Re: mshtml: Added IHTMLTable::width property implementation. (try 4)

[Zhenbo Li]

Hi Jacek,

2014-04-26 21:33 GMT+08:00 Jacek Caban :
> On 04/26/14 15:20, Zhenbo Li wrote:
> > 2014-04-26 20:44 GMT+08:00 Jacek Caban :
> > > Hi Zhenbo,
> > >
> > > This is better, but:
> > >
> > > On 04/26/14 05:12, Zhenbo Li wrote:
> > > - hres = var2str(&v, &val);
> > > -
> > > - if (hres != S_OK){
> > > -
> > >    ERR("Set Width(%s) failed when initializing a nsAString!\n",
> > > -
> > >        debugstr_variant(&v));
> > > -
> > >    nsAString_Finish(&val);
> > >
> > >
> > > Again, this is not initialized in the error case.
> >
> > As I've added
> > > - default:
> > > -
> > >    nsAString_Init(nsstr, NULL);
> > > -
> > >    FIXME("unsupported arg %s\n", debugstr_variant(p));
> > > -
> > >    return E_NOTIMPL;
> > > - }
> >
> > Isn't it enough?
>
> I missed that change, but I think it's wrong. There are other error
> cases as well. nsAString_Init failure also leaves the string
> uninitialized (and it's on my TODO list to make sure that we may make
> nsAString_Init infailable, but that's a different story). It's also
> generally sane to expect that if a function fails, it's output parameter
> is not initialized. Please remove this new nsAString_Init call and
> nsAString_Finish in error case.

Thank you for your explanation.
How about this solution:

+        return nsAString_Init(nsstr, V_BSTR(p))?
+            S_OK : E_OUTOFMEMORY;
+    case VT_R8:
+        hres = VarBstrFromR8(V_R8(p), 0, 0, &str);
+        break;
+    case VT_R4:
+        hres = VarBstrFromR4(V_R4(p), 0, 0, &str);
+        break;
+    case VT_I4:
+        hres = VarBstrFromI4(V_I4(p), 0, 0, &str);
+        break;
+    default:
+        FIXME("unsupported arg %s\n", debugstr_variant(p));
+        hres = E_NOTIMPL;
+        break;
+    }
+    if (FAILED(hres))
+        return hres;
+
+    ret = nsAString_Init(nsstr, str);
+    SysFreeString(str);
+    return ret ? S_OK : E_OUTOFMEMORY;
+}
> > Or you mean here?
> > > - ret = nsAString_Init(nsstr, str);
> > > - SysFreeString(str);
> > > - return ret ? S_OK : E_OUTOFMEMORY;
> >
> > Should I free a string which failed when initializing due to out-of-memory?
>
> Which one? The way it's done currently is right.
> > > -
> > > - hres = nsstr_to_truncated_bstr(&val, &bstr);
> > > - if (FAILED(hres)) {
> > > -
> > >    SysFreeString(bstr);
> > >
> > >
> > > And bstr is not initialized in error case.
> >
> > The error case comes from
> > > - ret = end ? SysAllocStringLen(str, end-str) : SysAllocString(str);
> > > - if(!ret)
> > > -
> > >    return E_OUTOFMEMORY;
> >
> > I have the same question.
>
> Please read the code again. bstr is not initialized in this case, so you
> can't free it.

Sorry, I made a mistake.
When SysAllocString failes, should we mark bstr as NULL?
Like this:

static HRESULT nsstr_to_truncated_bstr(const nsAString *nsstr, BSTR *ret_ptr)
{
//....
    ret = end ? SysAllocStringLen(str, end-str) : SysAllocString(str);

*ret_ptr = ret;
    return ret ? S_OK : E_OUTOFMEMORY;
}

static HRESULT WINAPI HTMLTable_get_width(IHTMLTable *iface, VARIANT *p)
{
//....
    hres = nsstr_to_truncated_bstr(&val, &bstr);
    if (FAILED(hres))
        return hres;
//...
}
> Jacek