/
cram.go
496 lines (460 loc) · 11 KB
/
cram.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
// Copyright ©2017 The bíogo Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package cram is a WIP CRAM reader implementation.
//
// Currently the package implements container, block and slice retrieval, and
// SAM header values can be retrieved from blocks.
//
// See https://samtools.github.io/hts-specs/CRAMv3.pdf for the CRAM
// specification.
package cram
import (
"bytes"
"compress/bzip2"
"compress/gzip"
"encoding/binary"
"errors"
"fmt"
"hash/crc32"
"io"
"os"
"reflect"
"github.com/ulikunitz/xz/lzma"
"github.com/biogo/hts/cram/encoding/itf8"
"github.com/biogo/hts/cram/encoding/ltf8"
"github.com/biogo/hts/sam"
)
// cramEOFmarker is the CRAM end of file marker.
//
// See CRAM spec section 9.
var cramEOFmarker = []byte{
0x0f, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, // |........|
0x0f, 0xe0, 0x45, 0x4f, 0x46, 0x00, 0x00, 0x00, // |..EOF...|
0x00, 0x01, 0x00, 0x05, 0xbd, 0xd9, 0x4f, 0x00, // |......O.|
0x01, 0x00, 0x06, 0x06, 0x01, 0x00, 0x01, 0x00, // |........|
0x01, 0x00, 0xee, 0x63, 0x01, 0x4b, /* */ // |...c.K|
}
// ErrNoEnd is returned when a stream cannot seek to a CRAM EOF block.
var ErrNoEnd = errors.New("cram: cannot determine offset from end")
// HasEOF checks for the presence of a CRAM magic EOF block.
// The magic block is defined in the CRAM specification. A magic block
// is written by a Writer on calling Close. The ReaderAt must provide
// some method for determining valid ReadAt offsets.
func HasEOF(r io.ReaderAt) (bool, error) {
type sizer interface {
Size() int64
}
type stater interface {
Stat() (os.FileInfo, error)
}
type lenSeeker interface {
io.Seeker
Len() int
}
var size int64
switch r := r.(type) {
case sizer:
size = r.Size()
case stater:
fi, err := r.Stat()
if err != nil {
return false, err
}
size = fi.Size()
case lenSeeker:
var err error
size, err = r.Seek(0, 1)
if err != nil {
return false, err
}
size += int64(r.Len())
default:
return false, ErrNoEnd
}
b := make([]byte, len(cramEOFmarker))
_, err := r.ReadAt(b, size-int64(len(cramEOFmarker)))
if err != nil {
return false, err
}
return bytes.Equal(b, cramEOFmarker), nil
}
// Reader is a CRAM format reader.
type Reader struct {
r io.Reader
d definition
c *Container
err error
}
// NewReader returns a new Reader.
func NewReader(r io.Reader) (*Reader, error) {
cr := Reader{r: r}
err := cr.d.readFrom(r)
if err != nil {
return nil, err
}
return &cr, nil
}
// Next advances the Reader to the next CRAM container. It returns false
// when the stream ends, either by reaching the end of the stream or
// encountering an error.
func (r *Reader) Next() bool {
if r.err != nil {
return false
}
if r.c != nil {
io.Copy(io.Discard, r.c.blockData)
}
var c Container
r.err = c.readFrom(r.r)
r.c = &c
return r.err == nil
}
// Container returns the current CRAM container. The returned Container
// is only valid after a previous call to Next has returned true.
func (r *Reader) Container() *Container {
return r.c
}
// Err returns the most recent error.
func (r *Reader) Err() error {
if r.err == io.EOF {
return nil
}
return r.err
}
// definition is a CRAM file definition.
//
// See CRAM spec section 6.
type definition struct {
Magic [4]byte `is:"CRAM"`
Version [2]byte
ID [20]byte
}
// readFrom populates a definition from the given io.Reader. If the magic
// number of the file is not "CRAM" readFrom returns an error.
func (d *definition) readFrom(r io.Reader) error {
err := binary.Read(r, binary.LittleEndian, d)
if err != nil {
return err
}
magic := reflect.TypeOf(*d).Field(0).Tag.Get("is")
if !bytes.Equal(d.Magic[:], []byte(magic)) {
return fmt.Errorf("cram: not a cram file: magic bytes %q", d.Magic)
}
return nil
}
// Container is a CRAM container.
