From 569b8ba4d9934a53fbf070a17f53f6bbdaf0df07 Mon Sep 17 00:00:00 2001
From: Yann Collet <cyan@fb.com>
Date: Tue, 20 Mar 2018 15:43:49 -0700
Subject: [PATCH] implemented ZSTD_DCtx_refDDict()

---
 lib/decompress/zstd_decompress.c | 21 ++++++++++++++++-----
 lib/zstd.h                       |  2 +-
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/lib/decompress/zstd_decompress.c b/lib/decompress/zstd_decompress.c
index 3aefcc6c..d3cd7a8c 100644
--- a/lib/decompress/zstd_decompress.c
+++ b/lib/decompress/zstd_decompress.c
@@ -2567,6 +2567,7 @@ size_t ZSTD_DStreamOutSize(void) { return ZSTD_BLOCKSIZE_MAX; }
 
 size_t ZSTD_DCtx_loadDictionary_advanced(ZSTD_DCtx* dctx, const void* dict, size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictContentType_e dictContentType)
 {
+    if (dctx->streamStage != zdss_init) return ERROR(stage_wrong);
     ZSTD_freeDDict(dctx->ddictLocal);
     if (dict && dictSize >= 8) {
         dctx->ddictLocal = ZSTD_createDDict_advanced(dict, dictSize, dictLoadMethod, dictContentType, dctx->customMem);
@@ -2588,15 +2589,15 @@ size_t ZSTD_DCtx_loadDictionary(ZSTD_DCtx* dctx, const void* dict, size_t dictSi
     return ZSTD_DCtx_loadDictionary_advanced(dctx, dict, dictSize, ZSTD_dlm_byCopy, ZSTD_dct_auto);
 }
 
+/* ZSTD_initDStream_usingDict() :
+ * return : expected size, aka ZSTD_frameHeaderSize_prefix.
+ * this function cannot fail */
 size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t dictSize)
 {
     DEBUGLOG(4, "ZSTD_initDStream_usingDict");
-    zds->streamStage = zdss_loadHeader;
-    zds->lhSize = zds->inPos = zds->outStart = zds->outEnd = 0;
+    zds->streamStage = zdss_init;
     CHECK_F( ZSTD_DCtx_loadDictionary(zds, dict, dictSize) );
-    zds->legacyVersion = 0;
-    zds->hostageByte = 0;
-    return ZSTD_frameHeaderSize_prefix;
+    return ZSTD_resetDStream(zds);
 }
 
 /* note : this variant can't fail */
@@ -2606,6 +2607,13 @@ size_t ZSTD_initDStream(ZSTD_DStream* zds)
     return ZSTD_initDStream_usingDict(zds, NULL, 0);
 }
 
+size_t ZSTD_DCtx_refDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict)
+{
+    if (dctx->streamStage != zdss_init) return ERROR(stage_wrong);
+    dctx->ddict = ddict;
+    return 0;
+}
+
 /* ZSTD_initDStream_usingDDict() :
  * ddict will just be referenced, and must outlive decompression session
  * this function cannot fail */
@@ -2616,6 +2624,9 @@ size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict)
     return initResult;
 }
 
+/* ZSTD_resetDStream() :
+ * return : expected size, aka ZSTD_frameHeaderSize_prefix.
+ * this function cannot fail */
 size_t ZSTD_resetDStream(ZSTD_DStream* zds)
 {
     DEBUGLOG(4, "ZSTD_resetDStream");
diff --git a/lib/zstd.h b/lib/zstd.h
index c90e8d22..4b825742 100644
--- a/lib/zstd.h
+++ b/lib/zstd.h
@@ -1286,7 +1286,7 @@ ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary_advanced(ZSTD_DCtx* dctx, const void
  *  Special : adding a NULL DDict means "return to no-dictionary mode".
  *  Note 2 : DDict is just referenced, its lifetime must outlive its usage from DCtx.
  */
-ZSTDLIB_API size_t ZSTD_DCtx_refDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict);   /* not implemented */
+ZSTDLIB_API size_t ZSTD_DCtx_refDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict);
 
 
 /*! ZSTD_DCtx_refPrefix() :