From 10381074b26da703a4330272166c81984e66dd0d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Carlos=20Venegas=20Arrab=C3=A9?= <carlos@magnitude.es>
Date: Thu, 30 Jul 2026 16:19:34 +0200
Subject: [PATCH] util: make OpenSafeFile work without fcntl (Windows)
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prjxray/util.py imported fcntl at module level, so merely importing
prjxray (e.g. from fasm2frames) failed on Windows, where fcntl does
not exist. The only user is OpenSafeFile's advisory flock, whose
timeout also relies on SIGALRM — equally POSIX-only.

Guard the import and skip the locking when fcntl is unavailable:
OpenSafeFile degrades to a plain open on Windows, while POSIX
behaviour is unchanged.
---
 prjxray/util.py | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/prjxray/util.py b/prjxray/util.py
index 615bf726..1fc1ac04 100644
--- a/prjxray/util.py
+++ b/prjxray/util.py
@@ -8,7 +8,12 @@
 # https://opensource.org/licenses/ISC
 #
 # SPDX-License-Identifier: ISC
-import fcntl
+try:
+    import fcntl
+except ImportError:
+    # Windows: no fcntl (and no SIGALRM); OpenSafeFile degrades to a plain
+    # open without inter-process locking.
+    fcntl = None
 import math
 import os
 import random
@@ -47,6 +52,8 @@ class OpenSafeFile:
 
     def lock_file(self):
         assert self.fd is not None
+        if fcntl is None:
+            return
         try:
             signal.signal(signal.SIGALRM, timeout_handler)
             signal.alarm(self.timeout)
@@ -58,6 +65,8 @@ class OpenSafeFile:
 
     def unlock_file(self):
         assert self.fd is not None
+        if fcntl is None:
+            return
         fcntl.flock(self.fd.fileno(), fcntl.LOCK_UN)