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From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.c
Subject: Re: Distributing C as headers.
Date: Sun, 27 Jan 2019 16:59:39 -0800
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Xref: csiph.com comp.lang.c:140340

"Pascal J. Bourguignon" <pjb@informatimago.com> writes:
[...]
> A lot of C functions take a pointer and a size (or a length; Hello
> off-by-one errors!).
>
> Instead they should take an object abstracting away those elements, so
> that their consistency can be ensured by the functional abstraction.
>
>
>      strncpy(dst,src,size); /* crash ensured */

No, a crash is not ensured.

Here's a complete C program that includes that line:

#include <string.h>
#include <stdio.h>
int main(void) {
    char dst[100];
    const char *src = "hello, world";
    const size_t size = sizeof dst;
    strncpy(dst,src,size);
    puts(dst);
}

It will not crash.

(I almost certainly wouldn't use strncpy myself, but that's not
the point.  It's certainly possible to use strncpy in a way that
will cause a program to crash; that also is not the point.)

>      string_copy(dst,src); /* no crash possible, because string_copy
>                               with handle all the cases, given
>                               src->characters, src->length and
>                               dst->characters, dst->allocated_size */

I don't believe there's a standard Pascal function called
"string_copy".  In fact you can simply assign strings in Pascal:

    dst := src;

What exactly are "src->characters", "src->length", and so forth?  As far
as I can tell, Pascal doesn't use that syntax.

You assert that your string_copy procedure can't crash, but you haven't
shown us its implementation.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Will write code for food.
void Void(void) { Void(); } /* The recursive call of the void */