kernel: processes have an environment now, and zsh is the shell

Porting zsh found four defects in the kernel and one in the filesystem. None
of them were about zsh; all of them had been there the whole time.

**exec threw the environment away.** kernel/fs/exec.c wrote a single zero for
envp with the comment "(no environment)" -- not yet, but ever, for every
process. musl has been passing a perfectly good envp to execve (Linux 59, which
SchOS answers) and it was never read. So $TERM was unset, $PATH was whatever
each program invented, and a variable exported in a shell did not survive the
exec meant to carry it. exec() takes an envp, sys_exec reads argument three,
and schinit manifests grew an Environment key. The userland two-argument
exec(path, argv) stays as a wrapper that passes null explicitly -- the raw stub
is execve now, so a short caller cannot leave %rdx holding a stray pointer.

**Which overflowed the kernel stack.** Three pointer arrays, ~1.8 KB, on a
4096-byte stack, under exec -> loaduvm -> readi -> SchFS -> btree. Pid 1 went
down on the first exec. The canary caught it and named the process, which is
what it is for. They live in one kalloc'd page now.

**waitpid returned a bare -1** for both "no children" and "interrupted". musl
reads [-4095,-1] as -errno, so userspace saw EPERM; zsh printed "wait failed:
operation not permitted" and abandoned the rest of /etc/zsh/zshrc. -ECHILD and
-EINTR now. Third time a bare -1 has cost real time -- on a system with no
permission model, EPERM should be read as "a syscall returned -1".

**NVMA was 64.** musl's allocator takes a mapping per size class and does not
release them eagerly, so compinit ran out of slots and got -1, which is EPERM,
which malloc turns into NULL, which zsh reports as "fatal error: out of memory"
-- on a machine with 1000 MB free. 256 slots, and -ENOMEM.

**And a small write to SchFS costs 58 ms.** 200 writes to one open file take
11.75 s; the same to /dev/null take 0.14 s. That is the design stated at the
top of kmount.c -- one transaction group per operation, and a commit is two
flushes and an uberblock -- not a bug. But compdump writes its digest with
thousands of separate prints, so it takes minutes and looks like a hang.
compinit -D, which skips the dump, finishes in 3.6 s. This one is a decision
rather than a fix, so it is written up and left: /etc/zsh/zshrc keeps compinit
switched off and explains exactly why, with the measurements.

zsh runs as /bin/zsh and is the console shell. ZLE works -- arrow keys recall
history through terminfo, $COLUMNS reads the real 160 because TIOCGWINSZ was
fixed, colour and prompt expansion work, startup is 0.14 s. mksh keeps /bin/sh,
so schinit's no-jobs fallback is a different program from the one that could
have failed.

Also fixed while here: AT_CLKTCK was the literal 100 and is USER_HZ; the
extract rule in four ports could move a source tree inside itself when make
re-ran it, which is how zsh's configure came to write modfile=zsh-5.9/... into
config.modules and fail three steps later.

schfs-check passes. Full writeup in docs/history/kernel.md section 14.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VQ7Qx8E1q1M1bbCq8QLHS2
This commit is contained in:
Nexoniarz 2026-09-12 23:26:50 +02:00
commit 14f0e4d0e2
22 changed files with 684 additions and 24 deletions

View file

@ -6,6 +6,7 @@
# ports/mksh/ MirBSD Korn Shell — installed as sysroot/bin/sh
# ports/toybox/ core utilities — installed as sysroot/bin/<applet>
# ports/ncurses/ terminfo + screen library — link-time only, ships nothing
# ports/zsh/ the Z shell — installed as sysroot/bin/zsh, beside /bin/sh
#
# A port directory holds only a Makefile and optional patches/. Everything
# generated lives in build/ports/<name>/ — see mk/port.mk for the contract.
@ -29,6 +30,7 @@ mksh: musl
toybox: musl
fastfetch: musl
ncurses: musl
zsh: musl ncurses
$(PORTS):
$(MAKE) -C $@

View file

@ -53,8 +53,10 @@ download: $(TARBALL)
$(SRCDIR): $(TARBALL)
mkdir -p $(PORTDIR)
rm -rf $@ $(PORTDIR)/fastfetch-$(FF_VERSION)
tar -xzf $< -C $(PORTDIR)
mv $(PORTDIR)/fastfetch-$(FF_VERSION) $@
touch $@
extract: $(SRCDIR)

View file

@ -20,8 +20,10 @@ download: $(TARBALL)
$(SRCDIR): $(TARBALL)
mkdir -p $(PORTDIR)
rm -rf $@ $(PORTDIR)/mksh
tar -xzf $< -C $(PORTDIR)
mv $(PORTDIR)/mksh $@
touch $@
# Order-only (|) on $(SRCDIR): the extracted tarball never changes, so a
# directory mtime should not trigger a rebuild of an already-built shell.

