WIP Add checksum VFS shim as an opt-in feature

error.go

@@ -121,6 +121,7 @@ var (
 	ErrIoErrMMap              = ErrIoErr.Extend(24)
 	ErrIoErrGetTempPath       = ErrIoErr.Extend(25)
 	ErrIoErrConvPath          = ErrIoErr.Extend(26)
+	ErrIoErrData              = ErrIoErr.Extend(32)
 	ErrLockedSharedCache      = ErrLocked.Extend(1)
 	ErrBusyRecovery           = ErrBusy.Extend(1)
 	ErrBusySnapshot           = ErrBusy.Extend(2)

sqlite3.go

@@ -20,6 +20,7 @@ package sqlite3
 #cgo CFLAGS: -DSQLITE_OMIT_DEPRECATED
 #cgo CFLAGS: -DSQLITE_DEFAULT_WAL_SYNCHRONOUS=1
 #cgo CFLAGS: -DSQLITE_ENABLE_UPDATE_DELETE_LIMIT
+#cgo CFLAGS: -DSQLITE_CKSUMVFS_STATIC
 #cgo CFLAGS: -Wno-deprecated-declarations
 #cgo openbsd CFLAGS: -I/usr/local/include
 #cgo openbsd LDFLAGS: -L/usr/local/lib

sqlite3_opt_cksumvfs.go

@@ -0,0 +1,11 @@
+//go:build cksumvfs
+// +build cksumvfs
+
+package sqlite3
+
+//extern int sqlite3_register_cksumvfs(const char*);
+import "C"
+
+func InitCksumVFS() {
+	C.sqlite3_register_cksumvfs(nil)
+}

sqlite3_opt_cksumvfs_test.go

@@ -0,0 +1,96 @@
+//go:build cksumvfs
+// +build cksumvfs
+
+package sqlite3
+
+import (
+	"testing"
+	"os"
+	"database/sql"
+	"io/ioutil"
+	"bytes"
+	"errors"
+)
+
+func TestCksumVfs(t *testing.T) {
+	tempFilename := TempFilename(t)
+	defer os.Remove(tempFilename)
+
+	sql.Register("sqlite3_with_reserved_bytes", &SQLiteDriver{
+		ConnectHook: func(conn *SQLiteConn) error {
+			return conn.SetFileControlInt("", SQLITE_FCNTL_RESERVE_BYTES, 8)
+		},
+	})
+
+	db, err := sql.Open("sqlite3_with_reserved_bytes", tempFilename)
+	if err != nil {
+		t.Fatal("Failed to open database:", err)
+	}
+
+	InitCksumVFS()
+
+	_, err = db.Exec(`create table foo (v string)`)
+	if err != nil {
+		t.Fatal("Failed to create table:", err)
+	}
+
+	stmt, err := db.Prepare("insert into foo(v) values(?)")
+	if err != nil {
+		t.Fatal("Failed to prepare insert:", err)
+	}
+
+	for _, v := range []string{"this-is-the-target-string", "foo", "bar", "baz"} {
+		_, err = stmt.Exec(v)
+		if err != nil {
+			t.Fatal("Failed to insert value:", err)
+		}
+	}
+
+	stmt.Close()
+	db.Close()
+
+	// Corrupt the file by replacing one of the column's values
+	data, err := ioutil.ReadFile(tempFilename)
+	if err != nil {
+		t.Fatal("Failed to read database file as bytes:", err)
+	}
+
+	newData := bytes.Replace(data, []byte("this-is-the-target-string"), []byte("This-is-the-target-string"), 1)
+	if err := ioutil.WriteFile(tempFilename, newData, 0); err != nil {
+		t.Fatal("Failed to write database file as new bytes:", err)
+	}
+
+	db, err = sql.Open("sqlite3_with_reserved_bytes", tempFilename)
+	if err != nil {
+		t.Fatal("Failed to open database:", err)
+	}
+
+	InitCksumVFS()
+
+	rows, err := db.Query("SELECT * FROM foo")
+	if err != nil {
+		t.Fatal("Failed to query database:", err)
+	}
+
+	for rows.Next() {
+		var s string
+		if err := rows.Scan(&s); err != nil {
+			t.Fatal("Failed to scan row:", err)
+		}
+	}
+
+	if err := rows.Close(); err != nil {
+		t.Fatal("Failed to close rows:", err)
+	}
+
+	err = rows.Err()
+
+	var sqliteErr Error
+	if !errors.As(err, &sqliteErr) {
+		t.Fatal("Failed to get close error as SQLite error:", err)
+	}
+
+	if sqliteErr.ExtendedCode != ErrIoErrData {
+		t.Fatal("Expected extended error of ERR_IO_ERR_DATA, but got:", int(sqliteErr.ExtendedCode))
+	}
+}

upgrade/upgrade.go

@@ -15,12 +15,15 @@ import (
 	"os"
 	"path"
 	"path/filepath"
+	"regexp"
 	"strings"
 	"time"
 
 	"github.com/PuerkitoBio/goquery"
 )
 
+var includeRE = regexp.MustCompile(`^\s*#\s*include\s+"sqlite3.h"\s*$`)
+
 func download(prefix string) (url string, content []byte, err error) {
 	year := time.Now().Year()
 
@@ -76,20 +79,32 @@ func mergeFile(src string, dst string) error {
 	}
 	defer fdst.Close()
 
-	// Read source content
-	content, err := ioutil.ReadFile(src)
-	if err != nil {
+	// Add Additional newline
+	if _, err := fdst.WriteString("\n"); err != nil {
 		return err
 	}
 
-	// Add Additional newline
-	if _, err := fdst.WriteString("\n"); err != nil {
+	fsrc, err := os.OpenFile(src, os.O_RDONLY, 0)
+	if err != nil {
 		return err
 	}
+	defer fsrc.Close()
 
 	fmt.Printf("Merging: %s into %s\n", src, dst)
-	if _, err = fdst.Write(content); err != nil {
-		return err
+	scanner := bufio.NewScanner(fsrc)
+	for scanner.Scan() {
+		text := scanner.Text()
+		if includeRE.Match([]byte(text)) {
+			text = `#include "sqlite3-binding.h"`
+		}
+		_, err = fmt.Fprintln(fdst, text)
+		if err != nil {
+			break
+		}
+	}
+	err = scanner.Err()
+	if err != nil {
+		log.Fatal(err)
 	}
 
 	return nil
@@ -198,6 +213,8 @@ func main() {
 			f, err = os.Create("../userauth.c")
 		case "sqlite3userauth.h":
 			f, err = os.Create("../userauth.h")
+		case "cksumvfs.c":
+			f, err = os.Create("../cksumvfs.c")
 		default:
 			continue
 		}
@@ -226,6 +243,9 @@ func main() {
 	if err := mergeFile("../userauth.h", "../sqlite3-binding.h"); err != nil {
 		log.Fatal(err)
 	}
+	if err := mergeFile("../cksumvfs.c", "../sqlite3-binding.c"); err != nil {
+		log.Fatal(err)
+	}
 
 	os.Exit(0)
 }