windows: add QueryWorkingSetEx

This change adds the QueryWorkingSetEx function for inspecting
the virtual memory details of pointers.

https://docs.microsoft.com/en-us/windows/win32/api/psapi/nf-psapi-queryworkingsetex

Change-Id: I2bc92bb0b65d34ed1caf88e4d368d64946dfcc5c
GitHub-Last-Rev: c5ac00435245c4d6b83003949dd06014b52e59e0
GitHub-Pull-Request: golang/sys#124
Reviewed-on: https://go-review.googlesource.com/c/sys/+/402494
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>

windows/syscall_windows.go

@@ -417,6 +417,7 @@ func NewCallbackCDecl(fn interface{}) uintptr {
 //sys	GetModuleInformation(process Handle, module Handle, modinfo *ModuleInfo, cb uint32) (err error) = psapi.GetModuleInformation
 //sys	GetModuleFileNameEx(process Handle, module Handle, filename *uint16, size uint32) (err error) = psapi.GetModuleFileNameExW
 //sys	GetModuleBaseName(process Handle, module Handle, baseName *uint16, size uint32) (err error) = psapi.GetModuleBaseNameW
+//sys   QueryWorkingSetEx(process Handle, pv uintptr, cb uint32) (err error) = psapi.QueryWorkingSetEx
 
 // NT Native APIs
 //sys	rtlNtStatusToDosErrorNoTeb(ntstatus NTStatus) (ret syscall.Errno) = ntdll.RtlNtStatusToDosErrorNoTeb
@@ -1707,3 +1708,71 @@ func LoadResourceData(module, resInfo Handle) (data []byte, err error) {
 	h.Cap = int(size)
 	return
 }
+
+// PSAPI_WORKING_SET_EX_BLOCK contains extended working set information for a page.
+type PSAPI_WORKING_SET_EX_BLOCK uint64
+
+// Valid returns the validity of this page.
+// If this bit is 1, the subsequent members are valid; otherwise they should be ignored.
+func (b PSAPI_WORKING_SET_EX_BLOCK) Valid() bool {
+	return (b & 1) == 1
+}
+
+// ShareCount is the number of processes that share this page. The maximum value of this member is 7.
+func (b PSAPI_WORKING_SET_EX_BLOCK) ShareCount() uint64 {
+	return b.intField(1, 3)
+}
+
+// Win32Protection is the memory protection attributes of the page. For a list of values, see
+// https://docs.microsoft.com/en-us/windows/win32/memory/memory-protection-constants
+func (b PSAPI_WORKING_SET_EX_BLOCK) Win32Protection() uint64 {
+	return b.intField(4, 11)
+}
+
+// Shared returns the shared status of this page.
+// If this bit is 1, the page can be shared.
+func (b PSAPI_WORKING_SET_EX_BLOCK) Shared() bool {
+	return (b & (1 << 15)) == 1
+}
+
+// Node is the NUMA node. The maximum value of this member is 63.
+func (b PSAPI_WORKING_SET_EX_BLOCK) Node() uint64 {
+	return b.intField(16, 6)
+}
+
+// Locked returns the locked status of this page.
+// If this bit is 1, the virtual page is locked in physical memory.
+func (b PSAPI_WORKING_SET_EX_BLOCK) Locked() bool {
+	return (b & (1 << 22)) == 1
+}
+
+// LargePage returns the large page status of this page.
+// If this bit is 1, the page is a large page.
+func (b PSAPI_WORKING_SET_EX_BLOCK) LargePage() bool {
+	return (b & (1 << 23)) == 1
+}
+
+// Bad returns the bad status of this page.
+// If this bit is 1, the page is has been reported as bad.
+func (b PSAPI_WORKING_SET_EX_BLOCK) Bad() bool {
+	return (b & (1 << 31)) == 1
+}
+
+// intField extracts an integer field in the PSAPI_WORKING_SET_EX_BLOCK union.
+func (b PSAPI_WORKING_SET_EX_BLOCK) intField(start, length int) uint64 {
+	var mask PSAPI_WORKING_SET_EX_BLOCK
+	for pos := start; pos < start+length; pos++ {
+		mask |= (1 << pos)
+	}
+
+	masked := b & mask
+	return uint64(masked >> start)
+}
+
+// PSAPI_WORKING_SET_EX_INFORMATION contains extended working set information for a process.
+type PSAPI_WORKING_SET_EX_INFORMATION struct {
+	// The virtual address.
+	VirtualAddress Pointer
+	// A PSAPI_WORKING_SET_EX_BLOCK union that indicates the attributes of the page at VirtualAddress.
+	VirtualAttributes PSAPI_WORKING_SET_EX_BLOCK
+}