From b89032fbac3dd7895393b1db19fe1155f435948f Mon Sep 17 00:00:00 2001
From: Piotr Szarmanski
Date: Tue, 27 Sep 2022 17:41:09 +0200
Subject: Add an examples directory and a simple file-encoding system.

---
 examples/file/eris-file.lisp | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 examples/file/eris-file.lisp

(limited to 'examples/file/eris-file.lisp')

diff --git a/examples/file/eris-file.lisp b/examples/file/eris-file.lisp
new file mode 100644
index 0000000..fdc53ef
--- /dev/null
+++ b/examples/file/eris-file.lisp
@@ -0,0 +1,30 @@
+(in-package :eris-file)
+(defvar *eris-directory* "/tmp/")
+
+(defun output-to-file (block reference)
+  (let* ((base32 (eris:bytes-to-base32-unpadded reference))
+         (file (concatenate 'string *eris-directory* base32)))
+    (unless (probe-file file)
+      (alexandria:write-byte-vector-into-file block file))))
+
+(defun input-from-file (reference)
+  (let* ((base32 (eris:bytes-to-base32-unpadded reference))
+         (file (concatenate 'string *eris-directory* base32)))
+    (if (probe-file file)
+      (alexandria:read-file-into-byte-vector file)
+      nil)))
+
+(defun encode-file (input-file &optional (output-directory *eris-directory*))
+  (let ((*eris-directory* output-directory))
+    (with-open-file (file input-file :direction :input :element-type '(unsigned-byte 8))
+      (eris:read-capability-to-urn
+       (eris:eris-encode file
+                         (if (< (file-length file) (* 1024 16)) 1024 eris:32kib)
+                         #'output-to-file
+                         :hash-output nil)))))
+
+(defun decode-file (urn output-file &optional (output-directory *eris-directory*))
+  (let ((*eris-directory* output-directory))
+    (with-open-file (file output-file :direction :output :element-type '(unsigned-byte 8))
+      (alexandria:copy-stream (eris:eris-decode (eris:urn-to-read-capability urn) #'input-from-file)
+                              file))))
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