.

wcfs/__init__.py

@@ -104,9 +104,9 @@ class Conn(object):
 class _File(object):
     # .wconn        Conn
     # .foid         hex of ZBigFile root object ID
-    # .size     size of this file
     # .blksize      block size of this file
     # .headf        file object of head/file
+    # .headfsize    head/file size is known to be at least headfsize (size ↑=)
     # .pinned       {} blk -> rev   that wcfs already sent us for this file
     # .mmaps        []_Mapping ↑blk_start    mappings of this file
     pass
@@ -250,7 +250,7 @@ def resync(wconn, at):
     # XXX locking
 
     for foid in wconn._filetab:
-        # XXX if file was has no mappings and was not used during whole prev
+        # XXX if file has no mappings and was not used during whole prev
         # cycle - forget and stop watching it
         _ = wconn._wlink.sendReq(context.background(), b"watch %s @%s" % (h(foid), h(at)))
         if _ != "ok":
@@ -258,6 +258,9 @@ def resync(wconn, at):
             # XXX vvv -> errctx?
             raise RuntimeError("resync @%s -> @%s: f<%s>: %s" % (h(wconn.at), h(at), h(foid), _))
 
+        # XXX update f.headfsize
+        # XXX remmap appended data after old f.headfsize
+
     wconn.at = at
 
 
@@ -277,8 +280,8 @@ def mmap(wconn, foid, blk_start, blk_len): # -> Mapping
             f.mmaps     = []
 
             _ = os.fstat(f.headf.fileno())
-            f.size      = _.st_size
             f.blksize   = _.st_blksize
+            f.headfsize = _.st_size
 
             wconn._filetab[foid] = f
 
@@ -295,7 +298,7 @@ def mmap(wconn, foid, blk_start, blk_len): # -> Mapping
         # mmap-in zeros after f.size (else access to memory after file.size will raise SIGBUS)
         start = blk_start*f.blksize
         mem = mm.map_ro(f.headf.fileno(), start, blk_len*f.blksize)
-        zmemtail = mem[max(f.size, start) - start:]
+        zmemtail = mem[max(f.headfsize, start) - start:]
         if len(zmemtail) != 0:
             mm.map_zero_into_ro(zmemtail)
         mmap = _Mapping()