userland: 268 applets, an editor, names that resolve, and a web server

Four complaints, and only one of them was the thing it looked like.

**"toybox is too small."** Half true, and the fix cost no licensing at all:
236 of toybox's applets are what defconfig builds, and the rest live in
toys/pending/ -- awk, bc, diff, more, expr, tr, hexdump, stty among them. Same
0BSD tarball, switched off by a config default. 26 of them are on now, 236 ->
268. Not everything: strace wants ptrace, syslogd wants BSD's facilitynames[],
git wants OpenSSL, and those three break the link.

The toybox build also works again on this machine. Its scripts start
#!/bin/bash, which does not exist on NixOS, so the binary in the tree was one
nobody could reproduce; the shebangs are rewritten to /usr/bin/env bash on the
way in. Pending applets are enabled by editing .config directly, because
`make oldconfig` is the obvious way and undoes it -- every pending symbol is
`default n`.

**BusyBox was asked for and is not here.** It is GPL-2.0-only, and `make
ramroot` links the root image *into the kernel binary*, so it would put GPLv2
inside an Apache-2.0 executable -- which is the exact case ports/Makefile's
NOTPORTS filter and docs/licensing.md §4 exist for. nano is the same answer one
version later. Both recorded in licensing.md with what was done instead, since
"no" without an alternative is how a rule gets quietly broken later.

**An editor that is not vi.** kilo, BSD-2-Clause, one 1300-line file, no
dependencies beyond termios and TIOCGWINSZ, both of which zsh already needed.
Installed as /bin/edit as well as /bin/kilo, because somebody with a file to
fix will type `edit`.

**"wget doesn't work."** Not a userland problem, and BusyBox's wget would have
failed identically: nothing on this system could turn a name into an address,
so every program taking a hostname failed in its own way and each looked like
a separate bug. There is still no DNS client in SchOS and there does not need
to be -- musl has a complete resolver and it works over ordinary UDP sockets.
The one missing fact was which nameserver, which the kernel has had all along
from DHCP and never published. /proc/resolv.conf publishes it in resolv.conf's
exact syntax; cmd/resolvconf decides whether it becomes /etc/resolv.conf, and
will not overwrite a hand-written one without -f.

  # wget -O - http://example.com/ | head -1
  <!doctype html><html lang="en"><head><title>Example Domain</title>

**Something to host with.** cmd/httpd: GET and HEAD, static files, index.html
for a directory and a listing otherwise, a child per connection. No CGI, no
keep-alive, no TLS, no config file. The path check is the only
security-relevant code in it and it refuses rather than normalises -- no
component may be `..`, and percent-decoding happens first, because %2e%2e is
`..` and a check before decoding does not see it. Both forms answer 403.

And the disk is 100 MB, from 32. It is sparse, so the image is 21 MB on the
host. RAMDISK_BLOCKS went 6000 -> 8000 with it: the ramdisk was at 86% and the
next thing added would have broken `make ramroot`, which nobody would have
noticed until they used it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VQ7Qx8E1q1M1bbCq8QLHS2

ports/Makefile

@@ -5,6 +5,7 @@
 #   ports/musl/    libc — installs headers/libs to build/ports/musl/prefix
 #   ports/mksh/    MirBSD Korn Shell — installed as sysroot/bin/sh
 #   ports/toybox/  core utilities — installed as sysroot/bin/<applet>
+#   ports/kilo/    the text editor — installed as sysroot/bin/{kilo,edit}
 #   ports/ncurses/ terminfo + screen library — link-time only, ships nothing
 #   ports/zsh/     the Z shell — installed as sysroot/bin/zsh, beside /bin/sh
 #
@@ -28,6 +29,7 @@ all: $(PORTS)
 
 mksh:      musl
 toybox:    musl
+kilo:      musl
 fastfetch: musl
 ncurses:   musl
 zsh:       musl ncurses

