busybox/libbb/copy_file.c

/* 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;
}
1	/* vi: set sw=4 ts=4: */
2	/*
3	* Mini copy_file implementation for busybox
4	*
5	* Copyright (C) 2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
6	* SELinux support by Yuichi Nakamura <ynakam@hitachisoft.jp>
7	*
8	* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
9	*
10	*/
11
12	#include "libbb.h"
13
14	// POSIX: if exists and -i, ask (w/o -i assume yes).
15	// Then open w/o EXCL (yes, not unlink!).
16	// If open still fails and -f, try unlink, then try open again.
17	// Result: a mess:
18	// If dest is a softlink, we overwrite softlink's destination!
19	// (or fail, if it points to dir/nonexistent location/etc).
20	// This is strange, but POSIX-correct.
21	// coreutils cp has --remove-destination to override this...
22	//
23	// NB: we have special code which still allows for "cp file /dev/node"
24	// to work POSIX-ly (the only realistic case where it makes sense)
25
26	#define DO_POSIX_CP 0 /* 1 - POSIX behavior, 0 - safe behavior */
27
28	// errno must be set to relevant value ("why we cannot create dest?")
29	// for POSIX mode to give reasonable error message
30	static int ask_and_unlink(const char *dest, int flags)
31	{
32	int e = errno;
33	#if DO_POSIX_CP
34	if (!(flags & (FILEUTILS_FORCE\|FILEUTILS_INTERACTIVE))) {
35	// Either it exists, or the path doesnt exist
36	bb_perror_msg("cannot create '%s'", dest);
37	return -1;
38	}
39	#endif
40	// If !DO_POSIX_CP, act as if -f is always in effect - we don't want
41	// "cannot create" msg, we want unlink to be done (silently unless -i).
42
43	// TODO: maybe we should do it only if ctty is present?
44	if (flags & FILEUTILS_INTERACTIVE) {
45	// We would not do POSIX insanity. -i asks,
46	// then _unlinks_ the offender. Presto.
47	// (No "opening without O_EXCL", no "unlink only if -f")
48	// Or else we will end up having 3 open()s!
49	fprintf(stderr, "%s: overwrite '%s'? ", applet_name, dest);
50	if (!bb_ask_confirmation())
51	return 0; // not allowed to overwrite
52	}
53	if (unlink(dest) < 0) {
54	#if ENABLE_FEATURE_VERBOSE_CP_MESSAGE
55	if (e == errno && e == ENOENT) {
56	/* e == ENOTDIR is similar: path has non-dir component,
57	* but in this case we don't even reach copy_file() */
58	bb_error_msg("cannot create '%s': Path does not exist", dest);
59	return -1; // error
60	}
61	#endif
62	errno = e;
63	bb_perror_msg("cannot create '%s'", dest);
64	return -1; // error
65	}
66	return 1; // ok (to try again)
67	}
68
69	/* Return:
70	* -1 error, copy not made
71	* 0 copy is made or user answered "no" in interactive mode
72	* (failures to preserve mode/owner/times are not reported in exit code)
73	*/
74	int FAST_FUNC copy_file(const char source, const char dest, int flags)
75	{
76	/* This is a recursive function, try to minimize stack usage */
77	/* NB: each struct stat is ~100 bytes */
78	struct stat source_stat;
79	struct stat dest_stat;
80	signed char retval = 0;
81	signed char dest_exists = 0;
82	signed char ovr;
83
84	/* Inverse of cp -d ("cp without -d") */
85	#define FLAGS_DEREF (flags & FILEUTILS_DEREFERENCE)
86
87	if ((FLAGS_DEREF ? stat : lstat)(source, &source_stat) < 0) {
88	// This may be a dangling symlink.
89	// Making [sym]links to dangling symlinks works, so...
