From a43a7b215cf7b71d1371c63927c17bae7177aa95 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Wed, 29 Aug 2018 23:53:45 -0400 Subject: make vfprintf set stream orientation even for zero-length output if no output is produced, no underlying fwrite will ever be called, but byte-oriented printf functions are still required to set the orientation of the stream to byte-oriented. call __towrite explicitly if the FILE is not already in write mode. --- src/stdio/vfprintf.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'src/stdio') diff --git a/src/stdio/vfprintf.c b/src/stdio/vfprintf.c index af069d13..2100eb5e 100644 --- a/src/stdio/vfprintf.c +++ b/src/stdio/vfprintf.c @@ -678,7 +678,8 @@ int vfprintf(FILE *restrict f, const char *restrict fmt, va_list ap) f->buf_size = sizeof internal_buf; f->wpos = f->wbase = f->wend = 0; } - ret = printf_core(f, fmt, &ap2, nl_arg, nl_type); + if (!f->wend && __towrite(f)) ret = -1; + else ret = printf_core(f, fmt, &ap2, nl_arg, nl_type); if (saved_buf) { f->write(f, 0, 0); if (!f->wpos) ret = -1; -- cgit v1.2.1