From 0b44a0315b47dd8eced9f3b7f31580cf14bbfc01 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Sat, 12 Feb 2011 00:22:29 -0500 Subject: initial check-in, version 0.5.0 --- src/stdio/ungetwc.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) create mode 100644 src/stdio/ungetwc.c (limited to 'src/stdio/ungetwc.c') diff --git a/src/stdio/ungetwc.c b/src/stdio/ungetwc.c new file mode 100644 index 00000000..f7cde2e0 --- /dev/null +++ b/src/stdio/ungetwc.c @@ -0,0 +1,45 @@ +#include "stdio_impl.h" + +wint_t ungetwc(wint_t c, FILE *f) +{ + unsigned char mbc[MB_LEN_MAX]; + int l=1; + + if (c == WEOF) return c; + + /* Try conversion early so we can fail without locking if invalid */ + if (!isascii(c) && (l = wctomb(mbc, c)) < 0) + return WEOF; + + FLOCK(f); + + f->mode |= f->mode+1; + + /* Fail if unreadable or writing and unable to flush */ + if ((f->flags & (F_ERR|F_NORD)) || (f->wpos && __oflow(f))) { + FUNLOCK(f); + return EOF; + } + + /* Clear write mode */ + f->wpos = f->wstop = f->wend = 0; + + /* Put the file in read mode */ + if (!f->rpos) f->rpos = f->rend = f->buf; + + /* If unget buffer is nonempty, fail. */ + if (f->rpos < f->buf) { + FUNLOCK(f); + return WEOF; + } + + /* Put character back into the buffer */ + if (isascii(c)) *--f->rpos = c; + else memcpy(f->rpos -= l, mbc, l); + + /* Clear EOF */ + f->flags &= ~F_EOF; + + FUNLOCK(f); + return c; +} -- cgit v1.2.1