From 652b5ccbea930ed1e18f40cfe6fdc4c045b01ee7 Mon Sep 17 00:00:00 2001
From: "Dirk-Jan C. Binnema" <djcb@djcbsoftware.nl>
Date: Fri, 12 Sep 2025 19:46:23 +0300
Subject: [PATCH] labels: tighten labels regexp

---
 lib/message/mu-labels.cc | 11 +++++++----
 man/mu-labels.1.org      | 14 ++++++++------
 2 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/lib/message/mu-labels.cc b/lib/message/mu-labels.cc
index c3822ddd..87b92e37 100644
--- a/lib/message/mu-labels.cc
+++ b/lib/message/mu-labels.cc
@@ -51,16 +51,16 @@ Mu::Labels::validate_label(const std::string &label)
 
 		if (::iscntrl(uc))
 			return Err(Error{Error::Code::InvalidArgument,
-					"control character {} is not allowed",
+					"control character {} not allowed in label",
 					static_cast<int>(uc)});
 		if (::isblank(uc))
 			return Err(Error{Error::Code::InvalidArgument,
-					"blank character {} is not allowed",
+					"blank character {} not allowed in label",
 					static_cast<int>(uc)});
-		if (uc == '"' || uc == '\'' || uc == '`' ||
+		if (uc == '"' || uc == '\'' || uc == '`' || uc == ',' ||
 		    uc == '\\' || uc == '/' || uc == '$')
 			return Err(Error{Error::Code::InvalidArgument,
-					"character '{}' is not allowed", uc});
+					"character '{}' not allowed in label", uc});
 	}
 
 	return Ok();
@@ -217,11 +217,14 @@ test_validate_label()
 	g_assert_true(!!validate_label("@raven+king"));
 	g_assert_true(!!validate_label("operation:mindcrime"));
 	g_assert_true(!!validate_label("😨"));
+	g_assert_true(!!validate_label("foo%bar+1"));
 
 	g_assert_false(!!validate_label("norrell strange"));
 	g_assert_false(!!validate_label(""));
 	g_assert_false(!!validate_label("+"));
 	g_assert_false(!!validate_label("-"));
+	g_assert_false(!!validate_label("foo$bar"));
+	g_assert_false(!!validate_label("foo,bar"));
 	g_assert_false(!!validate_label("foo`bar"));
 	g_assert_false(!!validate_label("\"quoted\""));
 }
diff --git a/man/mu-labels.1.org b/man/mu-labels.1.org
index 88ed0f29..ad70479d 100644
--- a/man/mu-labels.1.org
+++ b/man/mu-labels.1.org
@@ -119,8 +119,8 @@ See *EXPORT FORMAT* below for details on the format.
 *mu* does not wish to limit your creativity, but nevertheless puts a few
 restrictions on what is accepted as a label.
 
-- a *valid label character* is any character that is not a control-character, a
-  blank, or any of *'*, *"*, *`*, */*, *\*, *$*
+- a *valid label character* is any character that is not a control-character, not
+  a blank, nor anything matching the regular expression ~[^\"$',/\\`]~
 - a *valid label* consists of one or more valid label characters, the first of
   which must *not* be either *+* or *-*
 
@@ -165,14 +165,16 @@ it is recognized as a single parameter.
 
 Remove the label "planet" and add the label "dwarf-planet" to all messages that
 have "pluto" in their subject:
-#+begin_export
+
+#+begin_example
 $ mu labels update "subject:pluto" --labels -planet,+dwarf-planet
-#+end_export
+#+end_example
 
 Clear all labels from messages with the label "boring":
-#+begin_export
+
+#+begin_example
 $ mu labels clear "label:boring"
-#+end_export
+#+end_example
 
 #+include: "prefooter.inc" :minlevel 1