1//===-- Implementation of strncpy -----------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "src/string/strncpy.h"
10
11#include "src/__support/common.h"
12#include "src/__support/macros/config.h"
13#include "src/__support/macros/null_check.h"
14#include <stddef.h> // For size_t.
15
16namespace LIBC_NAMESPACE_DECL {
17
18LLVM_LIBC_FUNCTION(char *, strncpy,
19 (char *__restrict dest, const char *__restrict src,
20 size_t n)) {
21 if (n) {
22 LIBC_CRASH_ON_NULLPTR(dest);
23 LIBC_CRASH_ON_NULLPTR(src);
24 }
25 size_t i = 0;
26 // Copy up until \0 is found.
27 for (; i < n && src[i] != '\0'; ++i)
28 dest[i] = src[i];
29 // When n>strlen(src), n-strlen(src) \0 are appended.
30 for (; i < n; ++i)
31 dest[i] = '\0';
32 return dest;
33}
34
35} // namespace LIBC_NAMESPACE_DECL
36

source code of libc/src/string/strncpy.cpp