libbb/copy_file.c - busybox - Git at Google

 /* vi: set sw=4 ts=4: */
 /*
  * Mini copy_file implementation for busybox
  *
  * Copyright (C) 2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
  * SELinux support by Yuichi Nakamura <ynakam@hitachisoft.jp>
  *
  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  *
  */

 #include "libbb.h"

 // POSIX: if exists and -i, ask (w/o -i assume yes).
 // Then open w/o EXCL (yes, not unlink!).
 // If open still fails and -f, try unlink, then try open again.
 // Result: a mess:
 // If dest is a softlink, we overwrite softlink's destination!
 // (or fail, if it points to dir/nonexistent location/etc).
 // This is strange, but POSIX-correct.
 // coreutils cp has --remove-destination to override this...
 //
 // NB: we have special code which still allows for "cp file /dev/node"
 // to work POSIX-ly (the only realistic case where it makes sense)

 #define DO_POSIX_CP 0  /* 1 - POSIX behavior, 0 - safe behavior */

 // errno must be set to relevant value ("why we cannot create dest?")
 // for POSIX mode to give reasonable error message
 static int ask_and_unlink(const char *dest, int flags)
 {
 	int e = errno;
 #if DO_POSIX_CP
 	if (!(flags & (FILEUTILS_FORCE|FILEUTILS_INTERACTIVE))) {
 		// Either it exists, or the *path* doesnt exist
 		bb_perror_msg("cannot create '%s'", dest);
 		return -1;
 	}
 #endif
 	// If !DO_POSIX_CP, act as if -f is always in effect - we don't want
 	// "cannot create" msg, we want unlink to be done (silently unless -i).

 	// TODO: maybe we should do it only if ctty is present?
 	if (flags & FILEUTILS_INTERACTIVE) {
 		// We would not do POSIX insanity. -i asks,
 		// then _unlinks_ the offender. Presto.
 		// (No "opening without O_EXCL", no "unlink only if -f")
 		// Or else we will end up having 3 open()s!
 		fprintf(stderr, "%s: overwrite '%s'? ", applet_name, dest);
 		if (!bb_ask_confirmation())
 			return 0; // not allowed to overwrite
 	}
 	if (unlink(dest) < 0) {
 #if ENABLE_FEATURE_VERBOSE_CP_MESSAGE
 		if (e == errno && e == ENOENT) {
 			/* e == ENOTDIR is similar: path has non-dir component,
 			 * but in this case we don't even reach copy_file() */
 			bb_error_msg("cannot create '%s': Path does not exist", dest);
 			return -1; // error
 		}
 #endif
 		errno = e;
 		bb_perror_msg("cannot create '%s'", dest);
 		return -1; // error
 	}
 	return 1; // ok (to try again)
 }

 /* Return:
  * -1 error, copy not made
  *  0 copy is made or user answered "no" in interactive mode
  *    (failures to preserve mode/owner/times are not reported in exit code)
  */
 int FAST_FUNC copy_file(const char *source, const char *dest, int flags)
 {
 	/* This is a recursive function, try to minimize stack usage */
 	/* NB: each struct stat is ~100 bytes */
 	struct stat source_stat;
 	struct stat dest_stat;
 	signed char retval = 0;
 	signed char dest_exists = 0;
 	signed char ovr;

 /* Inverse of cp -d ("cp without -d") */
 #define FLAGS_DEREF (flags & FILEUTILS_DEREFERENCE)

 	if ((FLAGS_DEREF ? stat : lstat)(source, &source_stat) < 0) {
 		// This may be a dangling symlink.
 		// Making [sym]links to dangling symlinks works, so...
 		if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK))
 			goto make_links;
 		bb_perror_msg("cannot stat '%s'", source);
 		return -1;
 	}

 	if (lstat(dest, &dest_stat) < 0) {
 		if (errno != ENOENT) {
 			bb_perror_msg("cannot stat '%s'", dest);
 			return -1;
 		}
 	} else {
 		if (source_stat.st_dev == dest_stat.st_dev
 		 && source_stat.st_ino == dest_stat.st_ino
 		) {
 			bb_error_msg("'%s' and '%s' are the same file", source, dest);
 			return -1;
 		}
 		dest_exists = 1;
 	}

