[fix] Always return dstSize_tooSmall when it is the case

lib/decompress/zstd_decompress.c

@@ -579,11 +579,11 @@ static size_t ZSTD_copyRawBlock(void* dst, size_t dstCapacity,
                           const void* src, size_t srcSize)
 {
     DEBUGLOG(5, "ZSTD_copyRawBlock");
+    RETURN_ERROR_IF(srcSize > dstCapacity, dstSize_tooSmall, "");
     if (dst == NULL) {
         if (srcSize == 0) return 0;
         RETURN_ERROR(dstBuffer_null, "");
     }
-    RETURN_ERROR_IF(srcSize > dstCapacity, dstSize_tooSmall, "");
     memcpy(dst, src, srcSize);
     return srcSize;
 }
@@ -592,11 +592,11 @@ static size_t ZSTD_setRleBlock(void* dst, size_t dstCapacity,
                                BYTE b,
                                size_t regenSize)
 {
+    RETURN_ERROR_IF(regenSize > dstCapacity, dstSize_tooSmall, "");
     if (dst == NULL) {
         if (regenSize == 0) return 0;
         RETURN_ERROR(dstBuffer_null, "");
     }
-    RETURN_ERROR_IF(regenSize > dstCapacity, dstSize_tooSmall, "");
     memset(dst, b, regenSize);
     return regenSize;
 }

lib/decompress/zstd_decompress_block.c

@@ -1084,14 +1084,14 @@ ZSTD_decompressSequences_body( ZSTD_DCtx* dctx,
 #endif
             DEBUGLOG(6, "regenerated sequence size : %u", (U32)oneSeqSize);
             BIT_reloadDStream(&(seqState.DStream));
+            op += oneSeqSize;
             /* gcc and clang both don't like early returns in this loop.
-             * gcc doesn't like early breaks either.
-             * Instead save an error and report it at the end.
-             * When there is an error, don't increment op, so we don't
-             * overwrite.
+             * Instead break and check for an error at the end of the loop.
              */
-            if (UNLIKELY(ZSTD_isError(oneSeqSize))) error = oneSeqSize;
-            else op += oneSeqSize;
+            if (UNLIKELY(ZSTD_isError(oneSeqSize))) {
+                error = oneSeqSize;
+                break;
+            }
             if (UNLIKELY(!--nbSeq)) break;
         }