GH-628: SFTP: Fix reading directories with trailing blanks in the name

ValidateUtils.checkNotNullAndNotEmpty(String, ...) as a side-effect
returns the trimmed string!

Add new methods ValidateUtils.hasContent(String, ...) that don't do so,
and use that instead.

CHANGES.md

@@ -41,10 +41,11 @@
 ## Bug Fixes
 
 * [GH-618](https://github.com/apache/mina-sshd/issues/618) Fix reading an `OpenSshCertificate` from a `Buffer`
+* [GH-628](https://github.com/apache/mina-sshd/issues/628) SFTP: fix reading directories with trailing blanks in the name
 
 ## New Features
 
-* [GH-606](https://github.com/apache/mina-sshd/issues/606) Support ML-KEM PQC key exchange
+* [GH-606](https://github.com/apache/mina-sshd/issues/606) Support ML-KEM PQC hybrid key exchanges
 
 ## Potential compatibility issues
 

sshd-common/src/main/java/org/apache/sshd/common/util/ValidateUtils.java

@@ -51,6 +51,27 @@ public static <T> T checkNotNull(T t, String message, Object... args) {
         return t;
     }
 
+    public static String hasContent(String t, String message) {
+        if (t == null || t.isEmpty()) {
+            throwIllegalArgumentException(message);
+        }
+        return t;
+    }
+
+    public static String hasContent(String t, String message, Object arg) {
+        if (t == null || t.isEmpty()) {
+            throwIllegalArgumentException(message, arg);
+        }
+        return t;
+    }
+
+    public static String hasContent(String t, String message, Object... args) {
+        if (t == null || t.isEmpty()) {
+            throwIllegalArgumentException(message, args);
+        }
+        return t;
+    }
+
     public static String checkNotNullAndNotEmpty(String t, String message) {
         t = checkNotNull(t, message).trim();
         checkTrue(GenericUtils.length(t) > 0, message);

sshd-sftp/src/main/java/org/apache/sshd/sftp/client/impl/SftpDirEntryIterator.java

@@ -77,7 +77,7 @@ public SftpDirEntryIterator(SftpClient client, Handle dirHandle) {
      */
     public SftpDirEntryIterator(SftpClient client, String path, Handle dirHandle, boolean closeOnFinished) {
         this.client = Objects.requireNonNull(client, "No SFTP client instance");
-        this.dirPath = ValidateUtils.checkNotNullAndNotEmpty(path, "No path");
+        this.dirPath = ValidateUtils.hasContent(path, "No path");
         this.dirHandle = Objects.requireNonNull(dirHandle, "No directory handle");
         this.closeOnFinished = closeOnFinished;
         this.dirEntries = load(dirHandle);

sshd-sftp/src/main/java/org/apache/sshd/sftp/client/impl/SftpIterableDirEntry.java

@@ -42,7 +42,7 @@ public class SftpIterableDirEntry implements SftpClientHolder, Iterable<DirEntry
      */
     public SftpIterableDirEntry(SftpClient client, String path) {
         this.client = Objects.requireNonNull(client, "No client instance");
-        this.path = ValidateUtils.checkNotNullAndNotEmpty(path, "No remote path");
+        this.path = ValidateUtils.hasContent(path, "No remote path");
     }
 
     @Override

sshd-sftp/src/test/java/org/apache/sshd/sftp/client/SftpTest.java

@@ -118,15 +118,6 @@
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.MethodSource;
 
-import static org.junit.jupiter.api.Assertions.assertArrayEquals;
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertFalse;
-import static org.junit.jupiter.api.Assertions.assertNotNull;
-import static org.junit.jupiter.api.Assertions.assertNull;
-import static org.junit.jupiter.api.Assertions.assertSame;
-import static org.junit.jupiter.api.Assertions.assertTrue;
-import static org.junit.jupiter.api.Assertions.fail;
-
 /**
  * @author <a href="mailto:dev@mina.apache.org">Apache MINA SSHD Project</a>
  */
@@ -1195,6 +1186,40 @@ public void writeCreateAppend(int handleSize) throws Exception {
         }
     }
 
+    @MethodSource("getParameters")
+    @ParameterizedTest(name = "FILE_HANDLE_SIZE {0}") // SSHD-1215
+    public void listDirWithBlank(int handleSize) throws Exception {
+        Assumptions.assumeFalse(OsUtils.isWin32(), "Windows does not allow trailing blanks anyway");
+        initSftpTest(handleSize);
+        Path targetPath = detectTargetFolder();
+        Path lclSftp = CommonTestSupportUtils.resolve(targetPath, SftpConstants.SFTP_SUBSYSTEM_NAME, getClass().getSimpleName(),
+                getCurrentTestName());
+        CommonTestSupportUtils.deleteRecursive(lclSftp);
+
+        Path parentPath = targetPath.getParent();
+        Path clientFolder = assertHierarchyTargetFolderExists(lclSftp.resolve("withBlank "));
+        String fileName = "file ";
+        Path clientFile = clientFolder.resolve(fileName);
+
+        byte[] foo = { 'f', 'o', 'o' };
+        Files.write(clientFile, foo);
+
+        String dir = CommonTestSupportUtils.resolveRelativeRemotePath(parentPath, clientFolder);
+
+        try (SftpClient sftp = createSingleSessionClient()) {
+            List<String> expected = new ArrayList<>();
+            expected.add(".");
+            expected.add("..");
+            expected.add(fileName);
+            List<String> actual = new ArrayList<>();
+            sftp.readDir(dir).iterator().forEachRemaining(e -> actual.add(e.getFilename()));
+            assertEquals(expected, actual, "Unexpected directory entries");
+            try (InputStream in = sftp.read(dir + '/' + fileName)) {
+                assertArrayEquals(foo, IoUtils.toByteArray(in), "Wrong file content");
+            }
+        }
+    }
+
     @MethodSource("getParameters")
     @ParameterizedTest(name = "FILE_HANDLE_SIZE {0}")
     public void handleSize(int handleSize) throws Exception {