aboutsummaryrefslogtreecommitdiffstats
path: root/vendor/github.com/klauspost/compress/s2/decode.go
diff options
context:
space:
mode:
authorLibravatar Rutger Broekhoff2024-01-02 18:56:31 +0100
committerLibravatar Rutger Broekhoff2024-01-02 18:56:31 +0100
commit8db41da676ac8368ef7c2549d56239a5ff5eedde (patch)
tree09c427fd66de2ec1ebffc8342f5fdbb84b0701b5 /vendor/github.com/klauspost/compress/s2/decode.go
parentd4f75fb6db22e57577867445a022227e70958931 (diff)
downloadgitolfs3-8db41da676ac8368ef7c2549d56239a5ff5eedde.tar.gz
gitolfs3-8db41da676ac8368ef7c2549d56239a5ff5eedde.zip
Delete vendor directory
Diffstat (limited to 'vendor/github.com/klauspost/compress/s2/decode.go')
-rw-r--r--vendor/github.com/klauspost/compress/s2/decode.go437
1 files changed, 0 insertions, 437 deletions
diff --git a/vendor/github.com/klauspost/compress/s2/decode.go b/vendor/github.com/klauspost/compress/s2/decode.go
deleted file mode 100644
index 6c7feaf..0000000
--- a/vendor/github.com/klauspost/compress/s2/decode.go
+++ /dev/null
@@ -1,437 +0,0 @@
1// Copyright 2011 The Snappy-Go Authors. All rights reserved.
2// Copyright (c) 2019 Klaus Post. All rights reserved.
3// Use of this source code is governed by a BSD-style
4// license that can be found in the LICENSE file.
5
6package s2
7
8import (
9 "encoding/binary"
10 "errors"
11 "fmt"
12 "strconv"
13)
14
15var (
16 // ErrCorrupt reports that the input is invalid.
17 ErrCorrupt = errors.New("s2: corrupt input")
18 // ErrCRC reports that the input failed CRC validation (streams only)
19 ErrCRC = errors.New("s2: corrupt input, crc mismatch")
20 // ErrTooLarge reports that the uncompressed length is too large.
21 ErrTooLarge = errors.New("s2: decoded block is too large")
22 // ErrUnsupported reports that the input isn't supported.
23 ErrUnsupported = errors.New("s2: unsupported input")
24)
25
26// DecodedLen returns the length of the decoded block.
27func DecodedLen(src []byte) (int, error) {
28 v, _, err := decodedLen(src)
29 return v, err
30}
31
32// decodedLen returns the length of the decoded block and the number of bytes
33// that the length header occupied.
34func decodedLen(src []byte) (blockLen, headerLen int, err error) {
35 v, n := binary.Uvarint(src)
36 if n <= 0 || v > 0xffffffff {
37 return 0, 0, ErrCorrupt
38 }
39
40 const wordSize = 32 << (^uint(0) >> 32 & 1)
41 if wordSize == 32 && v > 0x7fffffff {
42 return 0, 0, ErrTooLarge
43 }
44 return int(v), n, nil
45}
46
47const (
48 decodeErrCodeCorrupt = 1
49)
50
51// Decode returns the decoded form of src. The returned slice may be a sub-
52// slice of dst if dst was large enough to hold the entire decoded block.
53// Otherwise, a newly allocated slice will be returned.
54//
55// The dst and src must not overlap. It is valid to pass a nil dst.
56func Decode(dst, src []byte) ([]byte, error) {
57 dLen, s, err := decodedLen(src)
58 if err != nil {
59 return nil, err
60 }
61 if dLen <= cap(dst) {
62 dst = dst[:dLen]
63 } else {
64 dst = make([]byte, dLen)
65 }
66 if s2Decode(dst, src[s:]) != 0 {
67 return nil, ErrCorrupt
68 }
69 return dst, nil
70}
71
72// s2DecodeDict writes the decoding of src to dst. It assumes that the varint-encoded
73// length of the decompressed bytes has already been read, and that len(dst)
74// equals that length.
