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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: util.c,v 1.46 2021/10/24 21:24:17 deraadt Exp $	*/

/*
 * patch - a program to apply diffs to original files
 * 
 * Copyright 1986, Larry Wall
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following condition is met:
 * 1. Redistributions of source code must retain the above copyright notice,
 * this condition and the following disclaimer.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 * 
 * -C option added in 1998, original code by Marc Espie, based on FreeBSD
 * behaviour
 */

#include <sys/stat.h>

#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <paths.h>
#include <signal.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

#include "common.h"
#include "util.h"
#include "backupfile.h"

/* Rename a file, copying it if necessary. */

int
move_file(const char *from, const char *to)
{
	int	fromfd;
	ssize_t	i;

	/* to stdout? */

	if (strEQ(to, "-")) {
#ifdef DEBUGGING
		if (debug & 4)
			say("Moving %s to stdout.\n", from);
#endif
		fromfd = open(from, O_RDONLY);
		if (fromfd == -1)
			pfatal("internal error, can't reopen %s", from);
		while ((i = read(fromfd, buf, bufsz)) > 0)
			if (write(STDOUT_FILENO, buf, i) != i)
				pfatal("write failed");
		close(fromfd);
		return 0;
	}
	if (backup_file(to) < 0) {
		say("Can't backup %s, output is in %s: %s\n", to, from,
		    strerror(errno));
		return -1;
	}
#ifdef DEBUGGING
	if (debug & 4)
		say("Moving %s to %s.\n", from, to);
#endif
	if (rename(from, to) == -1) {
		if (errno != EXDEV || copy_file(from, to) < 0) {
			say("Can't create %s, output is in %s: %s\n",
			    to, from, strerror(errno));
			return -1;
		}
	}
	return 0;
}

/* Backup the original file.  */

int
backup_file(const char *orig)
{
	struct stat	filestat;
	char		bakname[PATH_MAX], *s, *simplename;
	dev_t		orig_device;
	ino_t		orig_inode;

	if (backup_type == none || stat(orig, &filestat) != 0)
		return 0;			/* nothing to do */
	orig_device = filestat.st_dev;
	orig_inode = filestat.st_ino;

	if (origprae) {
		if (strlcpy(bakname, origprae, sizeof(bakname)) >= sizeof(bakname) ||
		    strlcat(bakname, orig, sizeof(bakname)) >= sizeof(bakname))
			fatal("filename %s too long for buffer\n", origprae);
	} else {
		if ((s = find_backup_file_name(orig)) == NULL)
			fatal("out of memory\n");
		if (strlcpy(bakname, s, sizeof(bakname)) >= sizeof(bakname))
			fatal("filename %s too long for buffer\n", s);
		free(s);
	}

	if ((simplename = strrchr(bakname, '/')) != NULL)
		simplename = simplename + 1;
	else
		simplename = bakname;

	/*
	 * Find a backup name that is not the same file. Change the
	 * first lowercase char into uppercase; if that isn't
	 * sufficient, chop off the first char and try again.
	 */
	while (stat(bakname, &filestat) == 0 &&
	    orig_device == filestat.st_dev && orig_inode == filestat.st_ino) {
		/* Skip initial non-lowercase chars.  */
		for (s = simplename; *s && !islower((unsigned char)*s); s++)
			;
		if (*s)
			*s = toupper((unsigned char)*s);
		else
			memmove(simplename, simplename + 1,
			    strlen(simplename + 1) + 1);
	}
#ifdef DEBUGGING
	if (debug & 4)
		say("Moving %s to %s.\n", orig, bakname);
#endif
	if (rename(orig, bakname) == -1) {
		if (errno != EXDEV || copy_file(orig, bakname) < 0)
			return -1;
	}
	return 0;
}

/*
 * Copy a file.
 */
int
copy_file(const char *from, const char *to)
{
	int	tofd, fromfd;
	ssize_t	i;

	tofd = open(to, O_CREAT|O_TRUNC|O_WRONLY, 0666);
	if (tofd == -1)
		return -1;
	fromfd = open(from, O_RDONLY);
	if (fromfd == -1)
		pfatal("internal error, can't reopen %s", from);
	while ((i = read(fromfd, buf, bufsz)) > 0)
		if (write(tofd, buf, i) != i)
			pfatal("write to %s failed", to);
	close(fromfd);
	close(tofd);
	return 0;
}

/*
 * Allocate a unique area for a string.
 */
char *
savestr(const char *s)
{
	char	*rv;

	if (!s)
		s = "Oops";
	rv = strdup(s);
	if (rv == NULL) {
		if (using_plan_a)
			out_of_mem = true;
		else
			fatal("out of memory\n");
	}
	return rv;
}

/*
 * Allocate a unique area for a string.  Call fatal if out of memory.
 */
char *
xstrdup(const char *s)
{
	char	*rv;

	if (!s)
		s = "Oops";
	rv = strdup(s);
	if (rv == NULL)
		fatal("out of memory\n");
	return rv;
}

