Go: Resolve substed drives on Windows

Author: jketema

MODULE.bazel

@@ -280,7 +280,7 @@ go_sdk.download(version = "1.26.5")
 
 go_deps = use_extension("@gazelle//:extensions.bzl", "go_deps")
 go_deps.from_file(go_mod = "//go/extractor:go.mod")
-use_repo(go_deps, "com_github_stretchr_testify", "org_golang_x_mod", "org_golang_x_tools")
+use_repo(go_deps, "com_github_stretchr_testify", "org_golang_x_mod", "org_golang_x_sys", "org_golang_x_tools")
 
 ripunzip_archive = use_repo_rule("//misc/ripunzip:ripunzip.bzl", "ripunzip_archive")
 

go/extractor/extractor.go

@@ -770,7 +770,7 @@ func normalizedPath(ast *ast.File, fset *token.FileSet) string {
 	if err != nil {
 		return file
 	}
-	return path
+	return util.ResolvePath(path)
 }
 
 // extractFile extracts AST information for the given file

go/extractor/go.mod

@@ -13,7 +13,10 @@ require (
 	golang.org/x/tools v0.48.0
 )
 
-require github.com/stretchr/testify v1.11.1
+require (
+	github.com/stretchr/testify v1.11.1
+	golang.org/x/sys v0.47.0
+)
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect

go/extractor/go.sum

@@ -10,6 +10,8 @@ golang.org/x/mod v0.38.0 h1:MECBjubtXD7yj4HrhIUcywNaGeNVUdfVnxmPajOk4yk=
 golang.org/x/mod v0.38.0/go.mod h1:V6Xz0pq8TQ3dGqVQ1FVHuelZpAL0uNhSkk9ogYP3c40=
 golang.org/x/sync v0.22.0 h1:SZjpbeLmrCk4xhRSZFNZW5gFUeCeFgjekvI/+gfScek=
 golang.org/x/sync v0.22.0/go.mod h1:9xrNwdLfx4jkKbNva9FpL6vEN7evnE43NNNJQ2LF3+0=
+golang.org/x/sys v0.47.0 h1:o7XGOvZQCADBQQ4Y7VNq2dRWQR7JmOUW8Kxx4ZsNgWs=
+golang.org/x/sys v0.47.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
 golang.org/x/tools v0.48.0 h1:3+hClM1aLL5mjMKm5ovokw9epgRXPuu2tILgismM6RE=
 golang.org/x/tools v0.48.0/go.mod h1:08xX0orndb/F7jJxGDicx061tyd5pcMto75YMAXr6lk=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=

go/extractor/util/BUILD.bazel

@@ -0,0 +1,6 @@
+//go:build !windows
+
+package util
+
+// ResolvePath is a no-op on non-Windows platforms.
+func ResolvePath(path string) string { return path }

go/extractor/util/subst_other.go

@@ -0,0 +1,86 @@
+//go:build windows
+
+package util
+
+import (
+	"os"
+	"path/filepath"
+	"syscall"
+	"unsafe"
+
+	"golang.org/x/sys/windows"
+)
+
+var (
+	dll         *syscall.DLL
+	procResolve *syscall.Proc
+	procFree    *syscall.Proc
+	available   bool
+)
+
+func init() {
+	dist := os.Getenv("CODEQL_DIST")
+	if dist == "" {
+		return
+	}
+	dllPath := filepath.Join(dist, "tools", "win64", "canonicalize.dll")
+	d, err := syscall.LoadDLL(dllPath)
+	if err != nil {
+		return
+	}
+	p, err := d.FindProc("resolve_subst")
+	if err != nil {
+		return
+	}
+	f, _ := d.FindProc("resolve_subst_free")
+	dll = d
+	procResolve = p
+	procFree = f
+	available = true
+}
+
+// If "path" is an absolute path starting with a "subst"ed drive letter, return an
+// equivalent path with the drive letter replaced by its target. Otherwise return
+// "path" unchanged.
+func ResolvePath(path string) string {
+	if len(path) < 3 {
+		return path
+	}
+	if path[1] != ':' {
+		return path
+	}
+	if path[2] != '\\' && path[2] != '/' {
+		return path
+	}
+	c := path[0]
+	if !((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z')) {
+		return path
+	}
+
+	resolved, ok := resolveDrive(path[:3])
+	if !ok {
+		return path
+	}
+	return resolved + path[2:]
+}
+
+// Given a drive root like "X:\" (or "X:/"), returns the path that drive is
+// "subst"ed to. Returns false if the drive is not "subst"ed or an error occurred.
+func resolveDrive(driveRoot string) (string, bool) {
+	if !available {
+		return "", false
+	}
+	driveBytes, err := windows.ByteSliceFromString(driveRoot)
+	if err != nil {
+		return "", false
+	}
+	ret, _, _ := procResolve.Call(uintptr(unsafe.Pointer(&driveBytes[0])))
+	if ret == 0 {
+		return "", false
+	}
+	result := windows.BytePtrToString((*byte)(unsafe.Pointer(ret)))
+	if procFree != nil {
+		procFree.Call(ret)
+	}
+	return result, true
+}