Add --no-i-r-s-u/--no-inc-recursive-skip-unchanged for accurate progress on resumed transfers

NEWS.md

@@ -2,6 +2,16 @@
 
 ## Changes in this version:
 
+### ENHANCEMENTS:
+
+- Added `--no-i-r-skip-unchanged` option to provide accurate progress reporting
+  for resumed transfers. This option pre-scans the destination to identify
+  unchanged files, skips them from processing, and adjusts `stats.total_size`
+  accordingly. This fixes the issue where interrupted transfers show incorrect
+  progress percentages (e.g., 1% to 80% instead of 0% to 100%) when resumed.
+  The option works for all transfer types (local, local→remote, remote→local,
+  daemon) and implies `--no-i-r`.
+
 ### BUG FIXES:
 
 - ...

generator.c

@@ -30,9 +30,12 @@ extern int stdout_format_has_i;
 extern int logfile_format_has_i;
 extern int am_root;
 extern int am_server;
+extern int am_sender;
 extern int am_daemon;
 extern int inc_recurse;
+extern int no_i_r_skip_unchanged;
 extern int relative_paths;
+extern struct stats stats;
 extern int implied_dirs;
 extern int keep_dirlinks;
 extern int write_devices;
@@ -1242,6 +1245,13 @@ static void recv_generator(char *fname, struct file_struct *file, int ndx,
 		return;
 	}
 
+	if (!F_IS_ACTIVE(file)) {
+		/* File was marked as inactive (unchanged) during pre-scan */
+		if (DEBUG_GTE(GENR, 2))
+			rprintf(FINFO, "skipping inactive file: %s\n", fname);
+		return;
+	}
+
 	maybe_ATTRS_ACCURATE_TIME = always_checksum ? ATTRS_ACCURATE_TIME : 0;
 
 	if (skip_dir) {
@@ -2223,6 +2233,73 @@ void check_for_finished_files(int itemizing, enum logcode code, int check_redo)
 	}
 }
 
+/* Pre-scan the file list to mark unchanged files and adjust stats.total_size.
+ * This allows accurate progress reporting on resumed transfers. */
+void prescan_for_unchanged(const char *local_name)
+{
+	int i, active_count = 0, skipped_count = 0;
+	char fbuf[MAXPATHLEN];
+	STRUCT_STAT st;
+
+	/* Only prescan if feature is enabled */
+	if (!no_i_r_skip_unchanged || !cur_flist)
+		return;
+
+	if (DEBUG_GTE(GENR, 1))
+		rprintf(FINFO, "pre-scanning for unchanged files\n");
+
+	for (i = 0; i < cur_flist->used; i++) {
+		struct file_struct *file = cur_flist->files[i];
+		enum filetype ftype;
+
+		if (!file || !F_IS_ACTIVE(file))
+			continue;
+
+		ftype = get_file_type(file->mode);
+
+		/* Only check regular files */
+		if (ftype != FT_REG) {
+			active_count++;
+			continue;
+		}
+
+		/* Construct destination path */
+		if (local_name)
+			strlcpy(fbuf, local_name, sizeof fbuf);
+		else
+			f_name(file, fbuf);
+
+		/* Stat destination file */
+		if (do_stat(fbuf, &st) < 0) {
+			active_count++;
+			continue;
+		}
+
+		/* Check if file is unchanged */
+		if (quick_check_ok(ftype, fbuf, file, &st)) {
+			if (DEBUG_GTE(GENR, 2))
+				rprintf(FINFO, "skipping unchanged: %s\n", fbuf);
+
+			/* Subtract from total size for accurate progress */
+			stats.total_size -= F_LENGTH(file);
+
+			/* Mark as inactive to remove from file list */
+			clear_file(file);
+			skipped_count++;
+		} else {
+			active_count++;
+		}
+	}
+
+	/* Update stats to reflect only active files for progress display */
+	stats.num_files = active_count;
+	stats.num_skipped_files = skipped_count;
+
+	if (DEBUG_GTE(GENR, 1))
+		rprintf(FINFO, "skipped %d unchanged files, %d active, adjusted size: %.2f GB\n", 
+			skipped_count, active_count, (double)stats.total_size / 1024 / 1024 / 1024);
+}
+
 void generate_files(int f_out, const char *local_name)
 {
 	int i, ndx, next_loopchk = 0;
@@ -2278,6 +2355,7 @@ void generate_files(int f_out, const char *local_name)
 	}
 
 	dflt_perms = (ACCESSPERMS & ~orig_umask);
+	stats.current_active_index = 0;
 
