1
2
3
4
5
6
7 package zip
8
9 import (
10 "bytes"
11 "errors"
12 "fmt"
13 "hash"
14 "internal/testenv"
15 "io"
16 "runtime"
17 "sort"
18 "strings"
19 "testing"
20 "time"
21 )
22
23 func TestOver65kFiles(t *testing.T) {
24 if testing.Short() && testenv.Builder() == "" {
25 t.Skip("skipping in short mode")
26 }
27 buf := new(bytes.Buffer)
28 w := NewWriter(buf)
29 const nFiles = (1 << 16) + 42
30 for i := 0; i < nFiles; i++ {
31 _, err := w.CreateHeader(&FileHeader{
32 Name: fmt.Sprintf("%d.dat", i),
33 Method: Store,
34 })
35 if err != nil {
36 t.Fatalf("creating file %d: %v", i, err)
37 }
38 }
39 if err := w.Close(); err != nil {
40 t.Fatalf("Writer.Close: %v", err)
41 }
42 s := buf.String()
43 zr, err := NewReader(strings.NewReader(s), int64(len(s)))
44 if err != nil {
45 t.Fatalf("NewReader: %v", err)
46 }
47 if got := len(zr.File); got != nFiles {
48 t.Fatalf("File contains %d files, want %d", got, nFiles)
49 }
50 for i := 0; i < nFiles; i++ {
51 want := fmt.Sprintf("%d.dat", i)
52 if zr.File[i].Name != want {
53 t.Fatalf("File(%d) = %q, want %q", i, zr.File[i].Name, want)
54 }
55 }
56 }
57
58 func TestModTime(t *testing.T) {
59 var testTime = time.Date(2009, time.November, 10, 23, 45, 58, 0, time.UTC)
60 fh := new(FileHeader)
61 fh.SetModTime(testTime)
62 outTime := fh.ModTime()
63 if !outTime.Equal(testTime) {
64 t.Errorf("times don't match: got %s, want %s", outTime, testTime)
65 }
66 }
67
68 func testHeaderRoundTrip(fh *FileHeader, wantUncompressedSize uint32, wantUncompressedSize64 uint64, t *testing.T) {
69 fi := fh.FileInfo()
70 fh2, err := FileInfoHeader(fi)
71 if err != nil {
72 t.Fatal(err)
73 }
74 if got, want := fh2.Name, fh.Name; got != want {
75 t.Errorf("Name: got %s, want %s\n", got, want)
76 }
77 if got, want := fh2.UncompressedSize, wantUncompressedSize; got != want {
78 t.Errorf("UncompressedSize: got %d, want %d\n", got, want)
79 }
80 if got, want := fh2.UncompressedSize64, wantUncompressedSize64; got != want {
81 t.Errorf("UncompressedSize64: got %d, want %d\n", got, want)
82 }
83 if got, want := fh2.ModifiedTime, fh.ModifiedTime; got != want {
84 t.Errorf("ModifiedTime: got %d, want %d\n", got, want)
85 }
86 if got, want := fh2.ModifiedDate, fh.ModifiedDate; got != want {
87 t.Errorf("ModifiedDate: got %d, want %d\n", got, want)
88 }
89
90 if sysfh, ok := fi.Sys().(*FileHeader); !ok && sysfh != fh {
91 t.Errorf("Sys didn't return original *FileHeader")
92 }
93 }
94
95 func TestFileHeaderRoundTrip(t *testing.T) {
96 fh := &FileHeader{
97 Name: "foo.txt",
98 UncompressedSize: 987654321,
99 ModifiedTime: 1234,
100 ModifiedDate: 5678,
101 }
102 testHeaderRoundTrip(fh, fh.UncompressedSize, uint64(fh.UncompressedSize), t)
103 }
104
105 func TestFileHeaderRoundTrip64(t *testing.T) {
106 fh := &FileHeader{
107 Name: "foo.txt",
108 UncompressedSize64: 9876543210,
109 ModifiedTime: 1234,
110 ModifiedDate: 5678,
111 }
112 testHeaderRoundTrip(fh, uint32max, fh.UncompressedSize64, t)
113 }
114
115 func TestFileHeaderRoundTripModified(t *testing.T) {
