1 files changed, 23 insertions, 0 deletions

diff --git a/src/coding.c b/src/coding.c
index 2c6b2c4d051..9cba6494a8d 100644
--- a/src/coding.c
+++ b/src/coding.c
@@ -6353,6 +6353,29 @@ utf8_string_p (Lisp_Object string)
   return check_utf_8 (&coding) != -1;
 }
 
+/* Like make_string, but always returns a multibyte Lisp string, and
+   avoids decoding if TEXT encoded in UTF-8.  */
+
+Lisp_Object
+make_string_from_utf8 (const char *text, ptrdiff_t nbytes)
+{
+  ptrdiff_t chars, bytes;
+  parse_str_as_multibyte ((const unsigned char *) text, nbytes,
+                          &chars, &bytes);
+  /* If TEXT is a valid UTF-8 string, we can convert it to a Lisp
+     string directly.  Otherwise, we need to decode it.  */
+  if (chars == nbytes || bytes == nbytes)
+    return make_specified_string (text, chars, nbytes, true);
+  else
+    {
+      struct coding_system coding;
+      setup_coding_system (Qutf_8_unix, &coding);
+      coding.mode |= CODING_MODE_LAST_BLOCK;
+      coding.source = (const unsigned char *) text;
+      decode_coding_object (&coding, Qnil, 0, 0, nbytes, nbytes, Qt);
+      return coding.dst_object;
+    }
+}
 
 /* Detect how end-of-line of a text of length SRC_BYTES pointed by
    SOURCE is encoded.  If CATEGORY is one of