 #if ENABLE_SELINUX
 	if ((flags & FILEUTILS_PRESERVE_SECURITY_CONTEXT) && is_selinux_enabled() > 0) {
 		security_context_t con;
 		if (lgetfilecon(source, &con) >= 0) {
 			if (setfscreatecon(con) < 0) {
 				bb_perror_msg("cannot set setfscreatecon %s", con);
 				freecon(con);
 				return -1;
 			}
 		} else if (errno == ENOTSUP || errno == ENODATA) {
 			setfscreatecon_or_die(NULL);
 		} else {
 			bb_perror_msg("cannot lgetfilecon %s", source);
 			return -1;
 		}
 	}
 #endif

 	if (S_ISDIR(source_stat.st_mode)) {
 		DIR *dp;
 		const char *tp;
 		struct dirent *d;
 		mode_t saved_umask = 0;

 		if (!(flags & FILEUTILS_RECUR)) {
 			bb_error_msg("omitting directory '%s'", source);
 			return -1;
 		}

 		/* Did we ever create source ourself before? */
 		tp = is_in_ino_dev_hashtable(&source_stat);
 		if (tp) {
 			/* We did! it's a recursion! man the lifeboats... */
 			bb_error_msg("recursion detected, omitting directory '%s'",
 					source);
 			return -1;
 		}

 		/* Create DEST */
 		if (dest_exists) {
 			if (!S_ISDIR(dest_stat.st_mode)) {
 				bb_error_msg("target '%s' is not a directory", dest);
 				return -1;
 			}
 			/* race here: user can substitute a symlink between
 			 * this check and actual creation of files inside dest */
 		} else {
 			mode_t mode;
 			saved_umask = umask(0);

 			mode = source_stat.st_mode;
 			if (!(flags & FILEUTILS_PRESERVE_STATUS))
 				mode = source_stat.st_mode & ~saved_umask;
 			/* Allow owner to access new dir (at least for now) */
 			mode |= S_IRWXU;
 			if (mkdir(dest, mode) < 0) {
 				umask(saved_umask);
 				bb_perror_msg("cannot create directory '%s'", dest);
 				return -1;
 			}
 			umask(saved_umask);
 			/* need stat info for add_to_ino_dev_hashtable */
 			if (lstat(dest, &dest_stat) < 0) {
 				bb_perror_msg("cannot stat '%s'", dest);
 				return -1;
 			}
 		}
 		/* remember (dev,inode) of each created dir.
 		 * NULL: name is not remembered */
 		add_to_ino_dev_hashtable(&dest_stat, NULL);

 		/* Recursively copy files in SOURCE */
 		dp = opendir(source);
 		if (dp == NULL) {
 			retval = -1;
 			goto preserve_mode_ugid_time;
 		}

 		while ((d = readdir(dp)) != NULL) {
 			char *new_source, *new_dest;

 			new_source = concat_subpath_file(source, d->d_name);
 			if (new_source == NULL)
 				continue;
 			new_dest = concat_path_file(dest, d->d_name);
 			if (copy_file(new_source, new_dest, flags) < 0)
 				retval = -1;
 			free(new_source);
 			free(new_dest);
 		}
 		closedir(dp);

 		if (!dest_exists
 		 && chmod(dest, source_stat.st_mode & ~saved_umask) < 0
 		) {
 			bb_perror_msg("cannot preserve %s of '%s'", "permissions", dest);
 			/* retval = -1; - WRONG! copy *WAS* made */
 		}
 		goto preserve_mode_ugid_time;
 	}

 	if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) {
 		int (*lf)(const char *oldpath, const char *newpath);
  make_links:
 		// Hmm... maybe
 		// if (DEREF && MAKE_SOFTLINK) source = realpath(source) ?
 		// (but realpath returns NULL on dangling symlinks...)
 		lf = (flags & FILEUTILS_MAKE_SOFTLINK) ? symlink : link;
 		if (lf(source, dest) < 0) {
 			ovr = ask_and_unlink(dest, flags);
 			if (ovr <= 0)
 				return ovr;
 			if (lf(source, dest) < 0) {
 				bb_perror_msg("cannot create link '%s'", dest);
 				return -1;
 			}
 		}
 		/* _Not_ jumping to preserve_mode_ugid_time:
 		 * hard/softlinks don't have those */
 		return 0;
 	}

