From a34650acff3740980ef23d900d35004bcfe2ef04 Mon Sep 17 00:00:00 2001
From: Mattias Engdegård
Date: Mon, 20 Dec 2021 18:17:23 +0100
Subject: Fix sloppy base64 acceptance of some multibyte characters

The base64 encoding functions incorrectly accepted some multibyte
characters; stop doing that (bug#52670).

* src/fns.c (base64_encode_1): Reject all multibyte characters.
* test/src/fns-tests.el (fns-tests-base64-encode-string)
(fns-test-base64url-encode-region)
(fns-test-base64url-encode-string): Add tests.
* doc/lispref/text.texi (Base 64): Rephrase outdated manual text.
* etc/NEWS: Add a notice.
---
 src/fns.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

(limited to 'src')

diff --git a/src/fns.c b/src/fns.c
index 76c76c92ba9..23721334f76 100644
--- a/src/fns.c
+++ b/src/fns.c
@@ -3653,7 +3653,7 @@ base64_encode_1 (const char *from, char *to, ptrdiff_t length,
 	  c = string_char_and_length ((unsigned char *) from + i, &bytes);
 	  if (CHAR_BYTE8_P (c))
 	    c = CHAR_TO_BYTE8 (c);
-	  else if (c >= 256)
+	  else if (c >= 128)
 	    return -1;
 	  i += bytes;
 	}
@@ -3696,7 +3696,7 @@ base64_encode_1 (const char *from, char *to, ptrdiff_t length,
 	  c = string_char_and_length ((unsigned char *) from + i, &bytes);
 	  if (CHAR_BYTE8_P (c))
 	    c = CHAR_TO_BYTE8 (c);
-	  else if (c >= 256)
+	  else if (c >= 128)
 	    return -1;
 	  i += bytes;
 	}
@@ -3721,7 +3721,7 @@ base64_encode_1 (const char *from, char *to, ptrdiff_t length,
 	  c = string_char_and_length ((unsigned char *) from + i, &bytes);
 	  if (CHAR_BYTE8_P (c))
 	    c = CHAR_TO_BYTE8 (c);
-	  else if (c >= 256)
+	  else if (c >= 128)
 	    return -1;
 	  i += bytes;
 	}
-- 
cgit v1.2.1