Adding upstream version 3.2.7.upstream/3.2.7

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1274 insertions, 0 deletions

diff --git a/xattrs.c b/xattrs.c
new file mode 100644
index 0000000..26e50a6
--- /dev/null
+++ b/xattrs.c
@@ -0,0 +1,1274 @@
+/*
+ * Extended Attribute support for rsync.
+ * Written by Jay Fenlason, vaguely based on the ACLs patch.
+ *
+ * Copyright (C) 2004 Red Hat, Inc.
+ * Copyright (C) 2006-2022 Wayne Davison
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, visit the http://fsf.org website.
+ */
+
+#include "rsync.h"
+#include "ifuncs.h"
+#include "inums.h"
+#include "lib/sysxattrs.h"
+
+#ifdef SUPPORT_XATTRS
+
+extern int dry_run;
+extern int am_root;
+extern int am_sender;
+extern int am_generator;
+extern int read_only;
+extern int list_only;
+extern int preserve_xattrs;
+extern int preserve_links;
+extern int preserve_devices;
+extern int preserve_specials;
+extern int checksum_seed;
+extern int saw_xattr_filter;
+
+extern struct name_num_item *xattr_sum_nni;
+extern int xattr_sum_len;
+
+#define RSYNC_XAL_INITIAL 5
+#define RSYNC_XAL_LIST_INITIAL 100
+
+#define MAX_XATTR_DIGEST_LEN MD5_DIGEST_LEN
+#define MAX_FULL_DATUM 32
+
+#define HAS_PREFIX(str, prfx) (*(str) == *(prfx) && strncmp(str, prfx, sizeof (prfx) - 1) == 0)
+
+#define XATTR_ABBREV(x) ((size_t)((x).name - (x).datum) < (x).datum_len)
+
+#define XSTATE_ABBREV	1
+#define XSTATE_DONE	2
+#define XSTATE_TODO	3
+
+#define USER_PREFIX "user."
+#define UPRE_LEN ((int)sizeof USER_PREFIX - 1)
+#define SYSTEM_PREFIX "system."
+#define SPRE_LEN ((int)sizeof SYSTEM_PREFIX - 1)
+
+#ifdef HAVE_LINUX_XATTRS
+#define MIGHT_NEED_RPRE (am_root <= 0)
+#define RSYNC_PREFIX USER_PREFIX "rsync."
+#else
+#define MIGHT_NEED_RPRE am_root
+#define RSYNC_PREFIX "rsync."
+#endif
+#define RPRE_LEN ((int)sizeof RSYNC_PREFIX - 1)
+
+#define XSTAT_SUFFIX "stat"
+#define XSTAT_ATTR RSYNC_PREFIX "%" XSTAT_SUFFIX
+#define XACC_ACL_SUFFIX "aacl"
+#define XACC_ACL_ATTR RSYNC_PREFIX "%" XACC_ACL_SUFFIX
+#define XDEF_ACL_SUFFIX "dacl"
+#define XDEF_ACL_ATTR RSYNC_PREFIX "%" XDEF_ACL_SUFFIX
+
+typedef struct {
+	char *datum, *name;
+	size_t datum_len, name_len;
+	int num;
+} rsync_xa;
+
+struct _rsync_xa_list;
+
+typedef struct _rsync_xa_list_ref {
+	struct _rsync_xa_list_ref *next;
+	int ndx;
+} rsync_xa_list_ref;
+
+typedef struct _rsync_xa_list {
+	int ndx;
+	int64 key;
+	item_list xa_items;
+} rsync_xa_list;
+
+static size_t namebuf_len = 0;
+static char *namebuf = NULL;
+
+static const rsync_xa_list empty_xa_list = {
+	.xa_items = EMPTY_ITEM_LIST,
+};
+static const item_list empty_xattr = EMPTY_ITEM_LIST;
+static item_list rsync_xal_l = EMPTY_ITEM_LIST;
+static struct hashtable *rsync_xal_h = NULL;
+
+static size_t prior_xattr_count = (size_t)-1;
+
+/* ------------------------------------------------------------------------- */
+
+static void rsync_xal_free(item_list *xalp)
+{
+	size_t i;
+	rsync_xa *rxas = xalp->items;
+
+	if (!xalp->malloced)
+		return;
+
+	for (i = 0; i < xalp->count; i++) {
+		free(rxas[i].datum);
+		/*free(rxas[i].name);*/
+	}
+	free(xalp->items);
+}
+
+void free_xattr(stat_x *sxp)
+{
+	if (!sxp->xattr)
+		return;
+	rsync_xal_free(sxp->xattr);
+	free(sxp->xattr);
+	sxp->xattr = NULL;
+}
+
+static int rsync_xal_compare_names(const void *x1, const void *x2)
+{
+	const rsync_xa *xa1 = x1;
+	const rsync_xa *xa2 = x2;
+	return strcmp(xa1->name, xa2->name);
+}
+
+static ssize_t get_xattr_names(const char *fname)
+{
+	ssize_t list_len;
+	int64 arg;
+
+	if (!namebuf) {
+		namebuf_len = 1024;
+		namebuf = new_array(char, namebuf_len);
+	}
+
+	while (1) {
+		/* The length returned includes all the '\0' terminators. */
+		list_len = sys_llistxattr(fname, namebuf, namebuf_len);
+		if (list_len >= 0) {
+			if ((size_t)list_len <= namebuf_len)
+				break;
+		} else if (errno == ENOTSUP)
+			return 0;
+		else if (errno != ERANGE) {
+			arg = namebuf_len;
+		  got_error:
+			rsyserr(FERROR_XFER, errno,
+				"get_xattr_names: llistxattr(%s,%s) failed",
+				full_fname(fname), big_num(arg));
+			return -1;
+		}
