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Re: [Libvir] PATCH: 9/16: main internal storage driver



On Mon, Feb 18, 2008 at 03:20:37PM +0100, Jim Meyering wrote:
> "Daniel P. Berrange" <berrange redhat com> wrote:
> > +static int virStorageSize(virConnectPtr conn,
> > +                          const char *unit,
> > +                          const char *val,
> > +                          unsigned long long *ret) {
> > +    unsigned long long mult;
> > +    char *end;
> > +
> > +    if (!unit) {
> > +        mult = 1;
> > +    } else {
> > +        switch (unit[0]) {
> > +        case 'k':
> > +        case 'K':
> > +            mult = 1024ull;
> > +            break;
> > +
> > +        case 'm':
> > +        case 'M':
> > +            mult = 1024ull * 1024ull;
> > +            break;
> > +
> > +        case 'g':
> > +        case 'G':
> > +            mult = 1024ull * 1024ull * 1024ull;
> > +            break;
> > +
> > +        case 't':
> > +        case 'T':
> > +            mult = 1024ull * 1024ull * 1024ull * 1024ull;
> > +            break;
> 
> From our current perspective, 'T' looks big enough, but you might want
> to add 'P', 'Y', and 'Z', if only so the code doesn't seem clueless
> when reporting "unknown size units" :-)

Yeah, might as well.

> > +    *ret = strtoull(val, &end, 10);
> > +    if (end && *end) {
> > +        virStorageReportError(conn, VIR_ERR_XML_ERROR, "malformed capacity element");
> > +        return -1;
> > +    }
> > +    *ret *= mult;
> 
> If you change the guard to e.g.,
> 
>     if (*end || *ret > ULLONG_MAX / mult) {
>         virStorageReportError(conn, VIR_ERR_XML_ERROR,
>                               "malformed capacity element");
> 
> you avoid risk of overflow.

Ok, thanks

Dan.
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