Detect Windows junctions with GetFileAttributesEx #2013

jakebailey · 2025-11-04T03:32:59Z

Faster than doing a realpath + comparison.

goos: windows
goarch: amd64
pkg: github.com/microsoft/typescript-go/internal/vfs/osvfs
cpu: Intel(R) Core(TM) i9-10900K CPU @ 3.70GHz
                                    │   out.txt   │
                                    │   sec/op    │
Realpath/target-20                    76.62µ ± 1%
Realpath/link-20                      87.68µ ± 2%
IsSymlinkOrJunction/regular_file-20   28.60µ ± 2%
IsSymlinkOrJunction/junction-20       22.62µ ± 2%
IsSymlinkOrJunction/nonexistent-20    11.45µ ± 0%
geomean                               34.63µ

                                    │  out.txt   │
                                    │    B/op    │
Realpath/target-20                    944.0 ± 0%
Realpath/link-20                      944.0 ± 0%
IsSymlinkOrJunction/regular_file-20   192.0 ± 0%
IsSymlinkOrJunction/junction-20       176.0 ± 0%
IsSymlinkOrJunction/nonexistent-20    192.0 ± 0%
geomean                               356.8

                                    │  out.txt   │
                                    │ allocs/op  │
Realpath/target-20                    8.000 ± 0%
Realpath/link-20                      8.000 ± 0%
IsSymlinkOrJunction/regular_file-20   1.000 ± 0%
IsSymlinkOrJunction/junction-20       1.000 ± 0%
IsSymlinkOrJunction/nonexistent-20    1.000 ± 0%
geomean                               2.297

Copilot

Pull Request Overview

This PR refactors Windows junction and symlink detection by replacing the Realpath-based approach with a dedicated IsSymlinkOrJunction function. The change improves efficiency by using direct Windows API calls to check for reparse points instead of resolving full paths.

Adds platform-specific isSymlinkOrJunction implementations for Windows and Unix-like systems
Updates internal.Common struct to use IsSymlinkOrJunction instead of Realpath field
Simplifies junction detection logic in GetAccessibleEntries

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
internal/vfs/osvfs/symlink_windows.go	New file implementing Windows-specific junction/symlink detection using `FILE_ATTRIBUTE_REPARSE_POINT`
internal/vfs/osvfs/symlink_other.go	New file with nil function stub for Unix-like systems where detection is unnecessary
internal/vfs/osvfs/os.go	Updates `osVFS` initialization to use `IsSymlinkOrJunction` instead of `Realpath`
internal/vfs/internal/internal.go	Replaces `Realpath` field with `IsSymlinkOrJunction` in `Common` struct and simplifies detection logic in `GetAccessibleEntries`

internal/vfs/osvfs/reparsepoint_windows.go

DanielRosenwasser · 2025-11-04T21:09:24Z

Any specific differences you've seen in perf?

jakebailey · 2025-11-04T21:14:00Z

Haven't tested yet, just cleaning up some TODOs with my name on it. On any project I have it probably won't be very noticable...

internal/vfs/internal/internal.go

internal/vfs/osvfs/reparsepoint_windows.go

jakebailey · 2025-11-10T20:23:15Z

To actually test this, I switched us over to the Microsoft fork of Go, which disables the SEH bit that auto-handles longpaths. I can split that out into its own PR for clarity if desired.

jakebailey · 2025-11-12T23:20:46Z

Okay, this PR is now solely the junctions change.