+		list_len = sys_llistxattr(fname, NULL, 0);
+		if (list_len < 0) {
+			arg = 0;
+			goto got_error;
+		}
+		if (namebuf_len)
+			free(namebuf);
+		namebuf_len = list_len + 1024;
+		namebuf = new_array(char, namebuf_len);
+	}
+
+	return list_len;
+}
+
+/* On entry, the *len_ptr parameter contains the size of the extra space we
+ * should allocate when we create a buffer for the data.  On exit, it contains
+ * the length of the datum. */
+static char *get_xattr_data(const char *fname, const char *name, size_t *len_ptr, int no_missing_error)
+{
+	size_t datum_len = sys_lgetxattr(fname, name, NULL, 0);
+	size_t extra_len = *len_ptr;
+	char *ptr;
+
+	*len_ptr = datum_len;
+
+	if (datum_len == (size_t)-1) {
+		if (errno == ENOTSUP || no_missing_error)
+			return NULL;
+		rsyserr(FERROR_XFER, errno,
+			"get_xattr_data: lgetxattr(%s,\"%s\",0) failed",
+			full_fname(fname), name);
+		return NULL;
+	}
+
+	if (!datum_len && !extra_len)
+		extra_len = 1; /* request non-zero amount of memory */
+	if (SIZE_MAX - datum_len < extra_len)
+		overflow_exit("get_xattr_data");
+	ptr = new_array(char, datum_len + extra_len);
+
+	if (datum_len) {
+		size_t len = sys_lgetxattr(fname, name, ptr, datum_len);
+		if (len != datum_len) {
+			if (len == (size_t)-1) {
+				rsyserr(FERROR_XFER, errno,
+					"get_xattr_data: lgetxattr(%s,\"%s\",%ld) failed",
+					full_fname(fname), name, (long)datum_len);
+			} else {
+				rprintf(FERROR_XFER,
+					"get_xattr_data: lgetxattr(%s,\"%s\",%ld) returned %ld\n",
+					full_fname(fname), name,
+					(long)datum_len, (long)len);
+			}
+			free(ptr);
+			return NULL;
+		}
+	}
+
+	return ptr;
+}
+
+static int rsync_xal_get(const char *fname, item_list *xalp)
+{
+	ssize_t list_len, name_len;
+	size_t datum_len, name_offset;
+	char *name, *ptr;
+#ifdef HAVE_LINUX_XATTRS
+	int user_only = am_sender ? 0 : !am_root;
+#endif
+	rsync_xa *rxa;
+	int count;
+
+	/* This puts the name list into the "namebuf" buffer. */
+	if ((list_len = get_xattr_names(fname)) < 0)
+		return -1;
+
+	for (name = namebuf; list_len > 0; name += name_len) {
+		name_len = strlen(name) + 1;
+		list_len -= name_len;
+
+		if (saw_xattr_filter) {
+			if (name_is_excluded(name, NAME_IS_XATTR, ALL_FILTERS))
+				continue;
+		}
+#ifdef HAVE_LINUX_XATTRS
+		/* Choose between ignoring the system namespace or (non-root) ignoring any non-user namespace. */
+		else if (user_only ? !HAS_PREFIX(name, USER_PREFIX) : HAS_PREFIX(name, SYSTEM_PREFIX))
+			continue;
+#endif
+
+		/* No rsync.%FOO attributes are copied w/o 2 -X options. */
+		if (name_len > RPRE_LEN && name[RPRE_LEN] == '%' && HAS_PREFIX(name, RSYNC_PREFIX)) {
+			if ((am_sender && preserve_xattrs < 2)
+			 || (am_root < 0
+			  && (strcmp(name+RPRE_LEN+1, XSTAT_SUFFIX) == 0
+			   || strcmp(name+RPRE_LEN+1, XACC_ACL_SUFFIX) == 0
+			   || strcmp(name+RPRE_LEN+1, XDEF_ACL_SUFFIX) == 0)))
+				continue;
+		}
+
+		datum_len = name_len; /* Pass extra size to get_xattr_data() */
+		if (!(ptr = get_xattr_data(fname, name, &datum_len, 0)))
+			return -1;
+
+		if (datum_len > MAX_FULL_DATUM) {
+			/* For large datums, we store a flag and a checksum. */
+			name_offset = 1 + MAX_XATTR_DIGEST_LEN;
+			sum_init(xattr_sum_nni, checksum_seed);
+			sum_update(ptr, datum_len);
+			free(ptr);
+
+			ptr = new_array(char, name_offset + name_len);
+			*ptr = XSTATE_ABBREV;
+			sum_end(ptr + 1);
+		} else
+			name_offset = datum_len;
+
+		rxa = EXPAND_ITEM_LIST(xalp, rsync_xa, RSYNC_XAL_INITIAL);
+		rxa->name = ptr + name_offset;
+		memcpy(rxa->name, name, name_len);
+		rxa->datum = ptr;
+		rxa->name_len = name_len;
+		rxa->datum_len = datum_len;
+	}
+	count = xalp->count;
+	rxa = xalp->items;
+	if (count > 1)
+		qsort(rxa, count, sizeof (rsync_xa), rsync_xal_compare_names);
+	for (rxa += count-1; count; count--, rxa--)
+		rxa->num = count;
+	return 0;
+}
+
+/* Read the xattr(s) for this filename. */
+int get_xattr(const char *fname, stat_x *sxp)
+{
+	sxp->xattr = new(item_list);
+	*sxp->xattr = empty_xattr;
+
+	if (S_ISREG(sxp->st.st_mode) || S_ISDIR(sxp->st.st_mode)) {
+		/* Everyone supports this. */
