flock, fstatfs, ftruncate, fsync, fdatasync, getdirentries, fchmod, futimes and mmap on an archived descriptor acted on its null device and succeeded or failed with an unrelated errno. They now throw NotImplemented, each covered by the kernel archive test; mmap is noexcept, so its refusal is checked through the terminate handler.
sceKernelOpen and open give an archived file a read-only null-device descriptor. Reads, positioned, vectored and AIO reads, seeks, fstat and FIONREAD are served from the archive; dup, dup2 and F_DUPFD share the position. sceKernelStat and sceKernelCheckReachability see archived paths.
Writing opens fail with EROFS, O_CREAT|O_EXCL with EEXIST and O_DIRECTORY on a file with ENOTDIR. Opening an archived directory or one merged with the disk throws until getdents can list it.
Alexej Szpevák