 	do {
 #ifdef SUPPORT_HARD_LINKS

io.c

@@ -1511,6 +1511,15 @@ static void read_a_msg(void)
 		raw_read_buf((char*)&stats.total_read, sizeof stats.total_read);
 		iobuf.in_multiplexed = 1;
 		break;
+	case MSG_FLIST_COUNT:
+		if (msg_bytes != 12 || !am_sender)
+			goto invalid_msg;
+		val = raw_read_int();
+		stats.num_skipped_files = val;
+		stats.num_files -= val;
+		raw_read_buf((char*)&stats.total_size, 8);
+		iobuf.in_multiplexed = 1;
+		break;
 	case MSG_REDO:
 		if (msg_bytes != 4 || !am_generator)
 			goto invalid_msg;

main.c

@@ -40,6 +40,7 @@ extern int am_server;
 extern int am_sender;
 extern int am_daemon;
 extern int inc_recurse;
+extern int no_i_r_skip_unchanged;
 extern int blocking_io;
 extern int always_checksum;
 extern int remove_source_files;
@@ -1029,6 +1030,18 @@ static int do_recv(int f_in, int f_out, char *local_name)
 
 	io_flush(FULL_FLUSH);
 
+	/* Pre-scan for unchanged files before forking so both processes get updated stats */
+	prescan_for_unchanged(local_name);
+
+	/* Send adjusted stats to sender for accurate progress (local→remote transfers) */
+	if (no_i_r_skip_unchanged && stats.num_skipped_files > 0) {
+		char buf[12];
+		SIVAL(buf, 0, stats.num_skipped_files);
+		SIVAL64(buf, 4, stats.total_size);
+		send_msg(MSG_FLIST_COUNT, buf, 12, 0);
+		io_flush(NORMAL_FLUSH);
+	}
+
 	if ((pid = do_fork()) == -1) {
 		rsyserr(FERROR, errno, "fork failed in do_recv");
 		exit_cleanup(RERR_IPC);

options.c

@@ -112,6 +112,7 @@ int human_readable = 1;
 int recurse = 0;
 int mkpath_dest_arg = 0;
 int allow_inc_recurse = 1;
+int no_i_r_skip_unchanged = 0;
 int xfer_dirs = -1;
 int am_daemon = 0;
 int connect_timeout = 0;
@@ -585,7 +586,7 @@ enum {OPT_SERVER = 1000, OPT_DAEMON, OPT_SENDER, OPT_EXCLUDE, OPT_EXCLUDE_FROM,
       OPT_NO_D, OPT_APPEND, OPT_NO_ICONV, OPT_INFO, OPT_DEBUG, OPT_BLOCK_SIZE,
       OPT_USERMAP, OPT_GROUPMAP, OPT_CHOWN, OPT_BWLIMIT, OPT_STDERR,
       OPT_OLD_COMPRESS, OPT_NEW_COMPRESS, OPT_NO_COMPRESS, OPT_OLD_ARGS,
-      OPT_STOP_AFTER, OPT_STOP_AT,
+      OPT_STOP_AFTER, OPT_STOP_AT, OPT_NO_I_R_SKIP_UNCHANGED,
       OPT_REFUSED_BASE = 9000};
 
 static struct poptOption long_options[] = {
@@ -616,6 +617,9 @@ static struct poptOption long_options[] = {
   {"no-inc-recursive", 0,  POPT_ARG_VAL,    &allow_inc_recurse, 0, 0, 0 },
   {"i-r",              0,  POPT_ARG_VAL,    &allow_inc_recurse, 1, 0, 0 },
   {"no-i-r",           0,  POPT_ARG_VAL,    &allow_inc_recurse, 0, 0, 0 },
+  {"no-inc-recursive-skip-unchanged", 0, POPT_ARG_NONE, 0, OPT_NO_I_R_SKIP_UNCHANGED, 0, 0 },
+  {"no-i-r-skip-unchanged", 0, POPT_ARG_NONE, 0, OPT_NO_I_R_SKIP_UNCHANGED, 0, 0 },
+  {"no-i-r-s-u",       0,  POPT_ARG_NONE,   0, OPT_NO_I_R_SKIP_UNCHANGED, 0, 0 },
   {"dirs",            'd', POPT_ARG_VAL,    &xfer_dirs, 2, 0, 0 },
   {"no-dirs",          0,  POPT_ARG_VAL,    &xfer_dirs, 0, 0, 0 },
   {"no-d",             0,  POPT_ARG_VAL,    &xfer_dirs, 0, 0, 0 },
@@ -1900,6 +1904,11 @@ int parse_arguments(int *argc_p, const char ***argv_p)
 			break;
 #endif
 
+		case OPT_NO_I_R_SKIP_UNCHANGED:
+			no_i_r_skip_unchanged = 1;
+			allow_inc_recurse = 0;
+			break;
+
 		case OPT_STDERR: {
 			int len;
 			arg = poptGetOptArg(pc);
@@ -2987,6 +2996,9 @@ void server_options(char **args, int *argc_p)
 	if (mkpath_dest_arg && am_sender)
 		args[ac++] = "--mkpath";
 
