Fix timezone caching issues (#1499)

go.mod

@@ -1,6 +1,6 @@
 module github.com/prometheus-community/windows_exporter
 
-go 1.21
+go 1.22
 
 require (
 	github.com/Microsoft/hcsshim v0.12.4

pkg/collector/os/os.go

@@ -8,16 +8,19 @@ import (
 	"os"
 	"strconv"
 	"strings"
+	"syscall"
 	"time"
 
-	"github.com/alecthomas/kingpin/v2"
-	"github.com/go-kit/log"
-	"github.com/go-kit/log/level"
+	"github.com/prometheus-community/windows_exporter/pkg/headers/kernel32"
 	"github.com/prometheus-community/windows_exporter/pkg/headers/netapi32"
 	"github.com/prometheus-community/windows_exporter/pkg/headers/psapi"
 	"github.com/prometheus-community/windows_exporter/pkg/headers/sysinfoapi"
 	"github.com/prometheus-community/windows_exporter/pkg/perflib"
 	"github.com/prometheus-community/windows_exporter/pkg/types"
+
+	"github.com/alecthomas/kingpin/v2"
+	"github.com/go-kit/log"
+	"github.com/go-kit/log/level"
 	"github.com/prometheus/client_golang/prometheus"
 	"golang.org/x/sys/windows/registry"
 )
@@ -197,16 +200,36 @@ func (c *collector) collect(ctx *types.ScrapeContext, ch chan<- prometheus.Metri
 	}
 
 	currentTime := time.Now()
-	timezoneName, _ := currentTime.Zone()
+
+	timeZoneInfo, err := kernel32.GetDynamicTimeZoneInformation()
+	if err != nil {
+		return err
+	}
+
+	// timeZoneKeyName contains the english name of the timezone.
+	timezoneName := syscall.UTF16ToString(timeZoneInfo.TimeZoneKeyName[:])
 
 	// Get total allocation of paging files across all disks.
 	memManKey, err := registry.OpenKey(registry.LOCAL_MACHINE, `SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management`, registry.QUERY_VALUE)
 	defer memManKey.Close()
-
 	if err != nil {
 		return err
 	}
+
 	pagingFiles, _, pagingErr := memManKey.GetStringsValue("ExistingPageFiles")
+
+	var fsipf float64
+	for _, pagingFile := range pagingFiles {
+		fileString := strings.ReplaceAll(pagingFile, `\??\`, "")
+		file, err := os.Stat(fileString)
+		// For unknown reasons, Windows doesn't always create a page file. Continue collection rather than aborting.
+		if err != nil {
+			_ = level.Debug(c.logger).Log("msg", fmt.Sprintf("Failed to read page file (reason: %s): %s\n", err, fileString))
+		} else {
+			fsipf += float64(file.Size())
+		}
+	}
+
 	// Get build number and product name from registry
 	ntKey, err := registry.OpenKey(registry.LOCAL_MACHINE, `SOFTWARE\Microsoft\Windows NT\CurrentVersion`, registry.QUERY_VALUE)
 	defer ntKey.Close()
@@ -232,18 +255,6 @@ func (c *collector) collect(ctx *types.ScrapeContext, ch chan<- prometheus.Metri
 		return err
 	}
 
-	var fsipf float64
-	for _, pagingFile := range pagingFiles {
-		fileString := strings.ReplaceAll(pagingFile, `\??\`, "")
-		file, err := os.Stat(fileString)
-		// For unknown reasons, Windows doesn't always create a page file. Continue collection rather than aborting.
-		if err != nil {
-			_ = level.Debug(c.logger).Log("msg", fmt.Sprintf("Failed to read page file (reason: %s): %s\n", err, fileString))
-		} else {
-			fsipf += float64(file.Size())
-		}
-	}
-
 	gpi, err := psapi.GetPerformanceInfo()
 	if err != nil {
 		return err

pkg/headers/kernel32/kernel32.go

@@ -0,0 +1,52 @@
+package kernel32
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+var (
+	kernel32 = syscall.NewLazyDLL("kernel32.dll")
+
+	procGetDynamicTimeZoneInformationSys = kernel32.NewProc("GetDynamicTimeZoneInformation")
+)
+
+// SYSTEMTIME contains a date and time.
+// 📑 https://docs.microsoft.com/en-us/windows/win32/api/minwinbase/ns-minwinbase-systemtime
+type SYSTEMTIME struct {
+	WYear         uint16
+	WMonth        uint16
+	WDayOfWeek    uint16
+	WDay          uint16
+	WHour         uint16
+	WMinute       uint16
+	WSecond       uint16
+	WMilliseconds uint16
+}
+
+// DynamicTimezoneInformation contains the current dynamic daylight time settings.
+// 📑 https://docs.microsoft.com/en-us/windows/win32/api/timezoneapi/ns-timezoneapi-dynamic_time_zone_information
+type DynamicTimezoneInformation struct {
+	Bias                        int32
+	standardName                [32]uint16
+	StandardDate                SYSTEMTIME
+	StandardBias                int32
+	DaylightName                [32]uint16
+	DaylightDate                SYSTEMTIME
+	DaylightBias                int32
+	TimeZoneKeyName             [128]uint16
+	DynamicDaylightTimeDisabled uint8 // BOOLEAN
+}
+
+// GetDynamicTimeZoneInformation retrieves the current dynamic daylight time settings.
+// 📑 https://docs.microsoft.com/en-us/windows/win32/api/timezoneapi/nf-timezoneapi-getdynamictimezoneinformation
+func GetDynamicTimeZoneInformation() (DynamicTimezoneInformation, error) {
+	var tzi DynamicTimezoneInformation
+
+	r0, _, err := syscall.SyscallN(procGetDynamicTimeZoneInformationSys.Addr(), uintptr(unsafe.Pointer(&tzi)))
+	if uint32(r0) == 0xffffffff {
+		return tzi, err
+	}
+
+	return tzi, nil
+}