u2c: fix exfat's http502 allergy;

addendum to 23e00c0a04

bin/u2c.py

@@ -1,8 +1,8 @@
 #!/usr/bin/env python3
 from __future__ import division, print_function, unicode_literals
 
-S_VERSION = "2.23"
-S_BUILD_DT = "2026-09-06"
+S_VERSION = "2.24"
+S_BUILD_DT = "2026-09-26"
 
 """
 u2c.py: upload to copyparty
@@ -267,6 +267,7 @@ class File(object):
         self.wark = ""  # type: str
         self.url = ""  # type: str
         self.nhs = 0  # type: int
+        self.t_hs = 0.0  # type: float
 
         # set by upload
         self.t0_up = 0.0  # type: float
@@ -904,6 +905,7 @@ def handshake(ar, file, search):
     file.url = quotep(r["purl"].encode("utf-8", WTF8)).decode("utf-8")
     file.name = r["name"]
     file.wark = r["wark"]
+    file.t_hs = time.time()
 
     if ar.uon and not r["hash"]:
         printlink(ar, file.url, r["name"], r.get("fk"))
@@ -1027,7 +1029,7 @@ class Ctl(object):
             self.up_b = 0  # num bytes handled
             self.up_br = 0  # num bytes actually transferred
             self.uploader_busy = 0
-            self.serialized = False
+            self.oneconn = False
 
             self.t0 = time.time()
             self.t0_up = None
@@ -1403,10 +1405,10 @@ class Ctl(object):
                 self.recheck.append(file)
 
             with self.mutex:
-                if hs and not sprs and not self.serialized:
-                    t = "server filesystem does not support sparse files; serializing uploads\n"
+                if hs and not sprs and not self.oneconn:
+                    t = "server filesystem does not support sparse files; cannot parallelize uploads\n"
                     eprint(t)
-                    self.serialized = True
+                    self.oneconn = True
                     for _ in range(self.ar.j - 1):
                         self.q_upload.put(None)
                 if not hs:
@@ -1418,7 +1420,7 @@ class Ctl(object):
                     if not file.recheck:
                         self.up_done(file)
 
-                if hs and file.up_c:
+                if hs and file.up_c and not self.oneconn:
                     # some chunks failed
                     self.up_c -= len(hs)
                     file.up_c -= len(hs)
@@ -1476,6 +1478,7 @@ class Ctl(object):
                 self.q_upload.put(fsl)
 
     def uploader(self):
+        drop_hs = (0.0, "")
         while True:
             fsl = self.q_upload.get()
             if not fsl:
@@ -1494,6 +1497,9 @@ class Ctl(object):
             cids = fsl.cids
             self.last_file = file
 
+            if self.oneconn and drop_hs == (file.t_hs, file.wark):
+                continue
+
             with self.mutex:
                 if not self.uploader_busy:
                     self.at_upr = time.time()
@@ -1519,6 +1525,9 @@ class Ctl(object):
                 t = "upload failed, retrying: %s #%s+%d (%s)\n"
                 eprint(t % (file.name, cids[0][:8], len(cids) - 1, ex))
                 file.cd = time.time() + self.ar.cd
+                if self.oneconn:
+                    file.ucids = []
+                    drop_hs = (file.t_hs, file.wark)
                 # handshake will fix it
 
             with self.mutex: