import-tar/export-tar: add xattr support for PAX format, borgbackup#2521

src/borg/archive.py

@@ -1487,6 +1487,17 @@ def s_to_ns(s):
                     if name in ph:
                         ns = s_to_ns(ph[name])
                         setattr(item, name, ns)
+                xattrs = StableDict()
+                for key, value in ph.items():
+                    if key.startswith(SCHILY_XATTR):
+                        key = key.removeprefix(SCHILY_XATTR)
+                        # the tarfile code gives us str keys and str values,
+                        # but we need bytes keys and bytes values.
+                        bkey = key.encode("utf-8", errors="surrogateescape")
+                        bvalue = value.encode("utf-8", errors="surrogateescape")
+                        xattrs[bkey] = bvalue
+                if xattrs:
+                    item.xattrs = xattrs
         yield item, status
         # if we get here, "with"-block worked ok without error/exception, the item was processed ok...
         self.add_item(item, stats=self.stats)

src/borg/archiver/tar_cmds.py

@@ -211,6 +211,13 @@ def item_to_paxheaders(format, item):
                 if hasattr(item, name):
                     ns = getattr(item, name)
                     ph[name] = str(ns / 1e9)
+            if hasattr(item, "xattrs"):
+                for bkey, bvalue in item.xattrs.items():
+                    # we have bytes key and bytes value, but the tarfile code
+                    # expects str key and str value.
+                    key = SCHILY_XATTR + bkey.decode("utf-8", errors="surrogateescape")
+                    value = bvalue.decode("utf-8", errors="surrogateescape")
+                    ph[key] = value
             if format == "BORG":  # BORG format additions
                 ph["BORG.item.version"] = "1"
                 # BORG.item.meta - just serialize all metadata we have:
@@ -355,6 +362,7 @@ def build_parser_tar(self, subparsers, common_parser, mid_common_parser):
         | BORG         | BORG specific, like PAX   | all as supported by borg   |
         +--------------+---------------------------+----------------------------+
         | PAX          | POSIX.1-2001 (pax) format | GNU + atime/ctime/mtime ns |
+        |              |                           | + xattrs                   |
         +--------------+---------------------------+----------------------------+
         | GNU          | GNU tar format            | mtime s, no atime/ctime,   |
         |              |                           | no ACLs/xattrs/bsdflags    |

src/borg/constants.py

@@ -121,6 +121,9 @@
 # similar to above, but for bigger granularity / clock differences
 TIME_DIFFERS2_NS = 3000000000
 
+# tar related
+SCHILY_XATTR = "SCHILY.xattr."  # xattr key prefix in tar PAX headers
+
 # return codes returned by borg command
 EXIT_SUCCESS = 0  # everything done, no problems
 EXIT_WARNING = 1  # reached normal end of operation, but there were issues (generic warning)