From 5c4ae642f2f5ce5bc78deed40a87315f01068bf9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Ekl=C3=B6f?= <daniel@ekloef.se>
Date: Tue, 25 May 2021 17:34:09 +0200
Subject: [PATCH] =?UTF-8?q?tag:=20fix=20crash=20on=20empty=20tag=20specifi?=
 =?UTF-8?q?er,=20=E2=80=9C{}=E2=80=9D?=
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For strings with empty tag specifiers, “{}”, we ended up calling
tag_for_name() with a NULL pointer for name. This caused us to crash.

Closes #48
---
 CHANGELOG.md | 2 ++
 tag.c        | 5 +++--
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a02a7ba..c36baa8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -28,6 +28,8 @@
   (https://codeberg.org/dnkl/yambar/issues/32).
 * Crash in the `ramp` particle when the tag’s value was out-of-bounds
   (https://codeberg.org/dnkl/yambar/issues/45).
+* Crash when a string particle contained `{}`
+  (https://codeberg.org/dnkl/yambar/issues/48).
 
 
 ### Security
diff --git a/tag.c b/tag.c
index 02e0794..5b00218 100644
--- a/tag.c
+++ b/tag.c
@@ -446,8 +446,9 @@ tags_expand_template(const char *template, const struct tag_set *tags)
         }
 
         /* Lookup tag */
-        const struct tag *tag = tag_for_name(tags, tag_name);
-        if (tag == NULL) {
+        const struct tag *tag = NULL;
+
+        if (tag_name == NULL || (tag = tag_for_name(tags, tag_name)) == NULL) {
             /* No such tag, copy as-is instead */
             sbuf_append_at_most(&formatted, template, begin - template + 1);
             template = begin + 1;