ddidderr/zstd-rs
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make stableSrc compatible with regular streaming API

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including flushStream().

Now the only condition is for `input.size` to continuously grow.
This commit is contained in:
Yann Collet
2022-01-26 10:31:24 -08:00
parent c0c5ffa973
commit 37b87add7a
3 changed files with 48 additions and 44 deletions
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lib/compress/zstd_compress.c
+9 -8
View File
@@ -5338,7 +5338,7 @@ static size_t ZSTD_compressStream_generic(ZSTD_CStream* zcs,
U32 someMoreWork = 1;
/* check expectations */
DEBUGLOG(5, "ZSTD_compressStream_generic, flush=%u", (unsigned)flushMode);
DEBUGLOG(5, "ZSTD_compressStream_generic, flush=%i", (int)flushMode);
if (zcs->appliedParams.inBufferMode == ZSTD_bm_buffered) {
assert(zcs->inBuff != NULL);
assert(zcs->inBuffSize > 0);
@@ -5424,9 +5424,8 @@ static size_t ZSTD_compressStream_generic(ZSTD_CStream* zcs,
if (!lastBlock)
assert(zcs->inBuffTarget <= zcs->inBuffSize);
zcs->inToCompress = zcs->inBuffPos;
} else {
} else { /* !inputBuffered, hence ZSTD_bm_stable */
unsigned const lastBlock = (ip + iSize == iend);
assert(flushMode == ZSTD_e_end /* Already validated */);
cSize = lastBlock ?
ZSTD_compressEnd(zcs, cDst, oSize, ip, iSize) :
ZSTD_compressContinue(zcs, cDst, oSize, ip, iSize);
@@ -5533,11 +5532,10 @@ static size_t ZSTD_checkBufferStability(ZSTD_CCtx const* cctx,
{
if (cctx->appliedParams.inBufferMode == ZSTD_bm_stable) {
ZSTD_inBuffer const expect = cctx->expectedInBuffer;
if (expect.src != input->src || expect.pos != input->pos || expect.size != input->size)
if (expect.src != input->src || expect.pos != input->pos)
RETURN_ERROR(srcBuffer_wrong, "ZSTD_c_stableInBuffer enabled but input differs!");
if (endOp != ZSTD_e_end)
RETURN_ERROR(srcBuffer_wrong, "ZSTD_c_stableInBuffer can only be used with ZSTD_e_end!");
}
(void)endOp;
if (cctx->appliedParams.outBufferMode == ZSTD_bm_stable) {
size_t const outBufferSize = output->size - output->pos;
if (cctx->expectedOutBufferSize != outBufferSize)
@@ -5650,7 +5648,7 @@ size_t ZSTD_compressStream2( ZSTD_CCtx* cctx,
&& (endOp == ZSTD_e_continue) /* more to come */
&& (input->pos < ZSTD_BLOCKSIZE_MAX) ) { /* not even reached one block yet */
cctx->expectedInBuffer = *input;
return (ZSTD_BLOCKSIZE_MAX - input->pos); /* don't do anything : allows lazy compression parameters adaptation */
return (ZSTD_BLOCKSIZE_MAX - input->pos); /* don't do anything : allows lazy adaptation of compression parameters */
}
FORWARD_IF_ERROR(ZSTD_CCtx_init_compressStream2(cctx, endOp, input->size), "CompressStream2 initialization failed");
ZSTD_setBufferExpectations(cctx, output, input); /* Set initial buffer expectations now that we've initialized */
@@ -6167,7 +6165,10 @@ size_t ZSTD_compressSequences(ZSTD_CCtx* const cctx, void* dst, size_t dstCapaci
* @return : amount of data remaining to flush */
size_t ZSTD_flushStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output)
{
ZSTD_inBuffer input = { NULL, 0, 0 };
ZSTD_inBuffer const nullInput = { NULL, 0, 0 };
int const stableInput = (zcs->appliedParams.inBufferMode == ZSTD_bm_stable);
ZSTD_inBuffer input = stableInput ? zcs->expectedInBuffer : nullInput;
input.size = input.pos; /* do not ingest more input during flush */
return ZSTD_compressStream2(zcs, output, &input, ZSTD_e_flush);
}
lib/zstd.h
+14 -14
View File
@@ -1829,13 +1829,16 @@ ZSTDLIB_STATIC_API size_t ZSTD_CCtx_refPrefix_advanced(ZSTD_CCtx* cctx, const vo
* Experimental parameter.
* Default is 0 == disabled. Set to 1 to enable.
*
* Tells the compressor that the ZSTD_inBuffer will ALWAYS be the same
* between calls, except for the modifications that zstd makes to pos (the
* caller must not modify pos). This is checked by the compressor, and
* compression will fail if it ever changes. This means the only flush
* mode that makes sense is ZSTD_e_end, so zstd will error if ZSTD_e_end
* is not used. The data in the ZSTD_inBuffer in the range [src, src + pos)
* MUST not be modified during compression or you will get data corruption.
* Tells the compressor that input data presented with ZSTD_inBuffer
* will ALWAYS be the same between calls.
* Technically, the @src pointer must never be changed,
* and the @pos field can only be updated by zstd.
* However, it's possible to increase the @size field,
* allowing scenarios where more data can be appended after compressions starts.
* These conditions are checked by the compressor,
* and compression will fail if they are not respected.
* Also, data in the ZSTD_inBuffer within the range [src, src + pos)
* MUST not be modified during compression or it will result in data corruption.
*
* When this flag is enabled zstd won't allocate an input window buffer,
* because the user guarantees it can reference the ZSTD_inBuffer until
@@ -1843,18 +1846,15 @@ ZSTDLIB_STATIC_API size_t ZSTD_CCtx_refPrefix_advanced(ZSTD_CCtx* cctx, const vo
* large enough to fit a block (see ZSTD_c_stableOutBuffer). This will also
* avoid the memcpy() from the input buffer to the input window buffer.
*
* NOTE: ZSTD_compressStream2() will error if ZSTD_e_flush is used.
* That means this flag cannot be used with ZSTD_flushStream().
*
* NOTE: So long as the ZSTD_inBuffer always points to valid memory, using
* this flag is ALWAYS memory safe, and will never access out-of-bounds
* memory. However, compression WILL fail if you violate the preconditions.
* memory. However, compression WILL fail if conditions are not respected.
*
* WARNING: The data in the ZSTD_inBuffer in the range [src, src + pos) MUST
* not be modified during compression or you will get data corruption. This
* is because zstd needs to reference data in the ZSTD_inBuffer to find
* not be modified during compression or it sill result in data corruption.
* This is because zstd needs to reference data in the ZSTD_inBuffer to find
* matches. Normally zstd maintains its own window buffer for this purpose,
* but passing this flag tells zstd to use the user provided buffer.
* but passing this flag tells zstd to rely on user provided buffer instead.
*/
#define ZSTD_c_stableInBuffer ZSTD_c_experimentalParam9