116 fh := &FileHeader{
117 Name: "foo.txt",
118 UncompressedSize: 987654321,
119 Modified: time.Now().Local(),
120 ModifiedTime: 1234,
121 ModifiedDate: 5678,
122 }
123 fi := fh.FileInfo()
124 fh2, err := FileInfoHeader(fi)
125 if err != nil {
126 t.Fatal(err)
127 }
128 if got, want := fh2.Modified, fh.Modified.UTC(); got != want {
129 t.Errorf("Modified: got %s, want %s\n", got, want)
130 }
131 if got, want := fi.ModTime(), fh.Modified.UTC(); got != want {
132 t.Errorf("Modified: got %s, want %s\n", got, want)
133 }
134 }
135
136 func TestFileHeaderRoundTripWithoutModified(t *testing.T) {
137 fh := &FileHeader{
138 Name: "foo.txt",
139 UncompressedSize: 987654321,
140 ModifiedTime: 1234,
141 ModifiedDate: 5678,
142 }
143 fi := fh.FileInfo()
144 fh2, err := FileInfoHeader(fi)
145 if err != nil {
146 t.Fatal(err)
147 }
148 if got, want := fh2.ModTime(), fh.ModTime(); got != want {
149 t.Errorf("Modified: got %s, want %s\n", got, want)
150 }
151 if got, want := fi.ModTime(), fh.ModTime(); got != want {
152 t.Errorf("Modified: got %s, want %s\n", got, want)
153 }
154 }
155
156 type repeatedByte struct {
157 off int64
158 b byte
159 n int64
160 }
161
162
163
164
165 type rleBuffer struct {
166 buf []repeatedByte
167 }
168
169 func (r *rleBuffer) Size() int64 {
170 if len(r.buf) == 0 {
171 return 0
172 }
173 last := &r.buf[len(r.buf)-1]
174 return last.off + last.n
175 }
176
177 func (r *rleBuffer) Write(p []byte) (n int, err error) {
178 var rp *repeatedByte
179 if len(r.buf) > 0 {
180 rp = &r.buf[len(r.buf)-1]
181
182 if lastByte := rp.b; len(p) > 0 && p[0] == lastByte {
183 if bytes.Count(p, []byte{lastByte}) == len(p) {
184 rp.n += int64(len(p))
185 return len(p), nil
186 }
187 }
188 }
189
190 for _, b := range p {
191 if rp == nil || rp.b != b {
192 r.buf = append(r.buf, repeatedByte{r.Size(), b, 1})
193 rp = &r.buf[len(r.buf)-1]
194 } else {
195 rp.n++
196 }
197 }
198 return len(p), nil
199 }
200
201 func min(x, y int64) int64 {
202 if x < y {
203 return x
204 }
205 return y
206 }
207
208 func memset(a []byte, b byte) {
209 if len(a) == 0 {
210 return
211 }
212
213
214 a[0] = b
215 for i, l := 1, len(a); i < l; i *= 2 {
216 copy(a[i:], a[:i])
217 }
218 }
219
220 func (r *rleBuffer) ReadAt(p []byte, off int64) (n int, err error) {
221 if len(p) == 0 {
222 return
223 }
224 skipParts := sort.Search(len(r.buf), func(i int) bool {
225 part := &r.buf[i]
226 return part.off+part.n > off
227 })
228 parts := r.buf[skipParts:]
229 if len(parts) > 0 {
230 skipBytes := off - parts[0].off
231 for _, part := range parts {
232 repeat := int(min(part.n-skipBytes, int64(len(p)-n)))
233 memset(p[n:n+repeat], part.b)
234 n += repeat
235 if n == len(p) {
236 return
237 }
238 skipBytes = 0
239 }
240 }
241 if n != len(p) {
242 err = io.ErrUnexpectedEOF
243 }
244 return
245 }
246
247
248 func TestRLEBuffer(t *testing.T) {
249 b := new(rleBuffer)
250 var all []byte
251 writes := []string{"abcdeee", "eeeeeee", "eeeefghaaiii"}
252 for _, w := range writes {
253 b.Write([]byte(w))
254 all = append(all, w...)
