Fix golangci-lint issues

cmd/litestream/main.go

@@ -96,6 +96,7 @@ func (m *Main) Run(ctx context.Context, args []string) (err error) {
 
 		// Setup signal handler.
 		ctx, cancel := context.WithCancel(ctx)
+		defer cancel()
 		signalCh := make(chan os.Signal, 1)
 		signal.Notify(signalCh, notifySignals...)
 

cmd/litestream/restore.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"context"
-	"errors"
 	"flag"
 	"fmt"
 	"io"
@@ -276,5 +275,3 @@ Examples:
 		DefaultConfigPath(),
 	)
 }
-
-var errSkipDBExists = errors.New("database already exists, skipping")

db.go

@@ -12,13 +12,10 @@ import (
 	"io"
 	"io/ioutil"
 	"log"
-	"math"
 	"math/rand"
 	"os"
 	"path/filepath"
-	"regexp"
 	"sort"
-	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -429,7 +426,9 @@ func (db *DB) Close() (err error) {
 				err = e
 			}
 		}
-		r.Stop(true)
+		if e := r.Stop(true); e != nil && err == nil {
+			err = e
+		}
 	}
 
 	// Release the read lock to allow other applications to handle checkpointing.
@@ -1142,11 +1141,11 @@ func (db *DB) copyToShadowWAL(ctx context.Context) error {
 	go func() {
 		zw := lz4.NewWriter(pw)
 		if _, err := io.Copy(zw, &io.LimitedReader{R: f, N: walByteN}); err != nil {
-			pw.CloseWithError(err)
+			_ = pw.CloseWithError(err)
 		} else if err := zw.Close(); err != nil {
-			pw.CloseWithError(err)
+			_ = pw.CloseWithError(err)
 		}
-		pw.Close()
+		_ = pw.Close()
 	}()
 
 	// Write a new, compressed segment via pipe.
@@ -1336,47 +1335,12 @@ func (itr *shadowWALSegmentIterator) WALSegment() WALSegmentInfo {
 	return itr.infos[0]
 }
 
-// frameAlign returns a frame-aligned offset.
-// Returns zero if offset is less than the WAL header size.
-func frameAlign(offset int64, pageSize int) int64 {
-	assert(offset >= 0, "frameAlign(): offset must be non-negative")
-	assert(pageSize >= 0, "frameAlign(): page size must be non-negative")
-
-	if offset < WALHeaderSize {
-		return 0
-	}
-
-	frameSize := WALFrameHeaderSize + int64(pageSize)
-	frameN := (offset - WALHeaderSize) / frameSize
-	return (frameN * frameSize) + WALHeaderSize
-}
-
 // SQLite WAL constants
 const (
 	WALHeaderChecksumOffset      = 24
 	WALFrameHeaderChecksumOffset = 16
 )
 
-func readLastChecksumFrom(f *os.File, pageSize int) (uint32, uint32, error) {
-	// Determine the byte offset of the checksum for the header (if no pages
-	// exist) or for the last page (if at least one page exists).
-	offset := int64(WALHeaderChecksumOffset)
-	if fi, err := f.Stat(); err != nil {
-		return 0, 0, err
-	} else if sz := frameAlign(fi.Size(), pageSize); fi.Size() > WALHeaderSize {
-		offset = sz - int64(pageSize) - WALFrameHeaderSize + WALFrameHeaderChecksumOffset
-	}
-
-	// Read big endian checksum.
-	b := make([]byte, 8)
-	if n, err := f.ReadAt(b, offset); err != nil {
-		return 0, 0, err
-	} else if n != len(b) {
-		return 0, 0, io.ErrUnexpectedEOF
-	}
-	return binary.BigEndian.Uint32(b[0:]), binary.BigEndian.Uint32(b[4:]), nil
-}
-
 // Checkpoint performs a checkpoint on the WAL file.
 func (db *DB) Checkpoint(ctx context.Context, mode string) (err error) {
 	db.mu.Lock()
@@ -1584,31 +1548,6 @@ func (db *DB) CRC64(ctx context.Context) (uint64, Pos, error) {
 	return h.Sum64(), pos, nil
 }
 