View file

@ -82,8 +82,10 @@ download: $(TARBALL)
$(SRCDIR): $(TARBALL)
mkdir -p $(PORTDIR)
rm -rf $@ $(PORTDIR)/ncurses-$(NC_VERSION)
tar -xzf $< -C $(PORTDIR)
mv $(PORTDIR)/ncurses-$(NC_VERSION) $@
touch $@
extract: $(SRCDIR)
@ -106,7 +108,18 @@ $(PREFIX)/lib/libncursesw.a: $(BUILDDIR)/config.status
$(MAKE) -C $(BUILDDIR)
$(MAKE) -C $(BUILDDIR) install
build install: $(PREFIX)/lib/libncursesw.a
build: $(PREFIX)/lib/libncursesw.a
# The acceptance test. It is the one thing this port puts in sysroot/, and it
# earns the space: the build proving the library compiles says nothing about
# whether terminfo works on a SchOS console, which is a different question
# with a different answer. sysroot/bin already carries socktest, nettest and
# shmtest for the same reason.
$(SYSROOT)/bin/tinfotest: tinfotest.c $(PREFIX)/lib/libncursesw.a | $(SYSROOT)/bin
$(HOSTCC_NC) $(NC_CPPFLAGS) -isystem $(PREFIX)/include $(NC_CFLAGS) $(NC_LDFLAGS) -L$(PREFIX)/lib -o $@ $< -lncursesw $(NC_LIBS)
chmod 755 $@
install: $(PREFIX)/lib/libncursesw.a $(SYSROOT)/bin/tinfotest
clean:
rm -rf $(PORTDIR)