 	if (/* "cp thing1 thing2" without -R: just open and read() from thing1 */
 	    !(flags & FILEUTILS_RECUR)
 	    /* "cp [-opts] regular_file thing2" */
 	 || S_ISREG(source_stat.st_mode)
 	 /* DEREF uses stat, which never returns S_ISLNK() == true.
 	  * So the below is never true: */
 	 /* || (FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) */
 	) {
 		int src_fd;
 		int dst_fd;
 		mode_t new_mode;

 		if (!FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) {
 			/* "cp -d symlink dst": create a link */
 			goto dont_cat;
 		}

 		if (ENABLE_FEATURE_PRESERVE_HARDLINKS && !FLAGS_DEREF) {
 			const char *link_target;
 			link_target = is_in_ino_dev_hashtable(&source_stat);
 			if (link_target) {
 				if (link(link_target, dest) < 0) {
 					ovr = ask_and_unlink(dest, flags);
 					if (ovr <= 0)
 						return ovr;
 					if (link(link_target, dest) < 0) {
 						bb_perror_msg("cannot create link '%s'", dest);
 						return -1;
 					}
 				}
 				return 0;
 			}
 			add_to_ino_dev_hashtable(&source_stat, dest);
 		}

 		src_fd = open_or_warn(source, O_RDONLY);
 		if (src_fd < 0)
 			return -1;

 		/* Do not try to open with weird mode fields */
 		new_mode = source_stat.st_mode;
 		if (!S_ISREG(source_stat.st_mode))
 			new_mode = 0666;

 		/* POSIX way is a security problem versus symlink attacks,
 		 * we do it only for non-symlinks, and only for non-recursive,
 		 * non-interactive cp. NB: it is still racy
 		 * for "cp file /home/bad_user/file" case
 		 * (user can rm file and create a link to /etc/passwd) */
 		if (DO_POSIX_CP
 		 || (dest_exists
 		     && !(flags & (FILEUTILS_RECUR|FILEUTILS_INTERACTIVE))
 		     && !S_ISLNK(dest_stat.st_mode))
 		) {
 			dst_fd = open(dest, O_WRONLY|O_CREAT|O_TRUNC, new_mode);
 		} else  /* safe way: */
 			dst_fd = open(dest, O_WRONLY|O_CREAT|O_EXCL, new_mode);
 		if (dst_fd == -1) {
 			ovr = ask_and_unlink(dest, flags);
 			if (ovr <= 0) {
 				close(src_fd);
 				return ovr;
 			}
 			/* It shouldn't exist. If it exists, do not open (symlink attack?) */
 			dst_fd = open3_or_warn(dest, O_WRONLY|O_CREAT|O_EXCL, new_mode);
 			if (dst_fd < 0) {
 				close(src_fd);
 				return -1;
 			}
 		}

 #if ENABLE_SELINUX
 		if ((flags & (FILEUTILS_PRESERVE_SECURITY_CONTEXT|FILEUTILS_SET_SECURITY_CONTEXT))
 		 && is_selinux_enabled() > 0
 		) {
 			security_context_t con;
 			if (getfscreatecon(&con) == -1) {
 				bb_perror_msg("getfscreatecon");
 				return -1;
 			}
 			if (con) {
 				if (setfilecon(dest, con) == -1) {
 					bb_perror_msg("setfilecon:%s,%s", dest, con);
 					freecon(con);
 					return -1;
 				}
 				freecon(con);
 			}
 		}
 #endif
 		if (bb_copyfd_eof(src_fd, dst_fd) == -1)
 			retval = -1;
 		/* Ok, writing side I can understand... */
 		if (close(dst_fd) < 0) {
 			bb_perror_msg("cannot close '%s'", dest);
 			retval = -1;
 		}
 		/* ...but read size is already checked by bb_copyfd_eof */
 		close(src_fd);
 		/* "cp /dev/something new_file" should not
 		 * copy mode of /dev/something */
 		if (!S_ISREG(source_stat.st_mode))
 			return retval;
 		goto preserve_mode_ugid_time;
 	}
  dont_cat:

