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diff --git a/engine/inotify.scm b/engine/inotify.scm
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+;;; Lisp Game Jam 2018
+;;; Copyright © 2018 David Thompson <davet@gnu.org>
+;;;
+;;; This program is free software: you can redistribute it and/or
+;;; modify it under the terms of the GNU General Public License as
+;;; published by the Free Software Foundation, either version 3 of the
+;;; License, or (at your option) any later version.
+;;;
+;;; This program is distributed in the hope that it will be useful,
+;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with this program.  If not, see
+;;; <http://www.gnu.org/licenses/>.
+
+(define-module (engine inotify)
+  #:use-module (ice-9 binary-ports)
+  #:use-module (ice-9 format)
+  #:use-module (ice-9 match)
+  #:use-module (rnrs bytevectors)
+  #:use-module (srfi srfi-9)
+  #:use-module (srfi srfi-9 gnu)
+  #:use-module (system foreign)
+  #:export (make-inotify
+            inotify?
+            inotify-watches
+            inotify-add-watch!
+            inotify-pending-events?
+            inotify-read-event
+            inotify-watch?
+            inotify-watch-id
+            inotify-watch-file-name
+            inotify-watch-remove!
+            inotify-event?
+            inotify-event-watch
+            inotify-event-type
+            inotify-event-cookie
+            inotify-event-file-name))
+
+(define libc (dynamic-link))
+
+(define inotify-init
+  (pointer->procedure int (dynamic-func "inotify_init" libc) '()))
+
+(define inotify-add-watch
+  (pointer->procedure int (dynamic-func "inotify_add_watch" libc)
+                      (list int '* uint32)))
+
+(define inotify-rm-watch
+  (pointer->procedure int (dynamic-func "inotify_rm_watch" libc)
+                      (list int int)))
+
+(define IN_ACCESS #x00000001) ; file was accessed.
+(define IN_MODIFY #x00000002) ; file was modified.
+(define IN_ATTRIB #x00000004) ; metadata changed
+(define IN_CLOSE_WRITE #x00000008) ; file opened for writing closed
+(define IN_CLOSE_NOWRITE #x00000010) ; file not opened for writing closed
+(define IN_OPEN #x00000020) ; file was opened
+(define IN_MOVED_FROM #x00000040) ; file was moved from X
+(define IN_MOVED_TO #x00000080) ; file was moved to Y
+(define IN_CREATE #x00000100) ; subfile was created
+(define IN_DELETE #x00000200) ; subfile was deleted
+(define IN_DELETE_SELF #x00000400) ; self was deleted
+(define IN_MOVE_SELF #x00000800) ; self was moved
+;; Kernel flags
+(define IN_UNMOUNT #x00002000) ; backing fs was unmounted
+(define IN_Q_OVERFLOW #x00004000) ; event queue overflowed
+(define IN_IGNORED #x00008000) ; file was ignored
+;; Special flags
+(define IN_ONLYDIR #x01000000) ; only watch if directory
+(define IN_DONT_FOLLOW #x02000000) ; do not follow symlink
+(define IN_EXCL_UNLINK #x04000000) ; exclude events on unlinked objects
+(define IN_MASK_ADD #x20000000) ; add to the mask of an existing watch
+(define IN_ISDIR #x40000000) ; event occurred against directory
+(define IN_ONESHOT #x80000000) ; only send event once
+
+(define mask/symbol (make-hash-table))
+(define symbol/mask (make-hash-table))
+
+(for-each (match-lambda
+            ((sym mask)
+             (hashq-set! symbol/mask sym mask)
+             (hashv-set! mask/symbol mask sym)))
+          `((access ,IN_ACCESS)
+            (modify ,IN_MODIFY)
+            (attrib ,IN_ATTRIB)
+            (close-write ,IN_CLOSE_WRITE)
+            (close-no-write ,IN_CLOSE_NOWRITE)
+            (open ,IN_OPEN)
+            (moved-from ,IN_MOVED_FROM)
+            (moved-to ,IN_MOVED_TO)
+            (create ,IN_CREATE)
+            (delete ,IN_DELETE)
+            (delete-self ,IN_DELETE_SELF)
+            (move-self ,IN_MOVE_SELF)
+            (only-dir ,IN_ONLYDIR)
+            (dont-follow ,IN_DONT_FOLLOW)
+            (exclude-unlink ,IN_EXCL_UNLINK)
+            (is-directory ,IN_ISDIR)
+            (once ,IN_ONESHOT)))
+
+(define (symbol->mask sym)
+  (hashq-ref symbol/mask sym))
+
+(define (mask->symbol sym)
+  (hashq-ref mask/symbol sym))
+
+(define-record-type <inotify>
+  (%make-inotify port buffer buffer-pointer watches)
+  inotify?
