[bug#69291] [PATCH 5/5] scripts: substitute: Extract script specific output from download-nar.

[Christopher Baines <mail@cbaines.net>]

As this moves download-nar in a direction where it could be used outside the
substitute script.

* guix/scripts/substitute.scm (download-nar): Return more information and move
status-port output to…
(guix-substitute): here.

Change-Id: Icbddb9a47620b3520cdd2e8095f37a99824c1ce0
---
 guix/scripts/substitute.scm | 49 +++++++++++++++++++++----------------
 1 file changed, 28 insertions(+), 21 deletions(-)

diff --git a/guix/scripts/substitute.scm b/guix/scripts/substitute.scm
index 61e16b22db..94eb6d2f71 100755
--- a/guix/scripts/substitute.scm
+++ b/guix/scripts/substitute.scm
@@ -568,26 +568,10 @@ (define* (download-nar narinfo destination
       ;; Wait for the reporter to finish.
       (every (compose zero? cdr waitpid) pids)
 
-      ;; Skip a line after what 'progress-reporter/file' printed, and another
-      ;; one to visually separate substitutions.  When PRINT-BUILD-TRACE? is
-      ;; true, leave it up to (guix status) to prettify things.
-      (newline (current-error-port))
-      (unless print-build-trace?
-        (newline (current-error-port)))
-
-      ;; Check whether we got the data announced in NARINFO.
-      (let ((actual (get-hash)))
-        (if (bytevector=? actual expected)
-            ;; Tell the daemon that we're done.
-            (format status-port "success ~a ~a~%"
-                    (narinfo-hash narinfo) (narinfo-size narinfo))
-            ;; The actual data has a different hash than that in NARINFO.
-            (format status-port "hash-mismatch ~a ~a ~a~%"
-                    (hash-algorithm-name algorithm)
-                    (bytevector->nix-base32-string expected)
-                    (bytevector->nix-base32-string actual))))
-
-      cpu-usage)))
+      (values narinfo
+              expected
+              (get-hash)
+              cpu-usage))))
 
 (define (system-error? exception)
   "Return true if EXCEPTION is a Guile 'system-error exception."
@@ -891,7 +875,10 @@ (define-command (guix-substitute . args)
               ((? eof-object?)
                #t)
               ((= string-tokenize ("substitute" store-path destination))
-               (let ((cpu-usage
+               (let ((narinfo
+                      expected-hash
+                      actual-hash
+                      cpu-usage
                       (process-substitution reply-port store-path destination
                                             #:cache-urls (substitute-urls)
                                             #:acl (current-acl)
@@ -901,6 +888,26 @@ (define-command (guix-substitute . args)
                                             #:prefer-fast-decompression?
                                             prefer-fast-decompression?)))
 
+                 ;; Skip a line after what 'progress-reporter/file' printed,
+                 ;; and another one to visually separate substitutions.  When
+                 ;; PRINT-BUILD-TRACE? is true, leave it up to (guix status)
+                 ;; to prettify things.
+                 (newline (current-error-port))
+                 (unless print-build-trace?
+                   (newline (current-error-port)))
+
+                 ;; Check whether we got the data announced in NARINFO.
+                 (if (bytevector=? actual-hash expected-hash)
+                     ;; Tell the daemon that we're done.
+                     (format reply-port "success ~a ~a~%"
+                             (narinfo-hash narinfo) (narinfo-size narinfo))
+                     ;; The actual data has a different hash than that in NARINFO.
+                     (format reply-port "hash-mismatch ~a ~a ~a~%"
+                             (hash-algorithm-name
+                              (narinfo-hash-algorithm+value narinfo))
+                             (bytevector->nix-base32-string expected-hash)
+                             (bytevector->nix-base32-string actual-hash)))
+
                  ;; Create a hysteresis: depending on CPU usage, favor
                  ;; compression methods with faster decompression (like ztsd)
                  ;; or methods with better compression ratios (like lzip).
-- 
2.41.0