Add legacy support to decompressBound
diff --git a/lib/legacy/zstd_v02.c b/lib/legacy/zstd_v02.c
index c09ef8c..0649610 100644
--- a/lib/legacy/zstd_v02.c
+++ b/lib/legacy/zstd_v02.c
@@ -2728,6 +2728,9 @@
 #define LITERAL_NOENTROPY 63
 #define COMMAND_NOENTROPY 7   /* to remove */
 
+#define ZSTD_CONTENTSIZE_UNKNOWN (0ULL - 1)
+#define ZSTD_CONTENTSIZE_ERROR   (0ULL - 2)
+
 static const size_t ZSTD_blockHeaderSize = 3;
 static const size_t ZSTD_frameHeaderSize = 4;
 
@@ -3312,37 +3315,58 @@
     return ZSTD_decompressDCtx(&ctx, dst, maxDstSize, src, srcSize);
 }
 
-static size_t ZSTD_findFrameCompressedSize(const void *src, size_t srcSize)
+MEM_STATIC void ZSTD_errorFrameSizeInfoLegacy(size_t* cSize, unsigned long long* dBound, size_t ret)
 {
+    *cSize = ret;
+    *dBound = ZSTD_CONTENTSIZE_ERROR;
+}
 
+void ZSTDv02_findFrameSizeInfoLegacy(const void *src, size_t srcSize,
+                                     size_t* cSize, unsigned long long* dBound)
+{
     const BYTE* ip = (const BYTE*)src;
     size_t remainingSize = srcSize;
+    size_t nbBlocks = 0;
     U32 magicNumber;
     blockProperties_t blockProperties;
 
     /* Frame Header */
-    if (srcSize < ZSTD_frameHeaderSize+ZSTD_blockHeaderSize) return ERROR(srcSize_wrong);
+    if (srcSize < ZSTD_frameHeaderSize+ZSTD_blockHeaderSize) {
+        ZSTD_errorFrameSizeInfoLegacy(cSize, dBound, ERROR(srcSize_wrong));
+        return;
+    }
     magicNumber = MEM_readLE32(src);
-    if (magicNumber != ZSTD_magicNumber) return ERROR(prefix_unknown);
+    if (magicNumber != ZSTD_magicNumber) {
+        ZSTD_errorFrameSizeInfoLegacy(cSize, dBound, ERROR(prefix_unknown));
+        return;
+    }
     ip += ZSTD_frameHeaderSize; remainingSize -= ZSTD_frameHeaderSize;
 
     /* Loop on each block */
     while (1)
     {
         size_t cBlockSize = ZSTD_getcBlockSize(ip, remainingSize, &blockProperties);
-        if (ZSTD_isError(cBlockSize)) return cBlockSize;
+        if (ZSTD_isError(cBlockSize)) {
+            ZSTD_errorFrameSizeInfoLegacy(cSize, dBound, cBlockSize);
+            return;
+        }
 
         ip += ZSTD_blockHeaderSize;
         remainingSize -= ZSTD_blockHeaderSize;
-        if (cBlockSize > remainingSize) return ERROR(srcSize_wrong);
+        if (cBlockSize > remainingSize) {
+            ZSTD_errorFrameSizeInfoLegacy(cSize, dBound, ERROR(srcSize_wrong));
+            return;
+        }
 
         if (cBlockSize == 0) break;   /* bt_end */
 
         ip += cBlockSize;
         remainingSize -= cBlockSize;
+        nbBlocks++;
     }
 
-    return ip - (const BYTE*)src;
+    *cSize = ip - (const BYTE*)src;
+    *dBound = nbBlocks * BLOCKSIZE;
 }
 
 /*******************************
@@ -3458,11 +3482,6 @@
     return ZSTD_decompress(dst, maxOriginalSize, src, compressedSize);
 }
 
-size_t ZSTDv02_findFrameCompressedSize(const void *src, size_t compressedSize)
-{
-    return ZSTD_findFrameCompressedSize(src, compressedSize);
-}
-
 ZSTDv02_Dctx* ZSTDv02_createDCtx(void)
 {
     return (ZSTDv02_Dctx*)ZSTD_createDCtx();