+  (port inotify-port)
+  (buffer inotify-buffer)
+  (buffer-pointer inotify-buffer-pointer)
+  (watches inotify-watches))
+
+(define-record-type <inotify-watch>
+  (make-inotify-watch id file-name owner)
+  inotify-watch?
+  (id inotify-watch-id)
+  (file-name inotify-watch-file-name)
+  (owner inotify-watch-owner))
+
+(define-record-type <inotify-event>
+  (make-inotify-event watch type cookie file-name)
+  inotify-event?
+  (watch inotify-event-watch)
+  (type inotify-event-type)
+  (cookie inotify-event-cookie)
+  (file-name inotify-event-file-name))
+
+(define (display-inotify inotify port)
+  (format port "#<inotify port: ~a>" (inotify-port inotify)))
+
+(define (display-inotify-watch watch port)
+  (format port "#<inotify-watch id: ~d file-name: ~a>"
+          (inotify-watch-id watch)
+          (inotify-watch-file-name watch)))
+
+(define (display-inotify-event event port)
+  (format port "#<inotify-event type: ~s cookie: ~d file-name: ~a watch: ~a>"
+          (inotify-event-type event)
+          (inotify-event-cookie event)
+          (inotify-event-file-name event)
+          (inotify-event-watch event)))
+
+(set-record-type-printer! <inotify> display-inotify)
+(set-record-type-printer! <inotify-watch> display-inotify-watch)
+(set-record-type-printer! <inotify-event> display-inotify-event)
+
+(define (make-inotify)
+  (let ((fd (inotify-init))
+        (buffer (make-bytevector 4096)))
+    (%make-inotify (fdopen fd "r")
+                   buffer
+                   (bytevector->pointer buffer)
+                   (make-hash-table))))
+
+(define (inotify-fd inotify)
+  (port->fdes (inotify-port inotify)))
+
+(define (absolute-file-name file-name)
+  (if (absolute-file-name? file-name)
+      file-name
+      (string-append (getcwd) "/" file-name)))
+
+(define (inotify-add-watch! inotify file-name modes)
+  (let* ((abs-file-name (absolute-file-name file-name))
+         (wd (inotify-add-watch (inotify-fd inotify)
+                                (string->pointer abs-file-name)
+                                (apply logior (map symbol->mask modes))))
+         (watch (make-inotify-watch wd abs-file-name inotify)))
+    (hashv-set! (inotify-watches inotify) wd watch)
+    watch))
+
+(define (inotify-watch-remove! watch)
+  (inotify-rm-watch (inotify-fd (inotify-watch-owner watch))
+                    (inotify-watch-id watch))
+  (hashv-remove! (inotify-watches (inotify-watch-owner watch))
+                 (inotify-watch-id watch)))
+
+(define (inotify-pending-events? inotify)
+  (char-ready? (inotify-port inotify)))
+
+(define (read-int port buffer)
+  (get-bytevector-n! port buffer 0 (sizeof int))
+  (bytevector-sint-ref buffer 0 (native-endianness) (sizeof int)))
+
+(define (read-uint32 port buffer)
+  (get-bytevector-n! port buffer 0 (sizeof uint32))
+  (bytevector-uint-ref buffer 0 (native-endianness) (sizeof uint32)))
+
+(define (read-string port buffer buffer-pointer length)
+  (and (> length 0)
+       (begin
+         (get-bytevector-n! port buffer 0 length)
+         (pointer->string buffer-pointer))))
+
+(define (inotify-read-event inotify)
+  (let* ((port (inotify-port inotify))
+         (buffer (inotify-buffer inotify))
+         (wd (read-int port buffer))
+         (event-mask (read-uint32 port buffer))
+         (cookie (read-uint32 port buffer))
+         (len (read-uint32 port buffer))
+         (name (read-string port buffer (inotify-buffer-pointer inotify) len)))
+    (make-inotify-event (hashv-ref (inotify-watches inotify) wd)
+                        (mask->symbol event-mask) cookie name)))