Add support for preserving BSD file flags

Original patch by Rolf Grossmann <grossman@progtech.net>
Rsync 3.4.4 port by Dag-Erling Smørgrav <des@FreeBSD.org>

--- backup.c.orig
+++ backup.c
@@ -207,7 +207,7 @@ static inline int link_or_rename(const char *from, const char *to,
 			return 0;
 	}
 #endif
-	if (do_rename_at(from, to) == 0) {
+	if (do_rename_at(from, to, stp->st_mode, ST_FLAGS(*stp)) == 0) {
 		if (stp->st_nlink > 1 && !S_ISDIR(stp->st_mode)) {
 			/* If someone has hard-linked the file into the backup
 			 * dir, rename() might return success but do nothing! */
--- compat.c.orig
+++ compat.c
@@ -40,6 +40,7 @@ extern int checksum_seed;
 extern int basis_dir_cnt;
 extern int prune_empty_dirs;
 extern int protocol_version;
+extern int force_change;
 extern int protect_args;
 extern int preserve_uid;
 extern int preserve_gid;
@@ -47,6 +48,7 @@ extern int preserve_atimes;
 extern int preserve_crtimes;
 extern int preserve_acls;
 extern int preserve_xattrs;
+extern int preserve_file_flags;
 extern int xfer_flags_as_varint;
 extern int need_messages_from_generator;
 extern int delete_mode, delete_before, delete_during, delete_after;
@@ -87,7 +89,7 @@ struct name_num_item *xattr_sum_nni;
 int xattr_sum_len = 0;
 
 /* These index values are for the file-list's extra-attribute array. */
-int pathname_ndx, depth_ndx, atimes_ndx, crtimes_ndx, uid_ndx, gid_ndx, acls_ndx, xattrs_ndx, unsort_ndx;
+int pathname_ndx, depth_ndx, atimes_ndx, crtimes_ndx, uid_ndx, gid_ndx, file_flags_ndx, acls_ndx, xattrs_ndx, unsort_ndx;
 
 int receiver_symlink_times = 0; /* receiver can set the time on a symlink */
 int sender_symlink_iconv = 0;	/* sender should convert symlink content */
@@ -589,6 +591,8 @@ void setup_protocol(int f_out,int f_in)
 		uid_ndx = ++file_extra_cnt;
 	if (preserve_gid)
 		gid_ndx = ++file_extra_cnt;
+	if (preserve_file_flags || (force_change && !am_sender))
+		file_flags_ndx = ++file_extra_cnt;
 	if (preserve_acls && !am_sender)
 		acls_ndx = ++file_extra_cnt;
 	if (preserve_xattrs)
@@ -752,6 +756,10 @@ void setup_protocol(int f_out,int f_in)
 			fprintf(stderr, "Both rsync versions must be at least 3.2.0 for --crtimes.\n");
 			exit_cleanup(RERR_PROTOCOL);
 		}
+		if (!xfer_flags_as_varint && preserve_file_flags) {
+			fprintf(stderr, "Both rsync versions must be at least 3.2.0 for --file-flags.\n");
+			exit_cleanup(RERR_PROTOCOL);
+		}
 		if (am_sender) {
 			receiver_symlink_times = am_server
 			    ? strchr(client_info, 'L') != NULL
--- delete.c.orig
+++ delete.c
@@ -25,6 +25,7 @@
 extern int am_root;
 extern int make_backups;
 extern int max_delete;
+extern int force_change;
 extern char *backup_dir;
 extern char *backup_suffix;
 extern int backup_suffix_len;
@@ -97,8 +98,12 @@ static enum delret delete_dir_contents(char *fname, uint16 flags)
 		}
 
 		strlcpy(p, fp->basename, remainder);
+#ifdef SUPPORT_FORCE_CHANGE
+		if (force_change)
+			make_mutable(fname, fp->mode, F_FFLAGS(fp), force_change);
+#endif
 		if (!(fp->mode & S_IWUSR) && !am_root && fp->flags & FLAG_OWNED_BY_US)
-			do_chmod_at(fname, fp->mode | S_IWUSR);
+			do_chmod_at(fname, fp->mode | S_IWUSR, NO_FFLAGS);
 		/* Save stack by recursing to ourself directly. */
 		if (S_ISDIR(fp->mode)) {
 			if (delete_dir_contents(fname, flags | DEL_RECURSE) != DR_SUCCESS)
@@ -139,11 +144,18 @@ enum delret delete_item(char *fbuf, uint16 mode, uint16 flags)
 	}
 
 	if (flags & DEL_NO_UID_WRITE)
-		do_chmod_at(fbuf, mode | S_IWUSR);
+		do_chmod_at(fbuf, mode | S_IWUSR, NO_FFLAGS);
 
 	if (S_ISDIR(mode) && !(flags & DEL_DIR_IS_EMPTY)) {
 		/* This only happens on the first call to delete_item() since
 		 * delete_dir_contents() always calls us w/DEL_DIR_IS_EMPTY. */
+#ifdef SUPPORT_FORCE_CHANGE
+		if (force_change) {
+			STRUCT_STAT st;
+			if (x_lstat(fbuf, &st, NULL) == 0)
+				make_mutable(fbuf, st.st_mode, st.st_flags, force_change);
+		}
+#endif
 		ignore_perishable = 1;
 		/* If DEL_RECURSE is not set, this just reports emptiness. */
 		ret = delete_dir_contents(fbuf, flags);
--- flist.c.orig
+++ flist.c
@@ -52,6 +52,7 @@ extern int preserve_links;
 extern int preserve_hard_links;
 extern int preserve_devices;
 extern int preserve_specials;
+extern int preserve_file_flags;
 extern int delete_during;
 extern int missing_args;
 extern int eol_nulls;
@@ -400,6 +401,9 @@ static void send_file_entry(int f, const char *fname, struct file_struct *file,
 	static time_t crtime;
 #endif
 	static mode_t mode;
+#ifdef SUPPORT_FILE_FLAGS
+	static uint32 file_flags;
+#endif
 #ifdef SUPPORT_HARD_LINKS
 	static int64 dev;
 #endif
@@ -443,6 +447,14 @@ static void send_file_entry(int f, const char *fname, struct file_struct *file,
 		xflags |= XMIT_SAME_MODE;
 	else
 		mode = file->mode;
+#ifdef SUPPORT_FILE_FLAGS
+	if (preserve_file_flags) {
+		if (F_FFLAGS(file) == file_flags)
+			xflags |= XMIT_SAME_FLAGS;
+		else
+			file_flags = F_FFLAGS(file);
+	}
+#endif
 
 	if (preserve_devices && IS_DEVICE(mode)) {
 		if (protocol_version < 28) {
@@ -604,6 +616,10 @@ static void send_file_entry(int f, const char *fname, struct file_struct *file,
 #endif
 	if (!(xflags & XMIT_SAME_MODE))
 		write_int(f, to_wire_mode(mode));
+#ifdef SUPPORT_FILE_FLAGS
+	if (preserve_file_flags && !(xflags & XMIT_SAME_FLAGS))
+		write_int(f, (int)file_flags);
+#endif
 	if (atimes_ndx && !S_ISDIR(mode) && !(xflags & XMIT_SAME_ATIME))
 		write_varlong(f, atime, 4);
 	if (preserve_uid && !(xflags & XMIT_SAME_UID)) {
@@ -698,6 +714,9 @@ static struct file_struct *recv_file_entry(int f, struct file_list *flist, int x
 	static time_t crtime;
 #endif
 	static mode_t mode;
+#ifdef SUPPORT_FILE_FLAGS
+	static uint32 file_flags;
+#endif
 #ifdef SUPPORT_HARD_LINKS
 	static int64 dev;
 #endif
@@ -815,6 +834,10 @@ static struct file_struct *recv_file_entry(int f, struct file_list *flist, int x
 #ifdef SUPPORT_CRTIMES
 			if (crtimes_ndx)
 				crtime = F_CRTIME(first);
+#endif
+#ifdef SUPPORT_FILE_FLAGS
+			if (preserve_file_flags)
+				file_flags = F_FFLAGS(first);
 #endif
 			if (preserve_uid)
 				uid = F_OWNER(first);
@@ -904,6 +927,10 @@ static struct file_struct *recv_file_entry(int f, struct file_list *flist, int x
 
