Odd behavior: Command() is different from GetCommandLine() if an objman path with \?? to an existing file is in cmdline

[Cherry]

I ran into this super weird issue right now. I wrote a tool to update some links in the object manager namespace in Windows.

This is when I noticed that if I pass an object manager path that starts with \?? and points to an existing file - and only then! - the command line argument as seen with Command() is messed up and the first parts of the path are missing, up to (but not including) the last backslash! Looking at Windows' GetCommandLine() API confirms that this is indeed happening on FreeBasic's side of things and not in my shell or Windows.

To reproduce, compile this program:

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#Include "windows.bi"
Print *GetCommandLine()
Print Command()
Print Command(1)
Print Command(2)
Print Command(3)

Observe the following strange results:

Normal:

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C:\>test.exe a b c
C:\test.exe a b c
a b c
a
b
c

Bug (assuming C:\Windows\System32\calc.exe exists):

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C:\>test.exe a \??\C:\Windows\System32\calc.exe c
C:\test.exe a \??\C:\Windows\System32\calc.exe c
a \calc.exe c
a
\calc.exe
c

Note how "\??\C:\Windows\System32\calc.exe" got truncated to "\calc.exe"!

Also happening if I put the value in doublequotes:

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C:\>test.exe a "\??\C:\Windows\System32\calc.exe" c
C:\test.exe a "\??\C:\Windows\System32\calc.exe" c
a \calc.exe c
a
\calc.exe
c

Also happening with device files:

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C:\>test.exe a \??\NUL c
C:\test.exe a \??\NUL c
a \NUL c
a
\NUL
c

Even happening when the string doesn't even contain a regular path but still eventually resolves to a filesystem file somehow and still goes through the \?? directory at the beginning:

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C:\>test.exe a \??\GLOBALROOT\SystemRoot\System32\calc.exe b
C:\test.exe a "\??\GLOBALROOT\SystemRoot\System32\calc.exe b
a \calc.exe c
a
\calc.exe
c

Not happening with non-existing files: (This makes it extra weird!)

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C:\>test.exe a \??\C:\Windows\System32\IDontExist.exe c
C:\test.exe a \??\C:\Windows\System32\IDontExist.exe c
a \??\C:\Windows\System32\IDontExist.exe c
a
\??\C:\Windows\System32\IDontExist.exe
c

Not happening with other object manager paths which resolve to the same file but don't use \??:

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C:\>test.exe a \GLOBAL??\C:\Windows\System32\calc.exe c
C:\test.exe a \GLOBAL??\C:\Windows\System32\calc.exe c
a \GLOBAL??\C:\Windows\System32\calc.exe c
a
\GLOBAL??\C:\Windows\System32\calc.exe
c

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C:\>test.exe a \Device\HarddiskVolume3\Windows\System32\calc.exe c
C:\test.exe a \Device\HarddiskVolume3\Windows\System32\calc.exe c
a \Device\HarddiskVolume3\Windows\System32\calc.exe c
a
\Device\HarddiskVolume3\Windows\System32\calc.exe
c

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C:\>test.exe a \SystemRoot\System32\calc.exe c
C:\test.exe a \SystemRoot\System32\calc.exe c
a \SystemRoot\System32\calc.exe c
a
\SystemRoot\System32\calc.exe
c

What the heck is going on here and how can I prevent it?

If it was just always happening when the commandline argument started with "\??", I'd assume some kind of weird parsing bug, but the fact that it only happens for existing files makes this seem intentional but extremely unexpected.

---

EDIT: I looked at Process Monitor while starting the program and saw that it opens the file, and this is the stack:


This even happens with an entirely empty FreeBasic program, if I pass any argument starting with \??. I think this is very unexpected!

EDIT2: The Stack suggests it's part of _getmainargs which is part of msvcrt... so I'd assume that the same would happen with a C++ program compiled with Visual Studio, but it does not! I created this program to test:

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#include <iostream>
#include <windows.h>

int main(int argc, char* argv[]) {
    std::cout << GetCommandLineA() << std::endl;

    for (int i = 1; i < argc; i++) {
        std::cout << argv[i] << std::endl;
    }

    return 0;
}

...and it doesn't exhibit this behavior.

[hhr]

Please read 'Disabling filename globbing under Win32' in https://www.freebasic.net/wiki/KeyPgCommand

[Cherry]

Ah. I see. OK this has nothing to do with real globbing, I'd say, as the result makes no sense. But I guess "backslashes in arguments can cause problems" is broad enough to apply. Thanks, this solved the issue!

[hhr]

Pasting

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Extern _dowildcard Alias "_dowildcard" As Long
Dim Shared _dowildcard As Long = 0

into the program works for me.

@fxm
The second (For MinGW-w64 runtime) works with Win32/64 and gas, gas64, gcc.
Maybe 'Win32' in 'Disabling filename globbing under Win32' is outdated. I think 'Windows' or Win32/64 or something similar would be better.
Thanks in advance.