[fix] emberAfCopyString should accept size_t size[TE4] (project-chip#…

…8241)

* [fix] emberAfCopyString should accept size_t size

* Apply suggestions from code review

Co-authored-by: Boris Zbarsky <bzbarsky@apple.com>

src/app/util/af.h

@@ -559,13 +559,13 @@ void emberAfCopyInt32u(uint8_t * data, uint16_t index, uint32_t x);
  * parameter should indicate the maximum number of characters to copy to the
  * destination buffer not including the length byte.
  */
-void emberAfCopyString(uint8_t * dest, const uint8_t * src, uint8_t size);
+void emberAfCopyString(uint8_t * dest, const uint8_t * src, size_t size);
 /*
  * @brief Function that copies a ZCL long string into a buffer.  The size
  * parameter should indicate the maximum number of characters to copy to the
  * destination buffer not including the length bytes.
  */
-void emberAfCopyLongString(uint8_t * dest, const uint8_t * src, uint16_t size);
+void emberAfCopyLongString(uint8_t * dest, const uint8_t * src, size_t size);
 /*
  * @brief Function that determines the length of a zigbee Cluster Library string
  *   (where the first byte is assumed to be the length).

src/app/util/attribute-storage.cpp

@@ -480,15 +480,15 @@ static EmberAfStatus typeSensitiveMemCopy(ClusterId clusterId, uint8_t * dest, u
         {
             return EMBER_ZCL_STATUS_INSUFFICIENT_SPACE;
         }
-        emberAfCopyString(dest, src, static_cast<uint8_t>(bufferSize - 1));
+        emberAfCopyString(dest, src, bufferSize - 1);
     }
     else if (emberAfIsLongStringAttributeType(attributeType))
     {
         if (bufferSize < 2)
         {
             return EMBER_ZCL_STATUS_INSUFFICIENT_SPACE;
         }
-        emberAfCopyLongString(dest, src, static_cast<uint16_t>(bufferSize - 2));
+        emberAfCopyLongString(dest, src, bufferSize - 2);
     }
     else if (emberAfIsThisDataTypeAListType(attributeType))
     {

src/app/util/util.cpp

@@ -878,7 +878,7 @@ void emberAfCopyInt32u(uint8_t * data, uint16_t index, uint32_t x)
     data[index + 3] = (uint8_t)(((x) >> 24) & 0xFF);
 }
 
-void emberAfCopyString(uint8_t * dest, const uint8_t * src, uint8_t size)
+void emberAfCopyString(uint8_t * dest, const uint8_t * src, size_t size)
 {
     if (src == NULL)
     {
@@ -893,14 +893,15 @@ void emberAfCopyString(uint8_t * dest, const uint8_t * src, uint8_t size)
         uint8_t length = emberAfStringLength(src);
         if (size < length)
         {
-            length = size;
+            // Since we have checked that size < length, size must be able to fit into the type of length.
+            length = static_cast<decltype(length)>(size);
         }
         memmove(dest + 1, src + 1, length);
         dest[0] = length;
     }
 }
 
-void emberAfCopyLongString(uint8_t * dest, const uint8_t * src, uint16_t size)
+void emberAfCopyLongString(uint8_t * dest, const uint8_t * src, size_t size)
 {
     if (src == NULL)
     {
@@ -916,7 +917,8 @@ void emberAfCopyLongString(uint8_t * dest, const uint8_t * src, uint16_t size)
         uint16_t length = emberAfLongStringLength(src);
         if (size < length)
         {
-            length = size;
+            // Since we have checked that size < length, size must be able to fit into the type of length.
+            length = static_cast<decltype(length)>(size);
         }
         memmove(dest + 2, src + 2, length);
         dest[0] = EMBER_LOW_BYTE(length);