1 files changed, 28 insertions, 26 deletions
diff --git a/guix/store/deduplication.scm b/guix/store/deduplication.scm
index 6ff4a50de5..8c19d7309e 100644
--- a/guix/store/deduplication.scm
+++ b/guix/store/deduplication.scm
@@ -31,37 +31,39 @@
   #:export (nar-sha256
             deduplicate))
 
-;; Would it be better to just make WRITE-FILE give size as well? I question
-;; the general utility of this approach.
+;; XXX: This port is used as a workaround on Guile <= 2.2.4 where
+;; 'port-position' throws to 'out-of-range' when the offset is great than or
+;; equal to 2^32: <https://bugs.gnu.org/32161>.
 (define (counting-wrapper-port output-port)
-  "Some custom ports don't implement GET-POSITION at all. But if we want to
-figure out how many bytes are being written, we will want to use that. So this
-makes a wrapper around a port which implements GET-POSITION."
+  "Return two values: an output port that wraps OUTPUT-PORT, and a thunk to
+retrieve the number of bytes written to OUTPUT-PORT."
   (let ((byte-count 0))
-    (make-custom-binary-output-port "counting-wrapper"
-                                    (lambda (bytes offset count)
-                                      (set! byte-count
-                                        (+ byte-count count))
-                                      (put-bytevector output-port bytes
-                                                      offset count)
-                                      count)
-                                    (lambda ()
-                                      byte-count)
-                                    #f
-                                    (lambda ()
-                                      (close-port output-port)))))
+    (values (make-custom-binary-output-port "counting-wrapper"
+                                            (lambda (bytes offset count)
+                                              (put-bytevector output-port bytes
+                                                              offset count)
+                                              (set! byte-count
+                                                (+ byte-count count))
+                                              count)
+                                            (lambda ()
+                                              byte-count)
+                                            #f
+                                            (lambda ()
+                                              (close-port output-port)))
+            (lambda ()
+              byte-count))))
 
 (define (nar-sha256 file)
   "Gives the sha256 hash of a file and the size of the file in nar form."
-  (let-values (((port get-hash) (open-sha256-port)))
-    (let ((wrapper (counting-wrapper-port port)))
-      (write-file file wrapper)
-      (force-output wrapper)
-      (force-output port)
-      (let ((hash (get-hash))
-            (size (port-position wrapper)))
-        (close-port wrapper)
-        (values hash size)))))
+  (let*-values (((port get-hash) (open-sha256-port))
+                ((wrapper get-size) (counting-wrapper-port port)))
+    (write-file file wrapper)
+    (force-output wrapper)
+    (force-output port)
+    (let ((hash (get-hash))
+          (size (get-size)))
+      (close-port wrapper)
+      (values hash size))))
 
 (define (tempname-in directory)
   "Gives an unused temporary name under DIRECTORY. Not guaranteed to still be