Why do we need LinkOption.NOFOLLOW_LINKS on the target file in CopyMoveHelper.copyToForeignTarget? (original) (raw)

Volker Simonis volker.simonis at gmail.com
Mon Dec 23 15:48:29 UTC 2013

Hi,

while running the jdk/jtreg tests for our ppc-aix-port I found a problem for the demo/zipfs/basic.sh test on AIX:

Exception in thread "main" java.io.IOException: NOFOLLOW_LINKS is not supported on this platform at sun.nio.fs.UnixPath.openForAttributeAccess(UnixPath.java:773) at sun.nio.fs.UnixFileAttributeViews$Basic.setTimes(UnixFileAttributeViews.java:74) at java.nio.file.CopyMoveHelper.copyToForeignTarget(CopyMoveHelper.java:135) at java.nio.file.CopyMoveHelper.moveToForeignTarget(CopyMoveHelper.java:157) at java.nio.file.Files.move(Files.java:1395) at ZipFSTester.test1(ZipFSTester.java:141) at ZipFSTester.main(ZipFSTester.java:50)

The test calls java.nio.file.Files.move() without any CopyOptions. Files.move() in turn calls java.nio.file.CopyMoveHelper.moveToForeignTarget() which adds the two CopyOptions LinkOption.NOFOLLOW_LINKS and StandardCopyOption.COPY_ATTRIBUTES before calling CopyMoveHelper.copyToForeignTarget().

CopyMoveHelper.copyToForeignTarget() finally checks that the source file is no symbolic link and performs the copy operation. In a last step it also copies the file attributes of the source file to the target file. For this operation it first calls Files.getFileAttributeView(target, BasicFileAttributeView.class, linkOptions) before the new attributes are set with sun.nio.fs.UnixFileAttributeViews$Basic.setTimes(). But operation will always fail on system like AIX which do not support NOFOLLOW_LINKS (or more exactly the O_NOFOLLOW flag to the open system call). See the stack trace above.

However, I don't think that we need to set the LinkOption.NOFOLLOW_LINKS option when calling Files.getFileAttributeView() on the target file, because the target file can not be a symbolic link anyway for two reasons: first of all, copyToForeignTarget() already checks that the source file is no symbolic link and it deletes 'target' it that should exist before.

So from my point of view it would be safe to change CopyMoveHelper.copyToForeignTarget() as follows to make it work an systems which don't support NOFOLLOW_LINKS:

--- a/src/share/classes/java/nio/file/CopyMoveHelper.java Fri Dec 20 17:52:39 2013 +0100 +++ b/src/share/classes/java/nio/file/CopyMoveHelper.java Mon Dec 23 16:33:43 2013 +0100 @@ -130,7 +130,7 @@ // copy basic attributes to target if (opts.copyAttributes) { BasicFileAttributeView view =

BasicFileAttributeView.class, linkOptions);

BasicFileAttributeView.class); try { view.setTimes(attrs.lastModifiedTime(), attrs.lastAccessTime(),

What do you think, did I miss something? If nobody objects, I'll put this small change in the next AIX bug fix collection.

Thank you and best regards, Volker

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