 	/* Source is a symlink or a special file */
 	/* We are lazy here, a bit lax with races... */
 	if (dest_exists) {
 		errno = EEXIST;
 		ovr = ask_and_unlink(dest, flags);
 		if (ovr <= 0)
 			return ovr;
 	}
 	if (S_ISLNK(source_stat.st_mode)) {
 		char *lpath = xmalloc_readlink_or_warn(source);
 		if (lpath) {
 			int r = symlink(lpath, dest);
 			free(lpath);
 			if (r < 0) {
 				bb_perror_msg("cannot create symlink '%s'", dest);
 				return -1;
 			}
 			if (flags & FILEUTILS_PRESERVE_STATUS)
 				if (lchown(dest, source_stat.st_uid, source_stat.st_gid) < 0)
 					bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest);
 		}
 		/* _Not_ jumping to preserve_mode_ugid_time:
 		 * symlinks don't have those */
 		return 0;
 	}
 	if (S_ISBLK(source_stat.st_mode) || S_ISCHR(source_stat.st_mode)
 	 || S_ISSOCK(source_stat.st_mode) || S_ISFIFO(source_stat.st_mode)
 	) {
 		if (mknod(dest, source_stat.st_mode, source_stat.st_rdev) < 0) {
 			bb_perror_msg("cannot create '%s'", dest);
 			return -1;
 		}
 	} else {
 		bb_error_msg("unrecognized file '%s' with mode %x", source, source_stat.st_mode);
 		return -1;
 	}

  preserve_mode_ugid_time:

 	if (flags & FILEUTILS_PRESERVE_STATUS
 	/* Cannot happen: */
 	/* && !(flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) */
 	) {
 		struct utimbuf times;

 		times.actime = source_stat.st_atime;
 		times.modtime = source_stat.st_mtime;
 		/* BTW, utimes sets usec-precision time - just FYI */
 		if (utime(dest, &times) < 0)
 			bb_perror_msg("cannot preserve %s of '%s'", "times", dest);
 		if (chown(dest, source_stat.st_uid, source_stat.st_gid) < 0) {
 			source_stat.st_mode &= ~(S_ISUID | S_ISGID);
 			bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest);
 		}
 		if (chmod(dest, source_stat.st_mode) < 0)
 			bb_perror_msg("cannot preserve %s of '%s'", "permissions", dest);
 	}

 	return retval;
 }
	/* vi: set sw=4 ts=4: */
	/*
	* Mini copy_file implementation for busybox
	*
	* Copyright (C) 2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
	* SELinux support by Yuichi Nakamura <ynakam@hitachisoft.jp>
	*
	* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
	*
	*/

	#include "libbb.h"

	// POSIX: if exists and -i, ask (w/o -i assume yes).
	// Then open w/o EXCL (yes, not unlink!).
	// If open still fails and -f, try unlink, then try open again.
	// Result: a mess:
	// If dest is a softlink, we overwrite softlink's destination!
	// (or fail, if it points to dir/nonexistent location/etc).
	// This is strange, but POSIX-correct.
	// coreutils cp has --remove-destination to override this...
	//
	// NB: we have special code which still allows for "cp file /dev/node"
	// to work POSIX-ly (the only realistic case where it makes sense)

	#define DO_POSIX_CP 0 /* 1 - POSIX behavior, 0 - safe behavior */

	// errno must be set to relevant value ("why we cannot create dest?")
	// for POSIX mode to give reasonable error message
	static int ask_and_unlink(const char *dest, int flags)
	{
	int e = errno;
	#if DO_POSIX_CP
	if (!(flags & (FILEUTILS_FORCE\|FILEUTILS_INTERACTIVE))) {
	// Either it exists, or the path doesnt exist
	bb_perror_msg("cannot create '%s'", dest);
	return -1;
	}
	#endif
	// If !DO_POSIX_CP, act as if -f is always in effect - we don't want
	// "cannot create" msg, we want unlink to be done (silently unless -i).

