8073061: (fs) Files.copy(foo, bar, REPLACE_EXISTING) deletes bar even…

… if foo is not readable

Reviewed-by: alanb

src/java.base/share/classes/java/nio/file/CopyMoveHelper.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 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
@@ -69,6 +69,14 @@ static CopyOptions parse(CopyOption... options) {
             }
             return result;
         }
+
+        CopyOption[] replaceExistingOrEmpty() {
+            if (replaceExisting) {
+                return new CopyOption[] { StandardCopyOption.REPLACE_EXISTING };
+            } else {
+                return new CopyOption[0];
+            }
+        }
     }
 
     /**
@@ -129,18 +137,14 @@ static void copyToForeignTarget(Path source, Path target,
         if (sourceAttrs.isSymbolicLink())
             throw new IOException("Copying of symbolic links not supported");
 
-        // delete target if it exists and REPLACE_EXISTING is specified
-        if (opts.replaceExisting) {
-            Files.deleteIfExists(target);
-        } else if (Files.exists(target))
-            throw new FileAlreadyExistsException(target.toString());
-
         // create directory or copy file
         if (sourceAttrs.isDirectory()) {
+            if (opts.replaceExisting)
+                Files.deleteIfExists(target);
             Files.createDirectory(target);
         } else {
             try (InputStream in = Files.newInputStream(source)) {
-                Files.copy(in, target);
+                Files.copy(in, target, opts.replaceExistingOrEmpty());
             }
         }
 

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

@@ -891,6 +891,10 @@ void move(UnixPath source, UnixPath target, CopyOption... options)
         // get attributes of source file (don't follow links)
         try {
             sourceAttrs = UnixFileAttributes.get(source, false);
+            if (sourceAttrs.isDirectory()) {
+                // ensure source can be moved
+                access(source, W_OK);
+            }
         } catch (UnixException x) {
             x.rethrowAsIOException(source);
         }
@@ -910,10 +914,9 @@ void move(UnixPath source, UnixPath target, CopyOption... options)
         if (targetExists) {
             if (sourceAttrs.isSameFile(targetAttrs))
                 return;  // nothing to do as files are identical
-            if (!flags.replaceExisting) {
+            if (!flags.replaceExisting)
                 throw new FileAlreadyExistsException(
                     target.getPathForExceptionMessage());
-            }
 
             // attempt to delete target
             try {
@@ -1019,6 +1022,17 @@ void copy(final UnixPath source,
             sm.checkPermission(new LinkPermission("symbolic"));
         }
 
+        // ensure source can be copied
+        if (!sourceAttrs.isSymbolicLink() || flags.followLinks) {
+            try {
+                // the access(2) system call always follows links so it
+                // is suppressed if the source is an unfollowed link
+                access(source, R_OK);
+            } catch (UnixException exc) {
+                exc.rethrowAsIOException(source);
+            }
+        }
+
         // get attributes of target file (don't follow links)
         try {
             targetAttrs = UnixFileAttributes.get(target, false);
@@ -1037,6 +1051,7 @@ void copy(final UnixPath source,
             if (!flags.replaceExisting)
                 throw new FileAlreadyExistsException(
                     target.getPathForExceptionMessage());
+
             try {
                 if (targetAttrs.isDirectory()) {
                     rmdir(target);

src/java.base/unix/classes/sun/nio/fs/UnixFileSystemProvider.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
@@ -495,7 +495,7 @@ public void createSymbolicLink(Path obj1, Path obj2, FileAttribute<?>... attrs)
         if (attrs.length > 0) {
             UnixFileModeAttribute.toUnixMode(0, attrs);  // may throw NPE or UOE
             throw new UnsupportedOperationException("Initial file attributes" +
-                "not supported when creating symbolic link");
+                " not supported when creating symbolic link");
         }
 
         // permission check

test/jdk/java/nio/file/Files/CopyAndMove.java

@@ -22,7 +22,8 @@
  */
 
 /* @test
- * @bug 4313887 6838333 6917021 7006126 6950237 8006645 8201407 8264744 8267820
+ * @bug 4313887 6838333 6917021 7006126 6950237 8006645 8073061 8201407 8264744
+ *      8267820
  * @summary Unit test for java.nio.file.Files copy and move methods (use -Dseed=X to set PRNG seed)
  * @library .. /test/lib
  * @build jdk.test.lib.Platform jdk.test.lib.RandomFactory
@@ -35,8 +36,8 @@
 import java.nio.ByteBuffer;
 import java.nio.file.*;
 import static java.nio.file.Files.*;
-import static java.nio.file.StandardCopyOption.*;
 import static java.nio.file.LinkOption.*;
+import static java.nio.file.StandardCopyOption.*;
 import java.nio.file.attribute.*;
 import java.util.*;
 import java.util.concurrent.TimeUnit;
@@ -814,6 +815,25 @@ static void testCopyFileToFile(Path dir1, Path dir2, boolean supportsLinks)
         delete(target);
 
 
+        /**
+         * Test: ensure target not deleted if source permissions are zero
+         */
+        source = createSourceFile(dir1);
+        if (getFileStore(source).supportsFileAttributeView("posix")) {
+            Files.setPosixFilePermissions(source, Set.of());
+            target = getTargetFile(dir2);
+            createFile(target);
+            try {
+                Files.copy(source, target, REPLACE_EXISTING);
+                throw new RuntimeException("AccessDeniedException not thrown");
+            } catch (AccessDeniedException expected) {
+            }
+            if (!Files.exists(target))
+                throw new RuntimeException("target deleted");
+            delete(target);
+        }
+        delete(source);
+
         // -- directory --
 
         /*