From 801893cc732246bb9ef837ae81db35a7856abc3d Mon Sep 17 00:00:00 2001
From: Nicolas Sebrecht <nicolas.s-dev@laposte.net>
Date: Sat, 27 Apr 2019 14:51:41 +0200
Subject: [PATCH] make portalocker really optional

Signed-off-by: Nicolas Sebrecht <nicolas.s-dev@laposte.net>
---
 README.md               |  2 +-
 offlineimap/accounts.py | 17 +++++++++++++----
 requirements.txt        |  2 +-
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/README.md b/README.md
index 03ad084..cd5d2fc 100644
--- a/README.md
+++ b/README.md
@@ -105,7 +105,7 @@ Bugs, issues and contributions can be requested to both the mailing list or the
 * six (required)
 * imaplib2 >= 2.57 (optional)
 * gssapi (optional), for Kerberos authentication
-* portalocker(optional), if you need to run offlineimap in Cygwin for Windows
+* portalocker (optional), if you need to run offlineimap in Cygwin for Windows
 
 ## Documentation
 
diff --git a/offlineimap/accounts.py b/offlineimap/accounts.py
index 644d03d..9d49546 100644
--- a/offlineimap/accounts.py
+++ b/offlineimap/accounts.py
@@ -36,7 +36,10 @@ SYNC_MUTEXES_LOCK = Lock()
 try:
     import portalocker
 except:
-    pass # Ok if this fails, we can do without.
+    try:
+        import fcntl
+    except:
+        pass # Ok if this fails, we can do without.
 
 # FIXME: spaghetti code alert!
 def getaccountlist(customconfig):
@@ -234,8 +237,11 @@ class SyncableAccount(Account):
         try:
             portalocker.lock(self._lockfd, portalocker.LOCK_EX)
         except NameError:
-            #fcntl not available (Windows), disable file locking... :(
-            pass
+            # portalocker not available for Windows.
+            try:
+                fcntl.lockf(self._lockfd, fcntl.LOCK_EX|fcntl.LOCK_NB)
+            except NameError:
+                pass # fnctl not available, disable file locking... :(
         except IOError:
             self._lockfd.close()
             six.reraise(OfflineImapError,
@@ -250,7 +256,10 @@ class SyncableAccount(Account):
 
         #If we own the lock file, delete it
         if self._lockfd and not self._lockfd.closed:
-            portalocker.unlock(self._lockfd)
+            try:
+                portalocker.unlock(self._lockfd)
+            except NameError:
+                pass
             self._lockfd.close()
             try:
                 os.unlink(self._lockfilepath)
diff --git a/requirements.txt b/requirements.txt
index f4527a3..3b1819e 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
 # Requirements
 six
 gssapi[kerberos]
-portalocker
+portalocker[cygwin]