Merge from vscode 2b0b9136329c181a9e381463a1f7dc3a2d105a34 (#4880)

src/vs/base/common/extpath.ts

@@ -4,9 +4,9 @@
  *--------------------------------------------------------------------------------------------*/
 
 import { isWindows } from 'vs/base/common/platform';
-import { startsWithIgnoreCase, equalsIgnoreCase } from 'vs/base/common/strings';
+import { startsWithIgnoreCase, equalsIgnoreCase, endsWith, rtrim } from 'vs/base/common/strings';
 import { CharCode } from 'vs/base/common/charCode';
-import { sep, posix } from 'vs/base/common/path';
+import { sep, posix, isAbsolute, join, normalize } from 'vs/base/common/path';
 
 function isPathSeparator(code: number) {
 	return code === CharCode.Slash || code === CharCode.Backslash;
@@ -227,4 +227,56 @@ export function isEqualOrParent(path: string, candidate: string, ignoreCase?: bo
 
 export function isWindowsDriveLetter(char0: number): boolean {
 	return char0 >= CharCode.A && char0 <= CharCode.Z || char0 >= CharCode.a && char0 <= CharCode.z;
+}
+
+export function sanitizeFilePath(candidate: string, cwd: string): string {
+
+	// Special case: allow to open a drive letter without trailing backslash
+	if (isWindows && endsWith(candidate, ':')) {
+		candidate += sep;
+	}
+
+	// Ensure absolute
+	if (!isAbsolute(candidate)) {
+		candidate = join(cwd, candidate);
+	}
+
+	// Ensure normalized
+	candidate = normalize(candidate);
+
+	// Ensure no trailing slash/backslash
+	if (isWindows) {
+		candidate = rtrim(candidate, sep);
+
+		// Special case: allow to open drive root ('C:\')
+		if (endsWith(candidate, ':')) {
+			candidate += sep;
+		}
+
+	} else {
+		candidate = rtrim(candidate, sep);
+
+		// Special case: allow to open root ('/')
+		if (!candidate) {
+			candidate = sep;
+		}
+	}
+
+	return candidate;
+}
+
+export function isRootOrDriveLetter(path: string): boolean {
+	const pathNormalized = normalize(path);
+
+	if (isWindows) {
+		if (path.length > 3) {
+			return false;
+		}
+
+		return isWindowsDriveLetter(pathNormalized.charCodeAt(0))
+			&& pathNormalized.charCodeAt(1) === CharCode.Colon
+			&& (path.length === 2 || pathNormalized.charCodeAt(2) === CharCode.Backslash);
+	}
+
+	return pathNormalized === posix.sep;
 }