255 }
256 if len(b.buf) != 10 {
257 t.Fatalf("len(b.buf) = %d; want 10", len(b.buf))
258 }
259
260 for i := 0; i < len(all); i++ {
261 for j := 0; j < len(all)-i; j++ {
262 buf := make([]byte, j)
263 n, err := b.ReadAt(buf, int64(i))
264 if err != nil || n != len(buf) {
265 t.Errorf("ReadAt(%d, %d) = %d, %v; want %d, nil", i, j, n, err, len(buf))
266 }
267 if !bytes.Equal(buf, all[i:i+j]) {
268 t.Errorf("ReadAt(%d, %d) = %q; want %q", i, j, buf, all[i:i+j])
269 }
270 }
271 }
272 }
273
274
275 type fakeHash32 struct {
276 hash.Hash32
277 }
278
279 func (fakeHash32) Write(p []byte) (int, error) { return len(p), nil }
280 func (fakeHash32) Sum32() uint32 { return 0 }
281
282 func TestZip64(t *testing.T) {
283 if testing.Short() {
284 t.Skip("slow test; skipping")
285 }
286 t.Parallel()
287 const size = 1 << 32
288 buf := testZip64(t, size)
289 testZip64DirectoryRecordLength(buf, t)
290 }
291
292 func TestZip64EdgeCase(t *testing.T) {
293 if testing.Short() {
294 t.Skip("slow test; skipping")
295 }
296 t.Parallel()
297
298
299
300
301
302 const size = 1<<32 - 1 - int64(len("END\n"))
303 buf := testZip64(t, size)
304 testZip64DirectoryRecordLength(buf, t)
305 }
306
307
308
309 func TestZip64DirectoryOffset(t *testing.T) {
310 if testing.Short() {
311 t.Skip("skipping in short mode")
312 }
313 t.Parallel()
314 const filename = "huge.txt"
315 gen := func(wantOff uint64) func(*Writer) {
316 return func(w *Writer) {
317 w.testHookCloseSizeOffset = func(size, off uint64) {
318 if off != wantOff {
319 t.Errorf("central directory offset = %d (%x); want %d", off, off, wantOff)
320 }
321 }
322 f, err := w.CreateHeader(&FileHeader{
323 Name: filename,
324 Method: Store,
325 })
326 if err != nil {
327 t.Fatal(err)
328 }
329 f.(*fileWriter).crc32 = fakeHash32{}
330 size := wantOff - fileHeaderLen - uint64(len(filename)) - dataDescriptorLen
331 if _, err := io.CopyN(f, zeros{}, int64(size)); err != nil {
332 t.Fatal(err)
333 }
334 if err := w.Close(); err != nil {
335 t.Fatal(err)
336 }
337 }
338 }
339 t.Run("uint32max-2_NoZip64", func(t *testing.T) {
340 t.Parallel()
341 if generatesZip64(t, gen(0xfffffffe)) {
342 t.Error("unexpected zip64")
343 }
344 })
345 t.Run("uint32max-1_Zip64", func(t *testing.T) {
346 t.Parallel()
347 if !generatesZip64(t, gen(0xffffffff)) {
348 t.Error("expected zip64")
349 }
350 })
351 }
352
353
354 func TestZip64ManyRecords(t *testing.T) {
355 if testing.Short() {
356 t.Skip("skipping in short mode")
357 }
358 t.Parallel()
359 gen := func(numRec int) func(*Writer) {
360 return func(w *Writer) {
361 for i := 0; i < numRec; i++ {
362 _, err := w.CreateHeader(&FileHeader{
363 Name: "a.txt",
364 Method: Store,
365 })
366 if err != nil {
367 t.Fatal(err)
368 }
369 }
370 if err := w.Close(); err != nil {
371 t.Fatal(err)
372 }
373 }
374 }
375
376 t.Run("uint16max-1_NoZip64", func(t *testing.T) {
377 t.Parallel()
378 if generatesZip64(t, gen(0xfffe)) {
379 t.Error("unexpected zip64")
380 }
381 })
382
383 t.Run("uint16max_Zip64", func(t *testing.T) {
384 t.Parallel()
385 if !generatesZip64(t, gen(0xffff)) {
386 t.Error("expected zip64")
387 }
388 })
389 }
390
391
392
393
394 type suffixSaver struct {
395 keep int
396 buf []byte
397 start int
398 size int64
399 }
400
401 func (ss *suffixSaver) Size() int64 { return ss.size }
402
403 var errDiscardedBytes = errors.New("ReadAt of discarded bytes")
404
405 func (ss *suffixSaver) ReadAt(p []byte, off int64) (n int, err error) {
406 back := ss.size - off
407 if back > int64(ss.keep) {
408 return 0, errDiscardedBytes
409 }
410 suf := ss.Suffix()
411 n = copy(p, suf[len(suf)-int(back):])
412 if n != len(p) {
413 err = io.EOF
414 }
415 return
416 }
417
418 func (ss *suffixSaver) Suffix() []byte {
419 if len(ss.buf) < ss.keep {
420 return ss.buf
421 }
422 buf := make([]byte, ss.keep)
423 n := copy(buf, ss.buf[ss.start:])
424 copy(buf[n:], ss.buf[:])
425 return buf
426 }
427
428 func (ss *suffixSaver) Write(p []byte) (n int, err error) {
429 n = len(p)
430 ss.size += int64(len(p))
431 if len(ss.buf) < ss.keep {
432 space := ss.keep - len(ss.buf)
433 add := len(p)
434 if add > space {
435 add = space
436 }
437 ss.buf = append(ss.buf, p[:add]...)
