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# CMSDecoderUpdateMessage(_:_:_:)

Feeds raw bytes of the message to be decoded into the decoder.

```
func CMSDecoderUpdateMessage(_ cmsDecoder: CMSDecoder, _ msgBytes: UnsafeRawPointer, _ msgBytesLen: Int) -> OSStatus
```

## Parameters

`cmsDecoder`

The CMSDecoder reference returned by the `CMSDecoderCreate` function.

`msgBytes`

A pointer to the data to be decoded.

`msgBytesLen`

The length of the data, in bytes.

## Return Value

A result code. See [Security Framework Result Codes](/documentation/Security/security-framework-result-codes). Returns [`errSecUnknownFormat`](/documentation/Security/errSecUnknownFormat) upon detection of an improperly formatted CMS message.

## Discussion

This function can be called multiple times. Call the `CMSDecoderFinalizeMessage` function when you have no more data to decode.

## See Also

[`CMSDecoderCreate(_:)`](/documentation/Security/CMSDecoderCreate(_:))

Creates a CMSDecoder reference.


---

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