-// parseWALPath returns the index for the WAL file.
-// Returns an error if the path is not a valid WAL path.
-func parseWALPath(s string) (index int, err error) {
-	s = filepath.Base(s)
-
-	a := walPathRegex.FindStringSubmatch(s)
-	if a == nil {
-		return 0, fmt.Errorf("invalid wal path: %s", s)
-	}
-
-	i32, _ := strconv.ParseUint(a[1], 16, 32)
-	if i32 > math.MaxInt32 {
-		return 0, fmt.Errorf("index too large in wal path: %s", s)
-	}
-	return int(i32), nil
-}
-
-// formatWALPath formats a WAL filename with a given index.
-func formatWALPath(index int) string {
-	assert(index >= 0, "wal index must be non-negative")
-	return FormatIndex(index) + ".wal"
-}
-
-var walPathRegex = regexp.MustCompile(`^([0-9a-f]{8})\.wal$`)
-
 // ReadWALFields iterates over the header & frames in the WAL data in r.
 // Returns salt, checksum, byte order & the last frame. WAL data must start
 // from the beginning of the WAL header and must end on either the WAL header

internal/internal.go

@@ -1,6 +1,7 @@
 package internal
 
 import (
+	"crypto/md5"
 	"fmt"
 	"io"
 	"math"
@@ -180,7 +181,7 @@ func ParseWALSegmentPath(s string) (index int, offset int64, err error) {
 	if i32 > math.MaxInt32 {
 		return 0, 0, fmt.Errorf("index too large in wal segment path %q", s)
 	}
-	off64, _ := strconv.ParseInt(a[2], 16, 64)
+	off64, _ := strconv.ParseUint(a[2], 16, 64)
 	if off64 > math.MaxInt64 {
 		return 0, 0, fmt.Errorf("offset too large in wal segment path %q", s)
 	}
@@ -228,3 +229,8 @@ func TruncateDuration(d time.Duration) time.Duration {
 	}
 	return d
 }
+
+// MD5hash returns a hex-encoded MD5 hash of b.
+func MD5hash(b []byte) string {
+	return fmt.Sprintf("%x", md5.Sum(b))
+}

internal/testingutil/testingutil.go

@@ -1,9 +1,12 @@
 package testingutil
 
 import (
+	"bytes"
 	"io"
 	"os"
 	"testing"
+
+	"github.com/pierrec/lz4/v4"
 )
 
 // ReadFile reads all data from filename. Fail on error.
@@ -62,3 +65,26 @@ func Setenv(tb testing.TB, key, value string) func() {
 		}
 	}
 }
+
+func CompressLZ4(tb testing.TB, b []byte) []byte {
+	tb.Helper()
+
+	var buf bytes.Buffer
+	zw := lz4.NewWriter(&buf)
+	if _, err := zw.Write(b); err != nil {
+		tb.Fatal(err)
+	} else if err := zw.Close(); err != nil {
+		tb.Fatal(err)
+	}
+	return buf.Bytes()
+}
+
+func DecompressLZ4(tb testing.TB, b []byte) []byte {
+	tb.Helper()
+
+	buf, err := io.ReadAll(lz4.NewReader(bytes.NewReader(b)))
+	if err != nil {
+		tb.Fatal(err)
+	}
+	return buf
+}

litestream.go

@@ -1,10 +1,8 @@
 package litestream
 
 import (
-	"crypto/md5"
 	"database/sql"
 	"encoding/binary"
-	"encoding/hex"
 	"errors"
 	"fmt"
 	"io"
@@ -475,12 +473,6 @@ func isHexChar(ch rune) bool {
 	return (ch >= '0' && ch <= '9') || (ch >= 'a' && ch <= 'f')
 }
 
