Add new & improved `--copy-devices` option.

6 files changed, 65 insertions, 7 deletions

diff --git a/NEWS.md b/NEWS.md
index 6dfed8d0..2b08dfa8 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -116,6 +116,12 @@
 
  - Added the [`--fsync`](rsync.1#opt) option (promoted from the patches repo).
 
+ - Added the [`--copy-devices`](rsync.1#opt) option.  Compared to the
+   historical version from the rsync-patches repo, this version: properly
+   handles `--checksum`; fixes a truncation bug when doing an `--inplace` copy
+   onto a longer file; fixes several bugs in the `--itemize` output; and only
+   the sending side needs the enhanced rsync for the copy to work.
+
  - Reduced memory usage for an incremental transfer that has a bunch of small
    directories.
 
diff --git a/flist.c b/flist.c
index d72ba609..1ba306bc 100644
--- a/flist.c
+++ b/flist.c
@@ -43,6 +43,7 @@ extern int use_qsort;
 extern int xfer_dirs;
 extern int filesfrom_fd;
 extern int one_file_system;
+extern int copy_devices;
 extern int copy_dirlinks;
 extern int preserve_uid;
 extern int preserve_gid;
@@ -700,6 +701,7 @@ static struct file_struct *recv_file_entry(int f, struct file_list *flist, int x
 	int alloc_len, basename_len, linkname_len;
 	int extra_len = file_extra_cnt * EXTRA_LEN;
 	int first_hlink_ndx = -1;
+	char real_ISREG_entry;
 	int64 file_length;
 #ifdef CAN_SET_NSEC
 	uint32 modtime_nsec;
@@ -814,6 +816,7 @@ static struct file_struct *recv_file_entry(int f, struct file_list *flist, int x
 				linkname_len = strlen(F_SYMLINK(first)) + 1;
 			else
 				linkname_len = 0;
+			real_ISREG_entry = S_ISREG(mode) ? 1 : 0;
 			goto create_object;
 		}
 	}
@@ -941,10 +944,20 @@ static struct file_struct *recv_file_entry(int f, struct file_list *flist, int x
 #endif
 		linkname_len = 0;
 
+	if (copy_devices && IS_DEVICE(mode)) {
+		/* This is impossible in the official release, but some pre-release patches
+		 * didn't convert the device into a file before sending, so we'll do it here
+		 * (even though the length is typically 0 and any checksum data is zeros). */
+		mode = S_IFREG | (mode & ACCESSPERMS);
+		modtime = time(NULL); /* The mtime on the device is not up-to-date, so set it to "now". */
+		real_ISREG_entry = 0;
+	} else
+		real_ISREG_entry = S_ISREG(mode) ? 1 : 0;
+
 #ifdef SUPPORT_HARD_LINKS
   create_object:
 	if (preserve_hard_links) {
-		if (protocol_version < 28 && S_ISREG(mode))
+		if (protocol_version < 28 && real_ISREG_entry)
 			xflags |= XMIT_HLINKED;
 		if (xflags & XMIT_HLINKED)
 			extra_len += (inc_recurse+1) * EXTRA_LEN;
@@ -1160,8 +1173,8 @@ static struct file_struct *recv_file_entry(int f, struct file_list *flist, int x
 	}
 #endif
 
-	if (always_checksum && (S_ISREG(mode) || protocol_version < 28)) {
-		if (S_ISREG(mode))
+	if (always_checksum && (real_ISREG_entry || protocol_version < 28)) {
+		if (real_ISREG_entry)
 			bp = F_SUM(file);
 		else {
 			/* Prior to 28, we get a useless set of nulls. */
@@ -1360,6 +1373,18 @@ struct file_struct *make_file(const char *fname, struct file_list *flist,
 	linkname_len = 0;
 #endif
 
+	if (copy_devices && am_sender && IS_DEVICE(st.st_mode)) {
+		if (st.st_size == 0) {
+			int fd = do_open(fname, O_RDONLY, 0);
+			if (fd >= 0) {
+				st.st_size = get_device_size(fd, fname);
+				close(fd);
+			}
+		}
+		st.st_mode = S_IFREG | (st.st_mode & ACCESSPERMS);
+		st.st_mtime = time(NULL); /* The mtime on the device is not up-to-date, so set it to "now". */
+	}
+
 #ifdef ST_MTIME_NSEC
 	if (st.ST_MTIME_NSEC && protocol_version >= 31)
 		extra_len += EXTRA_LEN;
diff --git a/options.c b/options.c
index d08f0003..93bdb237 100644
--- a/options.c
+++ b/options.c
@@ -47,6 +47,7 @@ int append_mode = 0;
 int keep_dirlinks = 0;
 int copy_dirlinks = 0;
 int copy_links = 0;
+int copy_devices = 0;
 int write_devices = 0;
 int preserve_links = 0;
 int preserve_hard_links = 0;
@@ -656,6 +657,7 @@ static struct poptOption long_options[] = {
   {"no-D",             0,  POPT_ARG_NONE,   0, OPT_NO_D, 0, 0 },
   {"devices",          0,  POPT_ARG_VAL,    &preserve_devices, 1, 0, 0 },
   {"no-devices",       0,  POPT_ARG_VAL,    &preserve_devices, 0, 0, 0 },
+  {"copy-devices",     0,  POPT_ARG_NONE,   &copy_devices, 0, 0, 0 },
   {"write-devices",    0,  POPT_ARG_VAL,    &write_devices, 1, 0, 0 },
   {"no-write-devices", 0,  POPT_ARG_VAL,    &write_devices, 0, 0, 0 },
   {"specials",         0,  POPT_ARG_VAL,    &preserve_specials, 1, 0, 0 },
@@ -949,6 +951,7 @@ static void set_refuse_options(void)
 		 || strcmp("iconv", longName) == 0
 		 || strcmp("no-iconv", longName) == 0
 		 || strcmp("checksum-seed", longName) == 0
+		 || strcmp("copy-devices", longName) == 0 /* disable wild-match (it gets refused below) */
 		 || strcmp("write-devices", longName) == 0 /* disable wild-match (it gets refused below) */
 		 || strcmp("log-format", longName) == 0 /* aka out-format (NOT log-file-format) */
 		 || strcmp("sender", longName) == 0
@@ -960,6 +963,7 @@ static void set_refuse_options(void)
 	assert(list_end != NULL);
 
 	if (am_daemon) { /* Refused by default, but can be accepted via a negated exact match. */
+		parse_one_refuse_match(0, "copy-devices", list_end);
 		parse_one_refuse_match(0, "write-devices", list_end);
 	}
 
@@ -2917,6 +2921,9 @@ void server_options(char **args, int *argc_p)
 	else if (remove_source_files)
 		args[ac++] = "--remove-sent-files";
 
+	if (copy_devices && !am_sender)
+		args[ac++] = "--copy-devices";
+
 	if (preallocate_files && am_sender)
 		args[ac++] = "--preallocate";
 
diff --git a/rsync.1.md b/rsync.1.md
index ca0ed7f7..313025df 100644
--- a/rsync.1.md
+++ b/rsync.1.md
@@ -373,6 +373,8 @@ has its own detailed description later in this manpage.
 --owner, -o              preserve owner (super-user only)
 --group, -g              preserve group
 --devices                preserve device files (super-user only)
+--copy-devices           copy device contents as a regular file
+--write-devices          write to devices as files (implies --inplace)
 --specials               preserve special files
 -D                       same as --devices --specials
 --times, -t              preserve modification times
@@ -385,7 +387,6 @@ has its own detailed description later in this manpage.
 --fake-super             store/recover privileged attrs using xattrs
 --sparse, -S             turn sequences of nulls into sparse blocks
 --preallocate            allocate dest files before writing them
---write-devices          write to devices as files (implies --inplace)
 --dry-run, -n            perform a trial run with no changes made
 --whole-file, -W         copy files whole (w/o delta-xfer algorithm)
 --checksum-choice=STR    choose the checksum algorithm (aka --cc)
@@ -1473,6 +1474,14 @@ your home directory (remove the '=' for that).
     The `-D` option is equivalent to "[`--devices`](#opt)
     [`--specials`](#opt)".
 
+0.  `--copy-devices`
+
+    This tells rsync to treat a device on the sending side as a regular file,
+    allowing it to be copied to a normal destination file (or another device
+    if `--write-devices` was also specifed).
+
+    This option is refused by default by an rsync daemon.
+
 0.  `--write-devices`
 
     This tells rsync to treat a device on the receiving side as a regular file,
diff --git a/rsyncd.conf.5.md b/rsyncd.conf.5.md
index c386403b..c61765a7 100644
--- a/rsyncd.conf.5.md
+++ b/rsyncd.conf.5.md
@@ -933,9 +933,10 @@ the values of parameters.  See the GLOBAL PARAMETERS section for more details.
     If you are un-refusing the compress option, you may want to match
     "`!compress*`" if you also want to allow the `--compress-level` option.
 
-    Note that the "write-devices" option is refused by default, but can be
-    explicitly accepted with "`!write-devices`".  The options "log-file" and
-    "log-file-format" are forcibly refused and cannot be accepted.
+    Note that the "copy-devices" & "write-devices" options are refused by
+    default, but they can be explicitly accepted with "`!copy-devices`" and/or
+    "`!write-devices`".  The options "log-file" and "log-file-format" are
+    forcibly refused and cannot be accepted.
 
     Here are all the options that are not matched by wild-cards:
 
diff --git a/sender.c b/sender.c
index 92724c81..9159da4d 100644
--- a/sender.c
+++ b/sender.c
@@ -37,6 +37,7 @@ extern int io_error;
 extern int flist_eof;
 extern int whole_file;
 extern int allowed_lull;
+extern int copy_devices;
 extern int preserve_xattrs;
 extern int protocol_version;
 extern int remove_source_files;
@@ -366,6 +367,15 @@ void send_files(int f_in, int f_out)
 			exit_cleanup(RERR_FILEIO);
 		}
 
+		if (IS_DEVICE(st.st_mode)) {
+			if (!copy_devices) {
+				rprintf(FERROR, "attempt to copy device contents without --copy-devices\n");
+				exit_cleanup(RERR_PROTOCOL);
+			}
+			if (st.st_size == 0)
+				st.st_size = get_device_size(fd, fname);
+		}
+
 		if (append_mode > 0 && st.st_size < F_LENGTH(file)) {
 			rprintf(FWARNING, "skipped diminished file: %s\n",
 				full_fname(fname));