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For open/openat, if the flags parameter does not contain O_CREAT, the
3rd (variadic) mode_t parameter is irrelevant.  Many developers in the past
have passed mode_t (0, 044, 0644, or such), which might lead future people
to copy this broken idiom, and perhaps even believe this parameter has some
meaning or implication or application. Delete them all.
This comes out of a conversation where tb@ noticed that a strange (but
intentional) pledge behaviour is to always knock-out high-bits from
mode_t on a number of system calls as a safety factor, and his bewilderment
that this appeared to be happening against valid modes (at least visually),
but no sorry, they are all irrelevant junk.  They could all be 0xdeafbeef.
ok millert

/*	$OpenBSD: mv.c,v 1.47 2021/10/24 21:24:21 deraadt Exp $	*/
/*	$NetBSD: mv.c,v 1.9 1995/03/21 09:06:52 cgd Exp $	*/

/*
 * Copyright (c) 1989, 1993, 1994
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Ken Smith of The State University of New York at Buffalo.
 *
 * 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.
 */

#include <sys/time.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <sys/mount.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <limits.h>
#include <pwd.h>
#include <grp.h>

extern char *__progname;

int fflg, iflg, vflg;
int stdin_ok;

extern int cpmain(int argc, char **argv);
extern int rmmain(int argc, char **argv);

int	mvcopy(char *, char *);
int	do_move(char *, char *);
int	fastcopy(char *, char *, struct stat *);
void	usage(void);

int
main(int argc, char *argv[])
{
	int baselen, len, rval;
	char *p, *endp;
	struct stat sb;
	int ch;
	char path[PATH_MAX];

	while ((ch = getopt(argc, argv, "ifv")) != -1)
		switch (ch) {
		case 'i':
			fflg = 0;
			iflg = 1;
			break;
		case 'f':
			iflg = 0;
			fflg = 1;
			break;
		case 'v':
			vflg = 1;
			break;
		default:
			usage();
		}
	argc -= optind;
	argv += optind;

	if (argc < 2)
		usage();

	stdin_ok = isatty(STDIN_FILENO);

	/*
	 * If the stat on the target fails or the target isn't a directory,
	 * try the move.  More than 2 arguments is an error in this case.
	 */
	if (stat(argv[argc - 1], &sb) || !S_ISDIR(sb.st_mode)) {
		if (argc > 2)
			usage();
		exit(do_move(argv[0], argv[1]));
	}

	/* It's a directory, move each file into it. */
	if (strlcpy(path, argv[argc - 1], sizeof path) >= sizeof path)
		errx(1, "%s: destination pathname too long", *argv);
	baselen = strlen(path);
	endp = &path[baselen];
	if (*(endp - 1) != '/') {
		*endp++ = '/';
		++baselen;
	}
	for (rval = 0; --argc; ++argv) {
		char *current_arg = *argv;

		/*
		 * Get the name of the file to create from
		 * the argument. This is a bit tricky because
		 * in the case of b/ we actually want b and empty
		 * string
		 */
		if ((p = strrchr(current_arg, '/')) == NULL)
			p = current_arg;
		else {
			/* Special case foo/ */
			if (!*(p+1)) {
				while (p >= current_arg && *p == '/')
					p--;

				while (p >= current_arg && *p != '/')
					p--;
			}

			p++;
		}

		if ((baselen + (len = strlen(p))) >= PATH_MAX) {
			warnx("%s: destination pathname too long", *argv);
			rval = 1;
		} else {
			memmove(endp, p, len + 1);
			if (do_move(current_arg, path))
				rval = 1;
		}
	}
	exit(rval);
}

int
do_move(char *from, char *to)
{
	struct stat sb, fsb;
	char modep[15];

	/* Source path must exist (symlink is OK). */
	if (lstat(from, &fsb)) {
		warn("%s", from);
		return (1);
	}

	/*
	 * (1)	If the destination path exists, the -f option is not specified
	 *	and either of the following conditions are true:
	 *
	 *	(a) The permissions of the destination path do not permit
	 *	    writing and the standard input is a terminal.
	 *	(b) The -i option is specified.
	 *
	 *	the mv utility shall write a prompt to standard error and
	 *	read a line from standard input.  If the response is not
	 *	affirmative, mv shall do nothing more with the current
	 *	source file...
	 */
	if (!fflg && !access(to, F_OK)) {
		int ask = 1;
		int ch, first;

		if (iflg && !access(from, F_OK)) {
			(void)fprintf(stderr, "overwrite %s? ", to);
		} else if (stdin_ok && access(to, W_OK) && !stat(to, &sb)) {
			strmode(sb.st_mode, modep);
			(void)fprintf(stderr, "override %s%s%s/%s for %s? ",
			    modep + 1, modep[9] == ' ' ? "" : " ",
			    user_from_uid(sb.st_uid, 0),
			    group_from_gid(sb.st_gid, 0), to);
		} else
			ask = 0;
		if (ask) {
			first = ch = getchar();
			while (ch != '\n' && ch != EOF)
				ch = getchar();
			if (first != 'y' && first != 'Y')
				return (0);
		}
	}

