From b423f7b7b6da6f88301b14eaed5f9f8a4924847c Mon Sep 17 00:00:00 2001
From: Frank Denis <124872+jedisct1@users.noreply.github.com>
Date: Sun, 4 Oct 2026 17:09:47 +0200
Subject: [PATCH] std.base64: fix bogus decoderWithIgnore() definitions

standard_no_pad.decoderWithIgnore() constructed a decoder with
padding enabled, so it would accept padded base64 even when the
decoder was explicitly configured to reject padding.

And url_safe.decoderWithIgnore() constructed a decoder without
padding, so it would accept unpadded URL-safe Base64 even when
we require padding.
---
 lib/std/base64.zig | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/lib/std/base64.zig b/lib/std/base64.zig
index 8b90617c4130b3d7d8e3180fcc45a894fc3f099a..e9e3896c73ed52caacbccbe74bd010a2a01a4af5 100644
--- a/lib/std/base64.zig
+++ b/lib/std/base64.zig
@@ -31,6 +31,9 @@ pub const standard_alphabet_chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopq
 fn standardBase64DecoderWithIgnore(ignore: []const u8) Base64DecoderWithIgnore {
     return Base64DecoderWithIgnore.init(standard_alphabet_chars, '=', ignore);
 }
+fn standardNoPadBase64DecoderWithIgnore(ignore: []const u8) Base64DecoderWithIgnore {
+    return Base64DecoderWithIgnore.init(standard_alphabet_chars, null, ignore);
+}
 
 /// Standard Base64 codecs, with padding, as defined in
 /// [RFC 4648 section 4](https://datatracker.ietf.org/doc/html/rfc4648#section-4).
@@ -47,7 +50,7 @@ pub const standard = Codecs{
 pub const standard_no_pad = Codecs{
     .alphabet_chars = standard_alphabet_chars,
     .pad_char = null,
-    .decoderWithIgnore = standardBase64DecoderWithIgnore,
+    .decoderWithIgnore = standardNoPadBase64DecoderWithIgnore,
     .Encoder = Base64Encoder.init(standard_alphabet_chars, null),
     .Decoder = Base64Decoder.init(standard_alphabet_chars, null),
 };
@@ -56,6 +59,9 @@ pub const standard_no_pad = Codecs{
 /// [RFC 4648 section 5](https://datatracker.ietf.org/doc/html/rfc4648#section-5).
 pub const url_safe_alphabet_chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_".*;
 fn urlSafeBase64DecoderWithIgnore(ignore: []const u8) Base64DecoderWithIgnore {
+    return Base64DecoderWithIgnore.init(url_safe_alphabet_chars, '=', ignore);
+}
+fn urlSafeNoPadBase64DecoderWithIgnore(ignore: []const u8) Base64DecoderWithIgnore {
     return Base64DecoderWithIgnore.init(url_safe_alphabet_chars, null, ignore);
 }
 
@@ -74,7 +80,7 @@ pub const url_safe = Codecs{
 pub const url_safe_no_pad = Codecs{
     .alphabet_chars = url_safe_alphabet_chars,
     .pad_char = null,
-    .decoderWithIgnore = urlSafeBase64DecoderWithIgnore,
+    .decoderWithIgnore = urlSafeNoPadBase64DecoderWithIgnore,
     .Encoder = Base64Encoder.init(url_safe_alphabet_chars, null),
     .Decoder = Base64Decoder.init(url_safe_alphabet_chars, null),
 };
-- 
2.54.0