F2FS atomic writes. (#66)

https://sqlite.org/cgi/src/technote/714f6cbbf7

.github/workflows/bsd.sh

@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+set -euo pipefail
 
 echo 'set -euo pipefail' > test.sh
 

.github/workflows/repro.sh

@@ -13,7 +13,7 @@ elif [[ "$OSTYPE" == "msys" || "$OSTYPE" == "cygwin" ]]; then
 fi
 
 # Download tools
-mkdir -p tools
+mkdir -p tools/
 [ -d "tools/wasi-sdk"* ]         || curl -#L "$WASI_SDK" | tar xzC tools &
 [ -d "tools/binaryen-version"* ] || curl -#L "$BINARYEN" | tar xzC tools &
 wait

sqlite.go

@@ -99,8 +99,8 @@ func instantiateSQLite() (sqlt *sqlite, err error) {
 	}
 
 	sqlt.freer = util.ReadUint32(sqlt.mod, uint32(global.Get()))
-	if err != nil {
-		return nil, err
+	if sqlt.freer == 0 {
+		return nil, util.BadBinaryErr
 	}
 	return sqlt, nil
 }

tests/testdata/f2fs.sh

@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+cd -P -- "$(dirname -- "$0")"
+ROOT=../../
+
+if mountpoint -q f2fs/; then
+  sudo umount f2fs/
+fi
+
+mkdir -p f2fs/
+gunzip -c f2fs.img.gz > f2fs.img
+sudo mount -nv -o loop f2fs.img f2fs/
+mkdir -p f2fs/tmp/
+
+go test -c "$ROOT/tests" -coverpkg github.com/ncruces/go-sqlite3/...
+TMPDIR=f2fs/tmp/ ./tests.test -test.v -test.short -test.coverprofile cover.out
+go tool cover -html cover.out
+
+sudo umount f2fs/
+rm -r f2fs/ f2fs.img cover.out *.test

vfs/file.go

@@ -173,10 +173,14 @@ func (*vfsFile) SectorSize() int {
 }
 
 func (f *vfsFile) DeviceCharacteristics() DeviceCharacteristic {
-	if f.psow {
-		return IOCAP_POWERSAFE_OVERWRITE
+	var res DeviceCharacteristic
+	if osBatchAtomic(f.File) {
+		res |= IOCAP_BATCH_ATOMIC
 	}
-	return 0
+	if f.psow {
+		res |= IOCAP_POWERSAFE_OVERWRITE
+	}
+	return res
 }
 
 func (f *vfsFile) SizeHint(size int64) error {

vfs/os_f2fs_linux.go

@@ -0,0 +1,34 @@
+//go:build (amd64 || arm64) && !sqlite3_nosys
+
+package vfs
+
+import (
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+const (
+	_F2FS_IOC_START_ATOMIC_WRITE  = 62721
+	_F2FS_IOC_COMMIT_ATOMIC_WRITE = 62722
+	_F2FS_IOC_ABORT_ATOMIC_WRITE  = 62725
+	_F2FS_IOC_GET_FEATURES        = 2147808524
+	_F2FS_FEATURE_ATOMIC_WRITE    = 4
+)
+
+func osBatchAtomic(file *os.File) bool {
+	flags, err := unix.IoctlGetInt(int(file.Fd()), _F2FS_IOC_GET_FEATURES)
+	return err == nil && flags&_F2FS_FEATURE_ATOMIC_WRITE != 0
+}
+
+func (f *vfsFile) BeginAtomicWrite() error {
+	return unix.IoctlSetInt(int(f.Fd()), _F2FS_IOC_START_ATOMIC_WRITE, 0)
+}
+
+func (f *vfsFile) CommitAtomicWrite() error {
+	return unix.IoctlSetInt(int(f.Fd()), _F2FS_IOC_COMMIT_ATOMIC_WRITE, 0)
+}
+
+func (f *vfsFile) RollbackAtomicWrite() error {
+	return unix.IoctlSetInt(int(f.Fd()), _F2FS_IOC_ABORT_ATOMIC_WRITE, 0)
+}

vfs/os_std_atomic.go

@@ -0,0 +1,9 @@
+//go:build !linux || !(amd64 || arm64) || sqlite3_nosys
+
+package vfs
+
+import "os"
+
+func osBatchAtomic(*os.File) bool {
+	return false
+}