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/ungetc.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) create mode 100644 src/stdio/ungetc.c (limited to 'src/stdio/ungetc.c') diff --git a/src/stdio/ungetc.c b/src/stdio/ungetc.c new file mode 100644 index 00000000..07181684 --- /dev/null +++ b/src/stdio/ungetc.c @@ -0,0 +1,33 @@ +#include "stdio_impl.h" + +int ungetc(int c, FILE *f) +{ + if (c == EOF) return c; + + FLOCK(f); + + /* 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->wbase = 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 already full, fail. */ + if (f->rpos <= f->buf - UNGET) { + FUNLOCK(f); + return EOF; + } + + /* Put a byte back into the buffer */ + *--f->rpos = c; + f->flags &= ~F_EOF; + + FUNLOCK(f); + return c; +} -- cgit v1.2.1