209
ports/zsh/Makefile Normal file
View file

@ -0,0 +1,209 @@
# SPDX-License-Identifier: Apache-2.0
# zsh -- the Z shell, MIT-like: https://www.zsh.org/
#
# Installed as /bin/zsh, *beside* mksh, which keeps /bin/sh.
#
# That is deliberate and it is not about taste. schinit's no-jobs fallback
# execs /bin/sh. If zsh were /bin/sh and zsh failed to start, the fallback
# would be the same broken binary and the machine would have no shell at all.
# Two different programs means the recovery path is a different program.
# It is also what real systems do: a small POSIX /bin/sh for scripts, a large
# interactive shell for people. docs/history/kernel.md section 2 says "exactly
# one name per role" -- these are two roles.
#
# ---------------------------------------------------------------------------
# Licensing
#
# zsh's LICENCE is MIT-like, with one condition that has to be honoured rather
# than noted: a handful of shell functions are GPL, and the licence says so
# explicitly, adding that "none of the core functions are affected by this, so
# those files may simply be omitted."
#
# So they are omitted. GPL_FILES below is that list -- four files, deleted
# after extraction and verified absent before install. Every one completes a
# command SchOS does not have (darcs, qdbus, osc, zypper), which is why this
# costs nothing at all.
include ../mk/port.mk
ZSH_VERSION := 5.9
ZSH_URL := https://sourceforge.net/projects/zsh/files/zsh/$(ZSH_VERSION)/zsh-$(ZSH_VERSION).tar.xz/download
ZSH_SHA256 := 9b8d1ecedd5b5e81fbf1918e876752a7dd948e05c1a0dba10ab863842d45acd5
TARBALL := $(DISTDIR)/zsh-$(ZSH_VERSION).tar.xz
# The GPL-licensed functions. Removed from the source tree, not merely skipped
# at install: a file that is not there cannot be shipped by a later edit to
# this Makefile.
#
# This list is four files, and it was audited rather than grepped. The obvious
# search -- `grep -rl GPL` -- returns three more, and all three are wrong:
#
# _composer completes SPDX licence identifiers, so the word
# "licence" is data, not a licence
# _luarocks has '--license=... (e.g. "MIT/X11" or "GNU GPL
# v3")' as a completion string, same thing
# VCS_INFO_get_data_hg says "Distributed under the same BSD-ish license
# as zsh itself" -- it matched on HGPLAIN, a
# Mercurial environment variable with GPL in the
# middle of it
#
# Deleting those three would cost nothing and would still be a false claim in
# a licensing file, which is the kind of thing that is believed later.
GPL_FILES := \
Completion/Unix/Command/_darcs \
Completion/Linux/Command/_qdbus \
Completion/openSUSE/Command/_osc \
Completion/openSUSE/Command/_zypper
# Completion sets for systems that are not this one. Dropping them is size,
# not licensing -- together they are most of Completion/ and none of them can
# ever match a command that exists here.
FOREIGN_COMP := Completion/openSUSE Completion/Mandriva Completion/Redhat \
Completion/Debian Completion/Solaris Completion/Cygwin \
Completion/AIX Completion/BSD Completion/Darwin
HOSTCC_ZSH ?= gcc
GCC_INC := $(shell $(HOSTCC_ZSH) -print-file-name=include)
LIBGCC := $(shell $(HOSTCC_ZSH) -print-libgcc-file-name)
# Split the way autoconf consumes them -- see ports/ncurses/Makefile, which
# had to learn the same lesson: crt objects ride in LDFLAGS (before the object
# being linked), libraries in LIBS (after it).
ZSH_CPPFLAGS := -nostdinc -isystem $(MUSL)/include -isystem $(GCC_INC) \
-isystem $(NCURSES)/include -D__SCHOS__
# zsh 5.9 is from 2022; GCC 14 and 15 promoted three long-standing warnings to
# errors by default, and old autoconf projects fail their own feature probes on
# them. The probe that matters here is
#
# char **test = boolcodes; puts(*test);
#
# which ncurses answers with `const char * const boolcodes[]`. GCC 15 rejects
# the conversion outright, so the test "fails", HAVE_BOOLCODES goes undefined,
# and zsh helpfully declares its own `static char *boolcodes[]` -- which then
# collides with the declaration in term.h that was there the whole time. The
# error surfaces in termcap.c, three steps from the cause.
#
# These restore the diagnostic level the code was written against. They are
# scoped to this port and nothing else in the tree relaxes them.
ZSH_COMPAT := -Wno-incompatible-pointer-types -Wno-implicit-function-declaration \
