Numerous CosmOS devices implement the API deviceapi_block. For example:
- ata disks
- partitions
- ram disks
- virtio disks
CosmOS provides the utility functions in blockutil.h for interfacing with devices which implement deviceapi_block. It is strongly recommended to use the utility functions rather than using deviceapi_block directly. blockutil implements protections and checks to ensure that the API calls are reasonable and that the behaviour of the underlying block devices is reasonable.
Typically filesystem devices and partition table devices need to use the services of block devices: they always use blockutil.
Example code to read from block device:
uint32_t s = strlen(testdata);
uint32_t written = blockutil_write(obj, testdata, s + 1, 0);Example code to write from block devices.
uint8_t buffer[s + 1];
uint32_t read = blockutil_read(obj, (uint8_t*)buffer, s + 1, 0);