piolib: Increase data_bytes range to 32-bits #108
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In many places, the number of bytes in a data transfer is stored as a 32-bit (or greater) value, but the ioctl API to the kernel stores it in a 16-bit field, alongside which is a 16-bit gap due to the alignment requirements of the pointer that follows. Increase the size of data_bytes to a uint32_t, so that it can handle larger transfers. Since using different sizes as either end can lead to unpredictable results, a separate IOCTL is used for larger transfers, allowing the kernel support to be determined and backwards compatibility to be maintained. See: raspberrypi#107 Signed-off-by: Phil Elwell <[email protected]>
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In many places, the number of bytes in a data transfer is stored as a 32-bit (or greater) value, but the ioctl API to the kernel stores it in a 16-bit field, alongside which is a 16-bit gap due to the alignment requirements of the pointer that follows.
Increase the size of data_bytes to a uint32_t, so that it can handle larger transfers. Since using different sizes as either end can lead to unpredictable results, a separate IOCTL is used for larger transfers, allowing the kernel support to be determined and backwards compatibility to be maintained.
See: #107