Do not try to allocate memory on de-serialization when there is no need

to do so.

Author: Shumaro

src/lib/support/SerializationUtils.cpp

@@ -46,7 +46,9 @@ using namespace nl::Weave::TLV;
 //
 // The assumption is that de-serialization will likely be performed
 // only on resource-rich platforms where dynamic memory allocation is
-// supported.
+// supported. However, it is still possible to use de-serialization without
+// memory allocation provided that there is no string to de-serialize or if so,
+// strings are empty.
 //
 
 #if WEAVE_CONFIG_SERIALIZATION_ENABLE_DESERIALIZATION
@@ -877,18 +879,29 @@ WEAVE_ERROR ReadDataForType(TLVReader &aReader, void *aStructureData, const Fiel
 
         case SerializedFieldTypeUTF8String:
         {
-            char *dst = NULL;
             // TLV Strings are not null terminated
             uint32_t length = aReader.GetLength() + 1;
 
-            dst = (char *)memMgmt->mem_alloc(length);
-            VerifyOrExit(dst != NULL, err = WEAVE_ERROR_NO_MEMORY);
+            if (length > 1)
+            {
+                char *dst = NULL;
 
-            err = aReader.GetString(dst, length);
-            SuccessOrExit(err);
+                dst = (char *)memMgmt->mem_alloc(length);
+                VerifyOrExit(dst != NULL, err = WEAVE_ERROR_NO_MEMORY);
+
+                err = aReader.GetString(dst, length);
+                SuccessOrExit(err);
+
+                LogReadWrite("%s utf8string '%s' allocating %d bytes at %p", "R", dst, length, dst);
+
+                *static_cast<char**>(aStructureData) = dst;
+            }
+
+            else
+            {
+                *static_cast<char**>(aStructureData) = "";
+            }
 
-            LogReadWrite("%s utf8string '%s' allocating %d bytes at %p", "R", dst, length, dst);
-            *static_cast<char**>(aStructureData) = dst;
             break;
         }
 
@@ -897,11 +910,14 @@ WEAVE_ERROR ReadDataForType(TLVReader &aReader, void *aStructureData, const Fiel
             SerializedByteString byteString;
             byteString.mLen = aReader.GetLength();
 
-            byteString.mBuf = static_cast<uint8_t *>(memMgmt->mem_alloc(byteString.mLen));
-            VerifyOrExit(byteString.mBuf != NULL, err = WEAVE_ERROR_NO_MEMORY);
-            aReader.GetBytes(byteString.mBuf, byteString.mLen);
+            if (byteString.mLen > 0)
+            {
+                byteString.mBuf = static_cast<uint8_t *>(memMgmt->mem_alloc(byteString.mLen));
+                VerifyOrExit(byteString.mBuf != NULL, err = WEAVE_ERROR_NO_MEMORY);
+                aReader.GetBytes(byteString.mBuf, byteString.mLen);
 
-            LogReadWrite("%s bytestring allocated %d bytes at %p", "R", byteString.mLen, byteString.mBuf);
+                LogReadWrite("%s bytestring allocated %d bytes at %p", "R", byteString.mLen, byteString.mBuf);
+            }
             *static_cast<SerializedByteString *>(aStructureData) = byteString;
             break;
         }