Re: [PATCH v5 07/22] tools/9pfsd: add 9pfs attach request support

[Jürgen Groß <jgross@xxxxxxxx>]

On 14.02.24 18:40, Andrew Cooper wrote:
> On 08/02/2024 4:55 pm, Juergen Gross wrote:
> > +static struct p9_fid *alloc_fid_mem(device *device, unsigned int fid,
> > +                                    const char *path)
> > +{
> > +    struct p9_fid *fidp;
> > +    size_t pathlen;
> > +
> > +    pathlen = strlen(path);
> > +    fidp = calloc(sizeof(*fidp) + pathlen + 1, 1);
> > +    if ( !fidp )
> > +        return NULL;
> > +
> > +    fidp->fid = fid;
> > +    strncpy(fidp->path, path, pathlen);
> > +
> > +    return fidp;
> > +}
> GitlabCI has something to say about this.
> https://gitlab.com/xen-project/people/andyhhp/xen/-/pipelines/1176787593
>
> I think they're all variations of:
>
> io.c: In function 'alloc_fid_mem.isra.8':
> io.c:566:5: error: 'strncpy' output truncated before terminating nul
> copying as many bytes from a string as its length
> [-Werror=stringop-truncation]
>       strncpy(fidp->path, path, pathlen);
>       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> io.c:560:15: note: length computed here
>       pathlen = strlen(path);
>                 ^~~~~~~~~~~~
In the end the result is fine, as the buffer is large enough and it is
zeroed on allocation.

I'll change it nevertheless as it is a bad code pattern.


Juergen