/*
 * Vanilla terminal output (buffered).
 */
void
say(const char *fmt, ...)
{
	va_list	ap;

	va_start(ap, fmt);
	vfprintf(stdout, fmt, ap);
	va_end(ap);
	fflush(stdout);
}

/*
 * Terminal output, pun intended.
 */
void
fatal(const char *fmt, ...)
{
	va_list	ap;

	va_start(ap, fmt);
	fprintf(stderr, "patch: **** ");
	vfprintf(stderr, fmt, ap);
	va_end(ap);
	my_exit(2);
}

/*
 * Say something from patch, something from the system, then silence . . .
 */
void
pfatal(const char *fmt, ...)
{
	va_list	ap;
	int	errnum = errno;

	fprintf(stderr, "patch: **** ");
	va_start(ap, fmt);
	vfprintf(stderr, fmt, ap);
	va_end(ap);
	fprintf(stderr, ": %s\n", strerror(errnum));
	my_exit(2);
}

/*
 * Get a response from the user via /dev/tty
 */
void
ask(const char *fmt, ...)
{
	va_list	ap;
	ssize_t	nr;
	static	int ttyfd = -1;

	va_start(ap, fmt);
	vfprintf(stdout, fmt, ap);
	va_end(ap);
	fflush(stdout);
	if (ttyfd < 0)
		ttyfd = open(_PATH_TTY, O_RDONLY);
	if (ttyfd >= 0) {
		if ((nr = read(ttyfd, buf, bufsz)) > 0 &&
		    buf[nr - 1] == '\n')
			buf[nr - 1] = '\0';
	}
	if (ttyfd == -1 || nr <= 0) {
		/* no tty or error reading, pretend user entered 'return' */
		putchar('\n');
		buf[0] = '\0';
	}
}

/*
 * How to handle certain events when not in a critical region.
 */
void
set_signals(int reset)
{
	static sig_t	hupval, intval;

	if (!reset) {
		hupval = signal(SIGHUP, SIG_IGN);
		if (hupval != SIG_IGN)
			hupval = my_sigexit;
		intval = signal(SIGINT, SIG_IGN);
		if (intval != SIG_IGN)
			intval = my_sigexit;
	}
	signal(SIGHUP, hupval);
	signal(SIGINT, intval);
}

/*
 * How to handle certain events when in a critical region.
 */
void
ignore_signals(void)
{
	signal(SIGHUP, SIG_IGN);
	signal(SIGINT, SIG_IGN);
}

/*
 * Make sure we'll have the directories to create a file. If `striplast' is
 * true, ignore the last element of `filename'.
 */

void
makedirs(const char *filename, bool striplast)
{
	char	*tmpbuf;

	if ((tmpbuf = strdup(filename)) == NULL)
		fatal("out of memory\n");

	if (striplast) {
		char	*s = strrchr(tmpbuf, '/');
		if (s == NULL) {
			free(tmpbuf);
			return;	/* nothing to be done */
		}
		*s = '\0';
	}
	if (mkpath(tmpbuf) != 0)
		pfatal("creation of %s failed", tmpbuf);
	free(tmpbuf);
}

/*
 * Make filenames more reasonable.
 */
char *
fetchname(const char *at, bool *exists, int strip_leading)
{
	char		*fullname, *name, *t;
	int		sleading, tab;
	struct stat	filestat;

	if (at == NULL || *at == '\0')
		return NULL;
	while (isspace((unsigned char)*at))
		at++;
#ifdef DEBUGGING
	if (debug & 128)
		say("fetchname %s %d\n", at, strip_leading);
#endif
	/* So files can be created by diffing against /dev/null.  */
	if (strnEQ(at, _PATH_DEVNULL, sizeof(_PATH_DEVNULL) - 1))
		return NULL;
	name = fullname = t = savestr(at);

	tab = strchr(t, '\t') != NULL;
	/* Strip off up to `strip_leading' path components and NUL terminate. */
	for (sleading = strip_leading; *t != '\0' && ((tab && *t != '\t') ||
	    !isspace((unsigned char)*t)); t++) {
		if (t[0] == '/' && t[1] != '/' && t[1] != '\0')
			if (--sleading >= 0)
				name = t + 1;
	}
	*t = '\0';

	/*
	 * If no -p option was given (957 is the default value!), we were
	 * given a relative pathname, and the leading directories that we
	 * just stripped off all exist, put them back on.
	 */
	if (strip_leading == 957 && name != fullname && *fullname != '/') {
		name[-1] = '\0';
		if (stat(fullname, &filestat) == 0 && S_ISDIR(filestat.st_mode)) {
			name[-1] = '/';
			name = fullname;
		}
	}
	name = savestr(name);
	free(fullname);

	*exists = stat(name, &filestat) == 0;
	return name;
}

void
version(void)
{
	fprintf(stderr, "Patch version 2.0-12u8-OpenBSD\n");
	my_exit(EXIT_SUCCESS);
}

void
my_cleanup(void)
{
	unlink(TMPINNAME);
	if (!toutkeep)
		unlink(TMPOUTNAME);
	if (!trejkeep)
		unlink(TMPREJNAME);
	unlink(TMPPATNAME);
}

/*
 * Exit with cleanup.
 */
void
my_exit(int status)
{
	my_cleanup();
	exit(status);
}

/*
 * Exit with cleanup, from a signal handler.
 */
void
my_sigexit(int signo)
{
	my_cleanup();
	_exit(2);
}