From cf23c335acc7d3093001cdc54a56dda6bda25778 Mon Sep 17 00:00:00 2001 From: Wolfgang Jenkner Date: Wed, 17 Jun 2015 13:41:57 +0200 Subject: [PATCH] * src/editfns.c (Fbyte_to_position): Fix bytepos not at char boundary. The behavior now matches the description in the manual. (Bug#20783) --- src/editfns.c | 14 ++++++++++++-- 1 file 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, -- 2.39.2