On Windows, do not degenerate working directory through restarts causing command execution failure when APPDATA is a drive name-based path which maps to a UNC share

Author: MMulthaupt

cmd/launcher/gui/gui_windows.go

@@ -1,7 +1,6 @@
 package gui
 
 import (
-	"unicode/utf16"
 	"unsafe"
 
 	"github.com/setlog/trivrost/pkg/system"
@@ -145,7 +144,7 @@ func applyWindowStyle(handle uintptr) {
 }
 
 func loadIcons() {
-	binaryPath := goStringToConstantUTF16WinApiString(system.GetBinaryPath())
+	binaryPath := C.LPCWSTR(system.GoStringToConstantUTF16WinApiString(system.GetBinaryPath()))
 	extractedIconCount := C.loadIcons(binaryPath)
 	didLoadIcons = true
 	C.free(unsafe.Pointer(binaryPath))
@@ -160,17 +159,6 @@ func loadIcons() {
 	}
 }
 
-func goStringToConstantUTF16WinApiString(s string) C.LPCWSTR {
-	utf16String := utf16.Encode([]rune(s))
-	utf16StringPointer := (*uint16)(C.calloc(C.size_t(len(utf16String)+1), C.size_t(unsafe.Sizeof(uint16(0)))))
-	currentCharPointer := utf16StringPointer
-	for _, c := range utf16String {
-		*currentCharPointer = c
-		currentCharPointer = (*uint16)(unsafe.Pointer(uintptr(unsafe.Pointer(currentCharPointer)) + unsafe.Sizeof(uint16(0))))
-	}
-	return (C.LPCWSTR)(unsafe.Pointer(utf16StringPointer))
-}
-
 func setProgressState(s progressState) {
 	C.setProgressBarState(C.ULONG_PTR(panelDownloadStatus.barTotalProgress.Handle()), C.int(s))
 }

cmd/launcher/launcher/install.go

@@ -50,7 +50,7 @@ func IsInstanceInstalledInSystemMode() bool {
 
 // IsInstanceInstalledForCurrentUser returns true iff the launcher's desired path under user files is occupied by the program running this code.
 func IsInstanceInstalledForCurrentUser() bool {
-	return system.GetProgramPath() == getTargetProgramPath()
+	return system.FilepathsEquivalent(system.GetProgramPath(), getTargetProgramPath())
 }
 
 // IsInstallationOutdated returns true if the time the installed launcher binary was built

pkg/system/api_unix.go

@@ -47,3 +47,7 @@ func showLocalFileInFileManager(path string) error {
 func isProcessRunning(p *os.Process) bool {
 	return p.Signal(unix.Signal(0)) == nil
 }
+
+func universalPathName(p string) (string, error) {
+	return p, nil
+}

pkg/system/api_windows.go

@@ -6,11 +6,15 @@ import (
 	"os/exec"
 	"runtime"
 	"strings"
+	"unicode/utf16"
+	"unsafe"
 
 	"golang.org/x/sys/windows"
 )
 
+// #cgo LDFLAGS: -lMpr
 //#include <windows.h>
+//#include <winnetwk.h>
 import "C"
 