 	if (chmod_modes && !S_ISLNK(mode) && mode)
 		mode = tweak_mode(mode, chmod_modes);
+#ifdef SUPPORT_FILE_FLAGS
+	if (preserve_file_flags && !(xflags & XMIT_SAME_FLAGS))
+		file_flags = (uint32)read_int(f);
+#endif
 
 	if (preserve_uid && !(xflags & XMIT_SAME_UID)) {
 		if (protocol_version < 30)
@@ -1085,6 +1112,10 @@ static struct file_struct *recv_file_entry(int f, struct file_list *flist, int x
 	}
 #endif
 	file->mode = mode;
+#ifdef SUPPORT_FILE_FLAGS
+	if (preserve_file_flags)
+		F_FFLAGS(file) = file_flags;
+#endif
 	if (preserve_uid)
 		F_OWNER(file) = uid;
 	if (preserve_gid) {
@@ -1506,6 +1537,10 @@ struct file_struct *make_file(const char *fname, struct file_list *flist,
 	}
 #endif
 	file->mode = st.st_mode;
+#if defined SUPPORT_FILE_FLAGS || defined SUPPORT_FORCE_CHANGE
+	if (file_flags_ndx)
+		F_FFLAGS(file) = st.st_flags;
+#endif
 	if (preserve_uid)
 		F_OWNER(file) = st.st_uid;
 	if (preserve_gid)
--- generator.c.orig
+++ generator.c
@@ -43,10 +43,12 @@ extern int preserve_devices;
 extern int preserve_specials;
 extern int preserve_hard_links;
 extern int preserve_executability;
+extern int preserve_file_flags;
 extern int preserve_perms;
 extern int preserve_mtimes;
 extern int omit_dir_times;
 extern int omit_link_times;
+extern int force_change;
 extern int delete_mode;
 extern int delete_before;
 extern int delete_during;
@@ -493,6 +495,10 @@ int unchanged_attrs(const char *fname, struct file_struct *file, stat_x *sxp)
 			return 0;
 		if (perms_differ(file, sxp))
 			return 0;
+#ifdef SUPPORT_FILE_FLAGS
+		if (preserve_file_flags && sxp->st.st_flags != F_FFLAGS(file))
+			return 0;
+#endif
 		if (ownership_differs(file, sxp))
 			return 0;
 #ifdef SUPPORT_ACLS
@@ -554,6 +560,11 @@ void itemize(const char *fnamecmp, struct file_struct *file, int ndx, int statre
 			iflags |= ITEM_REPORT_OWNER;
 		if (gid_ndx && !(file->flags & FLAG_SKIP_GROUP) && sxp->st.st_gid != (gid_t)F_GROUP(file))
 			iflags |= ITEM_REPORT_GROUP;
+#ifdef SUPPORT_FILE_FLAGS
+		if (preserve_file_flags && !S_ISLNK(file->mode)
+		 && sxp->st.st_flags != F_FFLAGS(file))
+			iflags |= ITEM_REPORT_FFLAGS;
+#endif
 #ifdef SUPPORT_ACLS
 		if (preserve_acls && !S_ISLNK(file->mode)) {
 			if (!ACL_READY(*sxp))
@@ -1466,6 +1477,10 @@ static void recv_generator(char *fname, struct file_struct *file, int ndx,
 		if (!preserve_perms) { /* See comment in non-dir code below. */
 			file->mode = dest_mode(file->mode, sx.st.st_mode, dflt_perms, statret == 0);
 		}
+#ifdef SUPPORT_FORCE_CHANGE
+		if (force_change && !preserve_file_flags)
+			F_FFLAGS(file) = sx.st.st_flags;
+#endif
 		if (statret != 0 && basis_dir[0] != NULL) {
 			int j = try_dests_non(file, fname, ndx, fnamecmpbuf, &sx, itemizing, code);
 			if (j == -2) {
@@ -1508,10 +1523,15 @@ static void recv_generator(char *fname, struct file_struct *file, int ndx,
 		 * readable and writable permissions during the time we are
 		 * putting files within them.  This is then restored to the
 		 * former permissions after the transfer is done. */
+#ifdef SUPPORT_FORCE_CHANGE
+		if (force_change && F_FFLAGS(file) & force_change
+		 && make_mutable(fname, file->mode, F_FFLAGS(file), force_change))
+			need_retouch_dir_perms = 1;
+#endif
 #ifdef HAVE_CHMOD
 		if (!am_root && (file->mode & S_IRWXU) != S_IRWXU && dir_tweaking) {
 			mode_t mode = file->mode | S_IRWXU;
-			if (do_chmod_at(fname, mode) < 0) {
+			if (do_chmod_at(fname, mode, 0) < 0) {
 				rsyserr(FERROR_XFER, errno,
 					"failed to modify permissions on %s",
 					full_fname(fname));
@@ -1546,6 +1566,10 @@ static void recv_generator(char *fname, struct file_struct *file, int ndx,
 		int exists = statret == 0 && stype != FT_DIR;
 		file->mode = dest_mode(file->mode, sx.st.st_mode, dflt_perms, exists);
 	}
+#ifdef SUPPORT_FORCE_CHANGE
+	if (force_change && !preserve_file_flags)
+		F_FFLAGS(file) = sx.st.st_flags;
+#endif
 
 #ifdef SUPPORT_HARD_LINKS
 	if (preserve_hard_links && F_HLINK_NOT_FIRST(file)
@@ -2053,7 +2077,7 @@ int atomic_create(struct file_struct *file, char *fname, const char *slnk, const
 	}
 
 	if (!skip_atomic) {
-		if (do_rename_at(tmpname, fname) < 0) {
+		if (do_rename_at(tmpname, fname, file->mode, NO_FFLAGS) < 0) {
 			char *full_tmpname = strdup(full_fname(tmpname));
 			if (full_tmpname == NULL)
 				out_of_memory("atomic_create");
@@ -2124,17 +2148,25 @@ static void touch_up_dirs(struct file_list *flist, int ndx)
 			continue;
 		fname = f_name(file, NULL);
 		if (fix_dir_perms)
-			do_chmod_at(fname, file->mode);
+			do_chmod_at(fname, file->mode, 0);
 		if (need_retouch_dir_times) {
 			STRUCT_STAT st;
 			if (link_stat(fname, &st, 0) == 0 && mtime_differs(&st, file)) {
 				st.st_mtime = file->modtime;
 #ifdef ST_MTIME_NSEC
 				st.ST_MTIME_NSEC = F_MOD_NSEC_or_0(file);
+#endif
+#ifdef SUPPORT_FORCE_CHANGE
+				st.st_mode = file->mode;
+				st.st_flags = 0;
 #endif
 				set_times(fname, &st);
 			}
 		}
+#ifdef SUPPORT_FORCE_CHANGE
+		if (force_change && F_FFLAGS(file) & force_change)
+			undo_make_mutable(fname, F_FFLAGS(file));
+#endif
 		if (counter >= loopchk_limit) {
 			if (allowed_lull)
 				maybe_send_keepalive(time(NULL), MSK_ALLOW_FLUSH);
--- log.c.orig
+++ log.c
@@ -731,7 +731,8 @@ static void log_formatted(enum logcode code, const char *format, const char *op,
 			     : iflags & ITEM_REPORT_ATIME ? 'u' : 'n';
 			c[9] = !(iflags & ITEM_REPORT_ACL) ? '.' : 'a';
 			c[10] = !(iflags & ITEM_REPORT_XATTR) ? '.' : 'x';
-			c[11] = '\0';
+			c[11] = !(iflags & ITEM_REPORT_FFLAGS) ? '.' : 'f';
+			c[12] = '\0';
 