75//
76// It returns 0 on success or a decodeErrCodeXxx error code on failure.
77func s2DecodeDict(dst, src []byte, dict *Dict) int {
78 if dict == nil {
79 return s2Decode(dst, src)
80 }
81 const debug = false
82 const debugErrs = debug
83
84 if debug {
85 fmt.Println("Starting decode, dst len:", len(dst))
86 }
87 var d, s, length int
88 offset := len(dict.dict) - dict.repeat
89
90 // As long as we can read at least 5 bytes...
91 for s < len(src)-5 {
92 // Removing bounds checks is SLOWER, when if doing
93 // in := src[s:s+5]
94 // Checked on Go 1.18
95 switch src[s] & 0x03 {
96 case tagLiteral:
97 x := uint32(src[s] >> 2)
98 switch {
99 case x < 60:
100 s++
101 case x == 60:
102 s += 2
103 x = uint32(src[s-1])
104 case x == 61:
105 in := src[s : s+3]
106 x = uint32(in[1]) | uint32(in[2])<<8
107 s += 3
108 case x == 62:
109 in := src[s : s+4]
110 // Load as 32 bit and shift down.
111 x = uint32(in[0]) | uint32(in[1])<<8 | uint32(in[2])<<16 | uint32(in[3])<<24
112 x >>= 8
113 s += 4
114 case x == 63:
115 in := src[s : s+5]
116 x = uint32(in[1]) | uint32(in[2])<<8 | uint32(in[3])<<16 | uint32(in[4])<<24
117 s += 5
118 }
119 length = int(x) + 1
120 if debug {
121 fmt.Println("literals, length:", length, "d-after:", d+length)
122 }
123 if length > len(dst)-d || length > len(src)-s || (strconv.IntSize == 32 && length <= 0) {
124 if debugErrs {
125 fmt.Println("corrupt literal: length:", length, "d-left:", len(dst)-d, "src-left:", len(src)-s)
126 }
127 return decodeErrCodeCorrupt
128 }
129
130 copy(dst[d:], src[s:s+length])
131 d += length
132 s += length
133 continue
134
135 case tagCopy1:
136 s += 2
137 toffset := int(uint32(src[s-2])&0xe0<<3 | uint32(src[s-1]))
138 length = int(src[s-2]) >> 2 & 0x7
139 if toffset == 0 {
140 if debug {
141 fmt.Print("(repeat) ")
142 }
143 // keep last offset
144 switch length {
145 case 5:
146 length = int(src[s]) + 4
147 s += 1
148 case 6:
149 in := src[s : s+2]
150 length = int(uint32(in[0])|(uint32(in[1])<<8)) + (1 << 8)
151 s += 2
152 case 7:
153 in := src[s : s+3]
154 length = int((uint32(in[2])<<16)|(uint32(in[1])<<8)|uint32(in[0])) + (1 << 16)
155 s += 3
156 default: // 0-> 4
157 }
158 } else {
159 offset = toffset
160 }
161 length += 4
162 case tagCopy2:
163 in := src[s : s+3]
164 offset = int(uint32(in[1]) | uint32(in[2])<<8)
165 length = 1 + int(in[0])>>2
166 s += 3
167
168 case tagCopy4:
169 in := src[s : s+5]
170 offset = int(uint32(in[1]) | uint32(in[2])<<8 | uint32(in[3])<<16 | uint32(in[4])<<24)
171 length = 1 + int(in[0])>>2
172 s += 5
173 }
174
175 if offset <= 0 || length > len(dst)-d {
176 if debugErrs {
177 fmt.Println("match error; offset:", offset, "length:", length, "dst-left:", len(dst)-d)
178 }
179 return decodeErrCodeCorrupt
180 }
181
182 // copy from dict
183 if d < offset {
184 if d > MaxDictSrcOffset {
185 if debugErrs {
186 fmt.Println("dict after", MaxDictSrcOffset, "d:", d, "offset:", offset, "length:", length)
187 }
188 return decodeErrCodeCorrupt
189 }
190 startOff := len(dict.dict) - offset + d
191 if startOff < 0 || startOff+length > len(dict.dict) {
192 if debugErrs {
193 fmt.Printf("offset (%d) + length (%d) bigger than dict (%d)\n", offset, length, len(dict.dict))
194 }
195 return decodeErrCodeCorrupt
196 }
197 if debug {
198 fmt.Println("dict copy, length:", length, "offset:", offset, "d-after:", d+length, "dict start offset:", startOff)
199 }
200 copy(dst[d:d+length], dict.dict[startOff:])
201 d += length
202 continue
203 }
204
205 if debug {
206 fmt.Println("copy, length:", length, "offset:", offset, "d-after:", d+length)
207 }
208
209 // Copy from an earlier sub-slice of dst to a later sub-slice.