@typedef

* Port 'go to type definition' tests (microsoft#1883) * Fix panic in `getTokenAtPosition` for JSDoc type assertions (microsoft#1846) Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: jakebailey <[email protected]> Co-authored-by: andrewbranch <[email protected]> Co-authored-by: Andrew Branch <[email protected]> * Don’t look in JSExportAssignment and CommonJSExport for nodes (microsoft#1886) * Fix link in native preview platform packages (microsoft#1838) * fix(1880): No error message for JSDoc type parsing (microsoft#1881) * Add vscode editor issue template (microsoft#1893) Co-authored-by: Ryan Cavanaugh <[email protected]> * Add "Report Issue" button to TSGO status bar commands (microsoft#1889) Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: DanielRosenwasser <[email protected]> Co-authored-by: Daniel Rosenwasser <[email protected]> * fix(1898): adjust location handling in find-refs (microsoft#1901) * Fix panic of empty string in type reference directive (microsoft#1908) * Consistently error on full circle of circular import aliases (microsoft#1904) * Fix panic in textDocument/onTypeFormatting when tokenAtPosition is nil (microsoft#1845) Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: jakebailey <[email protected]> * Update submodule (microsoft#1913) * Disable create-cache.yml in forks (microsoft#1912) * Forbid platform specific package uses in agnostic files (microsoft#1911) * Fix JSDoc comment formatting with tab indentation (microsoft#1900) Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: jakebailey <[email protected]> * Clear local baseline dir in hereby test (microsoft#1921) * Unskip passing fourslash test (microsoft#1922) * Support auto-import completion fourslash tests, fix bugs (microsoft#1917) * Fix JSX indentation in JavaScript output (microsoft#1792) Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: jakebailey <[email protected]> * Implement printAllHelp to fix `tsgo --all` producing no output (microsoft#1843) Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: jakebailey <[email protected]> * Bump the github-actions group across 1 directory with 2 updates (microsoft#1909) Signed-off-by: dependabot[bot] <[email protected]> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com> Co-authored-by: Jake Bailey <[email protected]> * Ensure os package is forbidden in lint (microsoft#1924) * Speed up levenshteinWithMax by reusing buffers (microsoft#1823) * Fix incorrect formatting for comments inside multi-line argument lists and method chains (microsoft#1929) Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: jakebailey <[email protected]> * Handle nil end position in getMappedLocation (microsoft#1920) * Fix formatter adding extra space at end of line without trailing newline (microsoft#1933) Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: jakebailey <[email protected]> * Fix vscode issue template (microsoft#1934) * userpreferences parsing/ls config handing (microsoft#1729) * Plumb through TokenFlagsSingleQuote; use for auto import quote detection (microsoft#1937) * Invalidate caches on batches of 1000+ watch changes (microsoft#1869) * Create clickable links in quick info from @link JSDoc tags (microsoft#1935) * Don't report errors on `{@link foo.bar}` references (microsoft#1941) * Fix crash in `invocationErrorRecovery` function (microsoft#1944) * Fix leading source file comment emit bugs (microsoft#1945) * Implement selection ranges (microsoft#1939) * Fix porting bug in isArgumentAndStartLineOverlapsExpressionBeingCalled (microsoft#1948) * Add Range to Hover (microsoft#1489) Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: DanielRosenwasser <[email protected]> Co-authored-by: Jake Bailey <[email protected]> * Properly handle hovering on `this` (microsoft#1953) * Bump the github-actions group across 1 directory with 2 updates (microsoft#1959) Signed-off-by: dependabot[bot] <[email protected]> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com> * Fixed document highlight for reference directive (microsoft#1951) * Several fixes to JS typing of functions and methods (microsoft#1960) * Update submodule, port 6.0 options defaults (microsoft#1961) * Reapply microsoft#1951 and microsoft#1960 after bad merge (microsoft#1964) Co-authored-by: Anders Hejlsberg <[email protected]> Co-authored-by: John Favret <[email protected]> * Update submodule with ES5 removals (microsoft#1963) * Actually transform KindCommonJSExport in declaration emit (microsoft#1962) * Quick Info fixes (microsoft#1971) * Fix various named enum types (microsoft#1973) * Move change tracker, converters, utils to separate packages (microsoft#1977) * Consistent rules for mixing `@type`, `@param`, `@return`, `@template` (microsoft#1979) * Check for identifier before obtaining text of name (microsoft#1984) * Respect client capabilities for diagnostics (microsoft#1980) * Store explicitly declared members ahead of inherited members (microsoft#1987) * Add --checkers to control number of checkers per Program (microsoft#1985) * Export all types referenced through other exported APIs, enforce (microsoft#1978) * Switch custom runners from mariner-2.0 to azure-linux-3 (microsoft#1989) * Use `LocationLink` in go to definition (microsoft#1884) * Use a different set of commands to detect fourslash test updates (microsoft#1923) * Skip erasableSyntaxOnly checks for JavaScript files (microsoft#1956) Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: jakebailey <[email protected]> * Update submodule for new cherry-picks (microsoft#1996) * Port TypeScript PR #62604: Propagate variance reliability (microsoft#1916) Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: RyanCavanaugh <[email protected]> Co-authored-by: Jake Bailey <[email protected]> * Only export `@typedef` type aliases in modules (microsoft#1999) * Bump github/codeql-action from 4.31.0 to 4.31.2 in the github-actions group across 1 directory (microsoft#2005) Signed-off-by: dependabot[bot] <[email protected]> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com> * Hoist @typedef and @import tags to containing scopes that permit them (microsoft#2003) * Remove concept of "unsupported extensions", clean up test skips (microsoft#2004) * Update golangci-lint, fix issues, modernize (microsoft#1981) * Implement more handling of client capabilities (microsoft#1998) * Add docs to signature help (microsoft#2009) Co-authored-by: Copilot <[email protected]> * Fix unused identifier diags, LSP tag diags (microsoft#2007) * fix(2015): abstract property created, overshadowing override (microsoft#2016) * Always check refCount after acquiring lock (microsoft#1986) * Delete resolver unit tests (microsoft#2008) * Fix missing parent for `Expression` in `TypeParameterDeclaration` (microsoft#2017) * Add missing nil check in `getCompletionItemActions` (microsoft#2018) * Fix crash in find-all-refs on `exports.xxx` in .js file (microsoft#2023) * Properly include JSX attributes in find-all-references (microsoft#2025) * Fix crash by removing `getNameFromImportDeclaration` in