ports/kilo/Makefile

@@ -0,0 +1,84 @@
+# SPDX-License-Identifier: Apache-2.0
+# kilo — BSD-2-Clause: https://github.com/antirez/kilo
+#
+# SchOS's text editor, installed as sysroot/bin/kilo with `edit` beside it.
+#
+# It is here because the alternative every small system reaches for is vi, and
+# vi is a program you have to be taught before you can use it to fix the file
+# that is stopping the machine booting. kilo is the other kind: the arrow keys
+# move the cursor, typing inserts, Ctrl-S saves, Ctrl-Q quits, Ctrl-F finds,
+# and the bottom line says so while you work. Nobody has to be told any of it.
+#
+# The whole editor is one 1,300-line C file with no dependencies beyond libc --
+# termios and TIOCGWINSZ, both of which SchOS already has because zsh needs
+# them. That is the entire reason it was chosen over nano: nano is GPLv3 and
+# wants ncurses at runtime, and GPLv3 cannot be combined with Apache-2.0 any
+# more than GPLv2 can. See ../../docs/licensing.md.
+#
+# What it does not do: no undo, no multiple buffers, no configuration, no
+# mouse, no UTF-8 beyond passing bytes through. It edits one file.
+
+include ../mk/port.mk
+
+# Pinned to a commit rather than a release, because kilo has never had one --
+# it was written as the worked example for a tutorial and has been finished
+# ever since. A commit is at least an exact thing to name.
+#
+# The checksum is of GitHub's generated archive. Those are reproducible for a
+# given commit, but they are generated rather than uploaded, so if this ever
+# fails to verify check that upstream still has the commit before assuming the
+# tarball was tampered with.
+KILO_COMMIT  := 323d93b29bd89a2cb446de90c4ed4fea1764176e
+KILO_URL     := https://github.com/antirez/kilo/archive/$(KILO_COMMIT).tar.gz
+KILO_SHA256  := 79e62c23fdf369fa0cbbeaab9fd8ae2848dcc0156faf6efc89ea274528b39723
+
+TARBALL := $(DISTDIR)/kilo-$(KILO_COMMIT).tar.gz
+
+CFLAGS  := -static -Os -D__SCHOS__ -I$(MUSL)/include $(CFLAGS_BT) \
+           -D_BSD_SOURCE -std=c99 -Wall
+LDFLAGS := -static -L$(MUSL)/lib -lc
+
+$(TARBALL): | $(DISTDIR)
+	curl -fsSL -o $@ $(KILO_URL)
+	sh $(SHA256CHECK) "$(KILO_SHA256)" "$@"
+
+download: $(TARBALL)
+
+$(SRCDIR): $(TARBALL)
+	mkdir -p $(PORTDIR)
+	rm -rf $(PORTDIR)/kilo-$(KILO_COMMIT)
+	tar -xzf $< -C $(PORTDIR)
+	mv $(PORTDIR)/kilo-$(KILO_COMMIT) $@
+
+# One file, so its own Makefile is not worth invoking -- it hardcodes flags
+# that assume a hosted glibc and would link against the build host's libc.
+$(BUILDDIR)/kilo: | $(SRCDIR)
+	mkdir -p $(BUILDDIR)
+	$(CC) $(CFLAGS) -o $@ $(SRCDIR)/kilo.c $(LDFLAGS)
+
+build: $(BUILDDIR)/kilo
+
+# `edit` as well as `kilo`.
+#
+# Two real copies rather than a link, for the reason ports/toybox/Makefile
+# gives at length: mkschfs deduplicates by content, so the image holds one copy
+# with two names either way, and this needs nothing from the host filesystem.
+#
+# The second name is not decoration. Somebody who has just arrived at a SchOS
+# prompt with a file to fix will type `edit`; they will not guess `kilo`.
+$(PORTDIR)/.installed: $(BUILDDIR)/kilo | $(SYSROOT)/bin
+	cp $(BUILDDIR)/kilo $(SYSROOT)/bin/kilo
+	cp $(BUILDDIR)/kilo $(SYSROOT)/bin/edit
+	chmod 755 $(SYSROOT)/bin/kilo $(SYSROOT)/bin/edit
+	@mkdir -p $(SYSROOT)/usr/share/licenses/kilo
+	cp $(SRCDIR)/LICENSE $(SYSROOT)/usr/share/licenses/kilo/LICENSE
+	@touch $@
+	@echo "kilo: installed as /bin/kilo and /bin/edit"
+
+install: $(PORTDIR)/.installed
+
+clean:
+	rm -rf $(BUILDDIR) $(PORTDIR)/.installed
+
+distclean: clean
+	rm -rf $(PORTDIR)

ports/toybox/Makefile

@@ -47,17 +47,63 @@ $(SRCDIR): $(TARBALL)
 	tar -xzf $< -C $(PORTDIR)
 	mv $(PORTDIR)/toybox-$(TOYBOX_VERSION) $@
 
