1 files changed, 146 insertions, 0 deletions
diff --git a/lib/libc/stdio/fread.c b/lib/libc/stdio/fread.c
new file mode 100644
index 000000000000..65d9ecf94366
--- /dev/null
+++ b/lib/libc/stdio/fread.c
@@ -0,0 +1,146 @@
+/*-
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ * Copyright (c) 1990, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Chris Torek.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include "namespace.h"
+#include <errno.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include <ssp/ssp.h>
+#include "un-namespace.h"
+#include "local.h"
+#include "libc_private.h"
+
+/*
+ * MT-safe version
+ */
+
+size_t
+__ssp_real(fread)(void * __restrict buf, size_t size, size_t count,
+    FILE * __restrict fp)
+{
+	size_t ret;
+
+	FLOCKFILE_CANCELSAFE(fp);
+	ret = __fread(buf, size, count, fp);
+	FUNLOCKFILE_CANCELSAFE();
+	return (ret);
+}
+
+size_t
+__fread(void * __restrict buf, size_t size, size_t count, FILE * __restrict fp)
+{
+	size_t resid;
+	char *p;
+	int r;
+	size_t total;
+
+	/*
+	 * ANSI and SUSv2 require a return value of 0 if size or count are 0.
+	 */
+	if ((count == 0) || (size == 0))
+		return (0);
+
+	/*
+	 * Check for integer overflow.  As an optimization, first check that
+	 * at least one of {count, size} is at least 2^16, since if both
+	 * values are less than that, their product can't possible overflow
+	 * (size_t is always at least 32 bits on FreeBSD).
+	 */
+	if (((count | size) > 0xFFFF) &&
+	    (count > SIZE_MAX / size)) {
+		errno = EINVAL;
+		fp->_flags |= __SERR;
+		return (0);
+	}
+
+	/*
+	 * Compute the (now required to not overflow) number of bytes to
+	 * read and actually do the work.
+	 */
+	resid = count * size;
+	ORIENT(fp, -1);
+	if (fp->_r < 0)
+		fp->_r = 0;
+	total = resid;
+	p = buf;
+
+	/*
+	 * If we're unbuffered we know that the buffer in fp is empty so
+	 * we can read directly into buf.  This is much faster than a
+	 * series of one byte reads into fp->_nbuf.
+	 */
+	if ((fp->_flags & __SNBF) != 0 && buf != NULL) {
+		while (resid > 0) {
+			/* set up the buffer */
+			fp->_bf._base = fp->_p = p;
+			fp->_bf._size = resid;
+
+			if (__srefill(fp)) {
+				/* no more input: return partial result */
+				count = (total - resid) / size;
+				break;
+			}
+			p += fp->_r;
+			resid -= fp->_r;
+		}
+
+		/* restore the old buffer (see __smakebuf) */
+		fp->_bf._base = fp->_p = fp->_nbuf;
+		fp->_bf._size = 1;
+		fp->_r = 0;
+
+		return (count);
+	}
+
+	while (resid > (r = fp->_r)) {
+		if (r != 0) {
+			(void)memcpy((void *)p, (void *)fp->_p, (size_t)r);
+			fp->_p += r;
+			/* fp->_r = 0 ... done in __srefill */
+			p += r;
+			resid -= r;
+		}
+		if (__srefill(fp)) {
+			/* no more input: return partial result */
+			return ((total - resid) / size);
+		}
+	}
+	(void)memcpy((void *)p, (void *)fp->_p, resid);
+	fp->_r -= resid;
+	fp->_p += resid;
+	return (count);
+}
+
+__weak_reference(__fread, fread_unlocked);