	// TODO: maybe we should do it only if ctty is present?
	if (flags & FILEUTILS_INTERACTIVE) {
	// We would not do POSIX insanity. -i asks,
	// then _unlinks_ the offender. Presto.
	// (No "opening without O_EXCL", no "unlink only if -f")
	// Or else we will end up having 3 open()s!
	fprintf(stderr, "%s: overwrite '%s'? ", applet_name, dest);
	if (!bb_ask_confirmation())
	return 0; // not allowed to overwrite
	}
	if (unlink(dest) < 0) {
	#if ENABLE_FEATURE_VERBOSE_CP_MESSAGE
	if (e == errno && e == ENOENT) {
	/* e == ENOTDIR is similar: path has non-dir component,
	* but in this case we don't even reach copy_file() */
	bb_error_msg("cannot create '%s': Path does not exist", dest);
	return -1; // error
	}
	#endif
	errno = e;
	bb_perror_msg("cannot create '%s'", dest);
	return -1; // error
	}
	return 1; // ok (to try again)
	}

	/* Return:
	* -1 error, copy not made
	* 0 copy is made or user answered "no" in interactive mode
	* (failures to preserve mode/owner/times are not reported in exit code)
	*/
	int FAST_FUNC copy_file(const char source, const char dest, int flags)
	{
	/* This is a recursive function, try to minimize stack usage */
	/* NB: each struct stat is ~100 bytes */
	struct stat source_stat;
	struct stat dest_stat;
	signed char retval = 0;
	signed char dest_exists = 0;
	signed char ovr;

	/* Inverse of cp -d ("cp without -d") */
	#define FLAGS_DEREF (flags & FILEUTILS_DEREFERENCE)

	if ((FLAGS_DEREF ? stat : lstat)(source, &source_stat) < 0) {
	// This may be a dangling symlink.
	// Making [sym]links to dangling symlinks works, so...
	if (flags & (FILEUTILS_MAKE_SOFTLINK\|FILEUTILS_MAKE_HARDLINK))
	goto make_links;
	bb_perror_msg("cannot stat '%s'", source);
	return -1;
	}

	if (lstat(dest, &dest_stat) < 0) {
	if (errno != ENOENT) {
	bb_perror_msg("cannot stat '%s'", dest);
	return -1;
	}
	} else {
	if (source_stat.st_dev == dest_stat.st_dev
	&& source_stat.st_ino == dest_stat.st_ino
	) {
	bb_error_msg("'%s' and '%s' are the same file", source, dest);
	return -1;
	}
	dest_exists = 1;
	}

	#if ENABLE_SELINUX
	if ((flags & FILEUTILS_PRESERVE_SECURITY_CONTEXT) && is_selinux_enabled() > 0) {
	security_context_t con;
	if (lgetfilecon(source, &con) >= 0) {
	if (setfscreatecon(con) < 0) {
	bb_perror_msg("cannot set setfscreatecon %s", con);
	freecon(con);
	return -1;
	}
	} else if (errno == ENOTSUP \|\| errno == ENODATA) {
	setfscreatecon_or_die(NULL);
	} else {
	bb_perror_msg("cannot lgetfilecon %s", source);
	return -1;
	}
	}
	#endif

	if (S_ISDIR(source_stat.st_mode)) {
	DIR *dp;
	const char *tp;
	struct dirent *d;
	mode_t saved_umask = 0;

	if (!(flags & FILEUTILS_RECUR)) {
	bb_error_msg("omitting directory '%s'", source);
	return -1;
	}

	/* Did we ever create source ourself before? */
	tp = is_in_ino_dev_hashtable(&source_stat);
	if (tp) {
	/* We did! it's a recursion! man the lifeboats... */
	bb_error_msg("recursion detected, omitting directory '%s'",
	source);
	return -1;
	}

	/* Create DEST */
	if (dest_exists) {
	if (!S_ISDIR(dest_stat.st_mode)) {
	bb_error_msg("target '%s' is not a directory", dest);
	return -1;
	}
	/* race here: user can substitute a symlink between
	* this check and actual creation of files inside dest */
	} else {
	mode_t mode;
	saved_umask = umask(0);

	mode = source_stat.st_mode;
	if (!(flags & FILEUTILS_PRESERVE_STATUS))
	mode = source_stat.st_mode & ~saved_umask;
	/* Allow owner to access new dir (at least for now) */
	mode \|= S_IRWXU;
	if (mkdir(dest, mode) < 0) {
	umask(saved_umask);
	bb_perror_msg("cannot create directory '%s'", dest);
	return -1;
	}
	umask(saved_umask);
	/* need stat info for add_to_ino_dev_hashtable */
	if (lstat(dest, &dest_stat) < 0) {
	bb_perror_msg("cannot stat '%s'", dest);
	return -1;
	}
	}
	/* remember (dev,inode) of each created dir.
	* NULL: name is not remembered */
	add_to_ino_dev_hashtable(&dest_stat, NULL);

