compiler/zo-marshal: fix offsets in submodule search table

compiler-test/tests/compiler/zo.rkt

@@ -2,7 +2,8 @@
 (require racket/pretty
          compiler/zo-parse
          compiler/zo-marshal
-         compiler/decompile)
+         compiler/decompile
+         racket/file)
 
 (define ex-mod1
   '(module m racket
@@ -64,6 +65,12 @@
       (write c o)
       (let ([p (zo-parse (open-input-bytes (get-output-bytes o)))])
         (let ([b (zo-marshal p)])
+          ;; Check that submodule table is ok:
+          (parameterize ([read-accept-compiled #t]
+                         [current-output-port (open-output-bytes)])
+            (define f (make-temporary-file))
+            (call-with-output-file f #:exists 'truncate (lambda (f) (display b f)))
+            (dynamic-require f #f))
           (let ([p2 (zo-parse (open-input-bytes b))]
                 [to-string (lambda (p)
                              (let ([o (open-output-bytes)])

zo-lib/compiler/zo-marshal.rkt

@@ -85,9 +85,11 @@
              (iloop (loop (car subm) accum) (cdr subm)))))))
   (write-bytes (int->bytes (length pre-mod-bytess)) outp)
   ;; Size of btree:
-  (define btree-size 
+  (define header-size
     (+ 8
-       (string-length (version))
+       (string-length (version))))
+  (define btree-size
+    (+ header-size
        (apply + (for/list ([mb (in-list pre-mod-bytess)])
                   (+ (bytes-length (mod-bytes-name-bstr mb))
                      20)))))
@@ -108,7 +110,7 @@
   (define right-offsets (make-vector (vector-length sorted-mod-bytess) 0))
   ;; Write out btree or compute offsets:
   (define (write-btree write-bytes)
-    (let loop ([lo 0] [hi (vector-length sorted-mod-bytess)] [pos 0])
+    (let loop ([lo 0] [hi (vector-length sorted-mod-bytess)] [pos header-size])
       (define mid (quotient (+ lo hi) 2))
       (define mb (vector-ref sorted-mod-bytess mid))
       (define name-len (bytes-length (mod-bytes-name-bstr mb)))