+	} else if (S_ISLNK(sxp->st.st_mode)) {
+#ifndef NO_SYMLINK_XATTRS
+		if (!preserve_links)
+#endif
+			return 0;
+	} else if (IS_SPECIAL(sxp->st.st_mode)) {
+#ifndef NO_SPECIAL_XATTRS
+		if (!preserve_specials)
+#endif
+			return 0;
+	} else if (IS_DEVICE(sxp->st.st_mode)) {
+#ifndef NO_DEVICE_XATTRS
+		if (!preserve_devices)
+#endif
+			return 0;
+	} else if (IS_MISSING_FILE(sxp->st))
+		return 0;
+
+	if (rsync_xal_get(fname, sxp->xattr) < 0) {
+		free_xattr(sxp);
+		return -1;
+	}
+	return 0;
+}
+
+int copy_xattrs(const char *source, const char *dest)
+{
+	ssize_t list_len, name_len;
+	size_t datum_len;
+	char *name, *ptr;
+#ifdef HAVE_LINUX_XATTRS
+	int user_only = am_sender ? 0 : am_root <= 0;
+#endif
+
+	/* This puts the name list into the "namebuf" buffer. */
+	if ((list_len = get_xattr_names(source)) < 0)
+		return -1;
+
+	for (name = namebuf; list_len > 0; name += name_len) {
+		name_len = strlen(name) + 1;
+		list_len -= name_len;
+
+		if (saw_xattr_filter) {
+			if (name_is_excluded(name, NAME_IS_XATTR, ALL_FILTERS))
+				continue;
+		}
+#ifdef HAVE_LINUX_XATTRS
+		/* Choose between ignoring the system namespace or (non-root) ignoring any non-user namespace. */
+		else if (user_only ? !HAS_PREFIX(name, USER_PREFIX) : HAS_PREFIX(name, SYSTEM_PREFIX))
+			continue;
+#endif
+
+		datum_len = 0;
+		if (!(ptr = get_xattr_data(source, name, &datum_len, 0)))
+			return -1;
+		if (sys_lsetxattr(dest, name, ptr, datum_len) < 0) {
+			int save_errno = errno ? errno : EINVAL;
+			rsyserr(FERROR_XFER, errno,
+				"copy_xattrs: lsetxattr(%s,\"%s\") failed",
+				full_fname(dest), name);
+			errno = save_errno;
+			return -1;
+		}
+		free(ptr);
+	}
+
+	return 0;
+}
+
+static int64 xattr_lookup_hash(const item_list *xalp)
+{
+	const rsync_xa *rxas = xalp->items;
+	size_t i;
+	int64 key = hashlittle2(&xalp->count, sizeof xalp->count);
+
+	for (i = 0; i < xalp->count; i++) {
+		key += hashlittle2(rxas[i].name, rxas[i].name_len);
+		if (rxas[i].datum_len > MAX_FULL_DATUM)
+			key += hashlittle2(rxas[i].datum, xattr_sum_len);
+		else
+			key += hashlittle2(rxas[i].datum, rxas[i].datum_len);
+	}
+
+	return key;
+}
+
+static int find_matching_xattr(const item_list *xalp)
+{
+	const struct ht_int64_node *node;
+	const rsync_xa_list_ref *ref;
+	int64 key;
+
+	if (rsync_xal_h == NULL)
+		return -1;
+
+	key = xattr_lookup_hash(xalp);
+
+	node = hashtable_find(rsync_xal_h, key, NULL);
+	if (node == NULL)
+		return -1;
+
+	if (node->data == NULL)
+		return -1;
+
+	for (ref = node->data; ref != NULL; ref = ref->next) {
+		const rsync_xa_list *ptr = rsync_xal_l.items;
+		const rsync_xa *rxas1;
+		const rsync_xa *rxas2 = xalp->items;
+		size_t j;
+
+		ptr += ref->ndx;
+		rxas1 = ptr->xa_items.items;
+
+		/* Wrong number of elements? */
+		if (ptr->xa_items.count != xalp->count)
+			continue;
+		/* any elements different? */
+		for (j = 0; j < xalp->count; j++) {
+			if (rxas1[j].name_len != rxas2[j].name_len
+			 || rxas1[j].datum_len != rxas2[j].datum_len
+			 || strcmp(rxas1[j].name, rxas2[j].name))
+				break;
+			if (rxas1[j].datum_len > MAX_FULL_DATUM) {
+				if (memcmp(rxas1[j].datum + 1,
+					   rxas2[j].datum + 1,
+					   xattr_sum_len) != 0)
+					break;
+			} else {
+				if (memcmp(rxas1[j].datum, rxas2[j].datum,
+					   rxas2[j].datum_len))
+					break;
+			}
+		}
+		/* no differences found.  This is The One! */
+		if (j == xalp->count)
+			return ref->ndx;
+	}
+
+	return -1;
+}
+
+/* Store *xalp on the end of rsync_xal_l */
+static int rsync_xal_store(item_list *xalp)
+{
+	struct ht_int64_node *node;
+	int ndx = rsync_xal_l.count; /* pre-incremented count */
+	rsync_xa_list *new_list = EXPAND_ITEM_LIST(&rsync_xal_l, rsync_xa_list, RSYNC_XAL_LIST_INITIAL);
+	rsync_xa_list_ref *new_ref;
+	/* Since the following call starts a new list, we know it will hold the
+	 * entire initial-count, not just enough space for one new item. */
+	*new_list = empty_xa_list;
+	(void)EXPAND_ITEM_LIST(&new_list->xa_items, rsync_xa, xalp->count);
+	memcpy(new_list->xa_items.items, xalp->items, xalp->count * sizeof (rsync_xa));
