platform vtable

Platform vtable

Summary: platform_ops_t in include/sloth.h is the seam between kernel-facing code and the rest of sloth. Views never call platform ops directly; they read sloth_state_t. The test suite swaps the vtable for tests/fake_platform.c.

Sources: CLAUDE.md, docs/views/connections.md, docs/views/interfaces.md (referenced).

Last updated: 2026-05-25.

---

Why the seam matters

• Lets the test suite drive views with deterministic kernel-state fixtures (no rtnetlink chatter, no /proc reads).
• Keeps Linux-specific code (rtnetlink, nl80211, INET_DIAG, /proc/net/*) confined to src/platform/linux*.c.
• Makes per-view code portable: a view that only touches sloth_state_t doesn't care whether the data came from netlink or a fake.

What lives behind it

• rtnetlink — interface enumeration, MAC, MTU, link state.
• nl80211 — WiFi station info, RSSI, channel.
• /proc/net/{tcp,tcp6,udp,udp6} — socket table.
• /proc/<pid>/fd/* — inode → PID mapping (so connections can show process names).
• INET_DIAG netlink — per-socket RTT and retransmits.
• sysfs — interface counters used by the bandwidth smoother.

Discipline

• Views never call platform ops directly. They read sloth_state_t.
• No mocks of real-data interfaces. The fake platform in tests/fake_platform.c lives there so the seam stays narrow.
• Errors at boundaries only (user input, syscalls, parsing). Trust internal code beyond the platform layer.

Related pages

• architecture
• sloth
• views-catalog