Refactor remaining sysinfoapi calls into header package

Signed-off-by: Ben Ridley <benridley29@gmail.com>

headers/sysinfoapi/sysinfoapi.go

@@ -1,6 +1,7 @@
 package sysinfoapi
 
 import (
+	"unicode/utf16"
 	"unsafe"
 
 	"golang.org/x/sys/windows"
@@ -20,10 +21,49 @@ type MemoryStatusEx struct {
 	UllAvailExtendedVirtual uint64
 }
 
+// wProcessorArchitecture is a wrapper for the union found in LP_SYSTEM_INFO
+// https://docs.microsoft.com/en-us/windows/win32/api/sysinfoapi/ns-sysinfoapi-system_info
+type wProcessorArchitecture struct {
+	WReserved              uint16
+	WProcessorArchitecture uint16
+}
+
+// LpSystemInfo is a wrapper for LPSYSTEM_INFO
+// https://docs.microsoft.com/en-us/windows/win32/api/sysinfoapi/ns-sysinfoapi-system_info
+type LpSystemInfo struct {
+	Arch                        wProcessorArchitecture
+	DwPageSize                  uint32
+	LpMinimumApplicationAddress *byte
+	LpMaximumApplicationAddress *byte
+	DwActiveProcessorMask       *uint32
+	DwNumberOfProcessors        uint32
+	DwProcessorType             uint32
+	DwAllocationGranularity     uint32
+	WProcessorLevel             uint16
+	WProcessorRevision          uint16
+}
+
+// WinComputerNameFormat is a wrapper for COMPUTER_NAME_FORMAT
+type WinComputerNameFormat int
+
+// Definitions for WinComputerNameFormat constants
+const (
+	ComputerNameNetBIOS WinComputerNameFormat = iota
+	ComputerNameDNSHostname
+	ComputerNameDNSDomain
+	ComputerNameDNSFullyQualified
+	ComputerNamePhysicalNetBIOS
+	ComputerNamePhysicalDNSHostname
+	ComputerNamePhysicalDNSDomain
+	ComputerNamePhysicalDNSFullyQualified
+	ComputerNameMax
+)
+
 var (
 	kernel32                 = windows.NewLazySystemDLL("kernel32.dll")
 	procGetSystemInfo        = kernel32.NewProc("GetSystemInfo")
 	procGlobalMemoryStatusEx = kernel32.NewProc("GlobalMemoryStatusEx")
+	procGetComputerNameExW   = kernel32.NewProc("GetComputerNameExW")
 )
 
 // GlobalMemoryStatusEx retrieves information about the system's current usage of both physical and virtual memory.
@@ -41,3 +81,28 @@ func GlobalMemoryStatusEx() (MemoryStatusEx, error) {
 
 	return mse, nil
 }
+
+// GetSystemInfo wraps the GetSystemInfo function from sysinfoapi
+// https://docs.microsoft.com/en-us/windows/win32/api/sysinfoapi/nf-sysinfoapi-getsysteminfo
+func GetSystemInfo() LpSystemInfo {
+	var info LpSystemInfo
+	pInfo := uintptr(unsafe.Pointer(&info))
+	procGetSystemInfo.Call(pInfo)
+	return info
+}
+
+// GetComputerName wraps the GetComputerNameW function in a more Go-like way
+// https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-getcomputernamew
+func GetComputerName(f WinComputerNameFormat) (string, error) {
+	// 1kb buffer to accept computer name. This should be more than enough as the maximum size
+	// returned is the max length of a DNS name, which this author believes is 253 characters.
+	size := 1024
+	var buffer [4096]uint16
+	r1, _, err := procGetComputerNameExW.Call(uintptr(f), uintptr(unsafe.Pointer(&buffer)), uintptr(unsafe.Pointer(&size)))
+	if r1 == 0 {
+		return "", err
+	}
+	bytes := buffer[0:size]
+	out := utf16.Decode(bytes)
+	return string(out), nil
+}