+	new_list->xa_items.count = xalp->count;
+	xalp->count = 0;
+
+	new_list->ndx = ndx;
+	new_list->key = xattr_lookup_hash(&new_list->xa_items);
+
+	if (rsync_xal_h == NULL)
+		rsync_xal_h = hashtable_create(512, HT_KEY64);
+
+	new_ref = new0(rsync_xa_list_ref);
+	new_ref->ndx = ndx;
+
+	node = hashtable_find(rsync_xal_h, new_list->key, new_ref);
+	if (node->data != (void*)new_ref) {
+		rsync_xa_list_ref *ref = node->data;
+
+		while (ref != NULL) {
+			if (ref->next != NULL) {
+				ref = ref->next;
+				continue;
+			}
+
+			ref->next = new_ref;
+			break;
+		}
+	}
+
+	return ndx;
+}
+
+/* Send the make_xattr()-generated xattr list for this flist entry. */
+int send_xattr(int f, stat_x *sxp)
+{
+	int ndx = find_matching_xattr(sxp->xattr);
+
+	/* Send 0 (-1 + 1) to indicate that literal xattr data follows. */
+	write_varint(f, ndx + 1);
+
+	if (ndx < 0) {
+		rsync_xa *rxa;
+		int count = sxp->xattr->count;
+		write_varint(f, count);
+		for (rxa = sxp->xattr->items; count--; rxa++) {
+			size_t name_len = rxa->name_len;
+			const char *name = rxa->name;
+			/* Strip the rsync prefix from disguised namespaces. */
+			if (name_len > RPRE_LEN
+#ifdef HAVE_LINUX_XATTRS
+			 && am_root < 0
+#endif
+			 && name[RPRE_LEN] != '%' && HAS_PREFIX(name, RSYNC_PREFIX)) {
+				name += RPRE_LEN;
+				name_len -= RPRE_LEN;
+			}
+#ifndef HAVE_LINUX_XATTRS
+			else {
+				/* Put everything else in the user namespace. */
+				name_len += UPRE_LEN;
+			}
+#endif
+			write_varint(f, name_len);
+			write_varint(f, rxa->datum_len);
+#ifndef HAVE_LINUX_XATTRS
+			if (name_len > rxa->name_len) {
+				write_buf(f, USER_PREFIX, UPRE_LEN);
+				name_len -= UPRE_LEN;
+			}
+#endif
+			write_buf(f, name, name_len);
+			if (rxa->datum_len > MAX_FULL_DATUM)
+				write_buf(f, rxa->datum + 1, xattr_sum_len);
+			else
+				write_bigbuf(f, rxa->datum, rxa->datum_len);
+		}
+		ndx = rsync_xal_store(sxp->xattr); /* adds item to rsync_xal_l */
+	}
+
+	return ndx;
+}
+
+/* Return a flag indicating if we need to change a file's xattrs.  If
+ * "find_all" is specified, also mark any abbreviated xattrs that we
+ * need so that send_xattr_request() can tell the sender about them. */
+int xattr_diff(struct file_struct *file, stat_x *sxp, int find_all)
+{
+	const rsync_xa_list *glst = rsync_xal_l.items;
+	const item_list *lst;
+	rsync_xa *snd_rxa, *rec_rxa;
+	int snd_cnt, rec_cnt;
+	int cmp, same, xattrs_equal = 1;
+
+	if (sxp && XATTR_READY(*sxp)) {
+		rec_rxa = sxp->xattr->items;
+		rec_cnt = sxp->xattr->count;
+	} else {
+		rec_rxa = NULL;
+		rec_cnt = 0;
+	}
+
+	if (F_XATTR(file) >= 0) {
+		glst += F_XATTR(file);
+		lst = &glst->xa_items;
+	} else
+		lst = &empty_xattr;
+
+	snd_rxa = lst->items;
+	snd_cnt = lst->count;
+
+	/* If the count of the sender's xattrs is different from our
+	 * (receiver's) xattrs, the lists are not the same. */
+	if (snd_cnt != rec_cnt) {
+		if (!find_all)
+			return 1;
+		xattrs_equal = 0;
+	}
+
+	while (snd_cnt) {
+		cmp = rec_cnt ? strcmp(snd_rxa->name, rec_rxa->name) : -1;
+		if (cmp > 0)
+			same = 0;
+		else if (snd_rxa->datum_len > MAX_FULL_DATUM) {
+			same = cmp == 0 && snd_rxa->datum_len == rec_rxa->datum_len
+			    && memcmp(snd_rxa->datum + 1, rec_rxa->datum + 1,
+				      xattr_sum_len) == 0;
+			/* Flag unrequested items that we need. */
+			if (!same && find_all && snd_rxa->datum[0] == XSTATE_ABBREV)
+				snd_rxa->datum[0] = XSTATE_TODO;
+		} else {
+			same = cmp == 0 && snd_rxa->datum_len == rec_rxa->datum_len
+			    && memcmp(snd_rxa->datum, rec_rxa->datum,
+				      snd_rxa->datum_len) == 0;
+		}
+		if (!same) {
+			if (!find_all)
+				return 1;
+			xattrs_equal = 0;
+		}
+
+		if (cmp <= 0) {
+			snd_rxa++;
+			snd_cnt--;
+		}
+		if (cmp >= 0) {
+			rec_rxa++;
+			rec_cnt--;
+		}
+	}
+
+	if (rec_cnt)
+		xattrs_equal = 0;
+
+	return !xattrs_equal;
+}
+
+/* When called by the generator (with a NULL fname), this tells the sender
+ * all the abbreviated xattr values we need.  When called by the sender
+ * (with a non-NULL fname), we send all the extra xattr data it needs.