	/*
	 * (2)	If rename() succeeds, mv shall do nothing more with the
	 *	current source file.  If it fails for any other reason than
	 *	EXDEV, mv shall write a diagnostic message to the standard
	 *	error and do nothing more with the current source file.
	 *
	 * (3)	If the destination path exists, and it is a file of type
	 *	directory and source_file is not a file of type directory,
	 *	or it is a file not of type directory, and source file is
	 *	a file of type directory, mv shall write a diagnostic
	 *	message to standard error, and do nothing more with the
	 *	current source file...
	 */
	if (!rename(from, to)) {
		if (vflg)
			(void)fprintf(stdout, "%s -> %s\n", from, to);
		return (0);
	}

	if (errno != EXDEV) {
		warn("rename %s to %s", from, to);
		return (1);
	}

	/* Disallow moving a mount point. */
	if (S_ISDIR(fsb.st_mode)) {
		struct statfs sfs;
		char path[PATH_MAX];

		if (realpath(from, path) == NULL) {
			warnx("cannot resolve %s", from);
			return (1);
		}
		if (!statfs(path, &sfs) && !strcmp(path, sfs.f_mntonname)) {
			warnx("cannot rename a mount point");
			return (1);
		}
	}

	/*
	 * (4)	If the destination path exists, mv shall attempt to remove it.
	 *	If this fails for any reason, mv shall write a diagnostic
	 *	message to the standard error and do nothing more with the
	 *	current source file...
	 */
	if (!lstat(to, &sb)) {
		if ((S_ISDIR(sb.st_mode)) ? rmdir(to) : unlink(to)) {
			warn("can't remove %s", to);
			return (1);
		}
	}

	/*
	 * (5)	The file hierarchy rooted in source_file shall be duplicated
	 *	as a file hierarchy rooted in the destination path...
	 */
	return (S_ISREG(fsb.st_mode) ?
	    fastcopy(from, to, &fsb) : mvcopy(from, to));
}

int
fastcopy(char *from, char *to, struct stat *sbp)
{
	struct timespec ts[2];
	static u_int32_t blen;
	static char *bp;
	int nread, from_fd, to_fd;
	int badchown = 0, serrno = 0;

	if (!blen) {
		blen = sbp->st_blksize;
		if ((bp = malloc(blen)) == NULL) {
			warn(NULL);
			blen = 0;
			return (1);
		}
	}

	if ((from_fd = open(from, O_RDONLY)) == -1) {
		warn("%s", from);
		return (1);
	}
	if ((to_fd = open(to, O_CREAT | O_TRUNC | O_WRONLY, 0600)) == -1) {
		warn("%s", to);
		(void)close(from_fd);
		return (1);
	}

	if (fchown(to_fd, sbp->st_uid, sbp->st_gid)) {
		serrno = errno;
		badchown = 1;
	}
	(void) fchmod(to_fd, sbp->st_mode & ~(S_ISUID|S_ISGID));

	while ((nread = read(from_fd, bp, blen)) > 0)
		if (write(to_fd, bp, nread) != nread) {
			warn("%s", to);
			goto err;
		}
	if (nread == -1) {
		warn("%s", from);
err:		if (unlink(to))
			warn("%s: remove", to);
		(void)close(from_fd);
		(void)close(to_fd);
		return (1);
	}
	(void)close(from_fd);

	if (badchown) {
		if ((sbp->st_mode & (S_ISUID|S_ISGID)))  {
			warnc(serrno,
			    "%s: set owner/group; not setting setuid/setgid",
			    to);
			sbp->st_mode &= ~(S_ISUID|S_ISGID);
		} else if (!fflg)
			warnc(serrno, "%s: set owner/group", to);
	}
	if (fchmod(to_fd, sbp->st_mode))
		warn("%s: set mode", to);

	/*
	 * XXX
	 * NFS doesn't support chflags; ignore errors unless there's reason
	 * to believe we're losing bits.  (Note, this still won't be right
	 * if the server supports flags and we were trying to *remove* flags
	 * on a file that we copied, i.e., that we didn't create.)
	 */
	errno = 0;
	if (fchflags(to_fd, sbp->st_flags))
		if (errno != EOPNOTSUPP || sbp->st_flags != 0)
			warn("%s: set flags", to);

	ts[0] = sbp->st_atim;
	ts[1] = sbp->st_mtim;
	if (futimens(to_fd, ts))
		warn("%s: set times", to);

	if (close(to_fd)) {
		warn("%s", to);
		return (1);
	}

	if (unlink(from)) {
		warn("%s: remove", from);
		return (1);
	}

	if (vflg)
		(void)fprintf(stdout, "%s -> %s\n", from, to);

	return (0);
}

int
mvcopy(char *from, char *to)
{
	char *argv[3];

	argv[0] = from;
	argv[1] = to;
	argv[2] = NULL;
	if (cpmain(2, argv)) {
		warn("cp failed");
		_exit(1);
	}

	argv[0] = from;
	argv[1] = NULL;
	if (rmmain(1, argv)) {
		warn("rm failed");
		_exit(1);
	}

	/*
	 * XXX
	 * The external cpmain(), rmmain() approach (to avoid
	 * fork+exec) hides some of the details on what was moved.
	 * This can be improved upon during a refactor.
	 */
	if (vflg)
		(void)fprintf(stdout, "%s -> %s\n", from, to);

	return (0);
}

void
usage(void)
{
	(void)fprintf(stderr, "usage: %s [-fiv] source target\n", __progname);
	(void)fprintf(stderr, "       %s [-fiv] source ... directory\n",
	    __progname);
	exit(1);
}