[bug#51307] [PATCH 1/2] scripts: hash: Improve error handling.

[zimoun]

* guix/scripts/hash.scm (guix-hash): Allow several files.
[directory?]: New procedure.
[file-hash]: Catch system-error.
[hash-to-display]: New procedure.
---
 guix/scripts/hash.scm | 56 +++++++++++++++++++++++++++----------------
 1 file changed, 36 insertions(+), 20 deletions(-)

diff --git a/guix/scripts/hash.scm b/guix/scripts/hash.scm
index b8622373cc..f3363549d3 100644
--- a/guix/scripts/hash.scm
+++ b/guix/scripts/hash.scm
@@ -3,6 +3,7 @@
 ;;; Copyright © 2013 Nikita Karetnikov <nikita@karetnikov.org>
 ;;; Copyright © 2016 Jan Nieuwenhuizen <janneke@gnu.org>
 ;;; Copyright © 2018 Tim Gesthuizen <tim.gesthuizen@yahoo.de>
+;;; Copyright © 2021 Simon Tournier <zimon.toutoune@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -135,6 +136,11 @@ (define (vcs-file? file stat)
       (else
        #f)))
 
+  (define (directory? file)
+    (case (stat:type (stat file))
+      ((directory) #t)
+      (else #f)))
+
   (let* ((opts (parse-options))
          (args (filter-map (match-lambda
                             (('argument . value)
@@ -149,27 +155,37 @@ (define (vcs-file? file stat)
     (define (file-hash file)
       ;; Compute the hash of FILE.
       ;; Catch and gracefully report possible '&nar-error' conditions.
-      (with-error-handling
-        (if (assoc-ref opts 'recursive?)
+      (if (and (assoc-ref opts 'recursive?)
+               (directory? file))
+          (with-error-handling
             (let-values (((port get-hash)
                           (open-hash-port (assoc-ref opts 'hash-algorithm))))
               (write-file file port #:select? select?)
               (force-output port)
-              (get-hash))
-            (match file
-              ("-" (port-hash (assoc-ref opts 'hash-algorithm)
-                              (current-input-port)))
-              (_   (call-with-input-file file
-                     (cute port-hash (assoc-ref opts 'hash-algorithm)
-                           <>)))))))
-
-    (match args
-      ((file)
-       (catch 'system-error
-         (lambda ()
-           (format #t "~a~%" (fmt (file-hash file))))
-         (lambda args
-           (leave (G_ "~a~%")
-                  (strerror (system-error-errno args))))))
-      (x
-       (leave (G_ "wrong number of arguments~%"))))))
+              (get-hash)))
+          (catch 'system-error
+            (lambda _
+              (call-with-input-file file
+                (cute port-hash (assoc-ref opts 'hash-algorithm)
+                      <>)))
+            (lambda args
+              (when (directory? file)
+                (display-hint (G_ "Try @option{--recursive}.")))
+              (leave (G_ "~a ~a~%")
+                     file
+                     (strerror (system-error-errno args)))))))
+
+    (define (hash-to-display thing)
+      (match thing
+        ((? file-exists? file)
+         (fmt (file-hash file)))
+        ("-" (with-error-handling
+               (fmt (port-hash (assoc-ref opts 'hash-algorithm)
+                               (current-input-port)))))
+        (x
+         (leave (G_ "wrong argument~%")))))
+
+    (for-each
+     (lambda (arg)
+       (format #t "~a~%" (hash-to-display arg)))
+     args)))
-- 
2.32.0