Fork#41567: Some new Win32 APIs are missing from w32api
Open Date: 2021-02-12 16:20
Last Update: 2021-05-20 09:38
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Last Changes/Comment on this Ticket:
2021-05-20 09:38 Updated by: eliz
Comment:
Reply To keith
Reply To eliz
Fundamentally, the caveat is that, once the header files have been updated, and the import library thunks have been added, any code which is compiled with an appropriate NTDDI_VERSION definition may call the new functions directly, and, in the absence of coding errors, the program will compile, and link successfully. However, it will not load, much less run, on any legacy version of Windows, (which, in the case of the pseudo-console support, is anything pre-dating Win10-RS5); it will crash, at load time, with a "kernel32.dll entry point not found" exception, before the main() function even starts to run, and thus before it has any chance to offer a hint that it requires a newer version of Windows!
Now, I'm sure that you, Eli, are already aware of this limitation, and there is already precedent for such pitfalls, in MinGW import libraries, but I thought it worthy of mention, for the benefit of (possibly) less enlightened users. The defensive way, to manage this caveat, is to always call potentially unsupported functions via a pointer retrieved by GetProcAddress(), and never call them directly; in this way, the application can ensure that GetProcAddress() returns a valid pointer, or can provide a graceful fallback action, if NULL is returned. I've written quite a few such "legacy capable" functions, in the past year or so; they all look very similar, and I'm seriously considering factoring out the commonality, into generic helper functions, (perhaps in libkernel32.a), to make the task less repetitive, but that's probably a subject for another feature request ticket.
Yes, indeed. Any program that wants to use APIs only available on some modern versions of Windows must use GetProcAddress to test for the availability, and then call the API through a pointer populated by it. For example, GNU Emacs, when built for MS-Windows, uses this technique all over the place, because (when compiled by MinGW -- NOT MinGW64, not even their 32-bit variant!) it still supports every Windows version from Windows 98 onwards.
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Ticket Status:
Reporter: eliz
Owner: (None)
Type: Feature Request
Status: Open
Priority: 5 - Medium
MileStone: (None)
Component: WSL
Severity: 5 - Medium
Resolution: None
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Ticket details:
To compile programs that use the Pseudo Console feature introduced recently with Windows 10, there's a need in several additions to the MinGW w32api headers and import libraries.
First, we need a value for _WIN32_WINNT that specifies Windows 10, in sdkddkver.h:
#define _WIN32_WINNT_WIN10 0x0A00
Second, we need functions, data structures, and macros to create and update lists of attributes for process and thread creation. These are:
InitializeProcThreadAttributeList function
UpdateProcThreadAttribute function
DeleteProcThreadAttributeList function
PROC_THREAD_ATTRIBUTE_LIST structure
STARTUPINFOEX structure
PROC_THREAD_ATTRIBUTE_PSEUDOCONSOLE macro
Other PROC_THREAD_ATTRIBUTE_* macros
These seem to be supported since Windows 7, with the exception of PROC_THREAD_ATTRIBUTE_PSEUDOCONSOLE, which is only supported since Windows 10, and STARTUPINFOEX, which is supported since Vista. I think the proper place for them is in the winbase.h header file.
We also need the EXTENDED_STARTUPINFO_PRESENT flag for the CreateProcess function (this flag is supported since Vista and should be in winbase.h).
And finally, we need the functions, data types, and macros to manipulate pseudo-consoles, available only since Windows 10:
CreatePseudoConsole function
ClosePseudoConsole function
ResizePseudoConsole function
HPCON data type
Thanks in advance for providing these.
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