From ecc7c3deb9f347649c2078fcc0f94d4cedf92d60 Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Tue, 2 Jan 2024 14:36:17 +0100 Subject: [PATCH] libio: Check remaining buffer size in _IO_wdo_write (bug 31183) 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)"). --- libio/wfileops.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/libio/wfileops.c b/libio/wfileops.c index 17384296e6..6de5968358 100644 --- a/libio/wfileops.c +++ b/libio/wfileops.c @@ -55,7 +55,7 @@ _IO_wdo_write (FILE *fp, const wchar_t *data, size_t to_do) 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. */