438 p = p[add:]
439 }
440 for len(p) > 0 {
441 n := copy(ss.buf[ss.start:], p)
442 p = p[n:]
443 ss.start += n
444 if ss.start == ss.keep {
445 ss.start = 0
446 }
447 }
448 return
449 }
450
451
452
453 func generatesZip64(t *testing.T, f func(w *Writer)) bool {
454 ss := &suffixSaver{keep: 10 << 20}
455 w := NewWriter(ss)
456 f(w)
457 return suffixIsZip64(t, ss)
458 }
459
460 type sizedReaderAt interface {
461 io.ReaderAt
462 Size() int64
463 }
464
465 func suffixIsZip64(t *testing.T, zip sizedReaderAt) bool {
466 d := make([]byte, 1024)
467 if _, err := zip.ReadAt(d, zip.Size()-int64(len(d))); err != nil {
468 t.Fatalf("ReadAt: %v", err)
469 }
470
471 sigOff := findSignatureInBlock(d)
472 if sigOff == -1 {
473 t.Errorf("failed to find signature in block")
474 return false
475 }
476
477 dirOff, err := findDirectory64End(zip, zip.Size()-int64(len(d))+int64(sigOff))
478 if err != nil {
479 t.Fatalf("findDirectory64End: %v", err)
480 }
481 if dirOff == -1 {
482 return false
483 }
484
485 d = make([]byte, directory64EndLen)
486 if _, err := zip.ReadAt(d, dirOff); err != nil {
487 t.Fatalf("ReadAt(off=%d): %v", dirOff, err)
488 }
489
490 b := readBuf(d)
491 if sig := b.uint32(); sig != directory64EndSignature {
492 return false
493 }
494
495 size := b.uint64()
496 if size != directory64EndLen-12 {
497 t.Errorf("expected length of %d, got %d", directory64EndLen-12, size)
498 }
499 return true
500 }
501
502
503 func TestZip64LargeDirectory(t *testing.T) {
504 if runtime.GOARCH == "wasm" {
505 t.Skip("too slow on wasm")
506 }
507 if testing.Short() {
508 t.Skip("skipping in short mode")
509 }
510 t.Parallel()
511
512
513 gen := func(wantLen int64) func(*Writer) {
514 return func(w *Writer) {
515 w.testHookCloseSizeOffset = func(size, off uint64) {
516 if size != uint64(wantLen) {
517 t.Errorf("Close central directory size = %d; want %d", size, wantLen)
518 }
519 }
520
521 uint16string := strings.Repeat(".", uint16max)
522 remain := wantLen
523 for remain > 0 {
524 commentLen := int(uint16max) - directoryHeaderLen - 1
525 thisRecLen := directoryHeaderLen + int(uint16max) + commentLen
526 if int64(thisRecLen) > remain {
527 remove := thisRecLen - int(remain)
528 commentLen -= remove
529 thisRecLen -= remove
530 }
531 remain -= int64(thisRecLen)
532 f, err := w.CreateHeader(&FileHeader{
533 Name: uint16string,
534 Comment: uint16string[:commentLen],
535 })
536 if err != nil {
537 t.Fatalf("CreateHeader: %v", err)
538 }
539 f.(*fileWriter).crc32 = fakeHash32{}
540 }
541 if err := w.Close(); err != nil {
542 t.Fatalf("Close: %v", err)
543 }
544 }
545 }
546 t.Run("uint32max-1_NoZip64", func(t *testing.T) {
547 t.Parallel()
548 if generatesZip64(t, gen(uint32max-1)) {
549 t.Error("unexpected zip64")
550 }
551 })
552 t.Run("uint32max_HasZip64", func(t *testing.T) {
553 t.Parallel()
554 if !generatesZip64(t, gen(uint32max)) {
555 t.Error("expected zip64")
556 }
557 })
558 }
559
560 func testZip64(t testing.TB, size int64) *rleBuffer {
561 const chunkSize = 1024
562 chunks := int(size / chunkSize)
563
564 buf := new(rleBuffer)
565 w := NewWriter(buf)
566 f, err := w.CreateHeader(&FileHeader{
567 Name: "huge.txt",
568 Method: Store,
569 })
570 if err != nil {
571 t.Fatal(err)
572 }
573 f.(*fileWriter).crc32 = fakeHash32{}
574 chunk := make([]byte, chunkSize)
575 for i := range chunk {
576 chunk[i] = '.'
