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    SubjectRe: [PATCH] tpm: add support for partial reads
    On Thu, Jul 19, 2018 at 08:52:32AM -0700, Tadeusz Struk wrote:
    > Currently to read a response from the TPM device an application needs
    > provide "big enough" buffer for the whole response and read it in one go.
    > The application doesn't know how big the response it beforehand so it
    > always needs to maintain a 4K buffer and read the max (4K).
    > In case if the user of the TSS library doesn't provide big enough buffer
    > the TCTI spec says that the library should set the required size and return
    > TSS2_TCTI_RC_INSUFFICIENT_BUFFER error code so that the application could
    > allocate a bigger buffer and call receive again.
    > To make it possible in the TSS library this requires being able to do
    > partial reads from the driver.
    > The library would read the header first to get the actual size of the
    > response from the header and then read the rest of the response.
    > This patch adds support for partial reads.

    You should solve this in user space, the kernel API requires a full
    sized buffer here, the tss library should always provide such an
    internal buffer and then implement whatever scheme TSS wants by
    memcpying from that buffer..

    Jason

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