marfrit
ee4d7f86d6
Replaces the Phase 0 io.popen + sentinel-echo exit-code recovery with
forkpty + waitpid via ffi/pty. The §7 amendment paragraph on PHASE0.md
is rewritten to point at PHASE1.md §5 — the workaround is gone, not
just renamed.
User-visible behavioral changes:
- Interactive commands (vim, less, htop, top) now work via $cmd /
:exec / known-command shell paths because the child has a real
PTY for line discipline.
- Exit codes are accurate: `false` -> 1, `exit 7` -> 7, signal kill
-> 128+N (bash convention), shell parse error -> sh's 2.
- Broken-shell-syntax cmd now shows the actual sh diagnostic
(e.g. "Syntax error: end of file unexpected") instead of Phase 0's
"(no output — possible shell parse error)" guess.
- Output normalization: PTY emits CR LF; executor collapses \r\n
-> \n to keep the Phase 0 contract ("output uses \n separators").
Code path:
pty.spawn(cmd) -> drain master_fd until EOF
-> wait() returns ("exit", N) | ("signal", N) | ...
-> exit_code mapped: exit -> N, signal -> 128+N, else -1
Phase 0 invariants intact: `cd` interception unchanged (still libc.chdir
per §3 + §7), `CMD: ` extraction unchanged.
PHASE0.md §7: the "LuaJIT 2.1 popen-close caveat" paragraph is rewritten
to "Superseded by Phase 1" — points at PHASE1.md §5 for the live model.
The illustrative sketch is left in place as historical context.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
87 lines
3.0 KiB
Lua
87 lines
3.0 KiB
Lua
-- executor.lua — command execution.
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-- Phase 1: forkpty via ffi/pty. Replaces Phase 0's io.popen + sentinel-echo
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-- exit-code workaround; vim/less/htop now work because the child runs on a
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-- real PTY. `cd` interception is unchanged (still libc.chdir per §3, §7).
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-- See docs/PHASE0.md §7 and docs/PHASE1.md §5.
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local libc = require("ffi.libc")
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local pty = require("ffi.pty")
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local M = {}
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-- Execute a shell command.
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-- Returns: (output_string, exit_code).
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-- 0 success
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-- 1..255 child exited with that status
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-- 128+N child killed by signal N (bash convention)
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-- -1 forkpty / spawn / wait failure
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function M.exec(cmd)
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if not cmd or cmd:match("^%s*$") then
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return "(empty command)", -1
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end
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local sess, err = pty.spawn(cmd)
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if not sess then
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return "(pty.spawn failed: " .. tostring(err) .. ")", -1
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end
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-- Drain until the child closes its end. PTY combines stdout+stderr
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-- on the master fd (no 2>&1 needed); CR LF gets normalized below.
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local chunks = {}
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while true do
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local data, n = sess:read()
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if not data then break end
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if n == 0 then break end
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chunks[#chunks + 1] = data
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end
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local kind, code = sess:wait()
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sess:close()
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-- PTY line discipline emits \r\n for every \n the child writes; collapse
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-- back to \n so the Phase 0 caller contract ("output uses \n separators")
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-- still holds.
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local output = table.concat(chunks):gsub("\r\n", "\n")
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if kind == "exit" then return output, code end
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if kind == "signal" then return output, 128 + code end
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return output, -1
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end
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-- Intercept and apply `cd <path>` (or bare `cd` -> $HOME) without forking.
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-- Returns:
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-- nil : the command is not a `cd` (caller falls through to exec)
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-- true : it was a cd, libc.chdir succeeded
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-- false, err : it was a cd, libc.chdir failed with errmsg
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function M.maybe_chdir(cmd)
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local rest = cmd:match("^%s*cd%s*$") and ""
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or cmd:match("^%s*cd%s+(.+)$")
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if not rest then return nil end
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local target = rest:match("^%s*(.-)%s*$") or ""
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-- Phase 0: no $OLDPWD support, so `cd -` is not handled.
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if target == "" then target = os.getenv("HOME") or "/" end
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if target == "~" then target = os.getenv("HOME") or "/" end
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if target:sub(1, 2) == "~/" then
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target = (os.getenv("HOME") or "") .. target:sub(2)
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end
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return libc.chdir(target)
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end
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-- Extract `CMD: ` lines from an assistant response per the §6 broker contract.
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-- The "CMD: " prefix is a §3 substrate invariant: exact prefix, single space,
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-- start-of-line only. Leading whitespace before CMD: does NOT match.
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function M.extract_cmd_lines(text)
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local cmds = {}
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for line in (text or ""):gmatch("[^\n]+") do
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local cmd = line:match("^CMD: (.*)$")
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-- Skip whitespace-only / empty bodies; "CMD: " alone is degenerate.
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if cmd and cmd:match("%S") then cmds[#cmds + 1] = cmd end
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end
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return cmds
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end
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return M
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