The multibyte character needs to fit into the remaining buffer space,
not the already-written buffer space. Without the fix, we were never
moving the write pointer from the start of the buffer, always using
the single-character fallback buffer.
Fixes commit
04b76b5aa8b2d1d19066e42dd1 ("Don't error out writing
a multibyte character to an unbuffered stream (bug 17522)").
char mb_buf[MB_LEN_MAX];
char *write_base, *write_ptr, *buf_end;
- if (fp->_IO_write_ptr - fp->_IO_write_base < sizeof (mb_buf))
+ if (fp->_IO_buf_end - fp->_IO_write_ptr < sizeof (mb_buf))
{
/* Make sure we have room for at least one multibyte
character. */