Null terminate and add outbuf size

Author: cecille

src/controller/python/ChipDeviceController-Discovery.cpp

@@ -191,7 +191,7 @@ bool pychip_DeviceController_GetIPForDiscoveredDevice(Controller::DeviceCommissi
     return false;
 }
 
-PyChipError pychip_CreateManualCode(uint16_t longDiscriminator, uint32_t passcode, char * manualCodeBuffer, size_t bufsize)
+PyChipError pychip_CreateManualCode(uint16_t longDiscriminator, uint32_t passcode, char * manualCodeBuffer, size_t inBufSize, size_t* outBufSize)
 {
     SetupPayload payload;
     SetupDiscriminator discriminator;
@@ -200,11 +200,16 @@ PyChipError pychip_CreateManualCode(uint16_t longDiscriminator, uint32_t passcod
     payload.setUpPINCode  = passcode;
     std::string setupManualCode;
 
+    *outBufSize = 0;
     CHIP_ERROR err = ManualSetupPayloadGenerator(payload).payloadDecimalStringRepresentation(setupManualCode);
-    if (err == CHIP_NO_ERROR)
-    {
-        MutableCharSpan span(manualCodeBuffer, bufsize);
-        CopyCharSpanToMutableCharSpan(CharSpan(setupManualCode.c_str(), setupManualCode.length()), span);
+    if (err == CHIP_NO_ERROR) {
+        MutableCharSpan span(manualCodeBuffer, inBufSize);
+        // Plus 1 so we copy the null terminator
+        CopyCharSpanToMutableCharSpan(CharSpan(setupManualCode.c_str(), setupManualCode.length()+1), span);
+        *outBufSize = span.size();
+        if (*outBufSize == 0) {
+            err == CHIP_ERROR_NO_MEMORY;
+        }
     }
 
     return ToPyChipError(err);

src/controller/python/chip/ChipDeviceCtrl.py

@@ -1714,11 +1714,14 @@ def InitGroupTestingData(self):
     def CreateManualCode(self, discriminator: int, passcode: int) -> str:
         """ Creates a standard flow manual code from the given discriminator and passcode."""
         # 64 bytes is WAY more than required, but let's be safe
-        size = 64
-        buf = create_string_buffer(size)
+        in_size = 64
+        out_size = c_size_t(0)
+        buf = create_string_buffer(in_size)
         self._ChipStack.Call(
-            lambda: self._dmLib.pychip_CreateManualCode(discriminator, passcode, buf, size)
+            lambda: self._dmLib.pychip_CreateManualCode(discriminator, passcode, buf, in_size, pointer(out_size))
         ).raise_on_error()
+        if out_size.value == 0 or out_size.value > in_size:
+            raise MemoryError("Invalid output size for manual code")
         return buf.value.decode()
 
     # ----- Private Members -----
@@ -1949,7 +1952,7 @@ def _InitLib(self):
             self._dmLib.pychip_DeviceProxy_GetRemoteSessionParameters.argtypes = [c_void_p, c_char_p]
 
             self._dmLib.pychip_CreateManualCode.restype = PyChipError
-            self._dmLib.pychip_CreateManualCode.argtypes = [c_uint16, c_uint32, c_char_p, c_size_t]
+            self._dmLib.pychip_CreateManualCode.argtypes = [c_uint16, c_uint32, c_char_p, c_size_t, POINTER(c_size_t)]
 
 
 class ChipDeviceController(ChipDeviceControllerBase):