 			if (iflags & (ITEM_IS_NEW|ITEM_MISSING_DATA)) {
 				char ch = iflags & ITEM_IS_NEW ? '+' : '?';
--- main.c.orig
+++ main.c
@@ -31,6 +31,9 @@
 #ifdef __TANDEM
 #include <floss.h(floss_execlp)>
 #endif
+#ifdef SUPPORT_FORCE_CHANGE
+#include <sys/sysctl.h>
+#endif
 
 extern int dry_run;
 extern int list_only;
@@ -49,6 +52,7 @@ extern int need_messages_from_generator;
 extern int kluge_around_eof;
 extern int got_xfer_error;
 extern int old_style_args;
+extern int force_change;
 extern int msgs2stderr;
 extern int module_id;
 extern int read_only;
@@ -995,6 +999,22 @@ static int do_recv(int f_in, int f_out, char *local_name)
 	 * points to an identical file won't be replaced by the referent. */
 	copy_links = copy_dirlinks = copy_unsafe_links = 0;
 
+#ifdef SUPPORT_FORCE_CHANGE
+	if (force_change & SYS_IMMUTABLE) {
+		/* Determine whether we'll be able to unlock a system immutable item. */
+		int mib[2];
+		int securityLevel = 0;
+		size_t len = sizeof securityLevel;
+
+		mib[0] = CTL_KERN;
+		mib[1] = KERN_SECURELVL;
+		if (sysctl(mib, 2, &securityLevel, &len, NULL, 0) == 0 && securityLevel > 0) {
+			rprintf(FERROR, "System security level is too high to force mutability on system immutable files and directories.\n");
+			exit_cleanup(RERR_UNSUPPORTED);
+		}
+	}
+#endif
+
 #ifdef SUPPORT_HARD_LINKS
 	if (preserve_hard_links && !inc_recurse)
 		match_hard_links(first_flist);
--- options.c.orig
+++ options.c
@@ -56,6 +56,7 @@ int preserve_hard_links = 0;
 int preserve_acls = 0;
 int preserve_xattrs = 0;
 int preserve_perms = 0;
+int preserve_file_flags = 0;
 int preserve_executability = 0;
 int preserve_devices = 0;
 int preserve_specials = 0;
@@ -99,6 +100,7 @@ int msgs2stderr = 2; /* Default: send errors to stderr for local & remote-shell
 int saw_stderr_opt = 0;
 int allow_8bit_chars = 0;
 int force_delete = 0;
+int force_change = 0;
 int io_timeout = 0;
 int prune_empty_dirs = 0;
 int use_qsort = 0;
@@ -633,6 +635,10 @@ static struct poptOption long_options[] = {
   {"perms",           'p', POPT_ARG_VAL,    &preserve_perms, 1, 0, 0 },
   {"no-perms",         0,  POPT_ARG_VAL,    &preserve_perms, 0, 0, 0 },
   {"no-p",             0,  POPT_ARG_VAL,    &preserve_perms, 0, 0, 0 },
+  {"file-flags",       0,  POPT_ARG_VAL,    &preserve_file_flags, 1, 0, 0 },
+  {"fileflags",        0,  POPT_ARG_VAL,    &preserve_file_flags, 1, 0, 0 },
+  {"no-file-flags",    0,  POPT_ARG_VAL,    &preserve_file_flags, 0, 0, 0 },
+  {"no-fileflags",     0,  POPT_ARG_VAL,    &preserve_file_flags, 0, 0, 0 },
   {"executability",   'E', POPT_ARG_NONE,   &preserve_executability, 0, 0, 0 },
   {"acls",            'A', POPT_ARG_NONE,   0, 'A', 0, 0 },
   {"no-acls",          0,  POPT_ARG_VAL,    &preserve_acls, 0, 0, 0 },
@@ -731,6 +737,12 @@ static struct poptOption long_options[] = {
   {"remove-source-files",0,POPT_ARG_VAL,    &remove_source_files, 1, 0, 0 },
   {"force",            0,  POPT_ARG_VAL,    &force_delete, 1, 0, 0 },
   {"no-force",         0,  POPT_ARG_VAL,    &force_delete, 0, 0, 0 },
+  {"force-delete",     0,  POPT_ARG_VAL,    &force_delete, 1, 0, 0 },
+  {"no-force-delete",  0,  POPT_ARG_VAL,    &force_delete, 0, 0, 0 },
+  {"force-change",     0,  POPT_ARG_VAL,    &force_change, ALL_IMMUTABLE, 0, 0 },
+  {"no-force-change",  0,  POPT_ARG_VAL,    &force_change, 0, 0, 0 },
+  {"force-uchange",    0,  POPT_ARG_VAL,    &force_change, USR_IMMUTABLE, 0, 0 },
+  {"force-schange",    0,  POPT_ARG_VAL,    &force_change, SYS_IMMUTABLE, 0, 0 },
   {"ignore-errors",    0,  POPT_ARG_VAL,    &ignore_errors, 1, 0, 0 },
   {"no-ignore-errors", 0,  POPT_ARG_VAL,    &ignore_errors, 0, 0, 0 },
   {"max-delete",       0,  POPT_ARG_INT,    &max_delete, 0, 0, 0 },
@@ -1028,6 +1040,15 @@ static void set_refuse_options(void)
 #ifndef SUPPORT_CRTIMES
 	parse_one_refuse_match(0, "crtimes", list_end);
 #endif
+#ifndef SUPPORT_FILE_FLAGS
+	parse_one_refuse_match(0, "file-flags", list_end);
+	parse_one_refuse_match(0, "fileflags", list_end);
+#endif
+#ifndef SUPPORT_FORCE_CHANGE
+	parse_one_refuse_match(0, "force-change", list_end);
+	parse_one_refuse_match(0, "force-uchange", list_end);
+	parse_one_refuse_match(0, "force-schange", list_end);
+#endif
 
 	/* Now we use the descrip values to actually mark the options for refusal. */
 	for (op = long_options; op != list_end; op++) {
@@ -2752,6 +2773,9 @@ void server_options(char **args, int *argc_p)
 	if (xfer_dirs && !recurse && delete_mode && am_sender)
 		args[ac++] = "--no-r";
 
