Differential D3043 Diff 6863 lib/libc/secure/__strncpy_chk.c

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lib/libc/secure/__strncpy_chk.c

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				/*-
				* Copyright (C) 2012 The Android Open Source Project
				* All rights reserved.
				*
				* Redistribution and use in source and binary forms, with or without
				* modification, are permitted provided that the following conditions
				* are met:
				* * Redistributions of source code must retain the above copyright
				* notice, this list of conditions and the following disclaimer.
				* * 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.
				*
				* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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
				* COPYRIGHT OWNER 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.
				*
				* bionic rev: d807b9a12d3e49132b095df3d883618452033b51
				*
				* $FreeBSD$
				*/

				#undef _FORTIFY_SOURCE

				#include <sys/cdefs.h>
				#include <secure/security.h>
				#include <string.h>
				#include <stdlib.h>
				#include "secure/_string.h"

				char *
				__strncpy_chk(char __restrict dest, const char __restrict src,
				size_t len, size_t dest_len)
				{

				if (__predict_false(len > dest_len))
				__fortify_chk_fail(
				"strncpy: prevented write past end of buffer");

				return (strncpy(dest, src, len));
				}

				/*
				* __strncpy_chk2
				*
				* This is a variant of __strncpy_chk, but it also checks to make
				* sure we don't read beyond the end of "src". The code for this is
				* based on the original version of strncpy, but modified to check
				* how much we read from "src" at the end of the copy operation.
				*/
				char *
				__strncpy_chk2(char __restrict dst, const char __restrict src,
				size_t n, size_t dest_len, size_t src_len)
				{
				size_t s_copy_len;

				if (__predict_false(n > dest_len))
				__fortify_chk_fail(
				"strncpy: prevented write past end of buffer");
				if (n != 0) {
				char *d = dst;
				const char *s = src;

				do {
				if ((d++ = s++) == 0) {
				/* NUL pad the remaining n-1 bytes */
				while (--n != 0)
				*d++ = 0;
				break;
				}
				} while (--n != 0);

				s_copy_len = (size_t)(s - src);

				if (__predict_false(s_copy_len > src_len))
				__fortify_chk_fail("strncpy: prevented read past end of buffer");
				}

				return (dst);
				}