8062795: (fs) Files.setPermissions requires read access when NOFOLLOW_LINKS specified

Reviewed-by: alanb

src/java.base/unix/classes/sun/nio/fs/UnixFileAttributeViews.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2023, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -31,6 +31,7 @@ import java.util.*;
 import java.util.concurrent.TimeUnit;
 import java.io.IOException;
 
+import static sun.nio.fs.UnixConstants.*;
 import static sun.nio.fs.UnixNativeDispatcher.*;
 
 class UnixFileAttributeViews {
@@ -262,19 +263,44 @@ class UnixFileAttributeViews {
         // chmod
         final void setMode(int mode) throws IOException {
             checkWriteExtended();
-            try {
+
-                if (followLinks) {
+            if (followLinks) {
+                try {
                     chmod(file, mode);
-                } else {
+                } catch (UnixException e) {
-                    int fd = file.openForAttributeAccess(false);
+                    e.rethrowAsIOException(file);
-                    try {
-                        fchmod(fd, mode);
-                    } finally {
-                        close(fd);
-                    }
                 }
-            } catch (UnixException x) {
+                return;
-                x.rethrowAsIOException(file);
+            }
+
+            if (O_NOFOLLOW == 0) {
+                throw new IOException("NOFOLLOW_LINKS is not supported on this platform");
+            }
+
+            int fd = -1;
+            try {
+                fd = open(file, O_RDONLY, O_NOFOLLOW);
+            } catch (UnixException e1) {
+                if (e1.errno() == EACCES) {
+                    // retry with write access if there is no read permission
+                    try {
+                        fd = open(file, O_WRONLY, O_NOFOLLOW);
+                    } catch (UnixException e2) {
+                        e2.rethrowAsIOException(file);
+                    }
+                } else {
+                    e1.rethrowAsIOException(file);
+                }
+            }
+
+            try {
+                try {
+                    fchmod(fd, mode);
+                } finally {
+                    close(fd);
+                }
+            } catch (UnixException e) {
+                e.rethrowAsIOException(file);
             }
         }
 

test/jdk/java/nio/file/attribute/PosixFileAttributeView/Basic.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2023, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -22,7 +22,7 @@
  */
 
 /* @test
- * @bug 4313887 6838333
+ * @bug 4313887 6838333 8062795
  * @summary Unit test for java.nio.file.attribute.PosixFileAttributeView
  * @library ../..
  */
@@ -167,9 +167,9 @@ public class Basic {
             Files.delete(file);
         }
 
-        // create link (to file that doesn't exist) and test reading of
-        // permissions
         if (TestUtil.supportsLinks(dir)) {
+            // create link (to file that doesn't exist) and test reading of
+            // permissions
             Path link = dir.resolve("link");
             System.out.format("create link %s\n", link);
             Files.createSymbolicLink(link, file);
@@ -185,6 +185,46 @@ public class Basic {
             } finally {
                 Files.delete(link);
             }
+
+            // test that setting permissions on paths with and without
+            // links succeeds when the NOFOLLOW_LINKS option is set
+
+            // ensure there are no links in the path to test
+            Path realDir = dir.toRealPath();
+
+            // realDir/a/b/c/d
+            Path leaf = realDir.resolve(Path.of("a", "b", "c", "d"));
+            Files.createDirectories(leaf);
+
+            // realDir/a/b/c/d/FUBAR
+            Path sansLinks = Files.createTempFile(leaf, "FU", "BAR");
+
+            PosixFileAttributeView sansView =
+                Files.getFileAttributeView(sansLinks,
+                                           PosixFileAttributeView.class,
+                                           LinkOption.NOFOLLOW_LINKS);
+            sansView.setPermissions(Set.of(PosixFilePermission.OWNER_WRITE));
+            sansView.setPermissions(Set.of(PosixFilePermission.OWNER_WRITE));
+
+            // reinstate read permission
+            sansView.setPermissions(Set.of(PosixFilePermission.OWNER_READ,
+                                           PosixFilePermission.OWNER_WRITE));
+
+            // lien -> realDir/a/b/c
+            Path lien = realDir.resolve(Path.of("a", "lien"));
+            Files.createSymbolicLink(lien,
+                                     realDir.resolve(Path.of("a", "b", "c")));
+
+            // lien/d/FUBAR
+            Path withLinks = lien.resolve(Path.of("d"),
+                                          sansLinks.getFileName());
+
+            PosixFileAttributeView withView =
+                Files.getFileAttributeView(withLinks,
+                                           PosixFileAttributeView.class,
+                                           LinkOption.NOFOLLOW_LINKS);
+            withView.setPermissions(Set.of(PosixFilePermission.OWNER_WRITE));
+            withView.setPermissions(Set.of(PosixFilePermission.OWNER_WRITE));
         }
 
         System.out.println("OKAY");