Fix: Symlink Resolution for Cross-Platform Copy Operations (#1103)

* fix: resolve symlinks relative to their target to handle relative paths on Linux

* minor version update

* added unit test to copy symlink (created using relative path) to a file

* minor text update

* test: verify relative and absolute symlink resolution in recursive directory copy

Author: rishabhmalikMS

node/package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "azure-pipelines-task-lib",
-  "version": "5.1.0",
+  "version": "5.2.0",
   "description": "Azure Pipelines Task SDK",
   "main": "./task.js",
   "typings": "./task.d.ts",

node/package.json

@@ -1188,7 +1188,8 @@ export function cp(sourceOrOptions: unknown, destinationOrSource: string, option
 
         try {
             if (lstatSource.isSymbolicLink()) {
-                source = fs.readlinkSync(source);
+                const symlinkTarget = fs.readlinkSync(source);
+                source = path.resolve(path.dirname(source), symlinkTarget);
                 lstatSource = fs.lstatSync(source);
             }
             if (lstatSource.isFile()) {
@@ -1226,7 +1227,8 @@ const copyDirectoryWithResolvedSymlinks = (src: string, dest: string, force: boo
 
         if (entry.isSymbolicLink()) {
             // Resolve the symbolic link and copy the target
-            const resolvedPath = fs.readlinkSync(srcPath);
+            const symlinkTarget = fs.readlinkSync(srcPath);
+            const resolvedPath = path.resolve(path.dirname(srcPath), symlinkTarget);
             const stat = fs.lstatSync(resolvedPath);
 
             if (stat.isFile()) {

node/task.ts

@@ -17,17 +17,23 @@ describe('cp cases', () => {
   const TEST_SRC_DIR = 'test-src';
   const TEST_DEST_DIR = 'test-dest';
   const OUTSIDE_FILE = path.resolve(DIRNAME, 'outside-file.txt');
-  const SYMLINK_NAME = 'symlink-outside.txt';
+  const RELATIVE_TARGET_FILE = path.resolve(DIRNAME, 'outside-file2.txt');
+  const ABSOLUTE_SYMLINK = 'symlink-outside.txt';
+  const RELATIVE_SYMLINK = 'symlink-outside2.txt';
 
   before((done) => {
     tl.mkdirP(TEMP_DIR_1);
     tl.mkdirP(TEMP_DIR_2);
     fs.mkdirSync(TEST_SRC_DIR, { recursive: true });
-    const symlinkPath = path.join(TEST_SRC_DIR, SYMLINK_NAME);
+    const symlinkPath = path.join(TEST_SRC_DIR, ABSOLUTE_SYMLINK);
     fs.writeFileSync(OUTSIDE_FILE, 'This is a file outside the source folder.');
+    fs.writeFileSync(RELATIVE_TARGET_FILE, 'This is the second file outside the source folder.');
     fs.symlinkSync(OUTSIDE_FILE, symlinkPath);
     fs.mkdirSync(TEST_DEST_DIR, { recursive: true });
     fs.writeFileSync(TEMP_DIR_2_FILE_1, 'file1');
+    const symlinkPath2 = path.join(TEST_SRC_DIR, RELATIVE_SYMLINK);
+    const targetPath = path.relative(TEST_SRC_DIR, RELATIVE_TARGET_FILE);
+    fs.symlinkSync(targetPath, symlinkPath2, 'file');
 
     try {
       testutil.initialize();
@@ -154,10 +160,36 @@ describe('cp cases', () => {
 
     tl.cp(TEST_SRC_DIR, TEST_DEST_DIR, '-r', false, 0);
 
+    // Verify first symlink
     assert(fs.existsSync(path.join(TEST_DEST_DIR, TEST_SRC_DIR)), 'Directory was not copied');
     assert(fs.existsSync(path.join(TEST_DEST_DIR, TEST_SRC_DIR, 'outside-file.txt')), 'File was not copied');
     assert.equal(fs.readFileSync(path.join(TEST_DEST_DIR, TEST_SRC_DIR, 'outside-file.txt'), 'utf8'), 'This is a file outside the source folder.', 'File content is incorrect');
-    assert(!fs.existsSync(path.join(TEST_DEST_DIR, TEST_SRC_DIR, SYMLINK_NAME)), 'Symbolic link should not be copied');
+    assert(!fs.existsSync(path.join(TEST_DEST_DIR, TEST_SRC_DIR, ABSOLUTE_SYMLINK)), 'First symbolic link should not be copied');
+
+    // Verify second symlink with relative path
+    assert(fs.existsSync(path.join(TEST_DEST_DIR, TEST_SRC_DIR, 'outside-file2.txt')), 'Second file was not copied');
+    assert.equal(
+      fs.readFileSync(path.join(TEST_DEST_DIR, TEST_SRC_DIR, 'outside-file2.txt'), 'utf8'),
+      'This is the second file outside the source folder.',
+      'Second file content is incorrect'
+    );
+    assert(!fs.existsSync(path.join(TEST_DEST_DIR, TEST_SRC_DIR, RELATIVE_SYMLINK)), 'Second symbolic link should not be copied');
+
+    done();
+  });
+
+  it('copy symlink pointing to file where symlink is created using relative path to target file', (done) => {
+    const rootSymlinkName = 'root-symlink-to-temp2-file';
+    const symlinkPath = path.join(DIRNAME, rootSymlinkName);
+    const targetPath = path.relative(DIRNAME, TEMP_DIR_2_FILE_1);
+
+    fs.symlinkSync(targetPath, symlinkPath, 'file');
+
+    const destPath = path.join(TEST_DEST_DIR, rootSymlinkName);
+    tl.cp(symlinkPath, destPath);
+    assert(fs.existsSync(destPath), 'Destination file was not created');
+    assert(!fs.lstatSync(destPath).isSymbolicLink(), 'Destination should not be a symlink');
+    assert.equal(fs.readFileSync(destPath, 'utf8'), 'file1', 'File content does not match source');
 
     done();
   });