90	if (flags & (FILEUTILS_MAKE_SOFTLINK\|FILEUTILS_MAKE_HARDLINK))
91	goto make_links;
92	bb_perror_msg("cannot stat '%s'", source);
93	return -1;
94	}
95
96	if (lstat(dest, &dest_stat) < 0) {
97	if (errno != ENOENT) {
98	bb_perror_msg("cannot stat '%s'", dest);
99	return -1;
100	}
101	} else {
102	if (source_stat.st_dev == dest_stat.st_dev
103	&& source_stat.st_ino == dest_stat.st_ino
104	) {
105	bb_error_msg("'%s' and '%s' are the same file", source, dest);
106	return -1;
107	}
108	dest_exists = 1;
109	}
110
111	#if ENABLE_SELINUX
112	if ((flags & FILEUTILS_PRESERVE_SECURITY_CONTEXT) && is_selinux_enabled() > 0) {
113	security_context_t con;
114	if (lgetfilecon(source, &con) >= 0) {
115	if (setfscreatecon(con) < 0) {
116	bb_perror_msg("cannot set setfscreatecon %s", con);
117	freecon(con);
118	return -1;
119	}
120	} else if (errno == ENOTSUP \|\| errno == ENODATA) {
121	setfscreatecon_or_die(NULL);
122	} else {
123	bb_perror_msg("cannot lgetfilecon %s", source);
124	return -1;
125	}
126	}
127	#endif
128
129	if (S_ISDIR(source_stat.st_mode)) {
130	DIR *dp;
131	const char *tp;
132	struct dirent *d;
133	mode_t saved_umask = 0;
134
135	if (!(flags & FILEUTILS_RECUR)) {
136	bb_error_msg("omitting directory '%s'", source);
137	return -1;
138	}
139
140	/* Did we ever create source ourself before? */
141	tp = is_in_ino_dev_hashtable(&source_stat);
142	if (tp) {
143	/* We did! it's a recursion! man the lifeboats... */
144	bb_error_msg("recursion detected, omitting directory '%s'",
145	source);
146	return -1;
147	}
148
149	/* Create DEST */
150	if (dest_exists) {
151	if (!S_ISDIR(dest_stat.st_mode)) {
152	bb_error_msg("target '%s' is not a directory", dest);
153	return -1;
154	}
155	/* race here: user can substitute a symlink between
156	* this check and actual creation of files inside dest */
157	} else {
158	mode_t mode;
159	saved_umask = umask(0);
160
161	mode = source_stat.st_mode;
162	if (!(flags & FILEUTILS_PRESERVE_STATUS))
163	mode = source_stat.st_mode & ~saved_umask;
164	/* Allow owner to access new dir (at least for now) */
165	mode \|= S_IRWXU;
166	if (mkdir(dest, mode) < 0) {
167	umask(saved_umask);
168	bb_perror_msg("cannot create directory '%s'", dest);
169	return -1;
170	}
171	umask(saved_umask);
172	/* need stat info for add_to_ino_dev_hashtable */
173	if (lstat(dest, &dest_stat) < 0) {
174	bb_perror_msg("cannot stat '%s'", dest);
175	return -1;
176	}
177	}
178	/* remember (dev,inode) of each created dir.
179	* NULL: name is not remembered */
180	add_to_ino_dev_hashtable(&dest_stat, NULL);
181
182	/* Recursively copy files in SOURCE */
183	dp = opendir(source);
184	if (dp == NULL) {
185	retval = -1;
186	goto preserve_mode_ugid_time;
187	}
188
189	while ((d = readdir(dp)) != NULL) {
190	char new_source, new_dest;
191
192	new_source = concat_subpath_file(source, d->d_name);
193	if (new_source == NULL)
194	continue;
195	new_dest = concat_path_file(dest, d->d_name);
196	if (copy_file(new_source, new_dest, flags) < 0)
197	retval = -1;
198	free(new_source);
199	free(new_dest);
200	}
201	closedir(dp);
202
203	if (!dest_exists
204	&& chmod(dest, source_stat.st_mode & ~saved_umask) < 0
205	) {
206	bb_perror_msg("cannot preserve %s of '%s'", "permissions", dest);
207	/* retval = -1; - WRONG! copy WAS made */
208	}
209	goto preserve_mode_ugid_time;
210	}
211
212	if (flags & (FILEUTILS_MAKE_SOFTLINK\|FILEUTILS_MAKE_HARDLINK)) {
213	int (lf)(const char oldpath, const char *newpath);
214	make_links:
215	// Hmm... maybe
216	// if (DEREF && MAKE_SOFTLINK) source = realpath(source) ?
217	// (but realpath returns NULL on dangling symlinks...)
218	lf = (flags & FILEUTILS_MAKE_SOFTLINK) ? symlink : link;
219	if (lf(source, dest) < 0) {
220	ovr = ask_and_unlink(dest, flags);
221	if (ovr <= 0)
222	return ovr;
223	if (lf(source, dest) < 0) {
224	bb_perror_msg("cannot create link '%s'", dest);
225	return -1;
226	}
227	}
228	/* _Not_ jumping to preserve_mode_ugid_time:
229	* hard/softlinks don't have those */
230	return 0;
231	}
232
233	if (/* "cp thing1 thing2" without -R: just open and read() from thing1 */
234	!(flags & FILEUTILS_RECUR)
235	/* "cp [-opts] regular_file thing2" */
236	\|\| S_ISREG(source_stat.st_mode)
237	/* DEREF uses stat, which never returns S_ISLNK() == true.
238	* So the below is never true: */
239	/* \|\| (FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) */
240	) {
241	int src_fd;
242	int dst_fd;
243	mode_t new_mode;
244
245	if (!FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) {
246	/* "cp -d symlink dst": create a link */
247	goto dont_cat;
248	}
249
250	if (ENABLE_FEATURE_PRESERVE_HARDLINKS && !FLAGS_DEREF) {
251	const char *link_target;
252	link_target = is_in_ino_dev_hashtable(&source_stat);
253	if (link_target) {
254	if (link(link_target, dest) < 0) {
255	ovr = ask_and_unlink(dest, flags);
256	if (ovr <= 0)
257	return ovr;
258	if (link(link_target, dest) < 0) {
259	bb_perror_msg("cannot create link '%s'", dest);
260	return -1;
261	}
262	}
263	return 0;
264	}
265	add_to_ino_dev_hashtable(&source_stat, dest);
266	}
267
268	src_fd = open_or_warn(source, O_RDONLY);
269	if (src_fd < 0)
270	return -1;
271
272	/* Do not try to open with weird mode fields */
273	new_mode = source_stat.st_mode;
274	if (!S_ISREG(source_stat.st_mode))
275	new_mode = 0666;
276
277	/* POSIX way is a security problem versus symlink attacks,
278	* we do it only for non-symlinks, and only for non-recursive,
279	* non-interactive cp. NB: it is still racy
280	* for "cp file /home/bad_user/file" case
281	* (user can rm file and create a link to /etc/passwd) */
282	if (DO_POSIX_CP
283	\|\| (dest_exists
284	&& !(flags & (FILEUTILS_RECUR\|FILEUTILS_INTERACTIVE))
285	&& !S_ISLNK(dest_stat.st_mode))
286	) {
287	dst_fd = open(dest, O_WRONLY\|O_CREAT\|O_TRUNC, new_mode);
288	} else /* safe way: */
289	dst_fd = open(dest, O_WRONLY\|O_CREAT\|O_EXCL, new_mode);
290	if (dst_fd == -1) {
291	ovr = ask_and_unlink(dest, flags);
292	if (ovr <= 0) {
293	close(src_fd);
294	return ovr;
295	}
296	/* It shouldn't exist. If it exists, do not open (symlink attack?) */
297	dst_fd = open3_or_warn(dest, O_WRONLY\|O_CREAT\|O_EXCL, new_mode);
298	if (dst_fd < 0) {
299	close(src_fd);
300	return -1;
301	}
302	}
303
304	#if ENABLE_SELINUX
305	if ((flags & (FILEUTILS_PRESERVE_SECURITY_CONTEXT\|FILEUTILS_SET_SECURITY_CONTEXT))