+	if (preserve_file_flags)
+		args[ac++] = "--fileflags";
+
 	if (do_compression && do_compression_level != CLVL_NOT_SPECIFIED) {
 		if (asprintf(&arg, "--compress-level=%d", do_compression_level) < 0)
 			goto oom;
@@ -2847,6 +2871,16 @@ void server_options(char **args, int *argc_p)
 			args[ac++] = "--delete-excluded";
 		if (force_delete)
 			args[ac++] = "--force";
+#ifdef SUPPORT_FORCE_CHANGE
+		if (force_change) {
+			if (force_change == ALL_IMMUTABLE)
+				args[ac++] = "--force-change";
+			else if (force_change == USR_IMMUTABLE)
+				args[ac++] = "--force-uchange";
+			else if (force_change == SYS_IMMUTABLE)
+				args[ac++] = "--force-schange";
+		}
+#endif
 		if (write_batch < 0)
 			args[ac++] = "--only-write-batch=X";
 		if (am_root > 1)
--- receiver.c.orig
+++ receiver.c
@@ -543,7 +543,7 @@ static void handle_delayed_updates(char *local_name)
 			}
 			/* We don't use robust_rename() here because the
 			 * partial-dir must be on the same drive. */
-			if (do_rename_at(partialptr, fname) < 0) {
+			if (do_rename_at(partialptr, fname, 0, NO_FFLAGS) < 0) {
 				rsyserr(FERROR_XFER, errno,
 					"rename failed for %s (from %s)",
 					full_fname(fname), partialptr);
--- rsync.1.md.orig
+++ rsync.1.md
@@ -446,6 +446,7 @@ has its own detailed description later in this manpage.
 --keep-dirlinks, -K      treat symlinked dir on receiver as dir
 --hard-links, -H         preserve hard links
 --perms, -p              preserve permissions
+--file-flags             preserve file flags (aka chflags)
 --executability, -E      preserve executability
 --chmod=CHMOD            affect file and/or directory permissions
 --acls, -A               preserve ACLs (implies --perms)
@@ -487,7 +488,11 @@ has its own detailed description later in this manpage.
 --ignore-missing-args    ignore missing source args without error
 --delete-missing-args    delete missing source args from destination
 --ignore-errors          delete even if there are I/O errors
---force                  force deletion of dirs even if not empty
+--force                  an alias for --force-delete
+--force-delete           force deletion of directories even if not empty
+--force-change           affect user-/system-immutable files/dirs
+--force-uchange          affect user-immutable files/dirs
+--force-schange          affect system-immutable files/dirs
 --max-delete=NUM         don't delete more than NUM files
 --max-size=SIZE          don't transfer any file larger than SIZE
 --min-size=SIZE          don't transfer any file smaller than SIZE
@@ -832,6 +837,7 @@ expand it.
     recursion and want to preserve almost everything.  Be aware that it does
     **not** include preserving ACLs (`-A`), xattrs (`-X`), atimes (`-U`),
     crtimes (`-N`), nor the finding and preserving of hardlinks (`-H`).
+    It also does **not** imply [`--file-flags`](#opt).
 
     The only exception to the above equivalence is when [`--files-from`](#opt)
     is specified, in which case [`-r`](#opt) is not implied.
@@ -1296,7 +1302,7 @@ expand it.
     Without this option, if the sending side has replaced a directory with a
     symlink to a directory, the receiving side will delete anything that is in
     the way of the new symlink, including a directory hierarchy (as long as
-    [`--force`](#opt) or [`--delete`](#opt) is in effect).
+    [`--force-delete`](#opt) or [`--delete`](#opt) is in effect).
 
     See also [`--keep-dirlinks`](#opt) for an analogous option for the
     receiving side.
@@ -1491,6 +1497,37 @@ expand it.
     those used by [`--fake-super`](#opt)) unless you repeat the option (e.g. `-XX`).
     This "copy all xattrs" mode cannot be used with [`--fake-super`](#opt).
 
+0.  `--file-flags`
+
+    This option causes rsync to update the file flags to be the same as the
+    source files and directories (if your OS supports the **chflags**(2) system
+    call).   Some flags can only be altered by the super-user and some might
+    only be unset below a certain secure-level (usually single-user mode). It
+    will not make files alterable that are set to immutable on the receiver.
+    To do that, see [`--force-change`](#opt), [`--force-uchange`](#opt), and
+    [`--force-schange`](#opt).
+
+0.  `--force-change`
+
+    This option causes rsync to disable both user-immutable and
+    system-immutable flags on files and directories that are being updated or
+    deleted on the receiving side.  This option overrides
+    [`--force-uchange`](#opt) and [`--force-schange`](#opt).
+
+0.  `--force-uchange`
+
+    This option causes rsync to disable user-immutable flags on files and
+    directories that are being updated or deleted on the receiving side.  It
+    does not try to affect system flags.  This option overrides
+    [`--force-change`](#opt) and [`--force-schange`](#opt).
+
+0.  `--force-schange`
+
+    This option causes rsync to disable system-immutable flags on files and
+    directories that are being updated or deleted on the receiving side.  It
+    does not try to affect user flags.  This option overrides
+    [`--force-change`](#opt) and [`--force-uchange`](#opt).
+
 0.  `--chmod=CHMOD`
 
     This option tells rsync to apply one or more comma-separated "chmod" modes
@@ -2020,8 +2057,8 @@ expand it.
     [`--ignore-missing-args`](#opt) option a step farther: each missing arg
     will become a deletion request of the corresponding destination file on the
     receiving side (should it exist).  If the destination file is a non-empty
-    directory, it will only be successfully deleted if [`--force`](#opt) or
-    [`--delete`](#opt) are in effect.  Other than that, this option is
+    directory, it will only be successfully deleted if [`--force-delete`](#opt)
+    or [`--delete`](#opt) are in effect.  Other than that, this option is
     independent of any other type of delete processing.
 
     The missing source files are represented by special file-list entries which
@@ -2032,14 +2069,14 @@ expand it.
     Tells [`--delete`](#opt) to go ahead and delete files even when there are
     I/O errors.
 
-0.  `--force`
+0.  `--force-delete`, `--force`
 
     This option tells rsync to delete a non-empty directory when it is to be
     replaced by a non-directory.  This is only relevant if deletions are not
     active (see [`--delete`](#opt) for details).
 
-    Note for older rsync versions: `--force` used to still be required when
-    using [`--delete-after`](#opt), and it used to be non-functional unless the
+    Note that some older rsync versions used to require `--force` when using
+    [`--delete-after`](#opt), and it used to be non-functional unless the
     [`--recursive`](#opt) option was also enabled.
 
 0.  `--max-delete=NUM`
@@ -3116,7 +3153,7 @@ expand it.
     also turns on the output of other verbose messages).
 
     The "%i" escape has a cryptic output that is 11 letters long.  The general
-    format is like the string `YXcstpoguax`, where **Y** is replaced by the type
+    format is like the string `YXcstpoguaxf`, where **Y** is replaced by the type
     of update being done, **X** is replaced by the file-type, and the other
     letters represent attributes that may be output if they are being modified.
 
--- rsync.c.orig
+++ rsync.c
@@ -31,6 +31,7 @@ extern int dry_run;
 extern int preserve_acls;
 extern int preserve_xattrs;
 extern int preserve_perms;
+extern int preserve_file_flags;
 extern int preserve_executability;
 extern int preserve_mtimes;
 extern int omit_dir_times;
@@ -471,6 +472,39 @@ mode_t dest_mode(mode_t flist_mode, mode_t stat_mode, int dflt_perms,
 	return new_mode;
 }
 
+#if defined SUPPORT_FILE_FLAGS || defined SUPPORT_FORCE_CHANGE
+/* Set a file's st_flags. */
+static int set_file_flags(const char *fname, uint32 file_flags)
+{
+	if (do_chflags(fname, file_flags) != 0) {
+		rsyserr(FERROR_XFER, errno,
+			"failed to set file flags on %s",
+			full_fname(fname));
+		return 0;
+	}
+
+	return 1;
+}
+
+/* Remove immutable flags from an object, so it can be altered/removed. */
+int make_mutable(const char *fname, mode_t mode, uint32 file_flags, uint32 iflags)
+{
+	if (S_ISLNK(mode) || !(file_flags & iflags))
+		return 0;
+	if (!set_file_flags(fname, file_flags & ~iflags))
+		return -1;
+	return 1;
+}
+
+/* Undo a prior make_mutable() call that returned a 1. */
+int undo_make_mutable(const char *fname, uint32 file_flags)
+{
+	if (!set_file_flags(fname, file_flags))
+		return -1;
+	return 1;
+}
+#endif
+
 static int same_mtime(struct file_struct *file, STRUCT_STAT *st, int extra_accuracy)
 {
 #ifdef ST_MTIME_NSEC
@@ -547,7 +581,7 @@ int set_file_attrs(const char *fname, struct file_struct *file, stat_x *sxp,
 		if (am_root >= 0) {
 			uid_t uid = change_uid ? (uid_t)F_OWNER(file) : sxp->st.st_uid;
 			gid_t gid = change_gid ? (gid_t)F_GROUP(file) : sxp->st.st_gid;
-			if (do_lchown_at(fname, uid, gid) != 0) {
+			if (do_lchown_at(fname, uid, gid, sxp->st.st_mode, ST_FLAGS(sxp->st)) != 0) {
 				/* We shouldn't have attempted to change uid
 				 * or gid unless have the privilege. */
 				rsyserr(FERROR_XFER, errno, "%s %s failed",
@@ -657,7 +691,7 @@ int set_file_attrs(const char *fname, struct file_struct *file, stat_x *sxp,
 