 func mustDetectArchitecture() {
@@ -59,3 +63,129 @@ func isProcessRunning(p *os.Process) bool {
 	result := C.GetExitCodeProcess(handle, &lpExitCode)
 	return (result != 0) && (lpExitCode == C.STILL_ACTIVE)
 }
+
+func universalPathName(p string) (string, error) {
+	s, lpBufferSize, err := universalPathNameWithBufferSize(p, 1000)
+	if err != nil && err.(*universalNameRetrievalError).ErrorType() == errorMoreData {
+		s, _, err = universalPathNameWithBufferSize(s, lpBufferSize)
+	}
+	if err != nil {
+		return p, err
+	}
+	return s, err
+}
+
+func universalPathNameWithBufferSize(p string, lpBufferSizeUse C.DWORD) (universalPath string, lpBufferSize C.DWORD, err error) {
+	cp := C.LPCWSTR(GoStringToConstantUTF16WinApiString(p))
+	defer C.free(unsafe.Pointer(cp))
+
+	// The possible data written to infoStruct (we request a UNIVERSAL_NAME_INFO below) not only consists of the struct, but also of the data (strings)
+	// pointed to by pointer-members within the struct. That's why this allocation needs to be much larger than just large enough to hold the struct itself.
+	infoStruct := C.calloc(C.size_t(lpBufferSizeUse), 1)
+	defer C.free(unsafe.Pointer(infoStruct))
+
+	lpBufferSize = lpBufferSizeUse
+	errorCode := C.WNetGetUniversalNameW(cp, C.UNIVERSAL_NAME_INFO_LEVEL, C.LPVOID(infoStruct), C.LPDWORD(unsafe.Pointer(&lpBufferSize)))
+	err = getErrorOfWNetGetUniversalNameW(errorCode)
+	if err == nil {
+		universalPath = UTF16WinApiStringToGoString(infoStruct)
+	}
+	return universalPath, lpBufferSize, err
+}
+
+func getErrorOfWNetGetUniversalNameW(returnCode C.DWORD) error {
+	if returnCode == C.NO_ERROR {
+		return nil
+	}
+	if returnCode == C.ERROR_BAD_DEVICE {
+		return &universalNameRetrievalError{errorType: errorBadDevice,
+			message: `the string pointed to by the lpLocalPath parameter is invalid`}
+	}
+	if returnCode == C.ERROR_CONNECTION_UNAVAIL {
+		return &universalNameRetrievalError{errorType: errorConnectionUnavailable,
+			message: `there is no current connection to the remote device, but there is a remembered (persistent) connection to it`}
+	}
+	if returnCode == C.ERROR_EXTENDED_ERROR {
+		errorMessage, providerName, err := getLastWNetError()
+		if err != nil {
+			return &universalNameRetrievalError{errorType: errorExtendedError,
+				message: `a network-specific error occurred; getting extended error information failed: ` + err.Error()}
+		}
+		return &universalNameRetrievalError{errorType: errorExtendedError,
+			message: `a network-specific error occurred; Network provider "` + providerName + `" reports: ` + errorMessage}
+	}
+	if returnCode == C.ERROR_MORE_DATA {
+		return &universalNameRetrievalError{errorType: errorMoreData,
+			message: `despite trying to query with the requested buffer size, the buffer pointed to by the lpBuffer parameter was too small`}
+	}
+	if returnCode == C.ERROR_NOT_SUPPORTED {
+		return &universalNameRetrievalError{errorType: errorNotSupported,
+			message: `the dwInfoLevel parameter is set to UNIVERSAL_NAME_INFO_LEVEL, but the network provider does not support UNC names. (None of the network providers support this function)`}
+	}
+	if returnCode == C.ERROR_NO_NET_OR_BAD_PATH {
+		return &universalNameRetrievalError{errorType: errorNoNetOrBadPath,
+			message: `none of the network providers recognize the local name as having a connection. However, the network is not available for at least one provider to whom the connection may belong`}
+	}
+	if returnCode == C.ERROR_NO_NETWORK {
+		return &universalNameRetrievalError{errorType: errorNoNetwork,
+			message: `the network is unavailable`}
+	}
+	if returnCode == C.ERROR_NOT_CONNECTED {
+		return &universalNameRetrievalError{errorType: errorNotConnected,
+			message: `the device specified by the path is not redirected`}
+	}
+	return &universalNameRetrievalError{errorType: errorUndocumented,
+		message: fmt.Sprintf(`undocumented error code %d`, returnCode)}
+}
+
+func getLastWNetError() (errorMessage, providerName string, err error) {
+	var lpError C.DWORD
+
+	const errorBufferSize = 5000
+	const nErrorBufSize C.DWORD = errorBufferSize
+	lpErrorBuf := (C.LPWSTR)(C.calloc(C.size_t(errorBufferSize+1), C.size_t(unsafe.Sizeof(uint16(0)))))
+	defer C.free(unsafe.Pointer(lpErrorBuf))
+
+	const nameBufferSize = 1000
+	const nNameBufSize C.DWORD = nameBufferSize
+	lpNameBuf := (C.LPWSTR)(C.calloc(C.size_t(nameBufferSize+1), C.size_t(unsafe.Sizeof(uint16(0)))))
+	defer C.free(unsafe.Pointer(lpNameBuf))
+
+	returnCode := C.WNetGetLastErrorW(&lpError, lpErrorBuf, nErrorBufSize, lpNameBuf, nNameBufSize)
+	if returnCode == C.NO_ERROR {
+		return UTF16WinApiStringToGoString(unsafe.Pointer(lpErrorBuf)), UTF16WinApiStringToGoString(unsafe.Pointer(lpNameBuf)), nil
+	}
+	if returnCode == C.ERROR_INVALID_ADDRESS {
+		return "", "", fmt.Errorf("could not get last WNet error: ERROR_INVALID_ADDRESS")
+	}
+	return "", "", fmt.Errorf("could not get last WNet error: undocumented extended error code %d", returnCode)
+}
+
+// GoStringToConstantUTF16WinApiString returns a WINAPI LPWSTR for a given string.
+// The caller is responsible for freeing the returned pointer.
+func GoStringToConstantUTF16WinApiString(s string) unsafe.Pointer {
+	utf16String := utf16.Encode([]rune(s))
+	utf16StringPointer := (*uint16)(C.calloc(C.size_t(len(utf16String)+1), C.size_t(unsafe.Sizeof(uint16(0)))))
+	currentCharPointer := utf16StringPointer
+	for _, c := range utf16String {
+		*currentCharPointer = c
+		currentCharPointer = (*uint16)(unsafe.Pointer(uintptr(unsafe.Pointer(currentCharPointer)) + unsafe.Sizeof(uint16(0))))
+	}
+	return unsafe.Pointer(utf16StringPointer)
+}
+
+// UTF16WinApiStringToGoString returns a string for a given WINAPI LPWSTR or LPCWSTR.
+// This function does not free lpwString.
+func UTF16WinApiStringToGoString(lpwString unsafe.Pointer) string {
+	ptr := (*uint16)(lpwString)
+	data := make([]uint16, 0, 0)
+	for {
+		if *ptr == 0 {
+			break
+		}
+		data = append(data, *ptr)
+		ptr = (*uint16)(unsafe.Pointer(((uintptr)(unsafe.Pointer(ptr))) + unsafe.Sizeof(uint16(0))))
+	}
+	s := utf16.Decode(data)
+	return string(s)
+}