-// md5hash returns a hex-encoded MD5 hash of b.
-func md5hash(b []byte) string {
-	sum := md5.Sum(b)
-	return hex.EncodeToString(sum[:])
-}
-
 // Tracef is used for low-level tracing.
 var Tracef = func(format string, a ...interface{}) {}
 

litestream_test.go

@@ -4,13 +4,11 @@ import (
 	"bytes"
 	"encoding/binary"
 	"encoding/hex"
-	"io"
 	"os"
 	"testing"
 
 	"github.com/benbjohnson/litestream"
 	_ "github.com/mattn/go-sqlite3"
-	"github.com/pierrec/lz4/v4"
 )
 
 func TestChecksum(t *testing.T) {
@@ -80,26 +78,3 @@ func fileEqual(tb testing.TB, x, y string) bool {
 
 	return bytes.Equal(bx, by)
 }
-
-func compressLZ4(tb testing.TB, b []byte) []byte {
-	tb.Helper()
-
-	var buf bytes.Buffer
-	zw := lz4.NewWriter(&buf)
-	if _, err := zw.Write(b); err != nil {
-		tb.Fatal(err)
-	} else if err := zw.Close(); err != nil {
-		tb.Fatal(err)
-	}
-	return buf.Bytes()
-}
-
-func decompressLZ4(tb testing.TB, b []byte) []byte {
-	tb.Helper()
-
-	buf, err := io.ReadAll(lz4.NewReader(bytes.NewReader(b)))
-	if err != nil {
-		tb.Fatal(err)
-	}
-	return buf
-}

replica.go

@@ -105,14 +105,14 @@ func (r *Replica) DB() *DB { return r.db }
 func (r *Replica) Client() ReplicaClient { return r.client }
 
 // Starts replicating in a background goroutine.
-func (r *Replica) Start(ctx context.Context) error {
+func (r *Replica) Start(ctx context.Context) {
 	// Ignore if replica is being used sychronously.
 	if !r.MonitorEnabled {
-		return nil
+		return
 	}
 
 	// Stop previous replication.
-	r.Stop(false)
+	_ = r.Stop(false)
 
 	// Wrap context with cancelation.
 	ctx, r.cancel = context.WithCancel(ctx)
@@ -123,8 +123,6 @@ func (r *Replica) Start(ctx context.Context) error {
 	go func() { defer r.wg.Done(); r.retainer(ctx) }()
 	go func() { defer r.wg.Done(); r.snapshotter(ctx) }()
 	go func() { defer r.wg.Done(); r.validator(ctx) }()
-
-	return nil
 }
 
 // Stop cancels any outstanding replication and blocks until finished.
@@ -512,10 +510,10 @@ func (r *Replica) Snapshot(ctx context.Context) (info SnapshotInfo, err error) {
 		defer zr.Close()
 
 		if _, err := io.Copy(zr, r.f); err != nil {
-			pw.CloseWithError(err)
+			_ = pw.CloseWithError(err)
 			return err
 		} else if err := zr.Close(); err != nil {
-			pw.CloseWithError(err)
+			_ = pw.CloseWithError(err)
 			return err
 		}
 		return pw.Close()

wal_downloader_test.go

@@ -11,6 +11,7 @@ import (
 	"testing"
 
 	"github.com/benbjohnson/litestream"
+	"github.com/benbjohnson/litestream/internal/testingutil"
 	"github.com/benbjohnson/litestream/mock"
 )
 
@@ -193,7 +194,7 @@ func testWALDownloader(t *testing.T, parallelism int) {
 			filename := filepath.Join(tempDir, "generations", "0000000000000000", "wal", fmt.Sprintf("%08x", i), "00000000.wal.lz4")
 			if err := os.MkdirAll(filepath.Dir(filename), 0777); err != nil {
 				t.Fatal(err)
-			} else if err := os.WriteFile(filename, compressLZ4(t, []byte(fmt.Sprint(i))), 0666); err != nil {
+			} else if err := os.WriteFile(filename, testingutil.CompressLZ4(t, []byte(fmt.Sprint(i))), 0666); err != nil {
 				t.Fatal(err)
 			}
 		}