fusefrontend_reverse: use inomap for inode number translation

Gets rid of static inode number value limitations.

Fixes https://github.com/rfjakob/gocryptfs/issues/457

3 files changed, 30 insertions, 14 deletions

diff --git a/internal/inomap/inomap.go b/internal/inomap/inomap.go
index c277849..0ca43e4 100644
--- a/internal/inomap/inomap.go
+++ b/internal/inomap/inomap.go
@@ -15,6 +15,7 @@
 package inomap
 
 import (
+	"fmt"
 	"log"
 	"sync"
 	"syscall"
@@ -72,23 +73,30 @@ func (m *InoMap) spill(in QIno) (out uint64) {
 func (m *InoMap) Translate(in QIno) (out uint64) {
 	m.Lock()
 	defer m.Unlock()
+	defer func() {
+		fmt.Printf("Translate: %v -> %d\n", in, out)
+	}()
 
 	if in.Ino > maxPassthruIno {
-		return m.spill(in)
+		out = m.spill(in)
+		return out
 	}
 	ns, found := m.namespaceMap[in.namespaceData]
 	// Use existing namespace
 	if found {
-		return uint64(ns)<<48 | in.Ino
+		out = uint64(ns)<<48 | in.Ino
+		return out
 	}
 	// No free namespace slots?
 	if m.namespaceNext >= maxNamespaceId {
-		return m.spill(in)
+		out = m.spill(in)
+		return out
 	}
 	ns = m.namespaceNext
 	m.namespaceNext++
 	m.namespaceMap[in.namespaceData] = ns
-	return uint64(ns)<<48 | in.Ino
+	out = uint64(ns)<<48 | in.Ino
+	return out
 }
 
 // TranslateStat translates the inode number contained in "st" if neccessary.
diff --git a/internal/inomap/inomap_test.go b/internal/inomap/inomap_test.go
index 8efc960..78cb405 100644
--- a/internal/inomap/inomap_test.go
+++ b/internal/inomap/inomap_test.go
@@ -106,7 +106,7 @@ func TestUniqueness(t *testing.T) {
 	var q QIno
 	outMap := make(map[uint64]struct{})
 	for q.Dev = 0; q.Dev < 10; q.Dev++ {
-		for q.Flags = 0; q.Flags < 10; q.Flags++ {
+		for q.Tag = 0; q.Tag < 10; q.Tag++ {
 			// some go into spill
 			for q.Ino = maxPassthruIno - 100; q.Ino < maxPassthruIno+100; q.Ino++ {
 				out := m.Translate(q)
diff --git a/internal/inomap/qino.go b/internal/inomap/qino.go
index a74a96d..ed514e8 100644
--- a/internal/inomap/qino.go
+++ b/internal/inomap/qino.go
@@ -7,9 +7,11 @@ import (
 type namespaceData struct {
 	// Stat_t.Dev is uint64 on 32- and 64-bit Linux
 	Dev uint64
-	// Flags acts like an extension of the Dev field.
+	// Tag acts like an extension of the Dev field.
 	// It is used by reverse mode for virtual files.
-	Flags uint8
+	// Normal (forward) mode does not use it and it
+	// stays always zero there.
+	Tag uint8
 }
 
 // QIno = Qualified Inode number.
@@ -21,15 +23,21 @@ type QIno struct {
 	Ino uint64
 }
 
-// QInoFromStat fills a new QIno struct with the passed Stat_t info.
-func QInoFromStat(st *syscall.Stat_t) QIno {
+// NewQIno returns a filled QIno struct
+func NewQIno(dev uint64, tag uint8, ino uint64) QIno {
 	return QIno{
 		namespaceData: namespaceData{
-			// There are some architectures that use 32-bit values here
-			// (darwin, freebsd-32, maybe others). Add an explicit cast to make
-			// this function work everywhere.
-			Dev: uint64(st.Dev),
+			Dev: dev,
+			Tag: tag,
 		},
-		Ino: uint64(st.Ino),
+		Ino: ino,
 	}
 }
+
+// QInoFromStat fills a new QIno struct with the passed Stat_t info.
+func QInoFromStat(st *syscall.Stat_t) QIno {
+	// There are some architectures that use 32-bit values here
+	// (darwin, freebsd-32, maybe others). Add an explicit cast to make
+	// this function work everywhere.
+	return NewQIno(uint64(st.Dev), 0, uint64(st.Ino))
+}