+ * The generator may also call with f_out < 0 to just change all the
+ * XSTATE_ABBREV states into XSTATE_DONE. */
+void send_xattr_request(const char *fname, struct file_struct *file, int f_out)
+{
+	const rsync_xa_list *glst = rsync_xal_l.items;
+	const item_list *lst;
+	int cnt, prior_req = 0;
+	rsync_xa *rxa;
+
+	glst += F_XATTR(file);
+	lst = &glst->xa_items;
+
+	for (rxa = lst->items, cnt = lst->count; cnt--; rxa++) {
+		if (rxa->datum_len <= MAX_FULL_DATUM)
+			continue;
+		switch (rxa->datum[0]) {
+		case XSTATE_ABBREV:
+			/* Items left abbreviated matched the sender's checksum, so
+			 * the receiver will cache the local data for future use. */
+			if (am_generator)
+				rxa->datum[0] = XSTATE_DONE;
+			continue;
+		case XSTATE_TODO:
+			assert(f_out >= 0);
+			break;
+		default:
+			continue;
+		}
+
+		/* Flag that we handled this abbreviated item. */
+		rxa->datum[0] = XSTATE_DONE;
+
+		write_varint(f_out, rxa->num - prior_req);
+		prior_req = rxa->num;
+
+		if (fname) {
+			size_t len = 0;
+			char *ptr;
+
+			/* Re-read the long datum. */
+			if (!(ptr = get_xattr_data(fname, rxa->name, &len, 0))) {
+				rprintf(FERROR_XFER, "failed to re-read xattr %s for %s\n", rxa->name, fname);
+				write_varint(f_out, 0);
+				continue;
+			}
+
+			write_varint(f_out, len); /* length might have changed! */
+			write_bigbuf(f_out, ptr, len);
+			free(ptr);
+		}
+	}
+
+	if (f_out >= 0)
+		write_byte(f_out, 0); /* end the list */
+}
+
+/* When called by the sender, read the request from the generator and mark
+ * any needed xattrs with a flag that lets us know they need to be sent to
+ * the receiver.  When called by the receiver, reads the sent data and
+ * stores it in place of its checksum. */
+int recv_xattr_request(struct file_struct *file, int f_in)
+{
+	const rsync_xa_list *glst = rsync_xal_l.items;
+	const item_list *lst;
+	char *old_datum, *name;
+	rsync_xa *rxa;
+	int rel_pos, cnt, num, got_xattr_data = 0;
+
+	if (F_XATTR(file) < 0) {
+		rprintf(FERROR, "recv_xattr_request: internal data error!\n");
+		exit_cleanup(RERR_PROTOCOL);
+	}
+	glst += F_XATTR(file);
+	lst = &glst->xa_items;
+
+	cnt = lst->count;
+	rxa = lst->items;
+	num = 0;
+	while ((rel_pos = read_varint(f_in)) != 0) {
+		num += rel_pos;
+		if (am_sender) {
+			/* The sender-related num values are only in order on the sender.
+			 * We use that order here to scan forward or backward as needed. */
+			if (rel_pos < 0) {
+				while (cnt < (int)lst->count && rxa->num > num) {
+					rxa--;
+					cnt++;
+				}
+			} else {
+				while (cnt > 1 && rxa->num < num) {
+					rxa++;
+					cnt--;
+				}
+			}
+		} else {
+			int j;
+			/* The receiving side has no known num order, so we just scan
+			 * forward (w/wrap) and hope that the next value is near by. */
+			for (j = lst->count; j > 1 && rxa->num != num; j--) {
+				if (--cnt)
+					rxa++;
+				else {
+					cnt = lst->count;
+					rxa = lst->items;
+				}
+			}
+		}
+		if (!cnt || rxa->num != num) {
+			rprintf(FERROR, "[%s] could not find xattr #%d for %s\n",
+				who_am_i(), num, f_name(file, NULL));
+			exit_cleanup(RERR_PROTOCOL);
+		}
+		if (!XATTR_ABBREV(*rxa) || rxa->datum[0] != XSTATE_ABBREV) {
+			rprintf(FERROR, "[%s] internal abbrev error on %s (%s, len=%ld)!\n",
+				who_am_i(), f_name(file, NULL), rxa->name, (long)rxa->datum_len);
+			exit_cleanup(RERR_PROTOCOL);
+		}
+
+		if (am_sender) {
+			rxa->datum[0] = XSTATE_TODO;
+			continue;
+		}
+
+		old_datum = rxa->datum;
+		rxa->datum_len = read_varint(f_in);
+
+		if (SIZE_MAX - rxa->name_len < rxa->datum_len)
+			overflow_exit("recv_xattr_request");
+		rxa->datum = new_array(char, rxa->datum_len + rxa->name_len);
+		name = rxa->datum + rxa->datum_len;
+		memcpy(name, rxa->name, rxa->name_len);
+		rxa->name = name;
+		free(old_datum);
+		read_buf(f_in, rxa->datum, rxa->datum_len);
+		got_xattr_data = 1;
+	}
+
+	return got_xattr_data;
+}
+
+/* ------------------------------------------------------------------------- */
+
+/* receive and build the rsync_xattr_lists */
+void receive_xattr(int f, struct file_struct *file)
+{
+	static item_list temp_xattr = EMPTY_ITEM_LIST;
+	int count, num;
+#ifdef HAVE_LINUX_XATTRS
+	int need_sort = 0;
+#else
+	int need_sort = 1;
+#endif
+	int ndx = read_varint(f);
+
+	if (ndx < 0 || (size_t)ndx > rsync_xal_l.count) {
+		rprintf(FERROR, "receive_xattr: xa index %d out of"
+			" range for %s\n", ndx, f_name(file, NULL));
