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internal/zstd: allow zero dictionary id

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A value of 0 has same meaning as no Dictionary_ID,
in which case the frame may or may not need a dictionary to be decoded,
and the ID of such a dictionary is not specified.

See https://github.com/facebook/zstd/issues/2172

For #62513

Change-Id: If0eafcbc5d2188576f0cb687234e30c9eb4037a6
GitHub-Last-Rev: 9cf12dcf19
GitHub-Pull-Request: golang/go#63268
Reviewed-on: https://go-review.googlesource.com/c/go/+/531515
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
This commit is contained in:
Alexander Yastrebov 2023-09-27 23:53:37 +00:00 committed by Gopher Robot
parent 9d3cc85e51
commit a57658171f
2 changed files with 18 additions and 5 deletions
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src/internal/zstd/testdata/fcf30b99.zero-dictionary-ids.zst vendored Normal file
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23
src/internal/zstd/zstd.go
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@ -221,13 +221,15 @@ retry:
r.checksum.reset() r.checksum.reset()
} }
if descriptor&3 != 0 { // Dictionary_ID_Flag. RFC 3.1.1.1.1.6.
return r.makeError(relativeOffset, "dictionaries are not supported") dictionaryIdSize := 0
if dictIdFlag := descriptor & 3; dictIdFlag != 0 {
dictionaryIdSize = 1 << (dictIdFlag - 1)
} }
relativeOffset++ relativeOffset++
headerSize := windowDescriptorSize + fcsFieldSize headerSize := windowDescriptorSize + dictionaryIdSize + fcsFieldSize
if _, err := io.ReadFull(r.r, r.scratch[:headerSize]); err != nil { if _, err := io.ReadFull(r.r, r.scratch[:headerSize]); err != nil {
return r.wrapNonEOFError(relativeOffset, err) return r.wrapNonEOFError(relativeOffset, err)
@ -252,10 +254,21 @@ retry:
} }
} }
// Frame_Content_Size. RFC 3.1.1.4. // Dictionary_ID. RFC 3.1.1.1.3.
if dictionaryIdSize != 0 {
dictionaryId := r.scratch[windowDescriptorSize : windowDescriptorSize+dictionaryIdSize]
// Allow only zero Dictionary ID.
for _, b := range dictionaryId {
if b != 0 {
return r.makeError(relativeOffset, "dictionaries are not supported")
}
}
}
// Frame_Content_Size. RFC 3.1.1.1.4.
r.frameSizeUnknown = false r.frameSizeUnknown = false
r.remainingFrameSize = 0 r.remainingFrameSize = 0
fb := r.scratch[windowDescriptorSize:] fb := r.scratch[windowDescriptorSize+dictionaryIdSize:]
switch fcsFieldSize { switch fcsFieldSize {
case 0: case 0:
r.frameSizeUnknown = true r.frameSizeUnknown = true