14f0e4d0e2
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, $COLUMNS reads the real 160 because TIOCGWINSZ was fixed, colour and prompt expansion work, startup is 0.14 s. mksh keeps /bin/sh, so schinit's no-jobs fallback is a different program from the one that could have failed. Also fixed while here: AT_CLKTCK was the literal 100 and is USER_HZ; the extract rule in four ports could move a source tree inside itself when make re-ran it, which is how zsh's configure came to write modfile=zsh-5.9/... into config.modules and fail three steps later. schfs-check passes. Full writeup in docs/history/kernel.md section 14. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01VQ7Qx8E1q1M1bbCq8QLHS2
113 lines
5.1 KiB
Shell
113 lines
5.1 KiB
Shell
# /etc/zsh/zshrc — the system-wide interactive zsh configuration for SchOS.
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#
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# Deliberately short. This sets up the things an interactive shell is useless
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# without -- history, completion, and the keys a console sends -- and stops.
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# Anything beyond that belongs in a user's own ~/.zshrc, which is the file zsh
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# reads after this one.
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# ---------------------------------------------------------------------------
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# History
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# ---------------------------------------------------------------------------
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HISTFILE=${HOME:-/root}/.zsh_history
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HISTSIZE=2000
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SAVEHIST=2000
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setopt APPEND_HISTORY INC_APPEND_HISTORY SHARE_HISTORY
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setopt HIST_IGNORE_DUPS HIST_IGNORE_SPACE HIST_REDUCE_BLANKS
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# ---------------------------------------------------------------------------
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# Behaviour
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# ---------------------------------------------------------------------------
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setopt AUTO_CD # `cd /tmp` is implied by typing `/tmp`
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setopt EXTENDED_GLOB
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setopt INTERACTIVE_COMMENTS # a # in an interactive line is a comment
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setopt NO_BEEP # SchOS has no audio, but it would also scroll
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unsetopt FLOW_CONTROL # ^S/^Q are worth more as keys than as flow control
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# ---------------------------------------------------------------------------
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# Keys
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# ---------------------------------------------------------------------------
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# Emacs bindings, because that is what every other line editor on the system
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# does -- mksh's default and the kernel's own canonical-mode editing both.
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bindkey -e
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# Home, End, Delete and the arrows, taken from terminfo rather than written
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# out as escape sequences. The sequences differ between the SchOS console and
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# a serial terminal; the terminal's own description does not.
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typeset -A _sch_keys=(
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"${terminfo[khome]}" beginning-of-line
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"${terminfo[kend]}" end-of-line
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"${terminfo[kdch1]}" delete-char
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"${terminfo[kich1]}" overwrite-mode
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"${terminfo[kcuu1]}" up-line-or-search
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"${terminfo[kcud1]}" down-line-or-search
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"${terminfo[kcub1]}" backward-char
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"${terminfo[kcuf1]}" forward-char
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)
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for _k _w in "${(@kv)_sch_keys}"; do
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[[ -n $_k ]] && bindkey -- "$_k" "$_w"
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done
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unset _sch_keys _k _w
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# A terminal that has just been resized, or that zsh has just taken over, may
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# not have told terminfo yet. This puts the keypad in the mode the escape
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# sequences above were described for, and takes it back out on exit.
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if (( ${+terminfo[smkx]} && ${+terminfo[rmkx]} )); then
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autoload -Uz add-zle-hook-widget 2>/dev/null
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function _sch_zle_init { echoti smkx }
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function _sch_zle_line_finish { echoti rmkx }
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zle -N zle-line-init _sch_zle_init
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zle -N zle-line-finish _sch_zle_line_finish
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fi
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# ---------------------------------------------------------------------------
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# Completion
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# ---------------------------------------------------------------------------
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# Completion is NOT initialised here yet, and the reason is a filesystem
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# measurement rather than anything to do with zsh.
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#
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# A small write to SchFS costs about 58 ms, because every operation is its own
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# transaction group and a commit is two cache flushes and an uberblock write --
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# see the comment at the top of kernel/fs/schfs/kmount.c, which describes the
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# trade-off exactly. Measured on this machine, 200 writes:
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#
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# to one open file on SchFS 11.75 s (58 ms each)
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# open + write + close each 21.39 s (107 ms each)
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# to /dev/null 0.14 s (0.7 ms each)
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#
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# compdump writes the digest with a few thousand separate `print` calls, so
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# compinit -d takes minutes and looks exactly like a hang. compinit itself is
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# fine: with -D, which skips the dump, it finishes in 3.6 seconds.
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#
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# So this waits for deferred commits. When small writes stop costing a disk
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# barrier each, delete this comment and uncomment the three lines below.
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#
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# autoload -Uz compinit
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# compinit -u -d ${HOME:-/root}/.zcompdump
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#
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# Until then, completion is available on demand in a shell you do not mind
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# waiting three seconds for:
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#
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# autoload -Uz compinit && compinit -D -u
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#
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# -u is not optional whenever this is turned back on. Without it compinit runs
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# compaudit, decides the function directories are "insecure" because SchOS has
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# no ownership model to check, and *prompts* for an answer on a shell that is
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# still starting up -- which is a real hang, unlike the one above.
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# These take effect as soon as compinit is turned on above; a zstyle with no
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# completion system to read it is inert, not an error.
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zstyle ':completion:*' menu select
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zstyle ':completion:*' matcher-list 'm:{a-z}={A-Za-z}' # case-insensitive
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zstyle ':completion:*' list-colors ''
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zstyle ':completion:*:descriptions' format '%F{244}%d%f'
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# ---------------------------------------------------------------------------
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# Prompt
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# ---------------------------------------------------------------------------
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# The accent violet from include/theme.h, which is 99 in the 256-colour cube
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# and falls back to magenta on the 8-colour console. The last-status marker is
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# the only thing here that ever turns red -- same rule as the rest of the
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# system: normal states are calm, only failure is loud.
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setopt PROMPT_SUBST
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PROMPT='%F{magenta}%B%n@schos%b%f %F{cyan}%~%f %(?.%F{green}❯.%F{red}❯)%f '
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RPROMPT=''
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