+		exit_cleanup(RERR_STREAMIO);
+	}
+
+	if (ndx != 0) {
+		F_XATTR(file) = ndx - 1;
+		return;
+	}
+
+	if ((count = read_varint(f)) != 0) {
+		(void)EXPAND_ITEM_LIST(&temp_xattr, rsync_xa, count);
+		temp_xattr.count = 0;
+	}
+
+	for (num = 1; num <= count; num++) {
+		char *ptr, *name;
+		rsync_xa *rxa;
+		size_t name_len = read_varint(f);
+		size_t datum_len = read_varint(f);
+		size_t dget_len = datum_len > MAX_FULL_DATUM ? 1 + (size_t)xattr_sum_len : datum_len;
+		size_t extra_len = MIGHT_NEED_RPRE ? RPRE_LEN : 0;
+		if (SIZE_MAX - dget_len < extra_len || SIZE_MAX - dget_len - extra_len < name_len)
+			overflow_exit("receive_xattr");
+		ptr = new_array(char, dget_len + extra_len + name_len);
+		name = ptr + dget_len + extra_len;
+		read_buf(f, name, name_len);
+		if (name_len < 1 || name[name_len-1] != '\0') {
+			rprintf(FERROR, "Invalid xattr name received (missing trailing \\0).\n");
+			exit_cleanup(RERR_FILEIO);
+		}
+		if (dget_len == datum_len)
+			read_buf(f, ptr, dget_len);
+		else {
+			*ptr = XSTATE_ABBREV;
+			read_buf(f, ptr + 1, xattr_sum_len);
+		}
+
+		if (saw_xattr_filter) {
+			if (name_is_excluded(name, NAME_IS_XATTR, ALL_FILTERS)) {
+				free(ptr);
+				continue;
+			}
+		}
+#ifdef HAVE_LINUX_XATTRS
+		/* Non-root can only save the user namespace. */
+		if (am_root <= 0 && !HAS_PREFIX(name, USER_PREFIX)) {
+			if (!am_root && !saw_xattr_filter) {
+				free(ptr);
+				continue;
+			}
+			name -= RPRE_LEN;
+			name_len += RPRE_LEN;
+			memcpy(name, RSYNC_PREFIX, RPRE_LEN);
+			need_sort = 1;
+		}
+#else
+		/* This OS only has a user namespace, so we either
+		 * strip the user prefix, or we put a non-user
+		 * namespace inside our rsync hierarchy. */
+		if (HAS_PREFIX(name, USER_PREFIX)) {
+			name += UPRE_LEN;
+			name_len -= UPRE_LEN;
+		} else if (am_root) {
+			name -= RPRE_LEN;
+			name_len += RPRE_LEN;
+			memcpy(name, RSYNC_PREFIX, RPRE_LEN);
+		} else {
+			free(ptr);
+			continue;
+		}
+#endif
+		/* No rsync.%FOO attributes are copied w/o 2 -X options. */
+		if (preserve_xattrs < 2 && name_len > RPRE_LEN
+		 && name[RPRE_LEN] == '%' && HAS_PREFIX(name, RSYNC_PREFIX)) {
+			free(ptr);
+			continue;
+		}
+
+		rxa = EXPAND_ITEM_LIST(&temp_xattr, rsync_xa, 1);
+		rxa->name = name;
+		rxa->datum = ptr;
+		rxa->name_len = name_len;
+		rxa->datum_len = datum_len;
+		rxa->num = num;
+	}
+
+	if (need_sort && count > 1)
+		qsort(temp_xattr.items, count, sizeof (rsync_xa), rsync_xal_compare_names);
+
+	ndx = rsync_xal_store(&temp_xattr); /* adds item to rsync_xal_l */
+
+	F_XATTR(file) = ndx;
+}
+
+/* Turn the xattr data in stat_x into cached xattr data, setting the index
+ * values in the file struct. */
+void cache_tmp_xattr(struct file_struct *file, stat_x *sxp)
+{
+	int ndx;
+
+	if (!sxp->xattr)
+		return;
+
+	if (prior_xattr_count == (size_t)-1)
+		prior_xattr_count = rsync_xal_l.count;
+	ndx = find_matching_xattr(sxp->xattr);
+	if (ndx < 0)
+		rsync_xal_store(sxp->xattr); /* adds item to rsync_xal_l */
+
+	F_XATTR(file) = ndx;
+}
+
+void uncache_tmp_xattrs(void)
+{
+	if (prior_xattr_count != (size_t)-1) {
+		rsync_xa_list *xa_list_item = rsync_xal_l.items;
+		rsync_xa_list *xa_list_start = xa_list_item + prior_xattr_count;
+		xa_list_item += rsync_xal_l.count;
+		rsync_xal_l.count = prior_xattr_count;
+		while (xa_list_item-- > xa_list_start) {
+			struct ht_int64_node *node;
+			rsync_xa_list_ref *ref;
+
+			rsync_xal_free(&xa_list_item->xa_items);
+
+			if (rsync_xal_h == NULL)
+				continue;
+
+			node = hashtable_find(rsync_xal_h, xa_list_item->key, NULL);
+			if (node == NULL)
+				continue;
+
+			if (node->data == NULL)
+				continue;
+
+			ref = node->data;
+			if (xa_list_item->ndx == ref->ndx) {
+				/* xa_list_item is the first in the list. */
+				node->data = ref->next;
+				free(ref);
+				continue;
+			}
+
+			while (1) {
+				rsync_xa_list_ref *next = ref->next;
+				if (next == NULL)
+					break;
+				if (xa_list_item->ndx == next->ndx) {
+					ref->next = next->next;
+					free(next);
+					break;
+				}
+				ref = next;
+			}
+		}
+		prior_xattr_count = (size_t)-1;
+	}
+}
+
+static int rsync_xal_set(const char *fname, item_list *xalp,
+			 const char *fnamecmp, stat_x *sxp)
+{
+	rsync_xa *rxas = xalp->items;
+	ssize_t list_len;
+	size_t i, len;
+	char *name, *ptr, sum[MAX_XATTR_DIGEST_LEN];
+#ifdef HAVE_LINUX_XATTRS
+	int user_only = am_root <= 0;