 #ifdef HAVE_CHMOD
 	if (!BITS_EQUAL(sxp->st.st_mode, new_mode, CHMOD_BITS)) {
-		int ret = am_root < 0 ? 0 : do_chmod_at(fname, new_mode);
+		int ret = am_root < 0 ? 0 : do_chmod_at(fname, new_mode, ST_FLAGS(sxp->st));
 		if (ret < 0) {
 			rsyserr(FERROR_XFER, errno,
 				"failed to set permissions on %s",
@@ -669,6 +703,19 @@ int set_file_attrs(const char *fname, struct file_struct *file, stat_x *sxp,
 	}
 #endif
 
+#ifdef SUPPORT_FILE_FLAGS
+	if (preserve_file_flags && !S_ISLNK(sxp->st.st_mode)
+	 && sxp->st.st_flags != F_FFLAGS(file)) {
+		uint32 file_flags = F_FFLAGS(file);
+		if (flags & ATTRS_DELAY_IMMUTABLE)
+			file_flags &= ~ALL_IMMUTABLE;
+		if (sxp->st.st_flags != file_flags
+		 && !set_file_flags(fname, file_flags))
+			goto cleanup;
+		updated = 1;
+	}
+#endif
+
 	if (INFO_GTE(NAME, 2) && flags & ATTRS_REPORT) {
 		if (updated)
 			rprintf(FCLIENT, "%s\n", fname);
@@ -746,7 +793,8 @@ int finish_transfer(const char *fname, const char *fnametmp,
 
 	/* Change permissions before putting the file into place. */
 	set_file_attrs(fnametmp, file, NULL, fnamecmp,
-		       ok_to_set_time ? ATTRS_ACCURATE_TIME : ATTRS_SKIP_MTIME | ATTRS_SKIP_ATIME | ATTRS_SKIP_CRTIME);
+		       ATTRS_DELAY_IMMUTABLE
+		       | (ok_to_set_time ? ATTRS_ACCURATE_TIME : ATTRS_SKIP_MTIME | ATTRS_SKIP_ATIME | ATTRS_SKIP_CRTIME));
 
 	/* move tmp file over real file */
 	if (DEBUG_GTE(RECV, 1))
@@ -763,6 +811,10 @@ int finish_transfer(const char *fname, const char *fnametmp,
 	}
 	if (ret == 0) {
 		/* The file was moved into place (not copied), so it's done. */
+#ifdef SUPPORT_FILE_FLAGS
+		if (preserve_file_flags && F_FFLAGS(file) & ALL_IMMUTABLE)
+			set_file_flags(fname, F_FFLAGS(file));
+#endif
 		return 1;
 	}
 	/* The file was copied, so tweak the perms of the copied file.  If it
@@ -774,7 +826,7 @@ int finish_transfer(const char *fname, const char *fnametmp,
 		       ok_to_set_time ? ATTRS_ACCURATE_TIME : ATTRS_SKIP_MTIME | ATTRS_SKIP_ATIME | ATTRS_SKIP_CRTIME);
 
 	if (temp_copy_name) {
-		if (do_rename_at(fnametmp, fname) < 0) {
+		if (do_rename_at(fnametmp, fname, file->mode, NO_FFLAGS) < 0) {
 			rsyserr(FERROR_XFER, errno, "rename %s -> \"%s\"",
 				full_fname(fnametmp), fname);
 			return 0;
--- rsync.h.orig
+++ rsync.h
@@ -69,7 +69,7 @@
 
 /* The following XMIT flags require an rsync that uses a varint for the flag values */
 
-#define XMIT_RESERVED_16 (1<<16) 	/* reserved for future fileflags use */
+#define XMIT_SAME_FLAGS (1<<16) 	/* any protocol - restricted by command-line option */
 #define XMIT_CRTIME_EQ_MTIME (1<<17)	/* any protocol - restricted by command-line option */
 
 /* These flags are used in the live flist data. */
@@ -216,6 +216,7 @@
 #define ATTRS_SKIP_MTIME	(1<<1)
 #define ATTRS_ACCURATE_TIME	(1<<2)
 #define ATTRS_SKIP_ATIME	(1<<3)
+#define ATTRS_DELAY_IMMUTABLE	(1<<4)
 #define ATTRS_SKIP_CRTIME	(1<<5)
 
 #define MSG_FLUSH	2
@@ -244,6 +245,7 @@
 #define ITEM_REPORT_GROUP (1<<6)
 #define ITEM_REPORT_ACL (1<<7)
 #define ITEM_REPORT_XATTR (1<<8)
+#define ITEM_REPORT_FFLAGS (1<<9)
 #define ITEM_REPORT_CRTIME (1<<10)
 #define ITEM_BASIS_TYPE_FOLLOWS (1<<11)
 #define ITEM_XNAME_FOLLOWS (1<<12)
@@ -611,6 +613,31 @@ typedef unsigned int size_t;
 #define SUPPORT_CRTIMES 1
 #endif
 
+#define NO_FFLAGS ((uint32)-1)
+
+#ifdef HAVE_CHFLAGS
+#define SUPPORT_FILE_FLAGS 1
+#define SUPPORT_FORCE_CHANGE 1
+#endif
+
+#if defined SUPPORT_FILE_FLAGS || defined SUPPORT_FORCE_CHANGE
+#ifndef UF_NOUNLINK
+#define UF_NOUNLINK 0
+#endif
+#ifndef SF_NOUNLINK
+#define SF_NOUNLINK 0
+#endif
+#define USR_IMMUTABLE (UF_IMMUTABLE|UF_NOUNLINK|UF_APPEND)
+#define SYS_IMMUTABLE (SF_IMMUTABLE|SF_NOUNLINK|SF_APPEND)
+#define ALL_IMMUTABLE (USR_IMMUTABLE|SYS_IMMUTABLE)
+#define ST_FLAGS(st) ((st).st_flags)
+#else
+#define USR_IMMUTABLE 0
+#define SYS_IMMUTABLE 0
+#define ALL_IMMUTABLE 0
+#define ST_FLAGS(st) NO_FFLAGS
+#endif
+
 /* Find a variable that is either exactly 32-bits or longer.
  * If some code depends on 32-bit truncation, it will need to
  * take special action in a "#if SIZEOF_INT32 > 4" section. */
@@ -842,6 +869,7 @@ extern int pathname_ndx;
 extern int depth_ndx;
 extern int uid_ndx;
 extern int gid_ndx;
+extern int file_flags_ndx;
 extern int acls_ndx;
 extern int xattrs_ndx;
 extern int file_sum_extra_cnt;
@@ -897,6 +925,11 @@ extern int file_sum_extra_cnt;
 /* When the associated option is on, all entries will have these present: */
 #define F_OWNER(f) REQ_EXTRA(f, uid_ndx)->unum
 #define F_GROUP(f) REQ_EXTRA(f, gid_ndx)->unum
+#if defined SUPPORT_FILE_FLAGS || defined SUPPORT_FORCE_CHANGE
+#define F_FFLAGS(f) REQ_EXTRA(f, file_flags_ndx)->unum
+#else
+#define F_FFLAGS(f) NO_FFLAGS
+#endif
 #define F_ACL(f) REQ_EXTRA(f, acls_ndx)->num
 #define F_XATTR(f) REQ_EXTRA(f, xattrs_ndx)->num
 #define F_NDX(f) REQ_EXTRA(f, unsort_ndx)->num
--- syscall.c.orig
+++ syscall.c
@@ -45,6 +45,7 @@ extern int am_root;
 extern int am_sender;
 extern int read_only;
 extern int list_only;
+extern int force_change;
 extern int inplace;
 extern int preallocate_files;
 extern int preserve_perms;
@@ -90,7 +91,23 @@ int do_unlink(const char *path)
 {
 	if (dry_run) return 0;
 	RETURN_ERROR_IF_RO_OR_LO;
-	return unlink(path);
+	if (unlink(path) == 0)
+		return 0;
+#ifdef SUPPORT_FORCE_CHANGE
+	if (force_change && errno == EPERM) {
+		STRUCT_STAT st;
+
+		if (do_lstat(path, &st) == 0
+		    && make_mutable(path, st.st_mode, st.st_flags, force_change) > 0) {
+			if (unlink(path) == 0)
+				return 0;
+			undo_make_mutable(path, st.st_flags);
+		}
+		/* TODO: handle immutable directories */
+		errno = EPERM;
+	}
+#endif
+	return -1;
 }
 
