Add ZSTD_CCtx_resetParameters() function

* Fix docs for `ZSTD_CCtx_reset()`.
* Add `ZSTD_CCtx_resetParameters()`.

Fixes #1094.

diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c
index 590e92c8e8c568a83b65d548dbc3c46d6122ea5e..ecda036b5ae3d4019aeaf475ae8eec0260c4f22e 100644 (file)
--- a/lib/compress/zstd_compress.c
+++ b/lib/compress/zstd_compress.c
@@ -72,9 +72,11 @@ ZSTD_CCtx* ZSTD_createCCtx_advanced(ZSTD_customMem customMem)
     {   ZSTD_CCtx* const cctx = (ZSTD_CCtx*)ZSTD_calloc(sizeof(ZSTD_CCtx), customMem);
         if (!cctx) return NULL;
         cctx->customMem = customMem;
-        cctx->requestedParams.compressionLevel = ZSTD_CLEVEL_DEFAULT;
-        cctx->requestedParams.fParams.contentSizeFlag = 1;
         cctx->bmi2 = ZSTD_cpuid_bmi2(ZSTD_cpuid());
+        {   size_t const err = ZSTD_CCtx_resetParameters(cctx);
+            assert(!ZSTD_isError(err));
+            (void)err;
+        }
         return cctx;
     }
 }
@@ -671,6 +673,12 @@ void ZSTD_CCtx_reset(ZSTD_CCtx* cctx)
     cctx->cdict = NULL;
 }
 
+size_t ZSTD_CCtx_resetParameters(ZSTD_CCtx* cctx)
+{
+    if (cctx->streamStage != zcss_init) return ERROR(stage_wrong);
+    return ZSTD_CCtxParams_reset(&cctx->requestedParams);
+}
+
 /** ZSTD_checkCParams() :
     control CParam values remain within authorized range.
     @return : 0, or an error code if one value is beyond authorized range */

diff --git a/lib/zstd.h b/lib/zstd.h
index 913c599bb585df8631233b85e512f2e7d3c0a9ad..aaec49fe7fd03c8b03fab14532b2915e3b392ab4 100644 (file)
--- a/lib/zstd.h
+++ b/lib/zstd.h
@@ -1142,11 +1142,16 @@ ZSTDLIB_API size_t ZSTD_CCtx_refPrefix_advanced(ZSTD_CCtx* cctx, const void* pre
  *  Useful after an error, or to interrupt an ongoing compression job and start a new one.
  *  Any internal data not yet flushed is cancelled.
  *  Dictionary (if any) is dropped.
- *  All parameters are back to default values (compression level is ZSTD_CLEVEL_DEFAULT).
- *  After a reset, all compression parameters can be modified again.
  */
 ZSTDLIB_API void ZSTD_CCtx_reset(ZSTD_CCtx* cctx);
 
+/*! ZSTD_CCtx_resetParameters() :
+ *  All parameters are back to default values (compression level is ZSTD_CLEVEL_DEFAULT).
+ *  Resetting parameters is only possible during frame initialization (before starting compression).
+ *  @return 0 or an error code (which can be checked with ZSTD_isError()).
+ */
+ZSTDLIB_API size_t ZSTD_CCtx_resetParameters(ZSTD_CCtx* cctx);
+
 
 
 typedef enum {

diff --git a/tests/fuzzer.c b/tests/fuzzer.c
index 33d27cda79a36c819b4a235f764efa9d9163bdce..9b49ddd080e36df3536dec82070023ec77780cff 100644 (file)
--- a/tests/fuzzer.c
+++ b/tests/fuzzer.c
@@ -433,6 +433,12 @@ static int basicUnitTests(U32 seed, double compressibility)
         CHECK_EQ(value, 7);
         CHECK_Z(ZSTD_CCtx_getParameter(cctx, ZSTD_p_hashLog, &value));
         CHECK_EQ(value, ZSTD_HASHLOG_MIN);
+        /* Reset the parameters */
+        ZSTD_CCtx_resetParameters(cctx);
+        CHECK_Z(ZSTD_CCtx_getParameter(cctx, ZSTD_p_compressionLevel, &value));
+        CHECK_EQ(value, 3);
+        CHECK_Z(ZSTD_CCtx_getParameter(cctx, ZSTD_p_hashLog, &value));
+        CHECK_EQ(value, 0);
 
         ZSTD_freeCCtx(cctx);
     }