update go-sqlite3 => v0.20.0 (#3483)

vendor/github.com/ncruces/go-sqlite3/vfs/cksm.go

@@ -0,0 +1,149 @@
+package vfs
+
+import (
+	"bytes"
+	"context"
+	_ "embed"
+	"encoding/binary"
+	"strconv"
+
+	"github.com/tetratelabs/wazero/api"
+
+	"github.com/ncruces/go-sqlite3/internal/util"
+	"github.com/ncruces/go-sqlite3/util/sql3util"
+)
+
+func cksmWrapFile(name *Filename, flags OpenFlag, file File) File {
+	// Checksum only main databases and WALs.
+	if flags&(OPEN_MAIN_DB|OPEN_WAL) == 0 {
+		return file
+	}
+
+	cksm := cksmFile{File: file}
+
+	if flags&OPEN_WAL != 0 {
+		main, _ := name.DatabaseFile().(cksmFile)
+		cksm.cksmFlags = main.cksmFlags
+	} else {
+		cksm.cksmFlags = new(cksmFlags)
+		cksm.isDB = true
+	}
+
+	return cksm
+}
+
+type cksmFile struct {
+	File
+	*cksmFlags
+	isDB bool
+}
+
+type cksmFlags struct {
+	computeCksm bool
+	verifyCksm  bool
+	inCkpt      bool
+	pageSize    int
+}
+
+func (c cksmFile) ReadAt(p []byte, off int64) (n int, err error) {
+	n, err = c.File.ReadAt(p, off)
+
+	// SQLite is reading the header of a database file.
+	if c.isDB && off == 0 && len(p) >= 100 &&
+		bytes.HasPrefix(p, []byte("SQLite format 3\000")) {
+		c.init(p)
+	}
+
+	// Verify checksums.
+	if c.verifyCksm && !c.inCkpt && len(p) == c.pageSize {
+		cksm1 := cksmCompute(p[:len(p)-8])
+		cksm2 := *(*[8]byte)(p[len(p)-8:])
+		if cksm1 != cksm2 {
+			return 0, _IOERR_DATA
+		}
+	}
+	return n, err
+}
+
+func (c cksmFile) WriteAt(p []byte, off int64) (n int, err error) {
+	// SQLite is writing the first page of a database file.
+	if c.isDB && off == 0 && len(p) >= 100 &&
+		bytes.HasPrefix(p, []byte("SQLite format 3\000")) {
+		c.init(p)
+	}
+
+	// Compute checksums.
+	if c.computeCksm && !c.inCkpt && len(p) == c.pageSize {
+		*(*[8]byte)(p[len(p)-8:]) = cksmCompute(p[:len(p)-8])
+	}
+
+	return c.File.WriteAt(p, off)
+}
+
+func (c cksmFile) Pragma(name string, value string) (string, error) {
+	switch name {
+	case "checksum_verification":
+		b, ok := sql3util.ParseBool(value)
+		if ok {
+			c.verifyCksm = b && c.computeCksm
+		}
+		if !c.verifyCksm {
+			return "0", nil
+		}
+		return "1", nil
+
+	case "page_size":
+		if c.computeCksm {
+			// Do not allow page size changes on a checksum database.
+			return strconv.Itoa(c.pageSize), nil
+		}
+	}
+	return "", _NOTFOUND
+}
+
+func (c cksmFile) fileControl(ctx context.Context, mod api.Module, op _FcntlOpcode, pArg uint32) _ErrorCode {
+	switch op {
+	case _FCNTL_CKPT_START:
+		c.inCkpt = true
+	case _FCNTL_CKPT_DONE:
+		c.inCkpt = false
+	}
+	if rc := vfsFileControlImpl(ctx, mod, c, op, pArg); rc != _NOTFOUND {
+		return rc
+	}
+	return vfsFileControlImpl(ctx, mod, c.File, op, pArg)
+}
+
+func (f *cksmFlags) init(header []byte) {
+	f.pageSize = 256 * int(binary.LittleEndian.Uint16(header[16:18]))
+	if r := header[20] == 8; r != f.computeCksm {
+		f.computeCksm = r
+		f.verifyCksm = r
+	}
+}
+
+func cksmCompute(a []byte) (cksm [8]byte) {
+	var s1, s2 uint32
+	for len(a) >= 8 {
+		s1 += binary.LittleEndian.Uint32(a[0:4]) + s2
+		s2 += binary.LittleEndian.Uint32(a[4:8]) + s1
+		a = a[8:]
+	}
+	if len(a) != 0 {
+		panic(util.AssertErr())
+	}
+	binary.LittleEndian.PutUint32(cksm[0:4], s1)
+	binary.LittleEndian.PutUint32(cksm[4:8], s2)
+	return
+}
+
+func (c cksmFile) SharedMemory() SharedMemory {
+	if f, ok := c.File.(FileSharedMemory); ok {
+		return f.SharedMemory()
+	}
+	return nil
+}
+
+func (c cksmFile) Unwrap() File {
+	return c.File
+}