Fix rb_enc_left_char_head()

* Fixes #3267
oracle · Sep 20, 2023 · 4d17ba4 · 4d17ba4
1 parent 124a255
commit 4d17ba4
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -5,6 +5,7 @@ New features:
 
 Bug fixes:
 
+* Fix `rb_enc_left_char_head()` so it is not always `ArgumentError` (#3267, @eregon).
 
 Compatibility:
 

diff --git a/lib/cext/ABI_check.txt b/lib/cext/ABI_check.txt
@@ -1 +1 @@
-4
+5
diff --git a/src/main/c/cext/encoding.c b/src/main/c/cext/encoding.c
@@ -226,7 +226,10 @@ int rb_enc_get_index(VALUE obj) {
 }
 
 char* rb_enc_left_char_head(const char *start, const char *p, const char *end, rb_encoding *enc) {
- int length = start - end;
+ if (p <= start || p >= end) {
+ return p;
+ }
+ int length = end - start;
  int position = polyglot_as_i32(polyglot_invoke(RUBY_CEXT, "rb_enc_left_char_head",
  rb_tr_unwrap(rb_enc_from_encoding(enc)),
  rb_tr_unwrap(rb_str_new(start, length)),