favor of `Node.Name()` (microsoft#2027) * Fix losing options from command line in watch mode (microsoft#2024) * Add issue investigator agent (microsoft#2030) * Switch 1ESPT pipelines to 1ESPT-AzureLinux3 (microsoft#2031) * Port inlay hints (microsoft#1705) * Split "use strict" into separate transformer, fix bugs with prologues (microsoft#2028) Co-authored-by: Sheetal Nandi <[email protected]> * Use a more cross-architecture-friendly devcontainer image. (microsoft#2034) * Fix nil pointer dereference in range formatting (microsoft#1993) Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: DanielRosenwasser <[email protected]> Co-authored-by: jakebailey <[email protected]> Co-authored-by: Daniel Rosenwasser <[email protected]> Co-authored-by: Copilot <[email protected]> * Port missing `checkJs` logic (microsoft#2046) * Ignore reparsed nodes when determining external module indicator (microsoft#2044) * Fix various fuzzer-caught crashes in the parser (microsoft#2038) * Fix moduleDetection for node18, fix __esModule in detect=force (microsoft#2045) * Fix panic in syncmap on loading nil (microsoft#2056) * Use accessors on `Node` instead of casts and field accesses (microsoft#2052) * Add locks on concurrent alias following checker accesses under incremental mode (microsoft#2051) * Don't add `export` modifier to `JSTypeAliasDeclaration` from `@callback` (microsoft#2063) * Introduce GetECMALineOfPosition to avoid unused rune counting (microsoft#2065) * Don't add `export` modifier to `KindCommonJSExport` reparsed nodes (microsoft#2066) * Fix panic in inlay hints for tuple types (microsoft#2040) Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: jakebailey <[email protected]> * Accurately recognize fourslash test as submodule (microsoft#2068) * Implement auto-import code actions, port tests and fix some bugs (microsoft#2053) * Port tsc --init (microsoft#2033) * Make CheckerPool iteration concurrent by default (microsoft#2070) * Use Microsoft build of Go in CI (microsoft#2069) * Detect Windows junctions with GetFileAttributesEx (microsoft#2013) * Fix CI cache workflow (microsoft#2071) * Use information from contextual type in hovers/quick info (microsoft#2073) * fix(2074): No quick info on function and other similar tokens (microsoft#2078) * Unify locks used on checkers between exclusive pool borrows and EmitResolver scopes (microsoft#2080) * Port non-baseline diagnostics tests (microsoft#2079) * Use SkipTrivia instead of GetRangeOfTokenAtPosition where possible (microsoft#2089) * Move unreachable checks to checker, allowing more AST reuse (microsoft#2067) * Fix scanning of valid surrogate pairs (microsoft#2032) * Fix misplaced parentheses in `Checker.isIndirectCall` (microsoft#2093) * Various agent mode updates (microsoft#2094) * Handle configuration changes in LSP for 'typescript.*' options. (microsoft#2088) * Fix nil pointer dereference in getAdjustedLocation for type-only exports (microsoft#2090) Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: jakebailey <[email protected]> * Fix nil pointer dereference in code actions when diagnostic code is nil (microsoft#2091) Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: jakebailey <[email protected]> * Fully resolve LSP client caps to non-pointers, pass by context (microsoft#2095) * Fix hover on `module.exports` (microsoft#2098) * Accept and document jsdoc diffs, round 1 (microsoft#1426) Co-authored-by: Copilot <[email protected]> Co-authored-by: Jake Bailey <[email protected]> * Port baseline diagnostics tests (microsoft#2097) * Clean up disk space in CI before running (microsoft#2103) Co-authored-by: Copilot <[email protected]> * Add GOBIN to PATH in CI (microsoft#2105) * Make client requests type safe, unmarshal (microsoft#2099) * Display inherited JSDoc documentation in quick info (microsoft#2111) * Sort failingTests and manualTests in en-US (microsoft#2113) * fix(2047): Incomplete declaration emit of callback tag with no return tag (microsoft#2100) * Fix canHaveSyntheticDefault (microsoft#2101) * Misc fixes (microsoft#2112) * chore: fix incorrect function name in comment (microsoft#2109) Signed-off-by: weifangc <[email protected]> * Fix typedef binding with CJS `exports=` (microsoft#826) * Provide Program diagnostics as push diags in tsconfig.json (microsoft#2118) Co-authored-by: Copilot <[email protected]> * Update dependencies (microsoft#2116) * Remove copilot-setup-steps env var (microsoft#2124) * Fix panic on negative parameterIndex in type predicate flow analysis (microsoft#2122) Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: RyanCavanaugh <[email protected]> Co-authored-by: Ryan Cavanaugh <[email protected]> * Port tests for go to implementation and diff definitions tests (microsoft#2130) * Partially fix multi-checker diagnostics consistency (microsoft#2134) * Implement reportStyleChecksAsWarnings (microsoft#2132) * Include docs on resolved client caps (microsoft#2135) * Fix dynamic import grammar check (microsoft#2138) * Refine LSP with our own types, generate more stuff (microsoft#2141) * Display all symbol meanings in quick info (microsoft#2144) * Multiproject requests like find all refs, rename and workspace symbols (microsoft#1991) * Add stringer-alike String methods to non-string LSP enums (microsoft#2148) * Enable localization (microsoft#2123) * Port workspace symbols tests (microsoft#2146) * Update readme, issue template (microsoft#2140) * Ignore config port (microsoft#1755) * fix(2157): jsdocfunction param is inferred as implicit any when directly assigned to module.exports (microsoft#2158) * fixes after merge * some more fixes * more errors * builds * fmt * fix nil pointer deref * fix error messages --------- Signed-off-by: dependabot[bot] <[email protected]> Signed-off-by: weifangc <[email protected]> Co-authored-by: Gabriela Araujo Britto <[email protected]> Co-authored-by: Copilot <[email protected]> Co-authored-by: jakebailey <[email protected]> Co-authored-by: andrewbranch <[email protected]> Co-authored-by: Andrew Branch <[email protected]> Co-authored-by: Andrew Branch <[email protected]> Co-authored-by: Oleksandr T. <[email protected]> Co-authored-by: Matt Bierner <[email protected]> Co-authored-by: Ryan Cavanaugh <[email protected]> Co-authored-by: DanielRosenwasser <[email protected]> Co-authored-by: Daniel Rosenwasser <[email protected]> Co-authored-by: Twacqwq <[email protected]> Co-authored-by: Anders Hejlsberg <[email protected]> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com> Co-authored-by: Isabel Duan <[email protected]> Co-authored-by: John Favret <[email protected]> Co-authored-by: Wesley Wigham <[email protected]> Co-authored-by: RyanCavanaugh <[email protected]> Co-authored-by: Copilot <[email protected]> Co-authored-by: xu0o0 <[email protected]> Co-authored-by: Sheetal Nandi <[email protected]> Co-authored-by: Nathan Shively-Sanders <[email protected]> Co-authored-by: weifangc <[email protected]> Co-authored-by: Ryan Cavanaugh <[email protected]> Co-authored-by: Nathan Whitaker <[email protected]>