577 }
578 for i := 0; i < chunks; i++ {
579 _, err := f.Write(chunk)
580 if err != nil {
581 t.Fatal("write chunk:", err)
582 }
583 }
584 if frag := int(size % chunkSize); frag > 0 {
585 _, err := f.Write(chunk[:frag])
586 if err != nil {
587 t.Fatal("write chunk:", err)
588 }
589 }
590 end := []byte("END\n")
591 _, err = f.Write(end)
592 if err != nil {
593 t.Fatal("write end:", err)
594 }
595 if err := w.Close(); err != nil {
596 t.Fatal(err)
597 }
598
599
600 r, err := NewReader(buf, int64(buf.Size()))
601 if err != nil {
602 t.Fatal("reader:", err)
603 }
604 f0 := r.File[0]
605 rc, err := f0.Open()
606 if err != nil {
607 t.Fatal("opening:", err)
608 }
609 rc.(*checksumReader).hash = fakeHash32{}
610 for i := 0; i < chunks; i++ {
611 _, err := io.ReadFull(rc, chunk)
612 if err != nil {
613 t.Fatal("read:", err)
614 }
615 }
616 if frag := int(size % chunkSize); frag > 0 {
617 _, err := io.ReadFull(rc, chunk[:frag])
618 if err != nil {
619 t.Fatal("read:", err)
620 }
621 }
622 gotEnd, err := io.ReadAll(rc)
623 if err != nil {
624 t.Fatal("read end:", err)
625 }
626 if !bytes.Equal(gotEnd, end) {
627 t.Errorf("End of zip64 archive %q, want %q", gotEnd, end)
628 }
629 err = rc.Close()
630 if err != nil {
631 t.Fatal("closing:", err)
632 }
633 if size+int64(len("END\n")) >= 1<<32-1 {
634 if got, want := f0.UncompressedSize, uint32(uint32max); got != want {
635 t.Errorf("UncompressedSize %#x, want %#x", got, want)
636 }
637 }
638
639 if got, want := f0.UncompressedSize64, uint64(size)+uint64(len(end)); got != want {
640 t.Errorf("UncompressedSize64 %#x, want %#x", got, want)
641 }
642
643 return buf
644 }
645
646
647 func testZip64DirectoryRecordLength(buf *rleBuffer, t *testing.T) {
648 if !suffixIsZip64(t, buf) {
649 t.Fatal("not a zip64")
650 }
651 }
652
653 func testValidHeader(h *FileHeader, t *testing.T) {
654 var buf bytes.Buffer
655 z := NewWriter(&buf)
656
657 f, err := z.CreateHeader(h)
658 if err != nil {
659 t.Fatalf("error creating header: %v", err)
660 }
661 if _, err := f.Write([]byte("hi")); err != nil {
662 t.Fatalf("error writing content: %v", err)
663 }
664 if err := z.Close(); err != nil {
665 t.Fatalf("error closing zip writer: %v", err)
666 }
667
668 b := buf.Bytes()
669 zf, err := NewReader(bytes.NewReader(b), int64(len(b)))
670 if err != nil {
671 t.Fatalf("got %v, expected nil", err)
672 }
673 zh := zf.File[0].FileHeader
674 if zh.Name != h.Name || zh.Method != h.Method || zh.UncompressedSize64 != uint64(len("hi")) {
675 t.Fatalf("got %q/%d/%d expected %q/%d/%d", zh.Name, zh.Method, zh.UncompressedSize64, h.Name, h.Method, len("hi"))
676 }
677 }
678
679
680 func TestHeaderInvalidTagAndSize(t *testing.T) {
681 const timeFormat = "20060102T150405.000.txt"
682
683 ts := time.Now()
684 filename := ts.Format(timeFormat)
685
686 h := FileHeader{
687 Name: filename,
688 Method: Deflate,
689 Extra: []byte(ts.Format(time.RFC3339Nano)),
690 }
691 h.SetModTime(ts)
692
693 testValidHeader(&h, t)
694 }
695
696 func TestHeaderTooShort(t *testing.T) {
697 h := FileHeader{
698 Name: "foo.txt",
699 Method: Deflate,
