Tools for building the sdcard image

scripts/util.js

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+const { execSync } = require("child_process");
+const { statSync } = require("fs");
+const { exit } = require("process");
+
+module.exports = {
+    info,
+    runCommand,
+    logErrorAndExit,
+    registerSignalHandler,
+    initSignalHandlers,
+    assertOS,
+    assertEffectiveRoot,
+    assertFileExists,
+    assertInstalled
+};
+
+let signalHandlers = [];
+
+function registerSignalHandler(cb) {
+    signalHandlers.push(cb);
+
+    return () => (signalHandlers = signalHandlers.filter(h => h === cb));
+}
+
+function initSignalHandlers() {
+    process.on("SIGTERM", handle);
+    process.on("SIGINT", handle);
+    process.on("SIGHUP", handle);
+}
+
+function handle(signal) {
+    console.log(`Received ${signal}`);
+
+    for (const handler of signalHandlers) {
+        handler(signal);
+    }
+}
+
+function info(msg) {
+    console.log(`\n${msg}`);
+}
+
+function runCommand(command, _options) {
+    const options = {
+        encoding: "utf8",
+        ..._options,
+        shell: true
+    };
+
+    const { onError } = options;
+    delete options["onError"];
+
+    try {
+        const result = execSync(command, options);
+
+        return (typeof result === "string")
+            ? result.trim()
+            : result;
+    } catch (error) {
+        if (onError) {
+            onError(error);
+        } else {
+            throw error;
+        }
+    }
+}
+
+function logErrorAndExit(msg, error) {
+    const lines = msg.split("\n");
+
+    // Get rid of leading blank lines
+    while (lines.length) {
+        if (lines[0].trim().length == 0) {
+            lines.shift();
+        } else {
+            break;
+        }
+    }
+
+    // Get rid of trailing blank lines
+    while (lines.length) {
+        if (lines.at(-1).trim().length == 0) {
+            lines.pop();
+        } else {
+            break;
+        }
+    }
+
+    const [ whitespace ] = lines[0].match(/^\s*/);
+
+    console.error(lines
+        .map(line => line.replace(whitespace, "").trimEnd())
+        .join("\n")
+    );
+
+    if (error) {
+        console.error("Error:", JSON.stringify({
+            name: error.name,
+            code: error.code,
+            status: error.status,
+            signal: error.signal,
+            error: error.error,
+            pid: error.pid,
+            output: error.output,
+            msg: error.msg,
+            message: error.message
+        }, null, 4));
+    }
+
+    exit(1);
+}
+
+function assertOS() {
+    if (process.platform !== "linux") {
+        logErrorAndExit("This script requires linux.");
+    }
+}
+
+function assertEffectiveRoot() {
+    if (process.geteuid() !== 0) {
+        logErrorAndExit("Please run this script as root");
+    }
+}
+
+function assertFileExists(file) {
+    const stats = statSync(file);
+    if (!stats.isFile) {
+        logErrorAndExit(`${file} does not exist`);
+    }
+}
+
+function assertInstalled(tools) {
+    const missingTools = [];
+
+    for (const tool of tools) {
+        runCommand(`command -v ${tool}`, {
+            onError: () => missingTools.push(tool)
+        });
+    }
+
+    if (missingTools.length) {
+        logErrorAndExit(`
+            This script requires some tools that are not installed.
+
+            Install them via:
+                apt-get install -y ${missingTools.join(" ")}
+        `);
+    }
+}