diff options
| -rw-r--r-- | src/editfns.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/src/editfns.c b/src/editfns.c index bfa67e20e3e..e39eed6e870 100644 --- a/src/editfns.c +++ b/src/editfns.c @@ -1025,10 +1025,20 @@ DEFUN ("byte-to-position", Fbyte_to_position, Sbyte_to_position, 1, 1, 0, If BYTEPOS is out of range, the value is nil. */) (Lisp_Object bytepos) { + ptrdiff_t pos_byte; + CHECK_NUMBER (bytepos); - if (XINT (bytepos) < BEG_BYTE || XINT (bytepos) > Z_BYTE) + pos_byte = XINT (bytepos); + if (pos_byte < BEG_BYTE || pos_byte > Z_BYTE) return Qnil; - return make_number (BYTE_TO_CHAR (XINT (bytepos))); + if (Z != Z_BYTE) + /* There are multibyte characters in the buffer. + The argument of BYTE_TO_CHAR must be a byte position at + a character boundary, so search for the start of the current + character. */ + while (!CHAR_HEAD_P (FETCH_BYTE (pos_byte))) + pos_byte--; + return make_number (BYTE_TO_CHAR (pos_byte)); } DEFUN ("following-char", Ffollowing_char, Sfollowing_char, 0, 0, 0, |