//
// See CRAM spec section 7.
type Container struct {
blockLen int32
refID int32
start int32
span int32
nRec int32
recCount int64
bases int64
blocks int32
landmarks []int32
crc32 uint32
blockData io.Reader
block *Block
err error
}
// readFrom populates a Container from the given io.Reader checking that the
// CRC32 for the container header is correct.
func (c *Container) readFrom(r io.Reader) error {
crc := crc32.NewIEEE()
er := errorReader{r: io.TeeReader(r, crc)}
var buf [4]byte
io.ReadFull(&er, buf[:])
c.blockLen = int32(binary.LittleEndian.Uint32(buf[:]))
c.refID = er.itf8()
c.start = er.itf8()
c.span = er.itf8()
c.nRec = er.itf8()
c.recCount = er.ltf8()
c.bases = er.ltf8()
c.blocks = er.itf8()
c.landmarks = er.itf8slice()
sum := crc.Sum32()
_, err := io.ReadFull(&er, buf[:])
if err != nil {
return err
}
c.crc32 = binary.LittleEndian.Uint32(buf[:])
if c.crc32 != sum {
return fmt.Errorf("cram: container crc32 mismatch got:0x%08x want:0x%08x", sum, c.crc32)
}
if er.err != nil {
return er.err
}
// The spec says T[] is {itf8, element...}.
// This is not true for byte[] according to
// the EOF block.
c.blockData = &io.LimitedReader{R: r, N: int64(c.blockLen)}
return nil
}
// Next advances the Container to the next CRAM block. It returns false
// when the data ends, either by reaching the end of the container or
// encountering an error.
func (c *Container) Next() bool {
if c.err != nil {
return false
}
var b Block
c.err = b.readFrom(c.blockData)
if c.err == nil {
c.block = &b
return true
}
return false
}
// Block returns the current CRAM block. The returned Blcok is only
// valid after a previous call to Next has returned true.
func (c *Container) Block() *Block {
return c.block
}
// Err returns the most recent error.
func (c *Container) Err() error {
if c.err == io.EOF {
return nil
}
return c.err
}
// Block is a CRAM block structure.
//
// See CRAM spec section 8.
type Block struct {
method byte
typ byte
contentID int32
compressedSize int32
rawSize int32
blockData []byte
crc32 uint32
}
const (
rawMethod = iota
gzipMethod
bzip2Method
lzmaMethod
ransMethod
)
const (
fileHeader = iota
compressionHeader
mappedSliceHeader
_ // reserved
externalData
coreData
)
// readFrom fills a Block from the given io.Reader checking that the
// CRC32 for the block is correct.
func (b *Block) readFrom(r io.Reader) error {
crc := crc32.NewIEEE()
er := errorReader{r: io.TeeReader(r, crc)}
var buf [4]byte
io.ReadFull(&er, buf[:2])
b.method = buf[0]
b.typ = buf[1]
b.contentID = er.itf8()
b.compressedSize = er.itf8()
b.rawSize = er.itf8()
if b.method == rawMethod && b.compressedSize != b.rawSize {
return fmt.Errorf("cram: compressed (%d) != raw (%d) size for raw method", b.compressedSize, b.rawSize)
}
// The spec says T[] is {itf8, element...}.
// This is not true for byte[] according to
// the EOF block.
b.blockData = make([]byte, b.compressedSize)
_, err := io.ReadFull(&er, b.blockData)
if err != nil {
return err
}
sum := crc.Sum32()
_, err = io.ReadFull(&er, buf[:])
if err != nil {
return err
}
b.crc32 = binary.LittleEndian.Uint32(buf[:])
if b.crc32 != sum {
return fmt.Errorf("cram: block crc32 mismatch got:0x%08x want:0x%08x", sum, b.crc32)
}
return nil
}
// Value returns the value of the Block.