700 Extra: []byte{zip64ExtraID},
701 }
702 testValidHeader(&h, t)
703 }
704
705 func TestHeaderTooLongErr(t *testing.T) {
706 var headerTests = []struct {
707 name string
708 extra []byte
709 wanterr error
710 }{
711 {
712 name: strings.Repeat("x", 1<<16),
713 extra: []byte{},
714 wanterr: errLongName,
715 },
716 {
717 name: "long_extra",
718 extra: bytes.Repeat([]byte{0xff}, 1<<16),
719 wanterr: errLongExtra,
720 },
721 }
722
723
724 buf := new(bytes.Buffer)
725 w := NewWriter(buf)
726
727 for _, test := range headerTests {
728 h := &FileHeader{
729 Name: test.name,
730 Extra: test.extra,
731 }
732 _, err := w.CreateHeader(h)
733 if err != test.wanterr {
734 t.Errorf("error=%v, want %v", err, test.wanterr)
735 }
736 }
737
738 if err := w.Close(); err != nil {
739 t.Fatal(err)
740 }
741 }
742
743 func TestHeaderIgnoredSize(t *testing.T) {
744 h := FileHeader{
745 Name: "foo.txt",
746 Method: Deflate,
747 Extra: []byte{zip64ExtraID & 0xFF, zip64ExtraID >> 8, 24, 0, 1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8},
748 }
749 testValidHeader(&h, t)
750 }
751
752
753
754 func TestZeroLengthHeader(t *testing.T) {
755 h := FileHeader{
756 Name: "extadata.txt",
757 Method: Deflate,
758 Extra: []byte{
759 85, 84, 5, 0, 3, 154, 144, 195, 77,
760 85, 120, 0, 0,
761 },
762 }
763 testValidHeader(&h, t)
764 }
765
766
767
768 func BenchmarkZip64Test(b *testing.B) {
769 for i := 0; i < b.N; i++ {
770 testZip64(b, 1<<26)
771 }
772 }
773
774 func BenchmarkZip64TestSizes(b *testing.B) {
775 for _, size := range []int64{1 << 12, 1 << 20, 1 << 26} {
776 b.Run(fmt.Sprint(size), func(b *testing.B) {
777 b.RunParallel(func(pb *testing.PB) {
778 for pb.Next() {
779 testZip64(b, size)
780 }
781 })
782 })
783 }
784 }
785
786 func TestSuffixSaver(t *testing.T) {
787 const keep = 10
788 ss := &suffixSaver{keep: keep}
789 ss.Write([]byte("abc"))
790 if got := string(ss.Suffix()); got != "abc" {
791 t.Errorf("got = %q; want abc", got)
792 }
793 ss.Write([]byte("defghijklmno"))
794 if got := string(ss.Suffix()); got != "fghijklmno" {
795 t.Errorf("got = %q; want fghijklmno", got)
796 }
797 if got, want := ss.Size(), int64(len("abc")+len("defghijklmno")); got != want {
798 t.Errorf("Size = %d; want %d", got, want)
799 }
800 buf := make([]byte, ss.Size())
801 for off := int64(0); off < ss.Size(); off++ {
802 for size := 1; size <= int(ss.Size()-off); size++ {
803 readBuf := buf[:size]
804 n, err := ss.ReadAt(readBuf, off)
805 if off < ss.Size()-keep {
806 if err != errDiscardedBytes {
807 t.Errorf("off %d, size %d = %v, %v (%q); want errDiscardedBytes", off, size, n, err, readBuf[:n])
808 }
809 continue
810 }
811 want := "abcdefghijklmno"[off : off+int64(size)]
812 got := string(readBuf[:n])
813 if err != nil || got != want {
814 t.Errorf("off %d, size %d = %v, %v (%q); want %q", off, size, n, err, got, want)
815 }
816 }
817 }
818
819 }
820
821 type zeros struct{}
822
823 func (zeros) Read(p []byte) (int, error) {
824 for i := range p {
825 p[i] = 0
826 }
827 return len(p), nil
828 }
829
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