CPython sets SIGPIPE to SIG_IGN so EPIPE surfaces as BrokenPipeError.
A Go port must replicate this explicitly or the EPIPE path silently
becomes a SIGPIPE death.
24/24 green.
write_all() loops until the full buffer is transferred — os.write's return value was
ignored at the payload write and in the pump loop, so a short write silently truncated
the stream. EPIPE at the payload write (child already dead) now reaps the child and
inherits its status instead of dying with a BrokenPipeError traceback; EPIPE in the pump
loop falls through to the same waitpid, which is standard `cmd | head` semantics.
Tests use deterministic fault injection rather than racing signals: a fork wrapper that
waits with waitid(WNOWAIT) so the child is provably dead but still reapable before the
parent writes, and an os.write cap of 7 bytes per call as the stand-in for a
signal-interrupted partial write.
Reviewed three times. Known gaps, tracked, NOT fixed here: signal-killed children still
collapse to exit 1 (no 128+WTERMSIG), and the pump loop's `except OSError: pass` is
broader than it should be.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
- Pump loop after fork: parent streams stdin to child through pipe
- netstring: enforce .isdigit() on length field
- netstring: require exact consumption (no trailing data)
- argv split: use .split space not .split
- Non-ASCII command: fail loudly
- Child exec failure: os._exit(1)
17/17 pytest green
- Read preamble: magic byte \x00 + 4-byte BE length + netstring
- Split netstring at first NUL: command\0<payload>
- Exec command with payload + trailing stdin forwarded
- Nested payloads are netstrings for the next hop (one layer peeled per sicd)
- Bare -- survives as opaque data
- Malformed input: exit 1 with stderr diagnostic
- 14/14 pytest green
Client (sic) frames argv as netstrings and pipes it over ssh to a daemon
(sicd) that execvp's it, so no shell re-parses the arguments. exec mode by
default; opt-in sh mode for pipes/redirects/globs. Go client + daemon, Python
reference daemon, design doc, quoting-hell demo, and foreground/background
agent skills.
Renamed from the climcp prototype.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EWpfhDgYNA21tETDP9ueBE
Markus Fritsche