jakebailey added 2 commits November 3, 2025 19:16

Replace Realpath with more efficient GetFileAttributesEx

dd027bb

Nil it out, comment

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Copilot AI review requested due to automatic review settings November 4, 2025 03:33

Copilot AI reviewed Nov 4, 2025

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jakebailey marked this pull request as draft November 4, 2025 21:18

jakebailey added 9 commits November 9, 2025 23:18

Tessts

2527991

Fix tests a little

8e945e4

lint

7c7e29b

Install microsoft go fork to see if CI catches it

bbe9968

Pull in fix from go-infra PR

1b1dc85

Uncomment fix now that CI proves it matters

5d59ec8

Move impl

d30517a

Update comments

726a811

one more last thing

6c9d09c

jakebailey marked this pull request as ready for review November 10, 2025 20:21

jakebailey requested review from DanielRosenwasser and RyanCavanaugh November 10, 2025 20:22

jakebailey enabled auto-merge November 10, 2025 21:47

Merge branch 'main' into jabaile/windows-junctions

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jakebailey mentioned this pull request Nov 12, 2025

Use Microsoft build of Go in CI #2069

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jakebailey disabled auto-merge November 12, 2025 22:30

Merge branch 'main' into jabaile/windows-junctions

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Merged via the queue into main with commit 866dd59 Nov 12, 2025
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