[mgradwohl]

Description

Part of #2728: slice 3 of 3 for "processes hidden by hidepid (the helper lists them)", after #2972 (the parsing seam, protocol v6 and the helper reader). With this, the Processes table lists the processes hidepid hides from TaskSmack whenever a helper session is running.

• IProcessProbe::processFromFiles(pid, ProcFileTexts): a new optional virtual (default nullopt). ProcFileTexts moves to ProcessTypes.h, and LinuxProcessProbe's method from feat(linux): tasksmack-helper lists the processes hidepid hides, as a fixed set of their /proc files, for the probe's own parsers (#2728) #2972 becomes the override.

• BrokeredProcessProbe::enumerate() → listHiddenProcesses(): runs when the inner probe's capabilities().missingPrivileges has PROCESSES_HIDDEN and a helper is already running (callIfIdle, 1 s timeout; never prompts). It:

  • sends ListHiddenProcesses with the PIDs the probe saw;
  • builds each hidden process's record from its files' text;
  • keeps a record only when its start time matches the one the helper listed;
  • appends it before the counters read (feat(linux): tasksmack-helper reads other users' FD counts and I/O bytes for the Processes table (#2728) #2938, feat(linux): tasksmack-helper's socket inodes attribute other users' connections in the Processes table (#2728) #2947), which then fills its FD count, I/O and network like any refused process's.

  A helper that answers with an error isn't asked again. processFromFiles forwards to the inner probe.

• FAQ: the hidepid paragraph says the helper shows hidden processes while it runs, and which files it reads.

PR Size

✅ Small to medium (~170 lines, 9 files).

Type of Change

• New feature (non-breaking change that adds functionality)

Checklist

• I have read the CONTRIBUTING guidelines
• My code follows the project's coding standards
• I have run clang-tidy and addressed any warnings
• I have run clang-format on my changes
• I have run pre-commit run --all-files or installed pre-commit hooks
• I have added tests that prove my fix/feature works
• All new and existing tests pass
• I have updated documentation as needed

Testing

TASKSMACK_REQUIRE_DISPLAY=1 TASKSMACK_REQUIRE_SDBUS=1 xvfb-run -a env -u WAYLAND_DISPLAY ctest --preset debug -j 4   # 683/683

New tests, with a MockProcessProbe::setProcessFromFiles hook:

• BrokeredProcessProbeTest.ProcessesHidepidHidesAreListedByTheHelperAndJoinTheList:
  • the request carries the visible PIDs;
  • the hidden process joins the list;
  • a record whose start time changed is dropped;
  • the counters read covers the hidden process;
  • no call ever waits behind another.
• …NothingHiddenOrAHelperThatRefusesMeansNoListing: nothing is asked when nothing is hidden, and a helper that answers with an error is asked once.

Additional Notes

v0.10.0, no backport. The rest of #2728's Linux list is service actions through the helper. That needs a design call, because the helper's seccomp filter (#2752) forbids the new socket a D-Bus connection to systemd needs, so I'll raise it with the maintainer before writing code.

🤖 Generated with Claude Code

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

None