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authorGriffin Smith <grfn@gws.fyi>2022-05-28T18·17-0400
committerclbot <clbot@tvl.fyi>2022-05-28T18·30+0000
commit1fbed8e3178c2c2bc2f093374e0035a1fe567377 (patch)
tree72212b2e5ba42339d1ad8e1b77856d6d5d642e7e /web/panettone/src/util.lisp
parentb39ca017c0453c7420da64d062a2aa00e27d1fd3 (diff)
fix(web/panettone): Don't add extra padding when already padded r/4182
Because of math being upsetting, we were adding 4 padding characters to
an already-properly-padded base64 string, which broke tazjin.

This also breaks this function out into panettone.util, and adds a test
for it.

Change-Id: I7bc8a440ad9d0917272dd9f2e341081ea14693da
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5782
Autosubmit: grfn <grfn@gws.fyi>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Diffstat (limited to 'web/panettone/src/util.lisp')
-rw-r--r--web/panettone/src/util.lisp8
1 files changed, 8 insertions, 0 deletions
diff --git a/web/panettone/src/util.lisp b/web/panettone/src/util.lisp
index 9fd9ceaa79a4..2abedf7b8fbb 100644
--- a/web/panettone/src/util.lisp
+++ b/web/panettone/src/util.lisp
@@ -5,3 +5,11 @@
    (when-let ((str (uiop:getenvp var)))
      (try-parse-integer str))
    default))
+
+(defun add-missing-base64-padding (s)
+  "Add any missing padding characters to the (un-padded) base64 string `S', such
+that it can be successfully decoded by the `BASE64' package"
+  ;; I apologize
+  (let* ((needed-padding (mod (length s) 4))
+         (pad-chars (if (zerop needed-padding) 0 (- 4 needed-padding))))
+    (format nil "~A~v@{~A~:*~}" s pad-chars "=")))