1 files changed, 48 insertions, 0 deletions
diff --git a/libc/stdio/ungetwc.c b/libc/stdio/ungetwc.c
new file mode 100644
index 000000000..cf4b9c488
--- /dev/null
+++ b/libc/stdio/ungetwc.c
@@ -0,0 +1,48 @@
+/* Copyright (C) 2004       Manuel Novoa III    <mjn3@codepoet.org>
+ *
+ * GNU Library General Public License (LGPL) version 2 or later.
+ *
+ * Dedicated to Toni.  See uClibc/DEDICATION.mjn3 for details.
+ */
+
+#include "_stdio.h"
+
+/* Note: This is the application-callable ungetwc.  If wscanf calls this, it
+ * should also set stream->__ungot[1] to 0 if this is the only ungot, as well
+ * as reset stream->__ungot_width[1] for use by _stdio_adjpos().
+ */
+
+wint_t ungetwc(wint_t c, register FILE *stream)
+{
+	__STDIO_AUTO_THREADLOCK_VAR;
+
+	__STDIO_AUTO_THREADLOCK(stream);
+	__STDIO_STREAM_VALIDATE(stream); /* debugging only */
+
+	/* Note: Even if c == WEOF, we need to initialize/verify the
+	 * stream's orientation and ensure the stream is in reading
+	 * mode (if readable and properly oriented). */
+	if ((!__STDIO_STREAM_IS_WIDE_READING(stream)
+		 && __STDIO_STREAM_TRANS_TO_READ(stream, __FLAG_WIDE))
+		|| ((stream->__modeflags & __FLAG_UNGOT)
+			&& ((stream->__modeflags & 1) || stream->__ungot[1]))
+		|| (c == WEOF)
+		) {
+		c = WEOF;
+	} else {
+		/* In the wide case, getc macros should already be disabled. */
+		/* 	__STDIO_STREAM_DISABLE_GETC(stream); */
+
+		/* Flag this as a user ungot, as scanf does the necessary fixup. */
+		stream->__ungot[1] = 1;
+		stream->__ungot[(++stream->__modeflags) & 1] = c;
+		/* Note: ungot_width is handled by fgetwc. */
+
+		__STDIO_STREAM_CLEAR_EOF(stream); /* Must clear end-of-file flag. */
+	}
+
+	__STDIO_STREAM_VALIDATE(stream);
+	__STDIO_AUTO_THREADUNLOCK(stream);
+
+	return c;
+}