8263898: (fs) Files.newOutputStream on the "NUL" special device throws FileSystemException: "nul: Incorrect function" (win) #3183

bplb · 2021-03-24T23:45:16Z

This request proposes to change the native method WindowsNativeDispatcher.SetEndOfFile() to succeed even if the Windows function SetEndOfFile() returns zero if GetFileSizeEx() called on the handle succeeds and reveals a file size of zero.

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Issue

JDK-8263898: (fs) Files.newOutputStream on the "NUL" special device throws FileSystemException: "nul: Incorrect function" (win)

Reviewers

Jaikiran Pai (@jaikiran - Committer) ⚠️ Review applies to 8389cda
Alan Bateman (@AlanBateman - Reviewer)

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Update a local copy of the PR:
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…s FileSystemException: "nul: Incorrect function" (win)

bridgekeeper · 2021-03-24T23:45:41Z

👋 Welcome back bpb! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

openjdk · 2021-03-24T23:46:54Z

@bplb The following label will be automatically applied to this pull request:

nio

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mlbridge · 2021-03-24T23:49:55Z

Webrevs

AlanBateman · 2021-03-25T07:35:11Z

src/java.base/windows/native/libnio/fs/WindowsNativeDispatcher.c

+        } else if (size.QuadPart != 0) {
+            throwWindowsException(env, error);
+        }
+    }
 }


The native methods are meant to map to one win32 call where possible. In this case, I think the workaround needs to be in WindowsChannelFile.open.

I know. I tried at the Java level first and one cannot verify the size of the NUL device from Java.

it's okay to add a new method to WindowsNativeDispatcher if we need it.

Added GetFileSizeEx().

jaikiran · 2021-03-25T08:03:02Z

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

+ * @summary Verify a byte can be written to the null device.
+ * @run main NullDevice
+*/
+public class NullDevice {


Hello Brian,

Given what's being tested here, perhaps this test should only be run against Windows OS? So maybe something like @requires os.family=="windows"?

You are correct, I intended to but forgot to add that.

Added suggested @requires.

jaikiran

The test case (changes) looks fine to me. Thank you Brian.

AlanBateman · 2021-03-26T07:03:51Z

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

+            System.out.printf("Wrote a byte to %s%n", f);
+        }
+    }
+}


The updated changes to the Windows file system provider looks good. Have you checked that WindowsNativeDispatcher.GetFileSizeEx returns the correct size for a non-zero length file? (asking about that because it won't be exercised by the any of the tests and we might want to use it in order places).

The test name is "NullDevice" but it actually tests "nul" :-) so maybe it should be renamed. Files.newOutputStream is just one way to open the NUL device for writing. Would be good to also test opening it for wring without the TRUNCATE_EXISTING operation. I think we should do reading while we are there.
You can use Path.of("nul") to avoid first creating a java.io.File and using toPath.

I don't have the length check in public code. I'll see how it is possible. I'll translate "null" into French and look at the reading and writing cases. I should have thought to use Path.of() especially given that I wrote it (JDK-8194746).

bplb · 2021-03-26T16:04:11Z

The test case (changes) looks fine to me. Thank you Brian.

Thanks

AlanBateman

The change looks okay.

The test looks okay although there other cases that probably should be added at some point, in particular, FileChannel.open for reading, and AsynchronousFileChannel read & write.

AlanBateman · 2021-03-27T15:51:00Z

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

+*/
+public class NulDevice {
+    public static void main(final String[] args) throws IOException {
+        System.getProperties().list(System.out);


Is the printing of the system properties a left-over?

openjdk · 2021-03-27T15:56:07Z

@bplb This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8263898: (fs) Files.newOutputStream on the "NUL" special device throws FileSystemException: "nul: Incorrect function" (win)

Reviewed-by: jpai, alanb

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 183 new commits pushed to the master branch:

21e7402: 8263707: C1 RangeCheckEliminator support constant array and NewMultiArray
2ad6f2d: 8263896: Make not_suspended parameter from ObjectMonitor::exit() have default value
b652198: 8264429: Test runtime/cds/appcds/VerifyWithDefaultArchive.java assumes OpenJDK build
2c9365d: 8264271: Avoid creating non_oop_word oops
daeca3f: 8262958: (fs) UnixUserDefinedFileAttributeView cleanup
af02883: 8264191: Javadoc search is broken in Internet Explorer
6e74c3a: 8264193: Remove TRAPS parameters for modules and defaultmethods
ee5e00b: 8264279: Shenandoah: Missing handshake after JDK-8263427
ac604a1: 8264374: Shenandoah: Remove leftover parallel reference processing argument
f3726a8: 8264020: Optimize double negation elimination
... and 173 more: https://git.openjdk.java.net/jdk/compare/6aa28b3bdb78eb041a963d659d61e1622bc43ef8...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

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

+        try (final OutputStream os = Files.newOutputStream(path)) {
+            os.write(0x02);
+            System.out.printf("Wrote a byte to %s%n", path);
+            try (InputStream is = Files.newInputStream(path);) {


mlbridge · 2021-03-29T18:21:24Z

Mailing list message from Brian Burkhalter on nio-dev:

On Mar 27, 2021, at 8:57 AM, Alan Bateman <alanb at openjdk.java.net<mailto:alanb at openjdk.java.net>> wrote:

8263898: Fix accidentally reverted copyright year

The change looks okay.

