/* * This structure is used for the management of descriptors. It may be * shared by multiple processes. * * A process is initially started out with NDFILE descriptors stored within * this structure, selected to be enough for typical applications based on * the historical limit of 20 open files (and the usage of descriptors by * shells). If these descriptors are exhausted, a larger descriptor table * may be allocated, up to a process' resource limit; the internal arrays * are then unused. The initial expansion is set to NDEXTENT; each time * it runs out, it is doubled until the resource limit is reached. NDEXTENT * should be selected to be the biggest multiple of OFILESIZE (see below) * that will fit in a power-of-two sized piece of memory. */