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8280357: user.home = "?" when running with systemd DynamicUser=true #7534

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RogerRiggs
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@RogerRiggs RogerRiggs commented Feb 18, 2022

In some Linux configurations, the Linux home directory provided by getpwent is not usable.
The value of the system property user.home should fallback to the value of $HOME
if getpwent.user_home is null or less that 2 characters long. "/" is not a valid home directory name.

If $HOME is undefined or empty, the value of the getpwent.user_home is retained.

There are more details in the Jira issue: https://bugs.openjdk.java.net/browse/JDK-8280357

The fix has been tested manually on Ubuntu 20.0.4 using the suggested systemd command line and variations.


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Issues

  • JDK-8280357: user.home = "?" when running with systemd DynamicUser=true
  • JDK-8282102: If the users home directory is invalid, system property user.home is set to $HOME (CSR)

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👋 Welcome back rriggs! 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 openjdk bot added the rfr Pull request is ready for review label Feb 18, 2022
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@RogerRiggs The following label will be automatically applied to this pull request:

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mlbridge bot commented Feb 18, 2022

Webrevs

@RogerRiggs
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/csr

@openjdk openjdk bot added the csr Pull request needs approved CSR before integration label Feb 18, 2022
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openjdk bot commented Feb 18, 2022

@RogerRiggs this pull request will not be integrated until the CSR request JDK-8282102 for issue JDK-8280357 has been approved.

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There is an argument that the JDK should read $HOME first but changing it after 20+ years could be risky, probably difficult to get a list of configurations/environments where the two might yield different locations. So I think the approach is reasonable. Even if "/" were a configured as the home directory in the user entry then $HOME would need to agree so that I think the <2 check is okay too.

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I'm uncertain whether the fallback should only be done on Linux to cover the systemd case and Docker.
The need for a fallback seems less applicable on macOs, but since $HOME is usually set to the same value, may be harmless.

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I'm uncertain whether the fallback should only be done on Linux to cover the systemd case and Docker.
The need for a fallback seems less applicable on macOs, but since $HOME is usually set to the same value, may be harmless.

I think what you have is okay because it is only used when getpwent doesn't return something useful. It would add complexity if you tried to limit it systemd or containers. I can't think of scenarios on macOS that might trigger the fallback, but it's not a bad fallback to have there too.

@openjdk openjdk bot removed the csr Pull request needs approved CSR before integration label Feb 23, 2022
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The CSR has been approved, please review the PR and the Release note: https://bugs.openjdk.java.net/browse/JDK-8282101

char* user_home = getenv("HOME");
if ((user_home != NULL) && (user_home[0] != '\0')) {
sprops.user_home = user_home;
}
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Is there any possibility where user.home is not initialized, and later causes SEGV or NPE? I just wonder the previous version always init to ? which is odd, but guaranteed not to cause those errors.

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I can't imagine it not being set. But it is easier to track down the source of a "?" than the source of null.
I thought of changing from "?" to "UNKNOWN" or "NOHOMEDIR" or something but it seems quite remote
after adding the fallback to $HOME.

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Another option is an empty string "", but I don't have a strong preference if it won't throw any errors.

char* user_home = getenv("HOME");
if ((user_home != NULL) && (user_home[0] != '\0')) {
sprops.user_home = user_home;
}
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Another option is an empty string "", but I don't have a strong preference if it won't throw any errors.

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openjdk bot commented Feb 23, 2022

@RogerRiggs 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:

8280357: user.home = "?" when running with systemd DynamicUser=true

Reviewed-by: naoto, 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 76 new commits pushed to the master branch:

  • 23995f8: 8281525: Enable Zc:strictStrings flag in Visual Studio build
  • 20e78f7: 8282307: Parallel: Incorrect discovery mode in PCReferenceProcessor
  • 0b6862e: 8282348: Remove unused CardTable::dirty_card_iterate
  • 6fab8a2: 8277204: Implement PAC-RET branch protection on Linux/AArch64
  • abc0ce1: 8282316: Operation before String case conversion
  • 0796620: 8281944: JavaDoc throws java.lang.IllegalStateException: ERRONEOUS
  • 231e48f: 8282200: ShouldNotReachHere() reached by AsyncGetCallTrace after JDK-8280422
  • f4486a1: 8262400: runtime/exceptionMsgs/AbstractMethodError/AbstractMethodErrorTest.java fails in test_ame5_compiled_vtable_stub with wrapper
  • 3cfffa4: 8282188: Unused static field MathContext.DEFAULT_DIGITS
  • 379fd85: 8277369: Strange behavior of JMenuBar with RIGHT_TO_LEFT orientation, arrow keys behaves opposite traversing through keyboard
  • ... and 66 more: https://git.openjdk.java.net/jdk/compare/d0e11808fd688d96e5cfeb586d1de277f26da5ad...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.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

@openjdk openjdk bot added the ready Pull request is ready to be integrated label Feb 23, 2022
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/integrate

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openjdk bot commented Feb 24, 2022

Going to push as commit bf19fc6.
Since your change was applied there have been 77 commits pushed to the master branch:

  • b6843a1: 8005885: enhance PrintCodeCache to print more data
  • 23995f8: 8281525: Enable Zc:strictStrings flag in Visual Studio build
  • 20e78f7: 8282307: Parallel: Incorrect discovery mode in PCReferenceProcessor
  • 0b6862e: 8282348: Remove unused CardTable::dirty_card_iterate
  • 6fab8a2: 8277204: Implement PAC-RET branch protection on Linux/AArch64
  • abc0ce1: 8282316: Operation before String case conversion
  • 0796620: 8281944: JavaDoc throws java.lang.IllegalStateException: ERRONEOUS
  • 231e48f: 8282200: ShouldNotReachHere() reached by AsyncGetCallTrace after JDK-8280422
  • f4486a1: 8262400: runtime/exceptionMsgs/AbstractMethodError/AbstractMethodErrorTest.java fails in test_ame5_compiled_vtable_stub with wrapper
  • 3cfffa4: 8282188: Unused static field MathContext.DEFAULT_DIGITS
  • ... and 67 more: https://git.openjdk.java.net/jdk/compare/d0e11808fd688d96e5cfeb586d1de277f26da5ad...master

Your commit was automatically rebased without conflicts.

@openjdk openjdk bot added the integrated Pull request has been integrated label Feb 24, 2022
@openjdk openjdk bot closed this Feb 24, 2022
@openjdk openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Feb 24, 2022
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openjdk bot commented Feb 24, 2022

@RogerRiggs Pushed as commit bf19fc6.

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

@RogerRiggs RogerRiggs deleted the 8280357-user-home branch June 10, 2022 20:41
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