From e56c2e44cc4dd1484cae78956f8ff72a9eea42f2 Mon Sep 17 00:00:00 2001
From: Jakob Unterwurzacher
Date: Fri, 2 Jun 2023 14:24:44 +0200
Subject: fusefrontend: sharedstorage: use byte-range lock on file header
 creation

Multiple host writing to the same empty file at the same time
could have overwritten each other's newly created file header,
leading to data corruption.

Fix the race by placing a byte-range lock on the file when
creating the file header.
---
 internal/syscallcompat/sys_darwin.go | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'internal/syscallcompat/sys_darwin.go')

diff --git a/internal/syscallcompat/sys_darwin.go b/internal/syscallcompat/sys_darwin.go
index 52d4e0f..17e6a9e 100644
--- a/internal/syscallcompat/sys_darwin.go
+++ b/internal/syscallcompat/sys_darwin.go
@@ -33,6 +33,10 @@ const (
 	// On Darwin we use O_SYMLINK which allows opening a symlink itself.
 	// On Linux, we only have O_NOFOLLOW.
 	OpenatFlagNofollowSymlink = unix.O_SYMLINK
+
+	// F_OFD_SETLKW only exists on Linux. On Darwin, fall back to F_SETLKW as a
+	// flawed replacement.
+	F_OFD_SETLKW = unix.F_SETLKW
 )
 
 // Unfortunately fsetattrlist does not have a syscall wrapper yet.
-- 
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