/**
* slibc — Yet another C library
* Copyright © 2015 Mattias Andrée (maandree@member.fsf.org)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <string.h>
/**
* Copy a memory segment to another, non-overlapping, segment,
* stop when a NUL byte or a specified substring is encountered.
*
* This is a slibc extension added for completeness.
* It is only available if GNU extensions are available.
*
* @param whither The destination memory segment.
* @param whence The source memory segment.
* @param str The substring, ignored if `NULL`.
* NOTE that if the resulting string at least this
* long, no NUL byte will be written to `whither'.
* On the otherhand, if the resultnig string is
* shorter, `whither` will be filled with NUL bytes
* until this amount of bytes have been written.
* @param maxlen The maximum number of bytes to copy.
* @return `NULL` if `str` was not encountered, otherwise
* the position of `str` translated to `whither`,
* that is, the address of `whither` plus the
* number of copied characters; the address of
* one character passed the last written non-NUL
* character.
*
* @since Always.
*/
char* strstrncpy(char* restrict whither, const char* restrict whence,
const char* restrict str, size_t maxlen)
{
const char* stop = strnstr(whence, str, maxlen);
size_t n = stop == NULL ? strnlen(whence, maxlen) : (size_t)(stop - whence);
char* r = stop == NULL ? NULL : (whither + n);
memcpy(whither, whence, n);
memset(whither + n, 0, maxlen - n);
return r;
}