+	if (no_i_r_skip_unchanged)
+		args[ac++] = "--no-i-r-skip-unchanged";
+
 	if (ac > MAX_SERVER_ARGS) { /* Not possible... */
 		rprintf(FERROR, "argc overflow in server_options().\n");
 		exit_cleanup(RERR_MALLOC);

progress.c

@@ -78,7 +78,7 @@ static void rprint_progress(OFF_T ofs, OFF_T size, struct timeval *now, int is_l
 		int len = snprintf(eol, sizeof eol,
 			" (xfr#%d, %s-chk=%d/%d)\n",
 			stats.xferred_files, flist_eof ? "to" : "ir",
-			stats.num_files - current_file_index - 1,
+			stats.num_files - stats.current_active_index,
 			stats.num_files);
 		if (INFO_GTE(PROGRESS, 2)) {
 			static int last_len = 0;
@@ -153,6 +153,10 @@ void set_current_file_index(struct file_struct *file, int ndx)
 	else
 		current_file_index = ndx;
 	current_file_index -= cur_flist->flist_num;
+
+	/* Track active file index for accurate progress with --no-i-r-skip-unchanged */
+	if (file && F_IS_ACTIVE(file))
+		stats.current_active_index++;
 }
 
 void instant_progress(const char *fname)

rsync.1.md

@@ -909,6 +909,43 @@ expand it.
     before it begins to transfer files.  See [`--inc-recursive`](#opt) for more
     info.
 
+0. `--no-inc-recursive-skip-unchanged`, `--no-i-r-skip-unchanged`, `--no-i-r-s-u`
+
+    This option combines [`--no-i-r`](#opt) with pre-scanning to skip unchanged
+    files, providing accurate progress reporting for resumed transfers.  When
+    using [`--info=progress2`](#opt), interrupted transfers that are resumed
+    normally show incorrect progress percentages because `stats.total_size`
+    includes already-transferred files.  This option pre-scans the destination
+    during generator initialization, marks unchanged files for skipping, and
+    adjusts `stats.total_size` accordingly, resulting in accurate 0% to 100%
+    progress reporting.
+
+    The pre-scan uses the same comparison logic as normal rsync operations
+    (checking size, mtime, checksums if [`--checksum`](#opt) is used, etc.).
+    Files determined to be unchanged are completely skipped from processing,
+    reducing both CPU and I/O overhead while fixing progress reporting.
+
+    This option works for all transfer types: local-to-local, local-to-remote,
+    remote-to-local, and daemon transfers.  Because the generator runs on the
+    receiver side and has access to destination files in all scenarios, the
+    feature functions correctly regardless of transfer direction.
+
+    This option implies [`--no-i-r`](#opt), so it requires the full file list
+    to be available before processing begins.  The performance overhead is
+    minimal since the pre-scan performs the same stat operations that would
+    occur anyway during normal generator operation, just earlier in the pipeline.
+
+    Example use cases:
+
+    - Resuming interrupted transfers with accurate progress:
+      `rsync -av --no-i-r-s-u --info=progress2 src/ host:dest/`
+
+    - Large synchronization with mostly unchanged files:
+      `rsync -av --no-inc-recursive-skip-unchanged /data/ /backup/`
+
+    - Remote-to-local transfer with progress tracking:
+      `rsync -av --no-i-r-skip-unchanged --info=progress2 host:src/ dest/`
+
 0.  `--relative`, `-R`
 
     Use relative paths.  This means that the full path names specified on the

rsync.h

@@ -269,6 +269,7 @@ enum msgcode {
 	MSG_LOG=FLOG, MSG_CLIENT=FCLIENT, /* sibling logging */
 	MSG_REDO=9,	/* reprocess indicated flist index */
 	MSG_STATS=10,	/* message has stats data for generator */
+	MSG_FLIST_COUNT=11, /* receiver sends adjusted stats to sender after prescan */
 	MSG_IO_ERROR=22,/* the sending side had an I/O error */
 	MSG_IO_TIMEOUT=33,/* tell client about a daemon's timeout value */
 	MSG_NOOP=42,	/* a do-nothing message (legacy protocol-30 only) */
@@ -1044,6 +1045,8 @@ struct stats {
 	int created_files, created_dirs, created_symlinks, created_devices, created_specials;
 	int deleted_files, deleted_dirs, deleted_symlinks, deleted_devices, deleted_specials;
 	int xferred_files;
+	int num_skipped_files; /* files marked as unchanged by --no-i-r-skip-unchanged */
+	int current_active_index; /* current index among active files (excluding skipped) */
 };
 
 struct chmod_mode_struct;