+#endif
+	size_t name_len;
+	int ret = 0;
+
+	/* This puts the current name list into the "namebuf" buffer. */
+	if ((list_len = get_xattr_names(fname)) < 0)
+		return -1;
+
+	for (i = 0; i < xalp->count; i++) {
+		name = rxas[i].name;
+
+		if (XATTR_ABBREV(rxas[i])) {
+			/* See if the fnamecmp version is identical. */
+			len = name_len = rxas[i].name_len;
+			if ((ptr = get_xattr_data(fnamecmp, name, &len, 1)) == NULL) {
+			  still_abbrev:
+				if (am_generator)
+					continue;
+				rprintf(FERROR, "Missing abbreviated xattr value, %s, for %s\n",
+					rxas[i].name, full_fname(fname));
+				ret = -1;
+				continue;
+			}
+			if (len != rxas[i].datum_len) {
+				free(ptr);
+				goto still_abbrev;
+			}
+
+			sum_init(xattr_sum_nni, checksum_seed);
+			sum_update(ptr, len);
+			sum_end(sum);
+			if (memcmp(sum, rxas[i].datum + 1, xattr_sum_len) != 0) {
+				free(ptr);
+				goto still_abbrev;
+			}
+
+			if (fname == fnamecmp)
+				; /* Value is already set when identical */
+			else if (sys_lsetxattr(fname, name, ptr, len) < 0) {
+				rsyserr(FERROR_XFER, errno,
+					"rsync_xal_set: lsetxattr(%s,\"%s\") failed",
+					full_fname(fname), name);
+				ret = -1;
+			} else /* make sure caller sets mtime */
+				sxp->st.st_mtime = (time_t)-1;
+
+			if (am_generator) { /* generator items stay abbreviated */
+				free(ptr);
+				continue;
+			}
+
+			memcpy(ptr + len, name, name_len);
+			free(rxas[i].datum);
+
+			rxas[i].name = name = ptr + len;
+			rxas[i].datum = ptr;
+			continue;
+		}
+
+		if (sys_lsetxattr(fname, name, rxas[i].datum, rxas[i].datum_len) < 0) {
+			rsyserr(FERROR_XFER, errno,
+				"rsync_xal_set: lsetxattr(%s,\"%s\") failed",
+				full_fname(fname), name);
+			ret = -1;
+		} else /* make sure caller sets mtime */
+			sxp->st.st_mtime = (time_t)-1;
+	}
+
+	/* Remove any extraneous names. */
+	for (name = namebuf; list_len > 0; name += name_len) {
+		name_len = strlen(name) + 1;
+		list_len -= name_len;
+
+		if (saw_xattr_filter) {
+			if (name_is_excluded(name, NAME_IS_XATTR, ALL_FILTERS))
+				continue;
+		}
+#ifdef HAVE_LINUX_XATTRS
+		/* Choose between ignoring the system namespace or (non-root) ignoring any non-user namespace. */
+		else if (user_only ? !HAS_PREFIX(name, USER_PREFIX) : HAS_PREFIX(name, SYSTEM_PREFIX))
+			continue;
+#endif
+		if (am_root < 0 && name_len > RPRE_LEN && name[RPRE_LEN] == '%' && strcmp(name, XSTAT_ATTR) == 0)
+			continue;
+
+		for (i = 0; i < xalp->count; i++) {
+			if (strcmp(name, rxas[i].name) == 0)
+				break;
+		}
+		if (i == xalp->count) {
+			if (sys_lremovexattr(fname, name) < 0) {
+				rsyserr(FERROR_XFER, errno,
+					"rsync_xal_set: lremovexattr(%s,\"%s\") failed",
+					full_fname(fname), name);
+				ret = -1;
+			} else /* make sure caller sets mtime */
+				sxp->st.st_mtime = (time_t)-1;
+		}
+	}
+
+	return ret;
+}
+
+/* Set extended attributes on indicated filename. */
+int set_xattr(const char *fname, const struct file_struct *file, const char *fnamecmp, stat_x *sxp)
+{
+	rsync_xa_list *glst = rsync_xal_l.items;
+	item_list *lst;
+	int ndx, added_write_perm = 0;
+
+	if (dry_run)
+		return 1; /* FIXME: --dry-run needs to compute this value */
+
+	if (read_only || list_only) {
+		errno = EROFS;
+		return -1;
+	}
+
+#ifdef NO_SPECIAL_XATTRS
+	if (IS_SPECIAL(sxp->st.st_mode)) {
+		errno = ENOTSUP;
+		return -1;
+	}
+#endif
+#ifdef NO_DEVICE_XATTRS
+	if (IS_DEVICE(sxp->st.st_mode)) {
+		errno = ENOTSUP;
+		return -1;
+	}
+#endif
+#ifdef NO_SYMLINK_XATTRS
+	if (S_ISLNK(sxp->st.st_mode)) {
+		errno = ENOTSUP;
+		return -1;
+	}
+#endif
+
+	/* If the target file lacks write permission, we try to add it
+	 * temporarily so we can change the extended attributes. */
+	if (!am_root
+#ifdef SUPPORT_LINKS
+	 && !S_ISLNK(sxp->st.st_mode)
+#endif
+	 && access(fname, W_OK) < 0
+	 && do_chmod(fname, (sxp->st.st_mode & CHMOD_BITS) | S_IWUSR) == 0)
+		added_write_perm = 1;
+
+	ndx = F_XATTR(file);
+	glst += ndx;
+	lst = &glst->xa_items;
+	int return_value = rsync_xal_set(fname, lst, fnamecmp, sxp);
+	if (added_write_perm) /* remove the temporary write permission */
+		do_chmod(fname, sxp->st.st_mode);
+	return return_value;
+}
+
+#ifdef SUPPORT_ACLS
+char *get_xattr_acl(const char *fname, int is_access_acl, size_t *len_p)
+{
+	const char *name = is_access_acl ? XACC_ACL_ATTR : XDEF_ACL_ATTR;
+	*len_p = 0; /* no extra data alloc needed from get_xattr_data() */
