Re: [9front] strndup should use strnlen and memcpy

["Sigrid Solveig Haflínudóttir" <ftrvxmtrx@gmail.com>]

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In 9front, memcpy == memmove.

Why is strlen dangerous?

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From: Xiao-Yong Jin <meta.jxy@gmail.com>
To: 9front@9front.org
Subject: [9front] strndup should use strnlen and memcpy
Date: Fri, 18 Dec 2020 02:22:25 -0600
Message-ID: <CEDEBD0B-FC39-43D4-960F-05E348970FE8@gmail.com>

I just saw the new commit of strndup that uses strlen and memmove.
memmove is unnecessary.
strlen is dangerous.

Here is a reference implementation from musl.

http://git.musl-libc.org/cgit/musl/tree/src/string/strndup.c

#include <stdlib.h>
#include <string.h>

char *strndup(const char *s, size_t n)
{
	size_t l = strnlen(s, n);
	char *d = malloc(l+1);
	if (!d) return NULL;
	memcpy(d, s, l);
	d[l] = 0;
	return d;
}