RFR: 8364611: (process) Child process SIGPIPE signal disposition should be default [v4]

[Roger Riggs]

On Fri, 8 Aug 2025 05:25:02 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> A customer reported an error where a well-known system library, upon loading into the JVM process (via a longish indirect dependency chain), changed the signal disposition of the process for SIGPIPE to SIG_IGN. This gets inherited down to child processes, where it caused child processes to not react to SIGPIPE.
>> 
>> The system library is clearly at fault here, but the current workaround we recommend (pre-loading libjsig to interpose incorrect signal handling requests) is impractical for many customers. It is an okay solution when customers themselves have uncommon signal handling requirements; but for cases like these, where some version of system library does that, we should have a more pragmatic solution.
>> 
>> See further details and arguments for the fix in this mail thread: https://mail.openjdk.org/pipermail/core-libs-dev/2025-April/144077.html .
>> 
>> The behavior is changed changed such that we set SIGPIPE to SIG_DFL in the child processes, and a regression test is added. Note: Regression test deliberately prints outs details for other POSIX signals too; this can be both a good ad-hoc analysis tool as well as a point where we add more tests for other signals, should we ever need to. This patch, however, is deliberately restricted to just fixing SIGPIPE.
>
> Thomas Stuefe has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains seven commits:
> 
>  - merge
>  - fix comments about closeDescriptors
>  - Feedback Roger
>  - tolerate sigaction failing
>  - Fixes
>  - fix
>  - start+repro-case

Looks good, Thanks.

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Marked as reviewed by rriggs (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/26615#pullrequestreview-3101175850