From: Mark Wooding <mdw@distorted.org.uk>
Date: Mon, 22 Dec 2014 22:19:50 +0000 (+0000)
Subject: zone.lisp: New utility for hashing files.
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~mdw/git/zone/commitdiff_plain/476808d8bacf084e6632b3aebbe14c28ec49e09a?ds=sidebyside

zone.lisp: New utility for hashing files.
---

diff --git a/zone.lisp b/zone.lisp
index 28ee038..177ded6 100644
--- a/zone.lisp
+++ b/zone.lisp
@@ -202,6 +202,19 @@ (defun mapenum (func name)
   "Call FUNC on TAG/VALUE pairs from the enumeration called NAME."
   (maphash func (get name 'enum-forward)))
 
+(defun hash-file (hash file context)
+  "Hash the FILE using the OpenSSL HASH function, returning an octet string.
+
+   CONTEXT is a temporary-files context."
+  (let ((temp (temporary-file context "hash")))
+    (run-program (list "openssl" "dgst" (concatenate 'string "-" hash))
+		 :input file :output temp)
+    (with-open-file (in temp)
+      (let ((line (read-line in)))
+	(assert (and (>= (length line) 9)
+		     (string= line "(stdin)= " :end1 9)))
+	(decode-hex line :start 9)))))
+
 ;;;--------------------------------------------------------------------------
 ;;; Zone types.