From 9941f620c442f0996d7889d948b781304e5fb0f2 Mon Sep 17 00:00:00 2001
From: Brian McGee <brian@bmcgee.ie>
Date: Mon, 31 Jul 2023 18:40:45 +0100
Subject: [PATCH] base64Decode: clearer error message when an invalid character
 is detected

Output the offending string in its entirety to provide context.

Closes #8479

(cherry picked from commit dc3ccf02bfd4d359228b54f5c24ae2b6caf6428e)
---
 src/libutil/util.cc | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 698e181a1..174e7ce8f 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -260,8 +260,9 @@ std::string base64Decode(std::string_view s)
         if (c == '\n') continue;
 
         char digit = base64DecodeChars[(unsigned char) c];
-        if (digit == npos)
-            throw Error("invalid character in Base64 string: '%c'", c);
+        if (digit == npos) {
+            throw Error("invalid character in Base64 string: '%c' in '%s'", c, s.data());
+        }
 
         bits += 6;
         d = d << 6 | digit;