pkg/system/file_system_funcs.go

@@ -303,3 +303,25 @@ func CleanUpFileOperation(file *os.File, returnError *error) {
 		}
 	}
 }
+
+// FilepathsEquivalent returns true if the filepaths a and b are semantically equivalent (exceptions may exist).
+func FilepathsEquivalent(a, b string) bool {
+	a = filepath.Clean(a)
+	b = filepath.Clean(b)
+	if a == b {
+		return true
+	}
+	aResolved, aErr := universalPathName(a)
+	if aErr != nil && aErr.(*universalNameRetrievalError).ErrorType() != errorNotConnected {
+		log.Warnf(`could not determine UNC path for filepath "%s": %v\n`, a, aErr)
+	}
+	bResolved, bErr := universalPathName(b)
+	if bErr != nil && bErr.(*universalNameRetrievalError).ErrorType() != errorNotConnected {
+		log.Warnf(`could not determine UNC path for filepath "%s": %v\n`, b, bErr)
+	}
+	aResolved = filepath.Clean(aResolved)
+	bResolved = filepath.Clean(bResolved)
+	return (a == bResolved && bErr == nil) ||
+		(b == aResolved && aErr == nil) ||
+		(aResolved == bResolved && aErr == nil && bErr == nil)
+}

pkg/system/universal_path_error.go

@@ -0,0 +1,30 @@
+package system
+
+type universalNameRetrievalErrorType int
+
+const errorBadDevice universalNameRetrievalErrorType = 1
+const errorConnectionUnavailable universalNameRetrievalErrorType = 2
+const errorExtendedError universalNameRetrievalErrorType = 3
+const errorMoreData universalNameRetrievalErrorType = 4
+const errorNotSupported universalNameRetrievalErrorType = 5
+const errorNoNetOrBadPath universalNameRetrievalErrorType = 6
+const errorNoNetwork universalNameRetrievalErrorType = 7
+const errorNotConnected universalNameRetrievalErrorType = 8
+const errorUndocumented universalNameRetrievalErrorType = 9
+
+type universalNameRetrievalError struct {
+	message   string
+	errorType universalNameRetrievalErrorType
+}
+
+func (err *universalNameRetrievalError) Error() string {
+	if err == nil {
+		return "<nil>"
+	}
+	return err.message
+}
+
+// ErrorType returns the corresponsing WINAPI error type of the WNetGetUniversalNameW function call which generated the error.
+func (err *universalNameRetrievalError) ErrorType() universalNameRetrievalErrorType {
+	return err.errorType
+}