glibc/string/strlcpy.c

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/* Copy a null-terminated string to a fixed-size buffer, with length checking.
Copyright (C) 2023-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <string.h>
size_t
__strlcpy (char *__restrict dest, const char *__restrict src, size_t size)
{
size_t src_length = strlen (src);
if (__glibc_unlikely (src_length >= size))
{
if (size > 0)
{
/* Copy the leading portion of the string. The last
character is subsequently overwritten with the NUL
terminator, but the destination size is usually a
multiple of a small power of two, so writing it twice
should be more efficient than copying an odd number of
bytes. */
memcpy (dest, src, size);
dest[size - 1] = '\0';
}
}
else
/* Copy the string and its terminating NUL character. */
memcpy (dest, src, src_length + 1);
return src_length;
}
libc_hidden_def (__strlcpy)
weak_alias (__strlcpy, strlcpy)