Add GetPerformanceInfo syscall

Author: strawgate

psapi.go

@@ -30,6 +30,7 @@ import (
 //sys   _GetProcessMemoryInfo(handle syscall.Handle, psmemCounters *ProcessMemoryCountersEx, cb uint32) (err error) = psapi.GetProcessMemoryInfo
 //sys   _GetProcessImageFileNameA(handle syscall.Handle, imageFileName *byte, nSize uint32) (len uint32, err error) = psapi.GetProcessImageFileNameA
 //sys   _EnumProcesses(lpidProcess *uint32, cb uint32, lpcbNeeded *uint32) (err error) = psapi.EnumProcesses
+//sys   _GetPerformanceInfo(pi *PerformanceInformation, cb uint32) (err error) = psapi.GetPerformanceInfo
 
 var (
 	sizeofProcessMemoryCountersEx = uint32(unsafe.Sizeof(ProcessMemoryCountersEx{}))
@@ -98,3 +99,33 @@ func EnumProcesses() (pids []uint32, err error) {
 		}
 	}
 }
+
+// PerformanceInformation represents the PERFORMANCE_INFORMATION structure
+type PerformanceInformation struct {
+	CB                uint32
+	CommitTotal       uintptr
+	CommitLimit       uintptr
+	CommitPeak        uintptr
+	PhysicalTotal     uintptr
+	PhysicalAvailable uintptr
+	SystemCache       uintptr
+	KernelTotal       uintptr
+	KernelPaged       uintptr
+	KernelNonpaged    uintptr
+	PageSize          uintptr
+	HandleCount       uint32
+	ProcessCount      uint32
+	ThreadCount       uint32
+}
+
+// GetPerformanceInfo retrieves performance information for the system
+// https://learn.microsoft.com/en-us/windows/win32/api/psapi/nf-psapi-getperformanceinfo
+func GetPerformanceInfo() (PerformanceInformation, error) {
+	var pi PerformanceInformation
+	pi.CB = uint32(unsafe.Sizeof(pi))
+
+	if err := _GetPerformanceInfo(&pi, pi.CB); err != nil {
+		return PerformanceInformation{}, fmt.Errorf("GetPerformanceInfo failed: %w", err)
+	}
+	return pi, nil
+}

psapi_test.go

@@ -0,0 +1,131 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+//go:build windows
+// +build windows
+
+package windows
+
+import (
+	"syscall"
+	"testing"
+	"unsafe"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetPerformanceInfo(t *testing.T) {
+	pi, err := GetPerformanceInfo()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Verify the structure was populated correctly
+	assert.Equal(t, uint32(unsafe.Sizeof(pi)), pi.CB, "CB field should contain the size of the structure")
+
+	// Verify that physical memory values are reasonable
+	assert.True(t, pi.PhysicalTotal > 0, "PhysicalTotal should be greater than 0")
+	assert.True(t, pi.PhysicalAvailable <= pi.PhysicalTotal, "PhysicalAvailable should not exceed PhysicalTotal")
+
+	// Verify that commit values are reasonable
+	assert.True(t, pi.CommitTotal > 0, "CommitTotal should be greater than 0")
+	assert.True(t, pi.CommitLimit > 0, "CommitLimit should be greater than 0")
+	assert.True(t, pi.CommitTotal <= pi.CommitLimit, "CommitTotal should not exceed CommitLimit")
+
+	// Verify that page size is reasonable (typically at least 4KB on x86/x64)
+	assert.True(t, pi.PageSize >= 4096, "PageSize should be at least 4KB")
+
+	// Verify that process and thread counts are reasonable
+	assert.True(t, pi.ProcessCount > 0, "ProcessCount should be greater than 0")
+	assert.True(t, pi.ThreadCount > 0, "ThreadCount should be greater than 0")
+	assert.True(t, pi.ThreadCount >= pi.ProcessCount, "ThreadCount should be at least equal to ProcessCount")
+
+	// Verify that handle count is reasonable
+	assert.True(t, pi.HandleCount > 0, "HandleCount should be greater than 0")
+
+	// Verify that kernel memory values are reasonable
+	assert.True(t, pi.KernelTotal > 0, "KernelTotal should be greater than 0")
+	assert.True(t, pi.KernelPaged <= pi.KernelTotal, "KernelPaged should not exceed KernelTotal")
+	assert.True(t, pi.KernelNonpaged <= pi.KernelTotal, "KernelNonpaged should not exceed KernelTotal")
+
+	// Verify that system cache is reasonable
+	assert.True(t, pi.SystemCache >= 0, "SystemCache should be non-negative")
+}
+
+func TestGetProcessMemoryInfo(t *testing.T) {
+	h, err := syscall.GetCurrentProcess()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	info, err := GetProcessMemoryInfo(h)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Verify the structure was populated correctly
+	assert.Equal(t, uint32(unsafe.Sizeof(info)), info.cb, "cb field should contain the size of the structure")
+
+	// Verify that memory values are reasonable
+	assert.True(t, info.WorkingSetSize > 0, "WorkingSetSize should be greater than 0")
+	assert.True(t, info.PeakWorkingSetSize >= info.WorkingSetSize, "PeakWorkingSetSize should be at least equal to WorkingSetSize")
+	assert.True(t, info.PrivateUsage > 0, "PrivateUsage should be greater than 0")
+
+	// Verify that page fault count is reasonable
+	assert.True(t, info.PageFaultCount >= 0, "PageFaultCount should be non-negative")
+}
+
+func TestGetProcessImageFileName(t *testing.T) {
+	h, err := syscall.GetCurrentProcess()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	filename, err := GetProcessImageFileName(h)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Verify that we got a valid device path
+	assert.True(t, len(filename) > 0, "Filename should not be empty")
+	assert.Contains(t, filename, "\\Device\\", "Filename should be a device path starting with \\Device\\")
+
+	// The path should contain the executable name
+	assert.Contains(t, filename, ".exe", "Filename should contain .exe extension")
+}
+
+func TestEnumProcesses(t *testing.T) {
+	pids, err := EnumProcesses()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Verify that we got a reasonable number of processes
+	assert.True(t, len(pids) > 0, "Should return at least one process")
+	assert.True(t, len(pids) < 10000, "Should not return an unreasonable number of processes")
+
+	// Verify that the current process is in the list
+	currentPID := uint32(syscall.Getpid())
+	found := false
+	for _, pid := range pids {
+		if pid == currentPID {
+			found = true
+			break
+		}
+	}
+	assert.True(t, found, "Current process PID should be in the returned list")
+}