1 files changed, 45 insertions, 3 deletions
diff --git a/088file.mu b/088file.mu
index 09d3b0fa..f2dde0a1 100644
--- a/088file.mu
+++ b/088file.mu
@@ -73,12 +73,21 @@ def transmit-from-text contents:address:array:character, sink:address:sink:chara
 def start-writing fs:address:filesystem, filename:address:array:character -> sink:address:sink:character, routine-id:number [
   local-scope
   load-ingredients
-  file:number <- $open-file-for-writing filename
   source:address:source:character, sink:address:sink:character <- new-channel 30
-  routine-id <- start-running transmit-to-file file, source
+  {
+    break-if fs
+    # real file system
+    file:number <- $open-file-for-writing filename
+    assert file, [no such file]
+    routine-id <- start-running transmit-to-file file, source
+    reply
+  }
+  # fake file system
+  # beware: doesn't support multiple concurrent writes yet
+  routine-id <- start-running transmit-to-fake-file fs, filename, source
 ]
 
-def transmit-to-file file:number, source:address:source:character -> file:number, source:address:source:character [
+def transmit-to-file file:number, source:address:source:character -> source:address:source:character [
   local-scope
   load-ingredients
   {
@@ -89,3 +98,36 @@ def transmit-to-file file:number, source:address:source:character -> file:number
   }
   file <- $close-file file
 ]
+
+def transmit-to-fake-file fs:address:filesystem, filename:address:array:character, source:address:source:character -> fs:address:filesystem, source:address:source:character [
+  local-scope
+  load-ingredients
+  # compute new file contents
+  buf:address:buffer <- new-buffer 30
+  {
+    c:character, done?:boolean, source <- read source
+    break-if done?
+    buf <- append buf, c
+    loop
+  }
+  contents:address:array:character <- buffer-to-array buf
+  new-file-mapping:file-mapping <- merge filename, contents
+  # write to filesystem
+  curr-filename:address:array:character <- copy 0
+  data:address:array:file-mapping <- get *fs, data:offset
+  # replace file contents if it already exists
+  len:number <- length *data
+  new-len:number <- add len, 1
+  new-data:address:array:file-mapping <- new file-mapping:type, new-len
+  put *fs, data:offset, new-data
+  # copy over old files
+  i:number <- copy 0
+  {
+    done?:boolean <- greater-or-equal i, len
+    break-if done?
+    tmp:file-mapping <- index *data, i
+    put-index *new-data, i, tmp
+  }
+  # write new file
+  put-index *new-data, len, new-file-mapping
+]