wintun: registry: revise value reading
- Make getStringValueRetry() reusable for reading any value type. This merges code from GetIntegerValueWait(). - expandString() >> toString() and extend to support REG_MULTI_SZ (to return first value of REG_MULTI_SZ). Furthermore, doing our own UTF-16 to UTF-8 conversion works around a bug in windows/registry's GetStringValue() non-zero terminated string handling. - Provide toInteger() analogous to toString() - GetStringValueWait() tolerates and reads REG_MULTI_SZ too now. It returns REG_MULTI_SZ[0], making GetFirstStringValueWait() redundant. Signed-off-by: Simon Rozman <simon@rozman.si>
This commit is contained in:
Simon Rozman
Jason A. Donenfeld
parent
5669ed326f
commit
6c1b66802f
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@ -10,7 +10,9 @@ import (
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"fmt"
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"runtime"
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"strings"
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"syscall"
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"time"
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"unsafe"
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"golang.org/x/sys/windows"
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"golang.org/x/sys/windows/registry"
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@ -102,18 +104,44 @@ func WaitForKey(k registry.Key, path string, timeout time.Duration) error {
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}
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//
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// getStringValueRetry function reads a string value from registry. It waits for
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// getValue is the same as windows/registry's getValue, which is unfortunately
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// private.
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//
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func getValue(k registry.Key, name string, buf []byte) ([]byte, uint32, error) {
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p, err := syscall.UTF16PtrFromString(name)
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if err != nil {
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return nil, 0, err
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}
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var t uint32
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n := uint32(len(buf))
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for {
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err = syscall.RegQueryValueEx(syscall.Handle(k), p, nil, &t, (*byte)(unsafe.Pointer(&buf[0])), &n)
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if err == nil {
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return buf[:n], t, nil
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}
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if err != syscall.ERROR_MORE_DATA {
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return nil, 0, err
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}
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if n <= uint32(len(buf)) {
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return nil, 0, err
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}
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buf = make([]byte, n)
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}
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}
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//
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// getValueRetry function reads any value from registry. It waits for
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// the registry value to become available or returns error on timeout.
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//
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// Key must be opened with at least QUERY_VALUE|NOTIFY access.
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//
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func getStringValueRetry(key registry.Key, name string, timeout time.Duration, useFirstFromMulti bool) (string, uint32, error) {
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func getValueRetry(key registry.Key, name string, buf []byte, timeout time.Duration) ([]byte, uint32, error) {
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runtime.LockOSThread()
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defer runtime.UnlockOSThread()
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event, err := windows.CreateEvent(nil, 0, 0, nil)
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if err != nil {
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return "", 0, fmt.Errorf("Error creating event: %v", err)
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return nil, 0, fmt.Errorf("Error creating event: %v", err)
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}
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defer windows.CloseHandle(event)
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@ -121,46 +149,47 @@ func getStringValueRetry(key registry.Key, name string, timeout time.Duration, u
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for {
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err := regNotifyChangeKeyValue(windows.Handle(key), false, REG_NOTIFY_CHANGE_LAST_SET, windows.Handle(event), true)
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if err != nil {
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return "", 0, fmt.Errorf("Setting up change notification on registry value failed: %v", err)
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return nil, 0, fmt.Errorf("Setting up change notification on registry value failed: %v", err)
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}
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var value string
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var values []string
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var valueType uint32
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if !useFirstFromMulti {
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value, valueType, err = key.GetStringValue(name)
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} else {
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values, valueType, err = key.GetStringsValue(name)
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}
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if err == windows.ERROR_FILE_NOT_FOUND || err == windows.ERROR_PATH_NOT_FOUND || (useFirstFromMulti && len(values) == 0) {
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buf, valueType, err := getValue(key, name, buf)
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if err == windows.ERROR_FILE_NOT_FOUND || err == windows.ERROR_PATH_NOT_FOUND {
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timeout := time.Until(deadline) / time.Millisecond
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if timeout < 0 {
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timeout = 0
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}
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s, err := windows.WaitForSingleObject(event, uint32(timeout))
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if err != nil {
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return "", 0, fmt.Errorf("Unable to wait on registry value: %v", err)
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return nil, 0, fmt.Errorf("Unable to wait on registry value: %v", err)
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}
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if s == uint32(windows.WAIT_TIMEOUT) { // windows.WAIT_TIMEOUT status const is misclassified as error in golang.org/x/sys/windows
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return "", 0, errors.New("Timeout waiting for registry value")
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return nil, 0, errors.New("Timeout waiting for registry value")
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}
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} else if err != nil {
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return "", 0, fmt.Errorf("Error reading registry value %v: %v", name, err)
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return nil, 0, fmt.Errorf("Error reading registry value %v: %v", name, err)
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} else {
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if !useFirstFromMulti {
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return value, valueType, nil
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} else {
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return values[0], registry.SZ, nil
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}
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return buf, valueType, nil
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}
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}
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}
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func expandString(value string, valueType uint32, err error) (string, error) {
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func toString(buf []byte, valueType uint32, err error) (string, error) {
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if err != nil {
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return "", err
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}
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var value string
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switch valueType {
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case registry.SZ, registry.EXPAND_SZ, registry.MULTI_SZ:
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if len(buf) == 0 {
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return "", nil
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}
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value = syscall.UTF16ToString((*[1 << 29]uint16)(unsafe.Pointer(&buf[0]))[:len(buf)/2])
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default:
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return "", registry.ErrUnexpectedType
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}
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if valueType != registry.EXPAND_SZ {
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// Value does not require expansion.