-Wno-int-conversion
ZSH_CFLAGS := -O2 $(CFLAGS_BT) $(ZSH_COMPAT)
ZSH_LDFLAGS := -static -nostdlib -L$(MUSL)/lib -L$(NCURSES)/lib \
$(MUSL)/lib/crt1.o $(MUSL)/lib/crti.o
ZSH_LIBS := -lncursesw $(MUSL)/lib/libc.a $(LIBGCC) $(MUSL)/lib/libc.a \
$(MUSL)/lib/crtn.o
# Answers configure cannot work out without running a program on the target.
# Each one is a fact about SchOS, so each one is written down here rather than
# guessed by autoconf's cross-compilation defaults.
ZSH_CACHE := \
zsh_cv_shared_environ=yes \
zsh_cv_shared_tgetent=no \
zsh_cv_shared_tigetstr=no \
zsh_cv_sys_nis=no \
zsh_cv_sys_nss=no \
zsh_cv_func_realpath_accepts_null=yes \
zsh_cv_sys_path_dev_fd=/dev/fd \
zsh_cv_sys_fifo=yes \
zsh_cv_sys_killesrch=no \
zsh_cv_sys_signal_handler=void \
zsh_cv_prog_tcsetpgrp=yes \
ac_cv_func_mmap_fixed_mapped=yes \
ac_cv_func_setpgrp_void=yes
# --disable-dynamic: SchOS links everything static, and zsh's module system
# would otherwise want dlopen. Every module is compiled in instead.
# --with-term-lib: name it, so configure cannot quietly decide it needs none
# and leave the line editor unable to move a cursor.
# --enable-etcdir: where zsh looks for zshenv/zshrc. NOT --sysconfdir, which
# autoconf accepts, zsh ignores, and configure reports no complaint about --
# the shell simply starts with its default prompt and no completion, looking
# like a broken config file rather than a config file that was never read.
ZSH_CONFIGURE := \
--host=x86_64-linux-musl \
--build=x86_64-pc-linux-gnu \
--prefix=/usr \
--bindir=/bin \
--enable-etcdir=/etc/zsh \
--disable-dynamic \
--enable-multibyte \
--with-term-lib="ncursesw" \
--disable-gdbm \
--disable-pcre \
--disable-cap \
--disable-largefile \
--enable-zsh-secure-free \
--enable-fndir=/usr/share/zsh/$(ZSH_VERSION)/functions \
--enable-scriptdir=/usr/share/zsh/$(ZSH_VERSION)/scripts
$(TARBALL): | $(DISTDIR)
curl -fsSL -o $@ $(ZSH_URL)
sh $(SHA256CHECK) "$(ZSH_SHA256)" "$@"
download: $(TARBALL)
# rm -rf before the move, and touch after it. Both matter:
#
# Without the rm, `mv zsh-5.9 src` when src already exists moves the tree
# *inside* it, producing src/zsh-5.9 -- and zsh's configure globs */*/*.mdd,
# so it finds the nested copy and writes modfile=zsh-5.9/Src/zsh.mdd into
# config.modules. The build then fails a long way from the cause.
#
# Without the touch, this rule re-runs whenever the directory's mtime is
# older than the tarball's, which is how src came to exist in the first
# place. Editing files *inside* a directory does not update the directory.
$(SRCDIR): $(TARBALL)
mkdir -p $(PORTDIR)
rm -rf $@ $(PORTDIR)/zsh-$(ZSH_VERSION)
tar -xJf $< -C $(PORTDIR)
mv $(PORTDIR)/zsh-$(ZSH_VERSION) $@
@echo "zsh: removing GPL-licensed functions named by zsh's own LICENCE"
@cd $@ && rm -f $(GPL_FILES)
@cd $@ && rm -rf $(FOREIGN_COMP)
touch $@
extract: $(SRCDIR)
$(BUILDDIR)/config.status: | $(SRCDIR)
@test -f $(NCURSES)/lib/libncursesw.a || { \
echo "zsh: build ports/ncurses first -- no libncursesw.a" >&2; exit 1; }
mkdir -p $(BUILDDIR)
cd $(BUILDDIR) && \
CC="$(HOSTCC_ZSH)" \
CPPFLAGS="$(ZSH_CPPFLAGS)" \
CFLAGS="$(ZSH_CFLAGS)" \
LDFLAGS="$(ZSH_LDFLAGS)" \
LIBS="$(ZSH_LIBS)" \
$(ZSH_CACHE) \
$(SRCDIR)/configure $(ZSH_CONFIGURE)
$(BUILDDIR)/Src/zsh: $(BUILDDIR)/config.status
$(MAKE) -C $(BUILDDIR)
build: $(BUILDDIR)/Src/zsh
# Refuse to install if a GPL file is somehow present. The rm above should have
# made this impossible; the check is here because "should have" is not a
# licence audit, and this runs before every image is built.
.PHONY: licence-check
licence-check: | $(SRCDIR)
@bad=0; for f in $(GPL_FILES); do \
if [ -e "$(SRCDIR)/$$f" ]; then echo "zsh: GPL file present: $$f" >&2; bad=1; fi; \
done; \
if [ $$bad -ne 0 ]; then echo "zsh: refusing to install" >&2; exit 1; fi; \
echo "zsh: no GPL-licensed files in the tree"
$(SYSROOT)/bin/zsh: $(BUILDDIR)/Src/zsh licence-check | $(SYSROOT)/bin
$(MAKE) -C $(BUILDDIR) install DESTDIR=$(SYSROOT)
rm -rf $(SYSROOT)/usr/share/man $(SYSROOT)/usr/share/zsh/$(ZSH_VERSION)/help
chmod 755 $@
install: $(SYSROOT)/bin/zsh
clean:
rm -rf $(PORTDIR)
distclean: clean
rm -f $(TARBALL)