63 lines
3.1 KiB
Markdown
63 lines
3.1 KiB
Markdown
---
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name: schos-schinit
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description: "schinit is process 1, launchd-shaped; job manifests, the ControllingTerminal trap, and what milestones 2 and 3 are"
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metadata:
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node_type: memory
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type: project
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originSessionId: 9d8a2aef-bcf0-47a0-96c6-f706efab4a95
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modified: 2026-08-09T14:36:32.587Z
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---
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**`cmd/schinit/` is process 1**, chosen by Nexoniarz to be "close to Apple's
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launchd, the king of inits". `lib/initcode.S` execs `/bin/schinit`. The old
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`cmd/init` is still in the tree but nothing runs it.
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**Milestone 1 (done, 2026-08-09):** manifests, `RunAtLoad`, `KeepAlive` with
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`ThrottleInterval`, reaping, `ControllingTerminal`.
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**Milestone 2:** socket activation — schinit holds the listener and starts the
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job on first connect. `[Socket name]` / `Path` is already parsed and stored in
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`job.sock_path`, so manifests do not have to change.
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**Milestone 3:** `schinitctl` (list/start/stop/reload), `WatchPaths`, per-user
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agents.
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**The format is sectioned `key = value`**, not plists. Decided deliberately:
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the roadmap's own words are that "the point of copying launchd rather than
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sysvinit is not the config format, it is *demand launching*". Keys keep
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launchd's names so the model transfers. Files live in `etc/schinit/*.job` in the
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repo and are installed to `/etc/schinit/` by the `etc-install` target — **not
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written straight into `sysroot/`, which is gitignored**; that is why a fresh
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clone has no `/etc/passwd` or `/etc/motd` (still an open gap).
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**No libc in `cmd/`.** These programs link `lib/` — raw syscall stubs. No
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malloc, no printf, no strlen. Static storage and hand-rolled helpers only.
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**`getdents64` was exposed for this.** The kernel has had syscall 96/217 since
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the Linux ABI landed, but nothing declared it in `include/user.h` or
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`lib/usys.S`, so first-party programs could not list a directory at all. Step
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records by `d_reclen`, never `sizeof`.
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## The trap worth remembering: setsid() costs you the terminal
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`setsid()` puts a job in its own session, and **a new session has no controlling
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terminal**. The console delivers input only to the foreground process group it
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tracks (`tty_fg_pgrp`), so the shell started, echoed every keystroke through the
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line discipline, and executed nothing. It looks exactly like a hung shell and is
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really a terminal that is not listening to it. See
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[[schunix-tty-fg-pgrp-coupling]].
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`ControllingTerminal = yes` claims it in the child: `ioctl(0, TIOCSCTTY, 0)`
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then `ioctl(0, TIOCSPGRP, &pg)` where `pg = getpid()` (after `setsid()`, pgid ==
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pid). **Off by default** — a daemon has no business seizing the console.
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`TIOCSCTTY` is currently a no-op in the kernel; `TIOCSPGRP` does the real work.
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## Do not transcribe bootstrap() from memory
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The first version dropped `/dev/input/event0-1` and most of `/proc`, because it
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was copied from the part of the old `cmd/init/main.c` that had been read on
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screen rather than all 124 lines. `-Evdev` caught it with
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`inputtest: cannot open /dev/input/event0`. **Read the whole file before
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replacing it.**
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Also: `build/usbstick.img` must be built by `all`. Without it QEMU refuses the
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`-drive` and the entire `-Usb` run produces no output — which reads as a broken
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USB driver, not a missing file.
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