Golang: using Windows 10 API / UWP / System.WindowsRuntime?

Question

Using syscall in Go how can I call the UWP APIs within Windows 10? I have seen and tried many win32 examples, but when I tried using System.WindowsRuntime.dll it was a no-go; specifically, I received:

panic: Failed to load System.WindowsRuntime.dll: The specified module could not be found.

(this was at runtime, the binary built fine)

I tried building both with a standard go build as well as

go build -ldflags="-H windows"

example code:

var(
    windowsRuntime      = syscall.NewLazyDLL("System.WindowsRuntime.dll")
    getDiskFreeSpace    = windowsRuntime.NewProc("GetDiskFreeSpace")
)

Note: Other variants tried:

windowsRuntime      = syscall.NewLazyDLL("System.Runtime.WindowsRuntime.dll")

&

windowsRuntime      = syscall.NewLazyDLL("WindowsRuntime.dll")

Anyone been able to get this running or have any advice on the matter? As always, greatly appreciated!!

GetDiskFreeSpace lives in kernel32.dll (see msdn.microsoft.com/en-us/library/windows/desktop/… ). So you should have windowsRuntime = syscall.NewLazyDLL("kernel32.dll") — alex
– alex, Commented Mar 23, 2017 at 23:15
Yes, where did you get System.WindowsRuntime.dll from? Are you trying to call the GetDiskFreeSpace() method of a specific UWP class? If so, you're in for a world of hurt... — andlabs
– andlabs, Commented Mar 24, 2017 at 5:04
Right you are - kernel32.dll it is, not sure where I got that from, I am trying to retrace my steps, in any event, the System.WindowsRuntime.dll was not found with panic: Failed to load System.WindowsRuntime.dll: The specified module could not be found. whereas when I had the wrong function/procedure name GetDiskFreeSpace I received panic: Failed to find GetDiskFreeSpace procedure in Kernel32.dll: The specified procedure could not be found. So System.WindowsRuntime.dll is definitely missing. Now just to figure out where if that is even the proper name. I'll get back to you briefly. — ehiller
– ehiller, Commented Mar 24, 2017 at 14:46
By the way, you must use the Unicode function name, that is why the procedure wasn't found -- so GetDiskFreeSpaceW and you'll be good - just in case others come across this question. — ehiller
– ehiller, Commented Mar 24, 2017 at 14:47

Zombo · Accepted Answer · 2021-05-22 20:51:19Z

2

Create a file like this:

//go:generate mkwinsyscall -output zfree.go free.go
//sys getDiskFreeSpace(pathName string, sectorsPerCluster *int, bytesPerSector *int, freeClusters *int, numberOfClusters *int) (err error) = GetDiskFreeSpaceA
package main

func main() {
   var bytesPerSector, freeClusters, numberOfClusters, sectorsPerCluster int
   getDiskFreeSpace(
      `C:\`,
      &sectorsPerCluster,
      &bytesPerSector,
      &freeClusters,
      &numberOfClusters,
   )
   println("bytesPerSector", bytesPerSector)
   println("freeClusters", freeClusters)
   println("numberOfClusters", numberOfClusters)
   println("sectorsPerCluster", sectorsPerCluster)
}

Then build:

go generate
go mod init free
go mod tidy
go build

Result:

bytesPerSector 512
freeClusters 12511186
numberOfClusters 25434879
sectorsPerCluster 8

https://github.com/golang/sys/tree/master/windows/mkwinsyscall

edited May 22, 2021 at 20:51

answered Jan 10, 2021 at 21:46

Zombo

1

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Comments

Sunius · Accepted Answer · 2017-03-27 17:45:15Z

0

I have no idea where you found "System.WindowsRuntime.dll" because as far as I can tell, it doesn't exist (unless you manually made a DLL named that).

As for System.Runtime.WindowsRuntime.dll: it's part of .NET Framework, not Windows, and it is a managed DLL. You cannot load such DLLs using syscall.NewLazyDLL. What's more, that DLL doesn't really contain any Windows APIs - just glue for .NET to be able to work with them.

You're probably looking for functions like RoGetActivationFactory in combase.dll.

answered Mar 27, 2017 at 17:45

Sunius

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