//
// Note that rANS decompression is not implemented.
func (b *Block) Value() (interface{}, error) {
switch b.typ {
case fileHeader:
var h sam.Header
blockData, err := b.expandBlockdata()
if err != nil {
return nil, err
}
end := binary.LittleEndian.Uint32(blockData[:4])
err = h.UnmarshalText(blockData[4 : 4+end])
if err != nil {
return nil, err
}
return &h, nil
case mappedSliceHeader:
var s Slice
s.readFrom(bytes.NewReader(b.blockData))
return &s, nil
default:
// Experimental.
switch b.method {
case gzipMethod, bzip2Method, lzmaMethod:
var err error
b.blockData, err = b.expandBlockdata()
if err != nil {
return nil, err
}
b.method |= 0x80
default:
// Do nothing.
}
return b, nil
}
}
// expandBlockdata decompresses the block's compressed data.
func (b *Block) expandBlockdata() ([]byte, error) {
switch b.method {
default:
panic(fmt.Sprintf("cram: unknown method: %v", b.method))
case rawMethod:
return b.blockData, nil
case gzipMethod:
gz, err := gzip.NewReader(bytes.NewReader(b.blockData))
if err != nil {
return nil, err
}
return io.ReadAll(gz)
case bzip2Method:
return io.ReadAll(bzip2.NewReader(bytes.NewReader(b.blockData)))
case lzmaMethod:
lz, err := lzma.NewReader(bytes.NewReader(b.blockData))
if err != nil {
return nil, err
}
return io.ReadAll(lz)
case ransMethod:
// Unimplemented.
// BUG(kortschak): The rANS method is not implemented.
// Data blocks compressed with rANS will be returned
// compressed and an "unimplemented" error will be
// returned.
return b.blockData, errors.New("unimplemented")
}
}
// Slice is a CRAM slice header block.
//
// See CRAM spec section 8.5.
type Slice struct {
refID int32
start int32
span int32
nRec int32
recCount int64
blocks int32
blockIDs []int32
embeddedRefID int32
md5sum [16]byte
tags []byte
}
// readFrom populates a Slice from the given io.Reader.
func (s *Slice) readFrom(r io.Reader) error {
er := errorReader{r: r}
s.refID = er.itf8()
s.start = er.itf8()
s.span = er.itf8()
s.nRec = er.itf8()
s.recCount = er.ltf8()
s.blocks = er.itf8()
s.blockIDs = er.itf8slice()
s.embeddedRefID = er.itf8()
_, err := io.ReadFull(&er, s.md5sum[:])
if err != nil {
return err
}
s.tags, err = io.ReadAll(&er)
return err
}
// errorReader is a sticky error io.Reader.
type errorReader struct {
r io.Reader
err error
}
// Read implements the io.Reader interface.
func (r *errorReader) Read(b []byte) (int, error) {
if r.err != nil {
return 0, r.err
}
var n int
n, r.err = r.r.Read(b)
return n, r.err
}
// itf8 returns the ITF-8 encoded number at the current reader position.
func (r *errorReader) itf8() int32 {
var buf [5]byte
_, r.err = io.ReadFull(r, buf[:1])
if r.err != nil {
return 0
}
i, n, ok := itf8.Decode(buf[:1])
if ok {
return i
}
_, r.err = io.ReadFull(r, buf[1:n])
if r.err != nil {
return 0
}
i, _, ok = itf8.Decode(buf[:n])
if !ok {
r.err = fmt.Errorf("cram: failed to decode itf-8 stream %#v", buf[:n])
}
return i
}
// itf8slice returns the n[ITF-8] encoded numbers at the current reader position
// where n is an ITF-8 encoded number.
func (r *errorReader) itf8slice() []int32 {
n := r.itf8()
if r.err != nil {
return nil
}
if n == 0 {
return nil
}
s := make([]int32, n)
for i := range s {
s[i] = r.itf8()
if r.err != nil {
return s[:i]
}
}
return s
}
// itf8 returns the LTF-8 encoded number at the current reader position.
func (r *errorReader) ltf8() int64 {
var buf [9]byte
_, r.err = io.ReadFull(r, buf[:1])
if r.err != nil {
return 0
}
i, n, ok := ltf8.Decode(buf[:1])
if ok {
return i
}
_, r.err = io.ReadFull(r, buf[1:n])
if r.err != nil {
return 0
}
i, _, ok = ltf8.Decode(buf[:n])
if !ok {
r.err = fmt.Errorf("cram: failed to decode ltf-8 stream %#v", buf[:n])
}
return i
}