+# Applets toybox has written but leaves out of defconfig.
+#
+# `defconfig` builds the 236 applets upstream considers finished. The other
+# ~50 live in toys/pending/ -- complete enough to use, not yet held to toybox's
+# standard for a release -- and among them are **awk**, **bc** and **diff**,
+# which is a large part of why the shipped userland felt thin. They are the
+# same 0BSD code from the same tarball; the only thing standing between them
+# and the image was a config default.
+#
+# This list is curated rather than "enable everything", because everything does
+# not build: `strace` wants xfork and ptrace, `syslogd` wants BSD's
+# facilitynames[], and `git` wants OpenSSL. Those three break the link, so they
+# are not here. If one of them ever matters, it goes in with the patch it needs
+# rather than by widening a wildcard.
+#
+# `vi` is in pending too and is deliberately **not** on this list. SchOS ships
+# an editor you do not have to be taught -- see ports/kilo.
+TOYBOX_PENDING = \
+	AWK BC DIFF MORE EXPR TR HEXDUMP STTY XZCAT CSPLIT \
+	LSOF MAN LAST FDISK CHSH GETTY \
+	TELNET TRACEROUTE ARP ARPING ROUTE \
+	IPCS IPCRM USERADD USERDEL GROUPADD GROUPDEL
+
 # toybox has no out-of-tree build mode, so its source is copied into $(BUILDDIR)
 # and built in place. $(SRCDIR) is an order-only prerequisite (|): the extracted
 # tarball never changes, and depending on it normally made a directory mtime
 # trigger a rebuild. The rebuild then failed anyway, because `cp -r` over a
 # populated $(BUILDDIR) hits "File exists" on kconfig's symlinks — so wipe it
 # first and always build from a clean copy.
+#
+# Two things happen to the copy before it is built.
+#
+# **The shebangs are rewritten.** toybox's build scripts start `#!/bin/bash`,
+# and on a distribution that does not keep bash at that path -- NixOS, and any
+# other that takes the FHS as a suggestion -- the build fails at the first
+# script with ENOENT. bash is installed and on PATH; it is only the absolute
+# path that is wrong, so `/usr/bin/env bash` fixes it everywhere without
+# needing bash to move. This is not a nicety: without it toybox could not be
+# rebuilt on this machine at all, and the binary in the tree was one nobody
+# could reproduce.
+#
+# **Then the pending applets are switched on**, by editing .config directly.
+# Not via `make oldconfig`, which is the obvious way and does not work: every
+# pending symbol is `default n`, so oldconfig dutifully turns all of them back
+# off again. generated/ is removed so the edit is actually noticed -- toybox
+# caches the expanded config there and will otherwise link the previous set and
+# report success.
 $(BUILDDIR)/toybox: | $(SRCDIR)
 	rm -rf $(BUILDDIR)
 	mkdir -p $(BUILDDIR)
 	cp -r $(SRCDIR)/. $(BUILDDIR)/
+	sed -i '1s|^\#!/bin/bash$$|\#!/usr/bin/env bash|' $(BUILDDIR)/scripts/*.sh
 	$(MAKE) -C $(BUILDDIR) defconfig
+	for c in $(TOYBOX_PENDING); do \
+	    sed -i "s/^\# CONFIG_$$c is not set$$/CONFIG_$$c=y/" $(BUILDDIR)/.config; \
+	done
+	rm -rf $(BUILDDIR)/generated
 	$(MAKE) -C $(BUILDDIR) CC="$(CC)" CFLAGS="$(CFLAGS)" LDFLAGS="$(LDFLAGS)"
 
 # Install every applet the binary provides, one name per applet.