 /*
@@ -142,6 +159,18 @@ int do_unlink_at(const char *path)
 
 	ret = unlinkat(dfd, bname, 0);
 	e = errno;
+#ifdef SUPPORT_FORCE_CHANGE
+	if (force_change && e == EPERM) {
+		STRUCT_STAT st;
+		if (do_lstat(path, &st) == 0
+		    && make_mutable(path, st.st_mode, st.st_flags, force_change) > 0) {
+			ret = unlinkat(dfd, bname, 0);
+			e = errno;
+			if (ret != 0)
+				undo_make_mutable(path, st.st_flags);
+		}
+	}
+#endif
 	close(dfd);
 	errno = e;
 	return ret;
@@ -399,14 +428,35 @@ int do_link_at(const char *old_path, const char *new_path)
 }
 #endif
 
-int do_lchown(const char *path, uid_t owner, gid_t group)
+int do_lchown(const char *path, uid_t owner, gid_t group, UNUSED(mode_t mode), UNUSED(uint32 file_flags))
 {
 	if (dry_run) return 0;
 	RETURN_ERROR_IF_RO_OR_LO;
 #ifndef HAVE_LCHOWN
 #define lchown chown
 #endif
-	return lchown(path, owner, group);
+	if (lchown(path, owner, group) == 0)
+		return 0;
+#ifdef SUPPORT_FORCE_CHANGE
+	if (force_change && errno == EPERM) {
+		if (file_flags == NO_FFLAGS) {
+			STRUCT_STAT st;
+			if (do_lstat(path, &st) == 0) {
+				mode = st.st_mode;
+				file_flags = st.st_flags;
+			}
+		}
+		if (file_flags != NO_FFLAGS
+		    && make_mutable(path, mode, file_flags, force_change) > 0) {
+			int ret = lchown(path, owner, group);
+			undo_make_mutable(path, file_flags);
+			if (ret == 0)
+				return 0;
+		}
+		errno = EPERM;
+	}
+#endif
+	return -1;
 }
 
 /*
@@ -423,7 +473,7 @@ int do_lchown(const char *path, uid_t owner, gid_t group)
   Falls through to do_lchown() in the dry-run / non-daemon / chrooted /
   absolute-path / no-parent cases, identical to do_chmod_at().
 */
-int do_lchown_at(const char *fname, uid_t owner, gid_t group)
+int do_lchown_at(const char *fname, uid_t owner, gid_t group, UNUSED(mode_t mode), UNUSED(uint32 file_flags))
 {
 #ifdef AT_FDCWD
 	extern int am_daemon, am_chrooted;
@@ -437,14 +487,14 @@ int do_lchown_at(const char *fname, uid_t owner, gid_t group)
 	RETURN_ERROR_IF_RO_OR_LO;
 
 	if (!am_daemon || am_chrooted)
-		return do_lchown(fname, owner, group);
+		return do_lchown(fname, owner, group, mode, file_flags);
 
 	if (!fname || !*fname || *fname == '/')
-		return do_lchown(fname, owner, group);
+		return do_lchown(fname, owner, group, mode, file_flags);
 
 	slash = strrchr(fname, '/');
 	if (!slash)
-		return do_lchown(fname, owner, group);
+		return do_lchown(fname, owner, group, mode, file_flags);
 
 	dlen = slash - fname;
 	if (dlen >= sizeof dirpath) {
@@ -461,6 +511,23 @@ int do_lchown_at(const char *fname, uid_t owner, gid_t group)
 
 	ret = fchownat(dfd, bname, owner, group, AT_SYMLINK_NOFOLLOW);
 	e = errno;
+#ifdef SUPPORT_FORCE_CHANGE
+	if (force_change && e == EPERM) {
+		if (file_flags == NO_FFLAGS) {
+			STRUCT_STAT st;
+			if (do_lstat(fname, &st) == 0) {
+				mode = st.st_mode;
+				file_flags = st.st_flags;
+			}
+		}
+		if (file_flags != NO_FFLAGS
+		    && make_mutable(fname, mode, file_flags, force_change) > 0) {
+			ret = fchownat(dfd, bname, owner, group, AT_SYMLINK_NOFOLLOW);
+			e = errno;
+			undo_make_mutable(fname, file_flags);
+		}
+	}
+#endif
 	close(dfd);
 	errno = e;
 	return ret;
@@ -506,7 +573,7 @@ int do_mknod(const char *pathname, mode_t mode, dev_t dev)
 			return -1;
 		close(sock);
 #ifdef HAVE_CHMOD
-		return do_chmod(pathname, mode);
+		return do_chmod(pathname, mode, 0);
 #else
 		return 0;
 #endif
@@ -618,7 +685,21 @@ int do_rmdir(const char *pathname)
 {
 	if (dry_run) return 0;
 	RETURN_ERROR_IF_RO_OR_LO;
-	return rmdir(pathname);
+	if (rmdir(pathname) == 0)
+		return 0;
+#ifdef SUPPORT_FORCE_CHANGE
+	if (force_change && errno == EPERM) {
+		STRUCT_STAT st;
+		if (do_lstat(pathname, &st) == 0
+		    && make_mutable(pathname, st.st_mode, st.st_flags, force_change) > 0) {
+			if (rmdir(pathname) == 0)
+				return 0;
+			undo_make_mutable(pathname, st.st_flags);
+		}
+		errno = EPERM;
+	}
+#endif
+	return -1;
 }
 
 /*
@@ -664,6 +745,18 @@ int do_rmdir_at(const char *pathname)
 
 	ret = unlinkat(dfd, bname, AT_REMOVEDIR);
 	e = errno;
+#ifdef SUPPORT_FORCE_CHANGE
+	if (force_change && e == EPERM) {
+		STRUCT_STAT st;
+		if (do_lstat(pathname, &st) == 0
+		    && make_mutable(pathname, st.st_mode, st.st_flags, force_change) > 0) {
+			ret = unlinkat(dfd, bname, AT_REMOVEDIR);
+			e = errno;
+			if (ret != 0)
+				undo_make_mutable(pathname, st.st_flags);
+		}
+	}
+#endif
 	close(dfd);
 	errno = e;
 	return ret;
@@ -758,7 +851,7 @@ int do_open_at(const char *pathname, int flags, mode_t mode)
 }
 
