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author | Yann Collet <Cyan4973@users.noreply.github.com> | 2019-08-07 23:48:53 (GMT) |
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committer | GitHub <noreply@github.com> | 2019-08-07 23:48:53 (GMT) |
commit | 1bcde6414a68094601ecd57a968808fdd43fb986 (patch) | |
tree | 718b41f2409059aa4c3acb6ba22c8c98b4d16a51 | |
parent | b5b9760c80d70aaa5805c460cb61faad31cbf234 (diff) | |
parent | 4c580067199c4a7fdcacc6961842ee6d3832bb93 (diff) | |
download | lz4-1bcde6414a68094601ecd57a968808fdd43fb986.zip lz4-1bcde6414a68094601ecd57a968808fdd43fb986.tar.gz lz4-1bcde6414a68094601ecd57a968808fdd43fb986.tar.bz2 |
Merge pull request #773 from felixhandte/attach-empty-dict-behavior-conformance
Make Attaching an Empty Dict Behave the Same as Using it Directly
-rw-r--r-- | lib/lz4.c | 31 |
1 files changed, 21 insertions, 10 deletions
@@ -1408,18 +1408,18 @@ int LZ4_loadDict (LZ4_stream_t* LZ4_dict, const char* dictionary, int dictSize) * there are only valid offsets in the window, which allows an optimization * in LZ4_compress_fast_continue() where it uses noDictIssue even when the * dictionary isn't a full 64k. */ - - if ((dictEnd - p) > 64 KB) p = dictEnd - 64 KB; - base = dictEnd - 64 KB - dict->currentOffset; - dict->dictionary = p; - dict->dictSize = (U32)(dictEnd - p); dict->currentOffset += 64 KB; - dict->tableType = tableType; if (dictSize < (int)HASH_UNIT) { return 0; } + if ((dictEnd - p) > 64 KB) p = dictEnd - 64 KB; + base = dictEnd - dict->currentOffset; + dict->dictionary = p; + dict->dictSize = (U32)(dictEnd - p); + dict->tableType = tableType; + while (p <= dictEnd-HASH_UNIT) { LZ4_putPosition(p, dict->hashTable, tableType, base); p+=3; @@ -1429,13 +1429,20 @@ int LZ4_loadDict (LZ4_stream_t* LZ4_dict, const char* dictionary, int dictSize) } void LZ4_attach_dictionary(LZ4_stream_t* workingStream, const LZ4_stream_t* dictionaryStream) { + const LZ4_stream_t_internal* dictCtx = dictionaryStream == NULL ? NULL : + &(dictionaryStream->internal_donotuse); + + DEBUGLOG(4, "LZ4_attach_dictionary (%p, %p, size %u)", + workingStream, dictionaryStream, + dictCtx != NULL ? dictCtx->dictSize : 0); + /* Calling LZ4_resetStream_fast() here makes sure that changes will not be * erased by subsequent calls to LZ4_resetStream_fast() in case stream was * marked as having dirty context, e.g. requiring full reset. */ LZ4_resetStream_fast(workingStream); - if (dictionaryStream != NULL && dictionaryStream->internal_donotuse.dictSize > 0) { + if (dictCtx != NULL) { /* If the current offset is zero, we will never look in the * external dictionary context, since there is no value a table * entry can take that indicate a miss. In that case, we need @@ -1444,10 +1451,14 @@ void LZ4_attach_dictionary(LZ4_stream_t* workingStream, const LZ4_stream_t* dict if (workingStream->internal_donotuse.currentOffset == 0) { workingStream->internal_donotuse.currentOffset = 64 KB; } - workingStream->internal_donotuse.dictCtx = &(dictionaryStream->internal_donotuse); - } else { - workingStream->internal_donotuse.dictCtx = NULL; + + /* Don't actually attach an empty dictionary. + */ + if (dictCtx->dictSize == 0) { + dictCtx = NULL; + } } + workingStream->internal_donotuse.dictCtx = dictCtx; } |