On Thu, 8 Jun 2023, Alexandre Julliard wrote:
Martin Storsjö <[email protected]> writes:
When looking at the redistributable api-ms-win-crt*.dlls from the
redistributable UCRT, api-ms-win-crt-filesystem-l1-1-0.dll does not
contain these symbols; neither in the original releases of UCRT from
2015, nor in the current releases from the latest WinSDK. So if we
link against this function from api-ms-win-crt-filesystem-l1-1-0.dll,
a binary won't load with the redistributable version of UCRT.
As these DLLs don't exist physically on disk in actual Windows 10, I
can't inspect that, but I did try to link a test executable with this,
which imports _getcwd from api-ms-win-crt-filesystem-l1-1-0.dll and it
actually does seem to run successfully on Windows 10, so it is
somewhat there still.
Note that at runtime, imports of api-ms-* dlls are not resolved like
normal imports; first the dll name is mapped to the target dll through
the apiset data, and then the function is looked up in the target dll
only. The function is never actually looked up in the api-ms-* dll.
This means that the fact that a function is found on Windows at runtime
doesn't tell you anything about whether it should be in the api-ms-*
importlib.
Thanks, I didn't know that aspect!
It also means that there's no issue with having the same function
exported from multiple api-ms-win-crt-* importlibs, or with having extra
exports that may not exist on Windows. All that matters at runtime is
that the function can be found in ucrtbase.dll.
Except that for older OSes, the UCRT is a separate redistributable install
and not handled as OS-provided apisets.
My test executable, which imported _getcwd from
api-ms-win-crt-filesystem-l1-1-0.dll, which succeeded on Windows 10,
failed to load on Windows 7 (with UCRT installed), while a similar
executable linked with the current git version of import libs did load
successfully.
// Martin
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