From f179770c52cc4e45c27a5e3c72045ae28d901429 Mon Sep 17 00:00:00 2001
From: Vladimir Lagunov <vladimir.lagunov@jetbrains.com>
Date: Wed, 5 Feb 2025 22:54:22 +0100
Subject: [PATCH] JBR-8235 AIOOBE from newByteChannel on empty path name

---
 .../classes/sun/nio/fs/UnixChannelFactory.java   |  5 +++--
 test/jdk/java/nio/file/Files/Misc.java           | 16 +++++++++++++++-
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/src/java.base/unix/classes/sun/nio/fs/UnixChannelFactory.java b/src/java.base/unix/classes/sun/nio/fs/UnixChannelFactory.java
index dec13180f2f7..3076219d7156 100644
--- a/src/java.base/unix/classes/sun/nio/fs/UnixChannelFactory.java
+++ b/src/java.base/unix/classes/sun/nio/fs/UnixChannelFactory.java
@@ -197,8 +197,9 @@ protected static FileDescriptor open(int dfd,
             if (flags.createNew) {
                 byte[] pathForSysCall = path.asByteArray();
 
-                // throw exception if file name is "." to avoid confusing error
-                if ((pathForSysCall[pathForSysCall.length-1] == '.') &&
+                // throw exception if file name is "." or "" to avoid confusing error
+                if ((pathForSysCall.length == 0) ||
+                    (pathForSysCall[pathForSysCall.length-1] == '.') &&
                     (pathForSysCall.length == 1 ||
                     (pathForSysCall[pathForSysCall.length-2] == '/')))
                 {
diff --git a/test/jdk/java/nio/file/Files/Misc.java b/test/jdk/java/nio/file/Files/Misc.java
index 024b518141bb..e804cef3731c 100644
--- a/test/jdk/java/nio/file/Files/Misc.java
+++ b/test/jdk/java/nio/file/Files/Misc.java
@@ -30,16 +30,17 @@
  */
 
 import java.io.IOException;
-import java.io.File;
 import java.nio.file.FileAlreadyExistsException;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.nio.file.StandardOpenOption;
 import java.nio.file.attribute.AclEntry;
 import java.nio.file.attribute.AclEntryPermission;
 import java.nio.file.attribute.AclEntryType;
 import java.nio.file.attribute.AclFileAttributeView;
 import java.nio.file.attribute.DosFileAttributeView;
 import java.nio.file.attribute.UserPrincipal;
+import java.util.EnumSet;
 import java.util.List;
 import jdk.test.lib.Platform;
 
@@ -55,6 +56,7 @@ public static void main(String[] args) throws IOException {
             testIsSameFile(dir);
             testFileTypeMethods(dir);
             testAccessMethods(dir);
+            testEmptyPathForByteStream();
         } finally {
              TestUtil.removeAll(dir);
         }
@@ -363,6 +365,18 @@ static void testAccessMethods(Path tmpdir) throws IOException {
         }
     }
 
+    static void testEmptyPathForByteStream() throws IOException {
+        Path emptyPath = Path.of("");
+        try {
+            emptyPath.getFileSystem().provider()
+                    .newByteChannel(emptyPath, EnumSet.of(StandardOpenOption.WRITE, StandardOpenOption.CREATE_NEW))
+                    .close();
+            throw new RuntimeException("FileAlreadyExistsException was not thrown");
+        } catch (FileAlreadyExistsException e) {
+            // The expected behavior.
+        }
+    }
+
     static void assertTrue(boolean okay) {
         if (!okay)
             throw new RuntimeException("Assertion Failed");