[Fix] Re: Using UNIX:UNIX-MMAP to read large text files under CMUCL?

Try the following definition of unix-mmap (for unix-glibc2.lisp, which
includes linux)

(in-package "UNIX")
(defun unix-mmap (addr length prot flags fd offset)
  (declare (type (or null system-area-pointer) addr)
           (type (unsigned-byte 32) length)
           (type (integer 1 7) prot)
           (type (unsigned-byte 32) flags)
           (type (or null unix-fd) fd)
           (type (signed-byte 32) offset))
  ;; Can't use syscall, because the address that is returned could be
  ;; "negative".  Hence we explicitly check for mmap returning
  ;; MAP_FAILED.
  (let ((result
	 (alien-funcall (extern-alien "mmap" (function system-area-pointer
						       system-area-pointer
						       size-t int int
                                                       int off-t))
			(or addr +null+) length prot flags (or fd -1) offset)))
    (if (<= (sys:SAP-INT result) 0)
	(values nil (unix-errno))
	result)))