On Nov 21 11:42, Jeremy Drake via Cygwin-patches wrote:
> This was already used in the FAST_CWD check, and could be used in a
> couple other places.
>
> I found the "emulated"/process value returned from the function largely
> useless, so I did not cache it. It is useless because, as the docs say,
> it is set to IMAGE_FILE_MACHINE_UNKNOWN (0) if the process is not
> running under WOW64, but Microsoft also doesn't consider x64-on-ARM64 to
> be WOW64, so it is set to 0 regardless if the process is ARM64 or x64.
> You can tell the difference via
> GetProcessInformation(ProcessMachineTypeInfo), but for the current
> process even that's overkill: what we really want to know is the
> IMAGE_FILE_MACHINE_* constant for the Cygwin dll itself, which is
> conveniently located in memory already, so make an accessor function to
> access that. (It could also be cached in a member variable for a
> simpler accessor, and looked up in init).
> ---
> Note the elif defined (__i386__) case won't compile because it references
> the no-longer-present `wow64` value. This was written and tested against
> 3.3.6, and the __i386__ case could just go away here...
Yeah, just kill it.
> + const USHORT current_module_machine () const;
This is not necessary.
> @@ -282,4 +284,30 @@ wincapc::init ()
>
> __small_sprintf (osnam, "NT-%d.%d", version.dwMajorVersion,
> version.dwMinorVersion);
> +
> + if (!IsWow64Process2 (GetCurrentProcess (), &emul_mach, &host_mach))
> + {
> + /* assume the only way IsWow64Process2 fails for the current process is
> + that we're running on an OS version where it's not implemented yet.
> + As such, the only two realistic options are AMD64 or I386 */
> +#if defined (__x86_64__)
> + host_mach = IMAGE_FILE_MACHINE_AMD64;
> +#elif defined (__i386__)
> + host_mach = wow64 ? IMAGE_FILE_MACHINE_AMD64 : IMAGE_FILE_MACHINE_I386;
> +#else
> + /* this should not happen */
It should actually result in
#error unimplemented for this target
> +#endif
> + }
> +}
> +
> +extern const IMAGE_DOS_HEADER
> +dosheader __asm__ ("__image_base__");
> +
> +const USHORT
> +wincapc::current_module_machine () const
> +{
> + PIMAGE_NT_HEADERS ntheader = (PIMAGE_NT_HEADERS)((LPBYTE) &dosheader
> + + dosheader.e_lfanew);
> + return ntheader->FileHeader.Machine;
> }
Just scratch that. First, we're using GetModuleHandle(NULL)
throughout to access the image base, but apart from that,
the info is already available in wincap via cpu_arch().
Corinna
