Module Index_unix.Syscalls

Reads up to length bytes from fd (starting at position fd_offset) into buffer (starting at position buffer_offset). Returns the number of bytes actually read. fd's cursor position is unchanged.

Writes up to length bytes from buffer (starting at position buffer_offset) to the file descriptor fd (starting at position fd_offset). Returns the number of bytes actually written. fd's cursor position is unchanged.

Flushes all modified buffer cache pages for a given file descriptor to the disk device, so that all changed information can be retrieved even if the system crashes or is rebooted. This includes writing through or flushing a disk cache if present. Blocks until the device reports that the transfer has completed.