	/* Recursively copy files in SOURCE */
	dp = opendir(source);
	if (dp == NULL) {
	retval = -1;
	goto preserve_mode_ugid_time;
	}

	while ((d = readdir(dp)) != NULL) {
	char new_source, new_dest;

	new_source = concat_subpath_file(source, d->d_name);
	if (new_source == NULL)
	continue;
	new_dest = concat_path_file(dest, d->d_name);
	if (copy_file(new_source, new_dest, flags) < 0)
	retval = -1;
	free(new_source);
	free(new_dest);
	}
	closedir(dp);

	if (!dest_exists
	&& chmod(dest, source_stat.st_mode & ~saved_umask) < 0
	) {
	bb_perror_msg("cannot preserve %s of '%s'", "permissions", dest);
	/* retval = -1; - WRONG! copy WAS made */
	}
	goto preserve_mode_ugid_time;
	}

	if (flags & (FILEUTILS_MAKE_SOFTLINK\|FILEUTILS_MAKE_HARDLINK)) {
	int (lf)(const char oldpath, const char *newpath);
	make_links:
	// Hmm... maybe
	// if (DEREF && MAKE_SOFTLINK) source = realpath(source) ?
	// (but realpath returns NULL on dangling symlinks...)
	lf = (flags & FILEUTILS_MAKE_SOFTLINK) ? symlink : link;
	if (lf(source, dest) < 0) {
	ovr = ask_and_unlink(dest, flags);
	if (ovr <= 0)
	return ovr;
	if (lf(source, dest) < 0) {
	bb_perror_msg("cannot create link '%s'", dest);
	return -1;
	}
	}
	/* _Not_ jumping to preserve_mode_ugid_time:
	* hard/softlinks don't have those */
	return 0;
	}

	if (/* "cp thing1 thing2" without -R: just open and read() from thing1 */
	!(flags & FILEUTILS_RECUR)
	/* "cp [-opts] regular_file thing2" */
	\|\| S_ISREG(source_stat.st_mode)
	/* DEREF uses stat, which never returns S_ISLNK() == true.
	* So the below is never true: */
	/* \|\| (FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) */
	) {
	int src_fd;
	int dst_fd;
	mode_t new_mode;

	if (!FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) {
	/* "cp -d symlink dst": create a link */
	goto dont_cat;
	}

	if (ENABLE_FEATURE_PRESERVE_HARDLINKS && !FLAGS_DEREF) {
	const char *link_target;
	link_target = is_in_ino_dev_hashtable(&source_stat);
	if (link_target) {
	if (link(link_target, dest) < 0) {
	ovr = ask_and_unlink(dest, flags);
	if (ovr <= 0)
	return ovr;
	if (link(link_target, dest) < 0) {
	bb_perror_msg("cannot create link '%s'", dest);
	return -1;
	}
	}
	return 0;
	}
	add_to_ino_dev_hashtable(&source_stat, dest);
	}

	src_fd = open_or_warn(source, O_RDONLY);
	if (src_fd < 0)
	return -1;

	/* Do not try to open with weird mode fields */
	new_mode = source_stat.st_mode;
	if (!S_ISREG(source_stat.st_mode))
	new_mode = 0666;

