From 9b6e47fc0a2ed65d462424152a13f995a8d7dd9a Mon Sep 17 00:00:00 2001
From: Jakob Unterwurzacher
Date: Tue, 6 May 2025 09:11:49 +0200
Subject: Switch to the new atomic Uint64.Add api

The new api guarantees that the value is aligned, preventing
stuff like this on 32 bit platforms:

	goroutine 26 [running]:
	internal/runtime/atomic.panicUnaligned()
		/usr/lib/go-1.24/src/internal/runtime/atomic/unaligned.go:8 +0x24
	internal/runtime/atomic.Xadd64(0x2496c74, 0x1)
		/usr/lib/go-1.24/src/internal/runtime/atomic/atomic_arm.s:318 +0x14
	github.com/rfjakob/gocryptfs/internal/inomap.(*InoMap).NextSpillIno(0x2496c60)

Fixes https://github.com/rfjakob/gocryptfs/issues/912
---
 internal/inomap/inomap.go | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

(limited to 'internal/inomap/inomap.go')

diff --git a/internal/inomap/inomap.go b/internal/inomap/inomap.go
index b4dbf27..5749202 100644
--- a/internal/inomap/inomap.go
+++ b/internal/inomap/inomap.go
@@ -45,7 +45,7 @@ type InoMap struct {
 	// spill is used once the namespaces map is full
 	spillMap map[QIno]uint64
 	// spillNext is the next free inode number in the spill map
-	spillNext uint64
+	spillNext atomic.Uint64
 }
 
 // New returns a new InoMap.
@@ -57,8 +57,9 @@ func New(rootDev uint64) *InoMap {
 		namespaceMap:  make(map[namespaceData]uint16),
 		namespaceNext: 0,
 		spillMap:      make(map[QIno]uint64),
-		spillNext:     spillSpaceStart,
 	}
+	m.spillNext.Store(spillSpaceStart)
+
 	if rootDev > 0 {
 		// Reserve namespace 0 for rootDev
 		m.namespaceMap[namespaceData{rootDev, 0}] = 0
@@ -74,10 +75,10 @@ var spillWarn sync.Once
 // Reverse mode NextSpillIno() for gocryptfs.longname.*.name files where a stable
 // mapping is not needed.
 func (m *InoMap) NextSpillIno() (out uint64) {
-	if m.spillNext == math.MaxUint64 {
-		log.Panicf("spillMap overflow: spillNext = 0x%x", m.spillNext)
+	if m.spillNext.Load() == math.MaxUint64 {
+		log.Panicf("spillMap overflow: spillNext = 0x%x", m.spillNext.Load())
 	}
-	return atomic.AddUint64(&m.spillNext, 1) - 1
+	return m.spillNext.Add(1) - 1
 }
 
 func (m *InoMap) spill(in QIno) (out uint64) {
-- 
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