+	return get_xattr_data(fname, name, len_p, 1);
+}
+
+int set_xattr_acl(const char *fname, int is_access_acl, const char *buf, size_t buf_len)
+{
+	const char *name = is_access_acl ? XACC_ACL_ATTR : XDEF_ACL_ATTR;
+	if (sys_lsetxattr(fname, name, buf, buf_len) < 0) {
+		rsyserr(FERROR_XFER, errno,
+			"set_xattr_acl: lsetxattr(%s,\"%s\") failed",
+			full_fname(fname), name);
+		return -1;
+	}
+	return 0;
+}
+
+int del_def_xattr_acl(const char *fname)
+{
+	return sys_lremovexattr(fname, XDEF_ACL_ATTR);
+}
+#endif
+
+int get_stat_xattr(const char *fname, int fd, STRUCT_STAT *fst, STRUCT_STAT *xst)
+{
+	unsigned int mode;
+	int rdev_major, rdev_minor, uid, gid, len;
+	char buf[256];
+
+	if (am_root >= 0 || IS_DEVICE(fst->st_mode) || IS_SPECIAL(fst->st_mode))
+		return -1;
+
+	if (xst)
+		*xst = *fst;
+	else
+		xst = fst;
+	if (fname) {
+		fd = -1;
+		len = sys_lgetxattr(fname, XSTAT_ATTR, buf, sizeof buf - 1);
+	} else {
+		fname = "fd";
+		len = sys_fgetxattr(fd, XSTAT_ATTR, buf, sizeof buf - 1);
+	}
+	if (len >= (int)sizeof buf) {
+		len = -1;
+		errno = ERANGE;
+	}
+	if (len < 0) {
+		if (errno == ENOTSUP || errno == ENOATTR)
+			return -1;
+		if (errno == EPERM && S_ISLNK(fst->st_mode)) {
+			xst->st_uid = 0;
+			xst->st_gid = 0;
+			return 0;
+		}
+		rsyserr(FERROR_XFER, errno, "failed to read xattr %s for %s",
+			XSTAT_ATTR, full_fname(fname));
+		return -1;
+	}
+	buf[len] = '\0';
+
+	if (sscanf(buf, "%o %d,%d %d:%d",
+		   &mode, &rdev_major, &rdev_minor, &uid, &gid) != 5) {
+		rprintf(FERROR, "Corrupt %s xattr attached to %s: \"%s\"\n",
+			XSTAT_ATTR, full_fname(fname), buf);
+		exit_cleanup(RERR_FILEIO);
+	}
+
+	xst->st_mode = from_wire_mode(mode);
+	xst->st_rdev = MAKEDEV(rdev_major, rdev_minor);
+	xst->st_uid = uid;
+	xst->st_gid = gid;
+
+	return 0;
+}
+
+int set_stat_xattr(const char *fname, struct file_struct *file, mode_t new_mode)
+{
+	STRUCT_STAT fst, xst;
+	dev_t rdev;
+	mode_t mode, fmode;
+
+	if (dry_run)
+		return 0;
+
+	if (read_only || list_only) {
+		rsyserr(FERROR_XFER, EROFS, "failed to write xattr %s for %s",
+			XSTAT_ATTR, full_fname(fname));
+		return -1;
+	}
+
+	if (x_lstat(fname, &fst, &xst) < 0) {
+		rsyserr(FERROR_XFER, errno, "failed to re-stat %s",
+			full_fname(fname));
+		return -1;
+	}
+
+	fst.st_mode &= (_S_IFMT | CHMOD_BITS);
+	fmode = new_mode & (_S_IFMT | CHMOD_BITS);
+
+	if (IS_DEVICE(fmode)) {
+		uint32 *devp = F_RDEV_P(file);
+		rdev = MAKEDEV(DEV_MAJOR(devp), DEV_MINOR(devp));
+	} else
+		rdev = 0;
+
+	/* Dump the special permissions and enable full owner access. */
+	mode = (fst.st_mode & _S_IFMT) | (fmode & ACCESSPERMS)
+	     | (S_ISDIR(fst.st_mode) ? 0700 : 0600);
+	if (fst.st_mode != mode)
+		do_chmod(fname, mode);
+	if (!IS_DEVICE(fst.st_mode))
+		fst.st_rdev = 0; /* just in case */
+
+	if (mode == fmode && fst.st_rdev == rdev
+	 && fst.st_uid == F_OWNER(file) && fst.st_gid == F_GROUP(file)) {
+		/* xst.st_mode will be 0 if there's no current stat xattr */
+		if (xst.st_mode && sys_lremovexattr(fname, XSTAT_ATTR) < 0) {
+			rsyserr(FERROR_XFER, errno,
+				"delete of stat xattr failed for %s",
+				full_fname(fname));
+			return -1;
+		}
+		return 0;
+	}
+
+	if (xst.st_mode != fmode || xst.st_rdev != rdev
+	 || xst.st_uid != F_OWNER(file) || xst.st_gid != F_GROUP(file)) {
+		char buf[256];
+		int len = snprintf(buf, sizeof buf, "%o %u,%u %u:%u",
+			to_wire_mode(fmode),
+			(int)major(rdev), (int)minor(rdev),
+			F_OWNER(file), F_GROUP(file));
+		if (sys_lsetxattr(fname, XSTAT_ATTR, buf, len) < 0) {
+			if (errno == EPERM && S_ISLNK(fst.st_mode))
+				return 0;
+			rsyserr(FERROR_XFER, errno,
+				"failed to write xattr %s for %s",
+				XSTAT_ATTR, full_fname(fname));
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+int x_stat(const char *fname, STRUCT_STAT *fst, STRUCT_STAT *xst)
+{
+	int ret = do_stat(fname, fst);
+	if ((ret < 0 || get_stat_xattr(fname, -1, fst, xst) < 0) && xst)
+		xst->st_mode = 0;
+	return ret;
+}
+
+int x_lstat(const char *fname, STRUCT_STAT *fst, STRUCT_STAT *xst)
+{
+	int ret = do_lstat(fname, fst);
+	if ((ret < 0 || get_stat_xattr(fname, -1, fst, xst) < 0) && xst)
+		xst->st_mode = 0;
+	return ret;
+}
+
+int x_fstat(int fd, STRUCT_STAT *fst, STRUCT_STAT *xst)
+{
+	int ret = do_fstat(fd, fst);
+	if ((ret < 0 || get_stat_xattr(NULL, fd, fst, xst) < 0) && xst)
+		xst->st_mode = 0;
+	return ret;
+}
+
+#endif /* SUPPORT_XATTRS */