Fix onnxruntime search dll path.

[chinazhangchao]

Windows ships C:\Windows\System32\onnxruntime.dll (older API version) as part of the system WindowsML component.
When WinML EP plugin DLLs are loaded (via EpCatalog), they import "onnxruntime.dll" by base name and the loader binds them to the system copy, producing "The requested API version [N] is not available" errors.
Loading the wheel-bundled DLL by full path first makes later base-name imports resolve to the already-loaded module.

[xieofxie]

will it slow much? do we need to find the exact place before ort is loaded?

[chinazhangchao]

will it slow much? do we need to find the exact place before ort is loaded?

Didn't feel slow. Almost the same.

[timenick]

Review: missing regression coverage for the DLL preload mechanism.

[tezheng]

Do we have proof that "C:\Windows\System32\onnxruntime.dll" is indeed loaded? how can I repro if yest?

[tezheng]

At least we should try this first, and see which DLLs get loaded

import os, ctypes, onnxruntime as ort
from ctypes import wintypes

print("ort version:", ort.__version__)
print("ort package:", ort.__file__)
capi = os.path.join(os.path.dirname(ort.__file__), "capi")
for name in ("onnxruntime.dll", "onnxruntime_pybind11_state.pyd", "onnxruntime_providers_shared.dll", "DirectML.dll"):
    p = os.path.join(capi, name)
    print(f"  {'OK ' if os.path.isfile(p) else 'NO '} {p}")

k32 = ctypes.WinDLL("kernel32")
k32.GetCurrentProcess.restype = wintypes.HANDLE

psapi = ctypes.WinDLL("psapi")
psapi.EnumProcessModules.argtypes = [wintypes.HANDLE, ctypes.POINTER(ctypes.c_void_p), wintypes.DWORD, ctypes.POINTER(wintypes.DWORD)]
psapi.EnumProcessModules.restype = wintypes.BOOL
psapi.GetModuleFileNameExW.argtypes = [wintypes.HANDLE, ctypes.c_void_p, wintypes.LPWSTR, wintypes.DWORD]

mods = (ctypes.c_void_p * 4096)(); need = wintypes.DWORD()
psapi.EnumProcessModules(k32.GetCurrentProcess(), mods, ctypes.sizeof(mods), ctypes.byref(need))
print("--- onnxruntime* modules currently mapped in process ---")
for i in range(need.value // ctypes.sizeof(ctypes.c_void_p)):
    buf = ctypes.create_unicode_buffer(32768)
    psapi.GetModuleFileNameExW(k32.GetCurrentProcess(), mods[i], buf, len(buf))
    if "onnxruntime" in os.path.basename(buf.value).lower():
        print(" ", buf.value)

[xieofxie]

Do we have proof that "C:\Windows\System32\onnxruntime.dll" is indeed loaded? how can I repro if yest?

yes, I have tested this both by process explorer and also log show it