1/*
2 * Copyright (c) 2011 Apple, Inc. All rights reserved.
3 *
4 * @APPLE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. Please obtain a copy of the License at
10 * http://www.opensource.apple.com/apsl/ and read it before using this
11 * file.
12 *
13 * The Original Code and all software distributed under the License are
14 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
15 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
16 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
18 * Please see the License for the specific language governing rights and
19 * limitations under the License.
20 *
21 * @APPLE_LICENSE_HEADER_END@
22 */
23
24#include <string.h>
25
26char *
27stpncpy(char * restrict dst, const char * restrict src, size_t maxlen) {
28    const size_t srclen = strnlen(src, maxlen);
29    if (srclen < maxlen) {
30        //  The stpncpy() and strncpy() functions copy at most maxlen
31        //  characters from src into dst.
32        memcpy(dst, src, srclen);
33        //  If src is less than maxlen characters long, the remainder
34        //  of dst is filled with '\0' characters.
35        memset(dst+srclen, 0, maxlen-srclen);
36        //  The stpcpy() and stpncpy() functions return a pointer to the
37        //  terminating '\0' character of dst.
38        return dst+srclen;
39    } else {
40        //  The stpncpy() and strncpy() functions copy at most maxlen
41        //  characters from src into dst.
42        memcpy(dst, src, maxlen);
43        //  If stpncpy() does not terminate dst with a NUL character, it
44        //  instead returns a pointer to src[maxlen] (which does not
45        //  necessarily refer to a valid memory location.)
46        return dst+maxlen;
47    }
48}
49