sync with OpenBSD -current

lib/libc/stdio/freadptr.c

@@ -0,0 +1,45 @@
+/*	$OpenBSD: freadptr.c,v 1.1 2024/08/12 20:56:55 guenther Exp $	*/
+/*
+ * Copyright (c) 2024 Philip Guenther <guenther@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <stdlib.h>
+#include <stdio_ext.h>
+#include "local.h"
+
+const char *
+__freadptr(FILE *fp, size_t *sizep)
+{
+	if ((fp->_flags & __SRD) && fp->_r > 0) {
+		*sizep = fp->_r;
+		return fp->_p;
+	}
+	return NULL;
+}
+
+void
+__freadptrinc(FILE *fp, size_t inc)
+{
+	if (fp->_flags & __SRD) {
+		fp->_r -= inc;
+		fp->_p += inc;
+		if (fp->_r == 0 && HASUB(fp)) {
+			/* consumed the pushback buffer; switch back */
+			FREEUB(fp);
+			if ((fp->_r = fp->_ur) != 0)
+				fp->_p = fp->_up;
+		}
+	}
+}