Add subst drive resolution to Kotlin and Go extractors

go/extractor/BUILD.bazel

@@ -19,6 +19,7 @@ go_library(
         "//go/extractor/dbscheme",
         "//go/extractor/diagnostics",
         "//go/extractor/srcarchive",
+        "//go/extractor/subst",
         "//go/extractor/toolchain",
         "//go/extractor/trap",
         "//go/extractor/util",

go/extractor/extractor.go

@@ -25,6 +25,7 @@ import (
 	"github.com/github/codeql-go/extractor/dbscheme"
 	"github.com/github/codeql-go/extractor/diagnostics"
 	"github.com/github/codeql-go/extractor/srcarchive"
+	"github.com/github/codeql-go/extractor/subst"
 	"github.com/github/codeql-go/extractor/toolchain"
 	"github.com/github/codeql-go/extractor/trap"
 	"github.com/github/codeql-go/extractor/util"
@@ -764,9 +765,9 @@ func normalizedPath(ast *ast.File, fset *token.FileSet) string {
 	file := fset.File(ast.Package).Name()
 	path, err := filepath.EvalSymlinks(file)
 	if err != nil {
-		return file
+		path = file
 	}
-	return path
+	return subst.ResolvePath(path)
 }
 
 // extractFile extracts AST information for the given file

go/extractor/subst/subst.go

@@ -0,0 +1,30 @@
+package subst
+
+// ResolvePath resolves subst'd drive letters in a full path.
+// If the path starts with a subst'd drive letter, replaces it with the backing path.
+// Otherwise returns the path unchanged.
+func ResolvePath(path string) string {
+	return resolvePath(path, ResolveDrive)
+}
+
+func resolvePath(path string, resolveDrive func(string) 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 := resolveDrive(path[:3])
+	if resolved == "" {
+		return path
+	}
+	return resolved + path[2:]
+}

go/extractor/subst/subst_other.go

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

go/extractor/subst/subst_windows.go

@@ -0,0 +1,67 @@
+//go:build windows
+
+package subst
+
+import (
+	"os"
+	"path/filepath"
+	"syscall"
+	"unsafe"
+)
+
+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_u8")
+	if err != nil {
+		return
+	}
+	f, _ := d.FindProc("resolve_subst_free_u8")
+	dll = d
+	procResolve = p
+	procFree = f
+	available = true
+}
+
+// ResolveDrive resolves a subst'd drive root (e.g. "X:\") to its backing path.
+// Returns "" if the drive is not subst'd or on error.
+func ResolveDrive(driveRoot string) string {
+	if !available {
+		return ""
+	}
+	driveBytes := append([]byte(driveRoot), 0)
+	ret, _, _ := procResolve.Call(uintptr(unsafe.Pointer(&driveBytes[0])))
+	if ret == 0 {
+		return ""
+	}
+	result := goString((*byte)(unsafe.Pointer(ret)))
+	if procFree != nil {
+		procFree.Call(ret)
+	}
+	return result
+}
+
+func goString(p *byte) string {
+	if p == nil {
+		return ""
+	}
+	var n int
+	for ptr := unsafe.Pointer(p); *(*byte)(ptr) != 0; n++ {
+		ptr = unsafe.Add(ptr, 1)
+	}
+	return string(unsafe.Slice(p, n))
+}

java/kotlin-extractor/src/main/java/com/semmle/util/files/FileUtil.java

@@ -1242,12 +1242,13 @@ public static String relativePathLink (File f, File base)
 	public static File tryMakeCanonical (File f)
 	{
 		try {
-			return f.getCanonicalFile();
+			f = f.getCanonicalFile();
 		}
 		catch (IOException ignored) {
 			Exceptions.ignore(ignored, "Can't log error: Could be too verbose.");
-			return new File(simplifyPath(f));
+			f = new File(simplifyPath(f));
 		}
+		return SubstResolver.resolve(f);
 	}
 
 

java/kotlin-extractor/src/main/java/com/semmle/util/files/SubstResolver.java

@@ -0,0 +1,76 @@
+package com.semmle.util.files;
+
+import java.io.File;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+/**
+ * Resolves Windows {@code subst}ed drive letters to their underlying paths. On non-Windows
+ * platforms, or when the native library failed to load, {@link #resolve(File)} is a no-op that
+ * returns its argument unchanged.
+ */
+public class SubstResolver {
+	private static final boolean available;
+
+	static {
+		boolean loaded = false;
+		if (File.separatorChar == '\\') {
+			String dist = System.getenv("CODEQL_DIST");
+			if (dist != null && !dist.isEmpty()) {
+				try {
+					Path library = Paths.get(dist).resolve("tools").resolve("win64")
+							.resolve("canonicalize.dll").toAbsolutePath();
+					System.load(library.toString());
+					loaded = true;
+				} catch (RuntimeException | UnsatisfiedLinkError ignored) {
+				}
+			}
+		}
+		available = loaded;
+	}
+
+	private SubstResolver() {}
+
+	/**
+	 * Given a drive root like {@code "X:\\"}, returns the path that drive is
+	 * {@code subst}ed to, or {@code null} if the letter isn't a subst mapping.
+	 */
+	private static native String nativeResolveSubst(String driveRoot);
+
+	/**
+	 * If {@code f} is an absolute path starting with a {@code subst}ed drive letter, return an
+	 * equivalent path with the drive letter replaced by its target. Otherwise return {@code f}
+	 * unchanged.
+	 */
+	public static File resolve(File f) {
+		if (!available) {
+			return f;
+		}
+		String path = f.getPath();
+		if (path.length() < 3 || path.charAt(1) != ':') {
+			return f;
+		}
+		char sep = path.charAt(2);
+		if (sep != '\\' && sep != '/') {
+			return f;
+		}
+		if (!isDriveLetter(path.charAt(0))) {
+			return f;
+		}
+
+		String resolved = nativeResolveSubst(path.substring(0, 3));
+		if (resolved == null) {
+			return f;
+		}
+
+		return new File(resolved + path.substring(2));
+	}
+
+	private static boolean isDriveLetter(char c) {
+		return (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z');
+	}
+
+	public static boolean isAvailable() {
+		return available;
+	}
+}