From 25085c85a0055a94919bf522c96803db7c885431 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Wed, 7 Sep 2022 18:41:09 -0400 Subject: [PATCH] fix fwprintf missing output to open_wmemstream FILEs open_wmemstream's write method was written assuming no buffering, since it sets the FILE up with buf_len of zero in order to avoid issues with position/seeking. however, as a consequence of commit bd57e2b43a5b56c00a82adbde0e33e5820c81164, a FILE being written to by the printf core has a temporary local buffer for the duration of the operation if it was unbuffered to begin with. since this was disregarded by the wide memstream's write method, output produced through this code path, particularly numeric fields, was missing from the output wchar buffer. copy the equivalent logic for using the buffered data from the byte-oriented open_memstream. --- src/stdio/open_wmemstream.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/src/stdio/open_wmemstream.c b/src/stdio/open_wmemstream.c index ed1b561d..b8ae4a79 100644 --- a/src/stdio/open_wmemstream.c +++ b/src/stdio/open_wmemstream.c @@ -40,8 +40,12 @@ fail: static size_t wms_write(FILE *f, const unsigned char *buf, size_t len) { struct cookie *c = f->cookie; - size_t len2; + size_t len2 = f->wpos - f->wbase; wchar_t *newbuf; + if (len2) { + f->wpos = f->wbase; + if (wms_write(f, f->wbase, len2) < len2) return 0; + } if (len + c->pos >= c->space) { len2 = 2*c->space+1 | c->pos+len+1; if (len2 > SSIZE_MAX/4) return 0;