 #ifdef HAVE_CHMOD
-int do_chmod(const char *path, mode_t mode)
+int do_chmod(const char *path, mode_t mode, UNUSED(uint32 file_flags))
 {
 	static int switch_step = 0;
 	int code;
@@ -797,6 +890,23 @@ int do_chmod(const char *path, mode_t mode)
 			code = chmod(path, mode & CHMOD_BITS); /* DISCOURAGED FUNCTION */
 		break;
 	}
+#ifdef SUPPORT_FORCE_CHANGE
+	if (code < 0 && force_change && errno == EPERM && !S_ISLNK(mode)) {
+		if (file_flags == NO_FFLAGS) {
+			STRUCT_STAT st;
+			if (do_lstat(path, &st) == 0)
+				file_flags = st.st_flags;
+		}
+		if (file_flags != NO_FFLAGS
+		    && make_mutable(path, mode, file_flags, force_change) > 0) {
+			code = chmod(path, mode & CHMOD_BITS);
+			undo_make_mutable(path, file_flags);
+			if (code == 0)
+				return 0;
+		}
+		errno = EPERM;
+	}
+#endif
 	if (code != 0 && (preserve_perms || preserve_executability))
 		return code;
 	return 0;
@@ -830,7 +940,7 @@ int do_chmod(const char *path, mode_t mode)
   Falls back to do_chmod() for absolute paths and for paths with no parent
   component, where there is nothing to protect against.
 */
-int do_chmod_at(const char *fname, mode_t mode)
+int do_chmod_at(const char *fname, mode_t mode, UNUSED(uint32 file_flags))
 {
 #ifdef AT_FDCWD
 	extern int am_daemon, am_chrooted;
@@ -850,14 +960,14 @@ int do_chmod_at(const char *fname, mode_t mode)
 	 * already access.  Everywhere else, fall through to plain
 	 * do_chmod() to avoid the dirfd-open overhead on every call. */
 	if (!am_daemon || am_chrooted)
-		return do_chmod(fname, mode);
+		return do_chmod(fname, mode, file_flags);
 
 	if (!fname || !*fname || *fname == '/' || S_ISLNK(mode))
-		return do_chmod(fname, mode);
+		return do_chmod(fname, mode, file_flags);
 
 	slash = strrchr(fname, '/');
 	if (!slash)
-		return do_chmod(fname, mode);
+		return do_chmod(fname, mode, file_flags);
 
 	dlen = slash - fname;
 	if (dlen >= sizeof dirpath) {
@@ -872,8 +982,23 @@ int do_chmod_at(const char *fname, mode_t mode)
 	if (dfd < 0)
 		return -1;
 
-	ret = fchmodat(dfd, bname, mode, 0);
+	ret = fchmodat(dfd, bname, mode & CHMOD_BITS, 0);
 	e = errno;
+#ifdef SUPPORT_FORCE_CHANGE
+	if (ret < 0 && force_change && e == EPERM && !S_ISLNK(mode)) {
+		if (file_flags == NO_FFLAGS) {
+			STRUCT_STAT st;
+			if (do_lstat(fname, &st) == 0)
+				file_flags = st.st_flags;
+		}
+		if (file_flags != NO_FFLAGS
+		    && make_mutable(fname, mode, file_flags, force_change) > 0) {
+			ret = fchmodat(dfd, bname, mode & CHMOD_BITS, 0);
+			e = errno;
+			undo_make_mutable(fname, file_flags);
+		}
+	}
+#endif
 	close(dfd);
 	errno = e;
 	return ret;
@@ -883,11 +1008,40 @@ int do_chmod_at(const char *fname, mode_t mode)
 }
 #endif
 
-int do_rename(const char *old_path, const char *new_path)
+#ifdef HAVE_CHFLAGS
+int do_chflags(const char *path, uint32 file_flags)
 {
 	if (dry_run) return 0;
 	RETURN_ERROR_IF_RO_OR_LO;
-	return rename(old_path, new_path);
+	return chflags(path, file_flags);
+}
+#endif
+
+int do_rename(const char *old_path, const char *new_path, UNUSED(mode_t mode), UNUSED(uint32 file_flags))
+{
+	int ret;
+
+	if (dry_run) return 0;
+	RETURN_ERROR_IF_RO_OR_LO;
+	ret = rename(old_path, new_path);
+#ifdef SUPPORT_FORCE_CHANGE
+	if (ret < 0 && force_change && errno == EPERM) {
+		if (file_flags == NO_FFLAGS) {
+			STRUCT_STAT st;
+			if (do_lstat(new_path, &st) == 0)
+				file_flags = st.st_flags;
+		}
+		if (file_flags != NO_FFLAGS
+		    && make_mutable(new_path, mode, file_flags, force_change) > 0) {
+			ret = rename(old_path, new_path);
+			undo_make_mutable(new_path, file_flags);
+			if (ret == 0)
+				return 0;
+		}
+		errno = EPERM;
+	}
+#endif
+	return ret;
 }
 
 /*
@@ -907,7 +1061,7 @@ int do_rename(const char *old_path, const char *new_path)
   parent and absolute-path cases, identical to the other do_*_at()
   wrappers.
 */
-int do_rename_at(const char *old_path, const char *new_path)
+int do_rename_at(const char *old_path, const char *new_path, UNUSED(mode_t mode), UNUSED(uint32 file_flags))
 {
 #ifdef AT_FDCWD
 	extern int am_daemon, am_chrooted;
@@ -921,16 +1075,16 @@ int do_rename_at(const char *old_path, const char *new_path)
 	RETURN_ERROR_IF_RO_OR_LO;
 
 	if (!am_daemon || am_chrooted)
-		return do_rename(old_path, new_path);
+		return do_rename(old_path, new_path, mode, file_flags);
 
 	if (!old_path || !*old_path || *old_path == '/'
 	 || !new_path || !*new_path || *new_path == '/')
-		return do_rename(old_path, new_path);
+		return do_rename(old_path, new_path, mode, file_flags);
 
 	old_slash = strrchr(old_path, '/');
 	new_slash = strrchr(new_path, '/');
 	if (!old_slash || !new_slash)
-		return do_rename(old_path, new_path);
+		return do_rename(old_path, new_path, mode, file_flags);
 
 	old_dlen = old_slash - old_path;
 	new_dlen = new_slash - new_path;
@@ -963,6 +1117,24 @@ int do_rename_at(const char *old_path, const char *new_path)
 
 	ret = renameat(old_dfd, old_bname, new_dfd, new_bname);
 	e = errno;
+#ifdef SUPPORT_FORCE_CHANGE
+	if (ret < 0 && force_change && e == EPERM) {
+		if (file_flags == NO_FFLAGS) {
+			STRUCT_STAT st;
+			if (do_lstat(new_path, &st) == 0)
+				file_flags = st.st_flags;
+		}
+		if (file_flags != NO_FFLAGS
+		    && make_mutable(new_path, mode, file_flags, force_change) > 0) {
+			ret = renameat(old_dfd, old_bname, new_dfd, new_bname);
+			e = errno;
+			undo_make_mutable(new_path, file_flags);
+			if (ret == 0)
+				return 0;
+		}
+		errno = EPERM;
+	}
+#endif
 	if (new_dfd != old_dfd)
 		close(new_dfd);
 	close(old_dfd);
--- t_chmod_secure.c.orig
+++ t_chmod_secure.c
@@ -88,26 +88,26 @@ int main(int argc, char **argv)
 	 */
 
 	/* Scenario A: legitimate parent dir-symlink, chmod must succeed. */
-	int rc = do_chmod_at("inside_link/sentinel", 0640);
+	int rc = do_chmod_at("inside_link/sentinel", 0640, 0);
 	check("A: legit dir-symlink within tree",
 	      rc, 1, "realdir/sentinel", 0640);
 
 	/* Scenario B: parent symlink escapes the tree -- chmod must be
 	 * rejected and the outside file's mode must be unchanged. */
-	rc = do_chmod_at("escape_link/sentinel", 0666);
+	rc = do_chmod_at("escape_link/sentinel", 0666, 0);
 	check("B: parent symlink escapes tree (the attack)",
 	      rc, 0, "../trap/sentinel", 0600);
 
