] = '\0';
+	match = regexec(&cre, response, 0, NULL, 0);
+	(void)fclose(ttyfp);
+	regfree(&cre);
+	return (match == 0);
+}
+
+static void
+usage(void)
+{
+
+	fprintf(stderr,
+"usage: xargs [-0opt] [-E eofstr] [-I replstr [-R replacements] [-S replsize]]\n"
+"             [-J replstr] [-L number] [-n number [-x]] [-P maxprocs]\n"
+"             [-s size] [utility [argument ...]]\n");
+	exit(1);
+}