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Merged
EdSchouten merged 1 commit into from
Mar 16, 2026
Merged

Improve windows path parsing #329

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19 changes: 14 additions & 5 deletions pkg/filesystem/path/builder.go
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Original file line number Diff line number Diff line change
Expand Up @@ -109,14 +109,23 @@ func (b *Builder) GetWindowsString(format WindowsPathFormat) (string, error) {
prefix = "\\"
}

// Emit trailing slash in case the path refers to a directory,
// or a dot or slash if the path is empty. The suffix is been
// constructed by platform-independent code that uses forward
// slashes. To construct a Windows path we must use a
// If the path refers to a directory we should emit a trailing slash,
// and since the suffix has been constructed by platform-independent code
// that uses forward slashes we need to convert the path to use a
// backslash.
//
// Unfortunately, a trailing backslash is not a valid pathname component:
// https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-fscc/ffb795f3-027d-4a3c-997d-3085f2332f6f
// Instead we emit `\.` and rely on win32 path normalization. However,
// for WindowsPathFormatDevicePath we cannot do this as device paths
// bypass win32 path normalization so have to just emit a backlash.
suffix := b.suffix
if suffix == "/" {
suffix = "\\"
if format == WindowsPathFormatDevicePath {
suffix = "\\"
} else {
suffix = "\\."
}
}
out.WriteString(suffix)
return out.String(), nil
Expand Down
86 changes: 55 additions & 31 deletions pkg/filesystem/path/builder_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -63,14 +63,14 @@ func TestBuilder(t *testing.T) {
for _, data := range [][]string{
{".", "."},
{"..", ".."},
{"/", "\\"},
{"/", "\\."},
{"hello", "hello"},
{"hello/", "hello\\"},
{"hello/", "hello\\."},
{"hello/..", "hello\\.."},
{"/hello/", "\\hello\\"},
{"/hello/", "\\hello\\."},
{"/hello/..", "\\hello\\.."},
{"/hello/../world", "\\hello\\..\\world"},
{"/hello/../world/", "\\hello\\..\\world\\"},
{"/hello/../world/", "\\hello\\..\\world\\."},
{"/hello/../world/foo", "\\hello\\..\\world\\foo"},
} {
p := data[0]
Expand All @@ -92,16 +92,16 @@ func TestBuilder(t *testing.T) {

