From: Daan De Meyer <daan.j.demeyer@gmail.com>
Date: Thu, 10 Apr 2025 19:30:25 +0000 (+0200)
Subject: Take shared lock in copy_ephemeral()
X-Git-Tag: v26~249
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8235ddbc5baf83f27f6b6f6ab338ef6dbb524c01;p=thirdparty%2Fmkosi.git

Take shared lock in copy_ephemeral()

We don't need an exclusive lock to make this copy, so let's take only
a shared lock.
---

diff --git a/mkosi/qemu.py b/mkosi/qemu.py
index f138eca8a..3961bc849 100644
--- a/mkosi/qemu.py
+++ b/mkosi/qemu.py
@@ -615,7 +615,7 @@ def copy_ephemeral(config: Config, src: Path) -> Iterator[Path]:
                 sandbox=config.sandbox,
             )
 
-        with flock(src):
+        with flock(src, flags=fcntl.LOCK_SH):
             fork_and_wait(copy)
         yield tmp
     finally:
diff --git a/mkosi/util.py b/mkosi/util.py
index fe8c8006e..81710924f 100644
--- a/mkosi/util.py
+++ b/mkosi/util.py
@@ -139,9 +139,9 @@ def flock(path: Path, flags: int = fcntl.LOCK_EX) -> Iterator[int]:
 
 
 @contextlib.contextmanager
-def flock_or_die(path: Path) -> Iterator[Path]:
+def flock_or_die(path: Path, flags: int = fcntl.LOCK_EX) -> Iterator[Path]:
     try:
-        with flock(path, fcntl.LOCK_EX | fcntl.LOCK_NB):
+        with flock(path, flags | fcntl.LOCK_NB):
             yield path
     except OSError as e:
         if e.errno != errno.EWOULDBLOCK: