systemd: fix SystemdMeter parsing when falling back to systemctl show

[dengzhongyuan365-dev]

Summary

• Fix SystemdMeter displaying (?/? failed) (?/? jobs) when htop falls back to systemctl show for parsing systemd state

Root Cause

fgets() preserves trailing newlines in the buffer, so strtoul() leaves endptr pointing to '\n' instead of '\0'. The validation check *endptr == '\0' fails, causing all numeric fields to remain at INVALID_VALUE.

This only affects the systemctl show fallback path (used when sd_bus_open_user fails, e.g. under file capabilities). The sd_bus path is unaffected.

Note: SystemState= was already handled correctly — it explicitly strips the newline with strchr(lineBuffer, '\n').

Changes

File	Change
linux/SystemdMeter.c	Accept '\n' as valid end-of-value terminator in addition to '\0' (4 occurrences)

Test Plan

• Build passes with --enable-werror
• Verify on a system where sd_bus_open_user fails (e.g. Gentoo with filecaps), or test by temporarily forcing updateViaExec path

Fixes #1982

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: a7a00462-a0ef-44d6-87d3-967306ec6697

📥 Commits

Reviewing files that changed from the base of the PR and between 1ef4226 and 5839bca.

📒 Files selected for processing (1)

• linux/SystemdMeter.c

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📝 Walkthrough

Walkthrough

Changes

This change adjusts numeric parsing validation in updateViaExec within SystemdMeter.c. After calling strtoul on values for NFailedUnits, NNames, and NJobs, the code now accepts a result whose endptr points to either a newline character or the string terminator, rather than requiring only the null terminator. The UINT_MAX range check and assignment logic are unchanged.

Assessment against linked issues

Objective	Addressed	Explanation
Fix SystemdMeter showing "(?/? failed) (?/? jobs)" for user instances (#1982)	✅

Assessment against linked issues: Out-of-scope changes

No out-of-scope changes found.

Poem

A newline snuck in, systemctl's small quirk,
The parser once choked, refusing to work.
Now \n or \0, both welcomed with grace,
The failed units count back in their place. 🐰

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