t.Run("WindowsIdentity", func(t *testing.T) {
for _, p := range []string{
"C:\\",
"C:\\hello\\",
"C:\\.",
"C:\\hello\\.",
"C:\\hello\\..",
"C:\\hello\\..\\world",
"C:\\hello\\..\\world\\",
"C:\\hello\\..\\world\\.",
"C:\\hello\\..\\world\\foo",
"C:\\hello\\..\\world\\foo",
"\\\\server\\share\\hello\\",
"\\\\server\\share\\hello\\.",
"\\\\server\\share\\hello\\..\\world",
"\\\\server\\share\\hello\\..\\world\\",
"\\\\server\\share\\hello\\..\\world\\.",
"\\\\server\\share\\hello\\..\\world\\foo",
} {
t.Run(p, func(t *testing.T) {
Expand Down Expand Up @@ -146,19 +146,19 @@ func TestBuilder(t *testing.T) {
t.Run("WindowsParseCasing", func(t *testing.T) {
for _, data := range [][]string{
{"./bar", "bar"},
{"./bar\\", "bar\\"},
{"c:", "C:\\"},
{"c:.", "C:\\"},
{"./bar\\", "bar\\."},
{"c:", "C:\\."},
{"c:.", "C:\\."},
{"c:Hello", "C:\\Hello"},
{"c:\\", "C:\\"},
{"c:\\.", "C:\\"},
{"c:\\Hello\\", "C:\\Hello\\"},
{"c:\\Hello\\.", "C:\\Hello\\"},
{"c:\\", "C:\\."},
{"c:\\.", "C:\\."},
{"c:\\Hello\\", "C:\\Hello\\."},
{"c:\\Hello\\.", "C:\\Hello\\."},
{"c:\\Hello\\..", "C:\\Hello\\.."},
{"c:\\Hello\\.\\world", "C:\\Hello\\world"},
{"c:\\Hello\\..\\world", "C:\\Hello\\..\\world"},
{"c:\\Hello\\..\\world", "C:\\Hello\\..\\world"},
{"c:\\Hello\\..\\world\\", "C:\\Hello\\..\\world\\"},
{"c:\\Hello\\..\\world\\", "C:\\Hello\\..\\world\\."},
{"c:\\Hello\\..\\world\\foo", "C:\\Hello\\..\\world\\foo"},
{"c:\\\\Hello\\\\..\\world\\foo", "C:\\Hello\\..\\world\\foo"},
{"\\\\Server\\Share\\Hello\\\\..\\world\\foo", "\\\\Server\\Share\\Hello\\..\\world\\foo"},
Expand Down Expand Up @@ -213,25 +213,27 @@ func TestBuilder(t *testing.T) {
"./.": ".",
"../": "..",
"../.": "..",
"/.": "\\",
"/./": "\\",
"/..": "\\",
"/../": "\\",
"/hello/.": "\\hello\\",
"/.": "\\.",
"/./": "\\.",
"/..": "\\.",
"/../": "\\.",
"/hello/.": "\\hello\\.",
"/hello/../.": "\\hello\\..",
"//Server/Share/hello": "\\\\Server\\Share\\hello",
"//Server/Share/.": "\\\\Server\\Share\\",
"//Server/Share/./": "\\\\Server\\Share\\",
"//Server/Share/..": "\\\\Server\\Share\\",
"//Server/Share/../": "\\\\Server\\Share\\",
"//Server/Share/hello/.": "\\\\Server\\Share\\hello\\",
"//Server/Share/.": "\\\\Server\\Share\\.",
"//Server/Share/./": "\\\\Server\\Share\\.",
"//Server/Share/..": "\\\\Server\\Share\\.",
"//Server/Share/../": "\\\\Server\\Share\\.",
"//Server/Share/hello/.": "\\\\Server\\Share\\hello\\.",
"//Server/Share/hello/../.": "\\\\Server\\Share\\hello\\..",
"/\\Server\\Share/hello/../.": "\\\\Server\\Share\\hello\\..",
"\\\\?\\C:\\hello\\.": "C:\\hello\\",
"\\\\?\\UNC\\Server\\Share\\hello\\.": "\\\\Server\\Share\\hello\\",
"\\??\\C:\\hello\\.": "C:\\hello\\",
"\\\\?\\C:\\hello\\.": "C:\\hello\\.",
"\\\\?\\UNC\\Server\\Share\\hello\\.": "\\\\Server\\Share\\hello\\.",
"\\??\\C:\\hello\\.": "C:\\hello\\.",
"\\??\\Z:\\file0": "Z:\\file0",
"\\??\\UNC\\Server\\Share\\hello\\.": "\\\\Server\\Share\\hello\\",
"\\??\\UNC\\Server\\Share\\hello\\.": "\\\\Server\\Share\\hello\\.",
"\\\\.\\C:\\hello\\.": "C:\\hello\\.",
"\\\\.\\UNC\\Server\\Share\\hello\\.": "\\\\Server\\Share\\hello\\.",
} {
t.Run(from, func(t *testing.T) {
builder1, scopeWalker1 := path.EmptyBuilder.Join(path.VoidScopeWalker)
Expand Down Expand Up @@ -445,6 +447,28 @@ func TestBuilder(t *testing.T) {
require.Equal(t, "\\\\myserver\\myshare\\data.txt", mustGetWindowsString(builder))
})