210 // If no overlap, use the built-in copy:
211 if offset > length {
212 copy(dst[d:d+length], dst[d-offset:])
213 d += length
214 continue
215 }
216
217 // Unlike the built-in copy function, this byte-by-byte copy always runs
218 // forwards, even if the slices overlap. Conceptually, this is:
219 //
220 // d += forwardCopy(dst[d:d+length], dst[d-offset:])
221 //
222 // We align the slices into a and b and show the compiler they are the same size.
223 // This allows the loop to run without bounds checks.
224 a := dst[d : d+length]
225 b := dst[d-offset:]
226 b = b[:len(a)]
227 for i := range a {
228 a[i] = b[i]
229 }
230 d += length
231 }
232
233 // Remaining with extra checks...
234 for s < len(src) {
235 switch src[s] & 0x03 {
236 case tagLiteral:
237 x := uint32(src[s] >> 2)
238 switch {
239 case x < 60:
240 s++
241 case x == 60:
242 s += 2
243 if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
244 if debugErrs {
245 fmt.Println("src went oob")
246 }
247 return decodeErrCodeCorrupt
248 }
249 x = uint32(src[s-1])
250 case x == 61:
251 s += 3
252 if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
253 if debugErrs {
254 fmt.Println("src went oob")
255 }
256 return decodeErrCodeCorrupt
257 }
258 x = uint32(src[s-2]) | uint32(src[s-1])<<8
259 case x == 62:
260 s += 4
261 if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
262 if debugErrs {
263 fmt.Println("src went oob")
264 }
265 return decodeErrCodeCorrupt
266 }
267 x = uint32(src[s-3]) | uint32(src[s-2])<<8 | uint32(src[s-1])<<16
268 case x == 63:
269 s += 5
270 if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
271 if debugErrs {
272 fmt.Println("src went oob")
273 }
274 return decodeErrCodeCorrupt
275 }
276 x = uint32(src[s-4]) | uint32(src[s-3])<<8 | uint32(src[s-2])<<16 | uint32(src[s-1])<<24
277 }
278 length = int(x) + 1
279 if length > len(dst)-d || length > len(src)-s || (strconv.IntSize == 32 && length <= 0) {
280 if debugErrs {
281 fmt.Println("corrupt literal: length:", length, "d-left:", len(dst)-d, "src-left:", len(src)-s)
282 }
283 return decodeErrCodeCorrupt
284 }
285 if debug {
286 fmt.Println("literals, length:", length, "d-after:", d+length)
287 }
288
289 copy(dst[d:], src[s:s+length])
290 d += length
291 s += length
292 continue
293
294 case tagCopy1:
295 s += 2
296 if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
297 if debugErrs {
298 fmt.Println("src went oob")
299 }
300 return decodeErrCodeCorrupt
301 }
302 length = int(src[s-2]) >> 2 & 0x7
303 toffset := int(uint32(src[s-2])&0xe0<<3 | uint32(src[s-1]))
304 if toffset == 0 {
305 if debug {
306 fmt.Print("(repeat) ")
307 }
308 // keep last offset
309 switch length {
310 case 5:
311 s += 1
312 if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
313 if debugErrs {
314 fmt.Println("src went oob")
315 }
316 return decodeErrCodeCorrupt
317 }
318 length = int(uint32(src[s-1])) + 4
319 case 6:
320 s += 2
321 if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
322 if debugErrs {
323 fmt.Println("src went oob")
324 }
325 return decodeErrCodeCorrupt
326 }
327 length = int(uint32(src[s-2])|(uint32(src[s-1])<<8)) + (1 << 8)
328 case 7:
329 s += 3
330 if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
331 if debugErrs {
332 fmt.Println("src went oob")
333 }
334 return decodeErrCodeCorrupt
335 }
336 length = int(uint32(src[s-3])|(uint32(src[s-2])<<8)|(uint32(src[s-1])<<16)) + (1 << 16)
337 default: // 0-> 4
338 }
339 } else {
340 offset = toffset
341 }
342 length += 4
343 case tagCopy2:
344 s += 3
345 if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
346 if debugErrs {
347 fmt.Println("src went oob")
348 }
349 return decodeErrCodeCorrupt
350 }
351 length = 1 + int(src[s-3])>>2
352 offset = int(uint32(src[s-2]) | uint32(src[s-1])<<8)
353
354 case tagCopy4:
355 s += 5
356 if uint(s) > uint(len(src)) { // The uint conversions catch overflow from the previous line.