 	/* Scenario C: plain relative path with no symlink components,
 	 * regression check that the safe wrapper doesn't break the
 	 * normal case. */
-	rc = do_chmod_at("realdir/sentinel", 0644);
+	rc = do_chmod_at("realdir/sentinel", 0644, 0);
 	check("C: plain relative path (regression check)",
 	      rc, 1, "realdir/sentinel", 0644);
 
 	/* Scenario D: top-level file, no parent directory component.
 	 * Falls back to do_chmod(); should succeed. */
-	rc = do_chmod_at("topfile", 0640);
+	rc = do_chmod_at("topfile", 0640, 0);
 	check("D: top-level file, no parent component",
 	      rc, 1, "topfile", 0640);
 
--- t_stub.c.orig
+++ t_stub.c
@@ -30,7 +30,9 @@ int preallocate_files = 0;
 int protect_args = 0;
 int module_id = -1;
 int relative_paths = 0;
+int force_change = 0;
 unsigned int module_dirlen = 0;
+int preserve_acls = 0;
 int preserve_xattrs = 0;
 int preserve_perms = 0;
 int preserve_executability = 0;
@@ -118,3 +120,23 @@ filter_rule_list daemon_filter_list;
 {
 	return cst ? 0 : 0;
 }
+
+#if defined SUPPORT_FILE_FLAGS || defined SUPPORT_FORCE_CHANGE
+ int make_mutable(UNUSED(const char *fname), UNUSED(mode_t mode), UNUSED(uint32 file_flags), UNUSED(uint32 iflags))
+{
+	return 0;
+}
+
+/* Undo a prior make_mutable() call that returned a 1. */
+ int undo_make_mutable(UNUSED(const char *fname), UNUSED(uint32 file_flags))
+{
+	return 0;
+}
+#endif
+
+#ifdef SUPPORT_XATTRS
+ int x_lstat(UNUSED(const char *fname), UNUSED(STRUCT_STAT *fst), UNUSED(STRUCT_STAT *xst))
+{
+	return -1;
+}
+#endif
--- testsuite/rsync.fns.orig
+++ testsuite/rsync.fns
@@ -26,9 +26,9 @@ chkfile="$scratchdir/rsync.chk"
 outfile="$scratchdir/rsync.out"
 
 # For itemized output:
-all_plus='+++++++++'
-allspace='         '
-dots='.....' # trailing dots after changes
+all_plus='++++++++++'
+allspace='          '
+dots='......' # trailing dots after changes
 tab_ch='	' # a single tab character
 
 # Berkley's nice.
--- usage.c.orig
+++ usage.c
@@ -138,6 +138,11 @@ static void print_info_flags(enum logcode f)
 #endif
 			"crtimes",
 
+#ifndef SUPPORT_FILE_FLAGS
+		"no "
+#endif
+			"file-flags",
+
 	"*Optimizations",
 
 #ifndef USE_ROLL_SIMD
--- util1.c.orig
+++ util1.c
@@ -34,6 +34,7 @@ extern int relative_paths;
 extern int preserve_xattrs;
 extern int omit_link_times;
 extern int preallocate_files;
+extern int force_change;
 extern char *module_dir;
 extern unsigned int module_dirlen;
 extern char *partial_dir;
@@ -116,6 +117,33 @@ void print_child_argv(const char *prefix, char **cmd)
 	rprintf(FCLIENT, " (%d args)\n", cnt);
 }
 
+#ifdef SUPPORT_FORCE_CHANGE
+static int try_a_force_change(const char *fname, STRUCT_STAT *stp)
+{
+	uint32 file_flags = ST_FLAGS(*stp);
+	if (file_flags == NO_FFLAGS) {
+		STRUCT_STAT st;
+		if (x_lstat(fname, &st, NULL) == 0)
+			file_flags = st.st_flags;
+	}
+	if (file_flags != NO_FFLAGS && make_mutable(fname, stp->st_mode, file_flags, force_change) > 0) {
+		int ret, save_force_change = force_change;
+
+		force_change = 0; /* Make certain we can't come back here. */
+		ret = set_times(fname, stp);
+		force_change = save_force_change;
+
+		undo_make_mutable(fname, file_flags);
+
+		return ret;
+	}
+
+	errno = EPERM;
+
+	return -1;
+}
+#endif
+
 /* This returns 0 for success, 1 for a symlink if symlink time-setting
  * is not possible, or -1 for any other error. */
 int set_times(const char *fname, STRUCT_STAT *stp)
@@ -143,6 +171,10 @@ int set_times(const char *fname, STRUCT_STAT *stp)
 #include "case_N.h"
 		if (do_utimensat_at(fname, stp) == 0)
 			break;
+#ifdef SUPPORT_FORCE_CHANGE
+		if (force_change && errno == EPERM && try_a_force_change(fname, stp) == 0)
+			break;
+#endif
 		if (errno != ENOSYS)
 			return -1;
 		switch_step++;
@@ -152,6 +184,10 @@ int set_times(const char *fname, STRUCT_STAT *stp)
 #include "case_N.h"
 		if (do_lutimes(fname, stp) == 0)
 			break;
+#ifdef SUPPORT_FORCE_CHANGE
+		if (force_change && errno == EPERM && try_a_force_change(fname, stp) == 0)
+			break;
+#endif
 		if (errno != ENOSYS)
 			return -1;
 		switch_step++;
@@ -173,6 +209,10 @@ int set_times(const char *fname, STRUCT_STAT *stp)
 		if (do_utime(fname, stp) == 0)
 			break;
 #endif
+#ifdef SUPPORT_FORCE_CHANGE
+		if (force_change && errno == EPERM && try_a_force_change(fname, stp) == 0)
+			break;
+#endif
 
 		return -1;
 	}
@@ -532,7 +572,7 @@ int robust_unlink(const char *fname)
 	}
 
 	/* maybe we should return rename()'s exit status? Nah. */
-	if (do_rename_at(fname, path) != 0) {
+	if (do_rename_at(fname, path, 0, NO_FFLAGS) != 0) {
 		errno = ETXTBSY;
 		return -1;
 	}
@@ -555,7 +595,7 @@ int robust_rename(const char *from, const char *to, const char *partialptr,
 		return 0;
 
 	while (tries--) {
-		if (do_rename_at(from, to) == 0)
+		if (do_rename_at(from, to, 0, NO_FFLAGS) == 0)
 			return 0;
 
 		switch (errno) {
--- xattrs.c.orig
+++ xattrs.c
@@ -1094,7 +1094,7 @@ int set_xattr(const char *fname, const struct file_struct *file, const char *fna
 	 && !S_ISLNK(sxp->st.st_mode)
 #endif
 	 && access(fname, W_OK) < 0
-	 && do_chmod_at(fname, (sxp->st.st_mode & CHMOD_BITS) | S_IWUSR) == 0)
+	 && do_chmod_at(fname, (sxp->st.st_mode & CHMOD_BITS) | S_IWUSR, ST_FLAGS(sxp->st)) == 0)
 		added_write_perm = 1;
 
 	ndx = F_XATTR(file);
@@ -1102,7 +1102,7 @@ int set_xattr(const char *fname, const struct file_struct *file, const char *fna
 	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_at(fname, sxp->st.st_mode);
+		do_chmod_at(fname, sxp->st.st_mode, ST_FLAGS(sxp->st));
 	return return_value;
 }
 
@@ -1219,7 +1219,7 @@ int set_stat_xattr(const char *fname, struct file_struct *file, mode_t new_mode)
 	mode = (fst.st_mode & _S_IFMT) | (fmode & ACCESSPERMS)
 	     | (S_ISDIR(fst.st_mode) ? 0700 : 0600);
 	if (fst.st_mode != mode)
-		do_chmod_at(fname, mode);
+		do_chmod_at(fname, mode, ST_FLAGS(fst));
 	if (!IS_DEVICE(fst.st_mode))
 		fst.st_rdev = 0; /* just in case */