t.Run("DeviceNamespaceDrivePath", func(t *testing.T) {
scopeWalker := mock.NewMockScopeWalker(ctrl)
componentWalker := mock.NewMockComponentWalker(ctrl)
scopeWalker.EXPECT().OnDriveLetter('C').Return(componentWalker, nil)
componentWalker.EXPECT().OnTerminal(path.MustNewComponent("file.txt"))

builder, s := path.EmptyBuilder.Join(scopeWalker)
require.NoError(t, path.Resolve(path.WindowsFormat.NewParser(`\\.\C:\file.txt`), s))
require.Equal(t, "C:\\file.txt", mustGetWindowsString(builder))
})

t.Run("DeviceNamespaceUNCPath", func(t *testing.T) {
scopeWalker := mock.NewMockScopeWalker(ctrl)
componentWalker := mock.NewMockComponentWalker(ctrl)
scopeWalker.EXPECT().OnShare("server", "share").Return(componentWalker, nil)
componentWalker.EXPECT().OnTerminal(path.MustNewComponent("file.txt"))

builder, s := path.EmptyBuilder.Join(scopeWalker)
require.NoError(t, path.Resolve(path.WindowsFormat.NewParser(`\\.\UNC\server\share\file.txt`), s))
require.Equal(t, "\\\\server\\share\\file.txt", mustGetWindowsString(builder))
})

t.Run("RelativeDrivePaths", func(t *testing.T) {
builder1, s := path.EmptyBuilder.Join(path.VoidScopeWalker)
require.NoError(t, path.Resolve(path.WindowsFormat.NewParser("C:\\a\\b"), s))
Expand Down
30 changes: 17 additions & 13 deletions pkg/filesystem/path/windows_format.go
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Original file line number Diff line number Diff line change
Expand Up @@ -60,24 +60,28 @@ type windowsParser struct {
}

func (p windowsParser) ParseScope(scopeWalker ScopeWalker) (next ComponentWalker, remainder RelativeParser, err error) {
// Handle extended-length paths starting with \\?\.
path := p.path
hasPrefix := false
if len(p.path) >= 4 && p.path[0] == '\\' && p.path[1] == '\\' && p.path[2] == '?' && p.path[3] == '\\' {
// Extended-length paths starting with \\?\.
path = p.path[4:]
// Handle \\?\UNC\.
if len(path) >= 4 && strings.EqualFold(path[:4], "UNC\\") {
return parseUNCPath(path[4:], scopeWalker)
}
hasPrefix = true
} else if len(p.path) >= 4 && p.path[0] == '\\' && p.path[1] == '?' && p.path[2] == '?' && p.path[3] == '\\' {
// NT object namespace paths starting with \??\.
// https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-even/c1550f98-a1ce-426a-9991-7509e7c3787c
path = p.path[4:]
hasPrefix = true
} else if len(p.path) >= 4 && p.path[0] == '\\' && p.path[1] == '\\' && p.path[2] == '.' && p.path[3] == '\\' {
// Win32 device namespace paths starting with \\.\.
// https://learn.microsoft.com/en-us/windows/win32/fileio/naming-a-file#win32-device-namespaces
path = p.path[4:]
hasPrefix = true
}

// Handle NT object namespace paths starting with \??\.
// https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-even/c1550f98-a1ce-426a-9991-7509e7c3787c
if len(p.path) >= 4 && p.path[0] == '\\' && p.path[1] == '?' && p.path[2] == '?' && p.path[3] == '\\' {
path = p.path[4:]
// Handle \??\UNC\
if len(path) >= 4 && strings.EqualFold(path[:4], "UNC\\") {
return parseUNCPath(path[4:], scopeWalker)
}
// Handle UNC paths following a namespace prefix
// (e.g. \\?\UNC\server\share or \??\UNC\server\share).
if hasPrefix && len(path) >= 4 && strings.EqualFold(path[:4], "UNC\\") {
return parseUNCPath(path[4:], scopeWalker)
}

if len(path) >= 2 {
Expand Down