f270054cd3
in OpenBSD by Niels Provos. The patch introduces a bitmap of allocated file descriptors which is used to locate available descriptors when a new one is needed. It also moves the task of growing the file descriptor table out of fdalloc(), reducing complexity in both fdalloc() and do_dup(). Debts of gratitude are owed to tjr@ (who provided the original patch on which this work is based), grog@ (for the gdb(4) man page) and rwatson@ (for assistance with pxeboot(8)).