The test looks okay although there other cases that probably should be added at some point, in particular, FileChannel.open for reading, and AsynchronousFileChannel read & write.

Added.

test/jdk/java/nio/file/Files/NulDevice.java line 41:

39: public class NulDevice {
40: public static void main(final String[] args) throws IOException {
41: System.getProperties().list(System.out);

Is the printing of the system properties a left-over?

Yes, it is vestigial; removed.

On Mar 28, 2021, at 8:24 AM, Alan Bateman <alanb at openjdk.java.net<mailto:alanb at openjdk.java.net>> wrote:

test/jdk/java/nio/file/Files/NulDevice.java line 47:

45: os.write(0x02);
46: System.out.printf("Wrote a byte to %s%n", path);
47: try (InputStream is = Files.newInputStream(path);) {

One other test that you could add here is to test that available() returns 0. I've no doubt there are many file operations that will behavior in surprising ways when using the special "NUL" device if the common operations work in unsurprising ways then it would help.

Added.
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AlanBateman · 2021-03-30T07:12:35Z

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

+        }
+
+        try (final FileChannel ch = FileChannel.open(path, CREATE,
+             TRUNCATE_EXISTING, WRITE)) {


Did you mean to put a line break here? Same at L87. Asking because it would be easier to read if the open options were on the same line. If line length is the concern then you could drop the spurious "final" modifier.

bplb · 2021-03-30T18:17:47Z

/integrate

openjdk · 2021-03-30T18:19:14Z

@bplb Since your change was applied there have been 185 commits pushed to the master branch:

2bd80f9: 8264326: Modernize javax.script.ScriptEngineManager and related classes' implementation
b08d638: 8262503: Support records in Dynalink
21e7402: 8263707: C1 RangeCheckEliminator support constant array and NewMultiArray
2ad6f2d: 8263896: Make not_suspended parameter from ObjectMonitor::exit() have default value
b652198: 8264429: Test runtime/cds/appcds/VerifyWithDefaultArchive.java assumes OpenJDK build
2c9365d: 8264271: Avoid creating non_oop_word oops
daeca3f: 8262958: (fs) UnixUserDefinedFileAttributeView cleanup
af02883: 8264191: Javadoc search is broken in Internet Explorer
6e74c3a: 8264193: Remove TRAPS parameters for modules and defaultmethods
ee5e00b: 8264279: Shenandoah: Missing handshake after JDK-8263427
... and 175 more: https://git.openjdk.java.net/jdk/compare/6aa28b3bdb78eb041a963d659d61e1622bc43ef8...master

Your commit was automatically rebased without conflicts.

Pushed as commit 353807c.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

8263898: (fs) Files.newOutputStream on the "NUL" special device throw…

3414615

…s FileSystemException: "nul: Incorrect function" (win)

openjdk bot added the rfr Pull request is ready for review label Mar 24, 2021

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AlanBateman reviewed Mar 25, 2021

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Add GetFileSizeEx()

6a290df

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Remove whitespace

8389cda

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jaikiran approved these changes Mar 26, 2021

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bplb added 2 commits March 26, 2021 11:54

Rename test to NulDevice and improve

079b785

8263898: Fix accidentally reverted copyright year

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

try (final OutputStream os = Files.newOutputStream(path)) {

os.write(0x02);

System.out.printf("Wrote a byte to %s%n", path);

try (InputStream is = Files.newInputStream(path);) {

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8263898: Improve and clean up test

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AlanBateman approved these changes Mar 30, 2021

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bplb added 2 commits March 30, 2021 09:11

8263898: Remove final and link break

71f3d34

8263898: Fix one more line break

b6a5155

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openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Mar 30, 2021

bplb deleted the WindowsNullDevice-8263898 branch March 31, 2021 15:56

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8263898: (fs) Files.newOutputStream on the "NUL" special device throws FileSystemException: "nul: Incorrect function" (win) #3183

8263898: (fs) Files.newOutputStream on the "NUL" special device throws FileSystemException: "nul: Incorrect function" (win) #3183

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8263898: (fs) Files.newOutputStream on the "NUL" special device throws FileSystemException: "nul: Incorrect function" (win) #3183

8263898: (fs) Files.newOutputStream on the "NUL" special device throws FileSystemException: "nul: Incorrect function" (win) #3183

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