paseo/packages/cli/src/commands/daemon/runtime-toolchain.ts

import { spawnSync } from "node:child_process";

export interface NodePathFromPidResult {
  nodePath: string | null;
  error?: string;
}

function normalizeError(error: unknown): string {
  if (error instanceof Error) {
    return error.message;
  }
  return String(error);
}

export function resolveNodePathFromPid(pid: number): NodePathFromPidResult {
  const result = spawnSync("ps", ["-o", "comm=", "-p", String(pid)], {
    encoding: "utf8",
    stdio: ["ignore", "pipe", "pipe"],
  });

  if (result.error) {
    return {
      nodePath: null,
      error: `ps failed: ${normalizeError(result.error)}`,
    };
  }

  if ((result.status ?? 1) !== 0) {
    const details = result.stderr?.trim();
    return {
      nodePath: null,
      error: details ? `ps failed: ${details}` : `ps exited with code ${result.status ?? 1}`,
    };
  }

  const resolved = result.stdout.trim();
  if (!resolved) {
    return {
      nodePath: null,
      error: "ps returned an empty command path",
    };
  }

  return { nodePath: resolved };
}