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return value, nil
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@ -176,6 +205,29 @@ func expandString(value string, valueType uint32, err error) (string, error) {
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return valueExp, nil
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}
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func toInteger(buf []byte, valueType uint32, err error) (uint64, error) {
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if err != nil {
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return 0, err
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}
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switch valueType {
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case registry.DWORD:
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if len(buf) != 4 {
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return 0, errors.New("DWORD value is not 4 bytes long")
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}
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return uint64(*(*uint32)(unsafe.Pointer(&buf[0]))), nil
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case registry.QWORD:
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if len(buf) != 8 {
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return 0, errors.New("QWORD value is not 8 bytes long")
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}
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return uint64(*(*uint64)(unsafe.Pointer(&buf[0]))), nil
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default:
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return 0, registry.ErrUnexpectedType
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}
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}
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//
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// GetStringValueWait function reads a string value from registry. It waits
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// for the registry value to become available or returns error on timeout.
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@ -185,15 +237,10 @@ func expandString(value string, valueType uint32, err error) (string, error) {
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// If the value type is REG_EXPAND_SZ the environment variables are expanded.
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// Should expanding fail, original string value and nil error are returned.
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//
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// If the value type is REG_MULTI_SZ only the first string is returned.
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//
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func GetStringValueWait(key registry.Key, name string, timeout time.Duration) (string, error) {
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return expandString(getStringValueRetry(key, name, timeout, false))
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}
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//
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// Same as GetStringValueWait, but returns the first from a MULTI_SZ.
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//
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func GetFirstStringValueWait(key registry.Key, name string, timeout time.Duration) (string, error) {
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return expandString(getStringValueRetry(key, name, timeout, true))
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return toString(getValueRetry(key, name, make([]byte, 64), timeout))
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}
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//
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@ -204,8 +251,10 @@ func GetFirstStringValueWait(key registry.Key, name string, timeout time.Duratio
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// If the value type is REG_EXPAND_SZ the environment variables are expanded.
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// Should expanding fail, original string value and nil error are returned.
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//
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// If the value type is REG_MULTI_SZ only the first string is returned.
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//
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func GetStringValue(key registry.Key, name string) (string, error) {
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return expandString(key.GetStringValue(name))
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return toString(getValue(key, name, make([]byte, 64)))
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}
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//
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@ -216,39 +265,5 @@ func GetStringValue(key registry.Key, name string) (string, error) {
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// Key must be opened with at least QUERY_VALUE|NOTIFY access.
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//
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func GetIntegerValueWait(key registry.Key, name string, timeout time.Duration) (uint64, error) {
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runtime.LockOSThread()
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defer runtime.UnlockOSThread()
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event, err := windows.CreateEvent(nil, 0, 0, nil)
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if err != nil {
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return 0, fmt.Errorf("Error creating event: %v", err)
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}
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defer windows.CloseHandle(event)
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deadline := time.Now().Add(timeout)
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for {
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err := regNotifyChangeKeyValue(windows.Handle(key), false, REG_NOTIFY_CHANGE_LAST_SET, windows.Handle(event), true)
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if err != nil {
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return 0, fmt.Errorf("Setting up change notification on registry value failed: %v", err)
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}
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value, _, err := key.GetIntegerValue(name)
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if err == windows.ERROR_FILE_NOT_FOUND || err == windows.ERROR_PATH_NOT_FOUND {
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timeout := time.Until(deadline) / time.Millisecond
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if timeout < 0 {
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timeout = 0
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}
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s, err := windows.WaitForSingleObject(event, uint32(timeout))
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if err != nil {
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return 0, fmt.Errorf("Unable to wait on registry value: %v", err)
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}
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if s == uint32(windows.WAIT_TIMEOUT) { // windows.WAIT_TIMEOUT status const is misclassified as error in golang.org/x/sys/windows
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return 0, errors.New("Timeout waiting for registry value")
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}
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} else if err != nil {
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return 0, fmt.Errorf("Error reading registry value %v: %v", name, err)
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} else {
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return value, nil
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}
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}
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return toInteger(getValueRetry(key, name, make([]byte, 8), timeout))
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}
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@ -342,7 +342,7 @@ func CreateInterface(description string, hwndParent uintptr) (*Wintun, bool, err
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wintun.GetTcpipAdapterRegKeyName(), registry.QUERY_VALUE|registry.NOTIFY,
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waitForRegistryTimeout)
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if err == nil {
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_, err = registryEx.GetFirstStringValueWait(key, "IpConfig", waitForRegistryTimeout)
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_, err = registryEx.GetStringValueWait(key, "IpConfig", waitForRegistryTimeout)
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key.Close()
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}
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}
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