	/* POSIX way is a security problem versus symlink attacks,
	* we do it only for non-symlinks, and only for non-recursive,
	* non-interactive cp. NB: it is still racy
	* for "cp file /home/bad_user/file" case
	* (user can rm file and create a link to /etc/passwd) */
	if (DO_POSIX_CP
	\|\| (dest_exists
	&& !(flags & (FILEUTILS_RECUR\|FILEUTILS_INTERACTIVE))
	&& !S_ISLNK(dest_stat.st_mode))
	) {
	dst_fd = open(dest, O_WRONLY\|O_CREAT\|O_TRUNC, new_mode);
	} else /* safe way: */
	dst_fd = open(dest, O_WRONLY\|O_CREAT\|O_EXCL, new_mode);
	if (dst_fd == -1) {
	ovr = ask_and_unlink(dest, flags);
	if (ovr <= 0) {
	close(src_fd);
	return ovr;
	}
	/* It shouldn't exist. If it exists, do not open (symlink attack?) */
	dst_fd = open3_or_warn(dest, O_WRONLY\|O_CREAT\|O_EXCL, new_mode);
	if (dst_fd < 0) {
	close(src_fd);
	return -1;
	}
	}

	#if ENABLE_SELINUX
	if ((flags & (FILEUTILS_PRESERVE_SECURITY_CONTEXT\|FILEUTILS_SET_SECURITY_CONTEXT))
	&& is_selinux_enabled() > 0
	) {
	security_context_t con;
	if (getfscreatecon(&con) == -1) {
	bb_perror_msg("getfscreatecon");
	return -1;
	}
	if (con) {
	if (setfilecon(dest, con) == -1) {
	bb_perror_msg("setfilecon:%s,%s", dest, con);
	freecon(con);
	return -1;
	}
	freecon(con);
	}
	}
	#endif
	if (bb_copyfd_eof(src_fd, dst_fd) == -1)
	retval = -1;
	/* Ok, writing side I can understand... */
	if (close(dst_fd) < 0) {
	bb_perror_msg("cannot close '%s'", dest);
	retval = -1;
	}
	/* ...but read size is already checked by bb_copyfd_eof */
	close(src_fd);
	/* "cp /dev/something new_file" should not
	* copy mode of /dev/something */
	if (!S_ISREG(source_stat.st_mode))
	return retval;
	goto preserve_mode_ugid_time;
	}
	dont_cat:

	/* Source is a symlink or a special file */
	/* We are lazy here, a bit lax with races... */
	if (dest_exists) {
	errno = EEXIST;
	ovr = ask_and_unlink(dest, flags);
	if (ovr <= 0)
	return ovr;
	}
	if (S_ISLNK(source_stat.st_mode)) {
	char *lpath = xmalloc_readlink_or_warn(source);
	if (lpath) {
	int r = symlink(lpath, dest);
	free(lpath);
	if (r < 0) {
	bb_perror_msg("cannot create symlink '%s'", dest);
	return -1;
	}
	if (flags & FILEUTILS_PRESERVE_STATUS)
	if (lchown(dest, source_stat.st_uid, source_stat.st_gid) < 0)
	bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest);
	}
	/* _Not_ jumping to preserve_mode_ugid_time:
	* symlinks don't have those */
	return 0;
	}
	if (S_ISBLK(source_stat.st_mode) \|\| S_ISCHR(source_stat.st_mode)
	\|\| S_ISSOCK(source_stat.st_mode) \|\| S_ISFIFO(source_stat.st_mode)
	) {
	if (mknod(dest, source_stat.st_mode, source_stat.st_rdev) < 0) {
	bb_perror_msg("cannot create '%s'", dest);
	return -1;
	}
	} else {
	bb_error_msg("unrecognized file '%s' with mode %x", source, source_stat.st_mode);
	return -1;
	}

	preserve_mode_ugid_time:

	if (flags & FILEUTILS_PRESERVE_STATUS
	/* Cannot happen: */
	/* && !(flags & (FILEUTILS_MAKE_SOFTLINK\|FILEUTILS_MAKE_HARDLINK)) */
	) {
	struct utimbuf times;

	times.actime = source_stat.st_atime;
	times.modtime = source_stat.st_mtime;
	/* BTW, utimes sets usec-precision time - just FYI */
	if (utime(dest, &times) < 0)
	bb_perror_msg("cannot preserve %s of '%s'", "times", dest);
	if (chown(dest, source_stat.st_uid, source_stat.st_gid) < 0) {
	source_stat.st_mode &= ~(S_ISUID \| S_ISGID);
	bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest);
	}
	if (chmod(dest, source_stat.st_mode) < 0)
	bb_perror_msg("cannot preserve %s of '%s'", "permissions", dest);
	}

	return retval;
	}