Re: [ros-dev] [ros-diffs] [hbelusca] 73895: [NTGDI]: Few fixes & hacks for NtGdiGetGlyphIndicesW, see CORE-12825: - (Fix) Check for integer count overflow (per Thomas suggestion), - (Hack#1) Signal the particular calling ca...

[Thomas Faber]

On 2017-02-24 02:52, [e-mail] wrote:
> @@ -4419,12 +4422,31 @@
>      LPCWSTR UnSafepwc = pwc;
>      LPWORD UnSafepgi = pgi;
> if ((!UnSafepwc) && (!UnSafepgi)) return cwc;
> if ((UnSafepwc == NULL) || (UnSafepgi == NULL))
> /* Check for integer overflow */
> if (cwc & 0x80000000) // (INT_MAX + 1) == INT_MIN
>    return GDI_ERROR;
> if (!UnSafepwc && !UnSafepgi)
>    return cwc;
> if (!UnSafepwc || !UnSafepgi)
> {
>     DPRINT1("UnSafepwc == %p, UnSafepgi = %p\n", UnSafepwc, UnSafepgi);
>    return -1;
>    return GDI_ERROR;
> }
> // TODO: Special undocumented case!
> if (!pwc && !pgi && (cwc == 0))

Why the sudden switch away from using the Unsafe version?
> {
>    DPRINT1("ERR: NtGdiGetGlyphIndicesW with (!pwc && !pgi && (cwc == 0)) is UNIMPLEMENTED!\n");
>    return 0;
>
> }
>
> // FIXME: This is a hack!! (triggered by e.g. Word 2010). See CORE-12825
>
> if (cwc == 0)
>
> {
>    DPRINT1("ERR: NtGdiGetGlyphIndicesW with (cwc == 0) is UNIMPLEMENTED!\n");
>    return GDI_ERROR;
>
> }
>
> dc = DC_LockDc(hdc);

[Neo Love]

If 'cwc' is a pointer or anything that would ever become 64 bits in x64
this type of coding needs rewriting using symbolic sizes.
(Such as ULONG_PTR(-1) and similar constructs..)

On 2017-02-24 20.42, Thomas Faber wrote:
> /* Check for integer overflow */
> if (cwc & 0x80000000) // (INT_MAX + 1) == INT_MIN

L.

[Hermès BÉLUSCA-MAÏTO]

Hi,
I completely agree, and that's why I put in comment that INT_MIN stuff.

Hermès

-----Message d'origine-----
De : Ros-dev [mailto:[e-mail]] De la part de Neo Love
Envoyé : vendredi 3 mars 2017 01:26
À : ReactOS Development List
Objet : Re: [ros-dev] [ros-diffs] [hbelusca] 73895: [NTGDI]: Few fixes & hacks for NtGdiGetGlyphIndicesW, see CORE-12825: - (Fix) Check for integer count overflow (per Thomas suggestion), - (Hack#1) Signal the particular calling ca...

If 'cwc' is a pointer or anything that would ever become 64 bits in x64 this type of coding needs rewriting using symbolic sizes.
(Such as ULONG_PTR(-1) and similar constructs..)

On 2017-02-24 20.42, Thomas Faber wrote:
> /* Check for integer overflow */
> if (cwc & 0x80000000) // (INT_MAX + 1) == INT_MIN

L.
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