306	&& is_selinux_enabled() > 0
307	) {
308	security_context_t con;
309	if (getfscreatecon(&con) == -1) {
310	bb_perror_msg("getfscreatecon");
311	return -1;
312	}
313	if (con) {
314	if (setfilecon(dest, con) == -1) {
315	bb_perror_msg("setfilecon:%s,%s", dest, con);
316	freecon(con);
317	return -1;
318	}
319	freecon(con);
320	}
321	}
322	#endif
323	if (bb_copyfd_eof(src_fd, dst_fd) == -1)
324	retval = -1;
325	/* Ok, writing side I can understand... */
326	if (close(dst_fd) < 0) {
327	bb_perror_msg("cannot close '%s'", dest);
328	retval = -1;
329	}
330	/* ...but read size is already checked by bb_copyfd_eof */
331	close(src_fd);
332	/* "cp /dev/something new_file" should not
333	* copy mode of /dev/something */
334	if (!S_ISREG(source_stat.st_mode))
335	return retval;
336	goto preserve_mode_ugid_time;
337	}
338	dont_cat:
339
340	/* Source is a symlink or a special file */
341	/* We are lazy here, a bit lax with races... */
342	if (dest_exists) {
343	errno = EEXIST;
344	ovr = ask_and_unlink(dest, flags);
345	if (ovr <= 0)
346	return ovr;
347	}
348	if (S_ISLNK(source_stat.st_mode)) {
349	char *lpath = xmalloc_readlink_or_warn(source);
350	if (lpath) {
351	int r = symlink(lpath, dest);
352	free(lpath);
353	if (r < 0) {
354	bb_perror_msg("cannot create symlink '%s'", dest);
355	return -1;
356	}
357	if (flags & FILEUTILS_PRESERVE_STATUS)
358	if (lchown(dest, source_stat.st_uid, source_stat.st_gid) < 0)
359	bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest);
360	}
361	/* _Not_ jumping to preserve_mode_ugid_time:
362	* symlinks don't have those */
363	return 0;
364	}
365	if (S_ISBLK(source_stat.st_mode) \|\| S_ISCHR(source_stat.st_mode)
366	\|\| S_ISSOCK(source_stat.st_mode) \|\| S_ISFIFO(source_stat.st_mode)
367	) {
368	if (mknod(dest, source_stat.st_mode, source_stat.st_rdev) < 0) {
369	bb_perror_msg("cannot create '%s'", dest);
370	return -1;
371	}
372	} else {
373	bb_error_msg("unrecognized file '%s' with mode %x", source, source_stat.st_mode);
374	return -1;
375	}
376
377	preserve_mode_ugid_time:
378
379	if (flags & FILEUTILS_PRESERVE_STATUS
380	/* Cannot happen: */
381	/* && !(flags & (FILEUTILS_MAKE_SOFTLINK\|FILEUTILS_MAKE_HARDLINK)) */
382	) {
383	struct utimbuf times;
384
385	times.actime = source_stat.st_atime;
386	times.modtime = source_stat.st_mtime;
387	/* BTW, utimes sets usec-precision time - just FYI */
388	if (utime(dest, &times) < 0)
389	bb_perror_msg("cannot preserve %s of '%s'", "times", dest);
390	if (chown(dest, source_stat.st_uid, source_stat.st_gid) < 0) {
391	source_stat.st_mode &= ~(S_ISUID \| S_ISGID);
392	bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest);
393	}
394	if (chmod(dest, source_stat.st_mode) < 0)
395	bb_perror_msg("cannot preserve %s of '%s'", "permissions", dest);
396	}
397
398	return retval;
399	}