357 if debugErrs {
358 fmt.Println("src went oob")
359 }
360 return decodeErrCodeCorrupt
361 }
362 length = 1 + int(src[s-5])>>2
363 offset = int(uint32(src[s-4]) | uint32(src[s-3])<<8 | uint32(src[s-2])<<16 | uint32(src[s-1])<<24)
364 }
365
366 if offset <= 0 || length > len(dst)-d {
367 if debugErrs {
368 fmt.Println("match error; offset:", offset, "length:", length, "dst-left:", len(dst)-d)
369 }
370 return decodeErrCodeCorrupt
371 }
372
373 // copy from dict
374 if d < offset {
375 if d > MaxDictSrcOffset {
376 if debugErrs {
377 fmt.Println("dict after", MaxDictSrcOffset, "d:", d, "offset:", offset, "length:", length)
378 }
379 return decodeErrCodeCorrupt
380 }
381 rOff := len(dict.dict) - (offset - d)
382 if debug {
383 fmt.Println("starting dict entry from dict offset", len(dict.dict)-rOff)
384 }
385 if rOff+length > len(dict.dict) {
386 if debugErrs {
387 fmt.Println("err: END offset", rOff+length, "bigger than dict", len(dict.dict), "dict offset:", rOff, "length:", length)
388 }
389 return decodeErrCodeCorrupt
390 }
391 if rOff < 0 {
392 if debugErrs {
393 fmt.Println("err: START offset", rOff, "less than 0", len(dict.dict), "dict offset:", rOff, "length:", length)
394 }
395 return decodeErrCodeCorrupt
396 }
397 copy(dst[d:d+length], dict.dict[rOff:])
398 d += length
399 continue
400 }
401
402 if debug {
403 fmt.Println("copy, length:", length, "offset:", offset, "d-after:", d+length)
404 }
405
406 // Copy from an earlier sub-slice of dst to a later sub-slice.
407 // If no overlap, use the built-in copy:
408 if offset > length {
409 copy(dst[d:d+length], dst[d-offset:])
410 d += length
411 continue
412 }
413
414 // Unlike the built-in copy function, this byte-by-byte copy always runs
415 // forwards, even if the slices overlap. Conceptually, this is:
416 //
417 // d += forwardCopy(dst[d:d+length], dst[d-offset:])
418 //
419 // We align the slices into a and b and show the compiler they are the same size.
420 // This allows the loop to run without bounds checks.
421 a := dst[d : d+length]
422 b := dst[d-offset:]
423 b = b[:len(a)]
424 for i := range a {
425 a[i] = b[i]
426 }
427 d += length
428 }
429
430 if d != len(dst) {
431 if debugErrs {
432 fmt.Println("wanted length", len(dst), "got", d)
433 }
434 return decodeErrCodeCorrupt
435 }
436 return 0
437}
generated by cgit v1.2.3 (git 2.45.2) at 2024-11-18 23:07:15 +0000