Improve internal and external documentation

cli.js

@@ -7,11 +7,11 @@
 'use strict';
 
 const fs = require("fs");
-const path = require("path");
-const chef = require("cyberchef");
-const program = require("commander");
+
+///////// Helper Functions /////////
 
 let slurpStream = (istream) => { // {{{1
+    // Slurp the contents of a stream up into a Buffer to pass to CyberChef
     var ret = [];
     var len = 0;
     return new Promise(resolve => {
@@ -27,12 +27,13 @@ let slurpStream = (istream) => { // {{{1
 }; // }}}1
 
 let slurp = (fname) => { // {{{1
+    // Slurp the contents of a file (or stdin) into a Buffer
     let istream;
 
     if (fname === undefined || fname == '-') {
         istream = process.stdin;
         if (istream.isTTY) {
-            throw new Error("TTY input not supported");
+            return Promise.reject(new Error("TTY input not supported"));
         }
     }
     else {
@@ -53,16 +54,30 @@ let getPort = (value, dummyPrevious) => { // {{{1
 
 ///////// MAIN ///////// {{{1
 
+const chef = require("cyberchef");
+const program = require("commander");
+
 program
     .version(require('./package.json').version)
+    .description('Bake data from files and/or TCP clients '
+        + 'using a CyberChef recipe.')
     .usage('[options] [file [file ...]]')
     .requiredOption('-r, --recipe-file <file>',
         'recipe JSON file')
     .option('-l, --listen [port]',
-        'listen on TCP port for data (default:random)', getPort, false)
+        'listen on TCP port for data (random if not given)', getPort, false)
     .option('-o, --output <file-or-dir>',
-        'write result here (not for TCP; default:stdout)')
-    .parse(process.argv);
+        'where to write result (file input only; default:stdout)');
+
+try {
+    program.exitOverride().parse(process.argv);
+}
+catch (e) {
+    if (e.code != 'commander.helpDisplayed') {
+        console.error("Run with '--help' for usage");
+    }
+    process.exit(1);
+}
 
 // If we get no inputs and we aren't running a server,
 // make stdin our single input
@@ -73,6 +88,7 @@ if (inputs.length == 0 && !program.listen) {
 
 // Likewise stdout for our output
 let ostream;
+let path;
 let outputIsDir = false;
 if (program.output === undefined && !program.listen) {
     ostream = process.stdout;
@@ -85,20 +101,22 @@ else if (inputs.length > 0) {
         outputIsDir = st.isDirectory();
     }
     catch(err) {
+        // We're fine if the output doesn't exist yet
         if (err.code != 'ENOENT') throw err;
     }
     if (!outputIsDir) {
         ostream = fs.createWriteStream(program.output);
     }
 }
+if (outputIsDir) path = require("path");
 
 let recipe;
 slurp(program.recipeFile).then((data) => {
     recipe = JSON.parse(data);
 })
 .catch((err) => {
-    console.error(`Error parsing recipe: ${err}`);
-    process.exit(1);
+    console.error(`Error parsing recipe: ${err.message}`);
+    process.exit(2);
 })
 .then(() => {
     // First, deal with any files we want to read
@@ -113,9 +131,14 @@ slurp(program.recipeFile).then((data) => {
             }
             ostream.write(output.presentAs("string", true));
             if (outputIsDir) ostream.end();
+        },
+        (err) => {
+            console.error(err.message);
+            process.exitCode = 2;
         })
         .catch((err) => {
-            console.error(err);
+            console.error(err.message);
+            process.exitCode = 2;
         });
     }
 
@@ -135,7 +158,7 @@ slurp(program.recipeFile).then((data) => {
             });
         });
 
-        // If no port given, let the OS choose one
+        // If no port given by user, let the OS choose one
         if (program.listen === true) program.listen = 0;
         server.listen(program.listen, '127.0.0.1')
             .on('listening', () => {
@@ -153,5 +176,5 @@ slurp(program.recipeFile).then((data) => {
 })
 .catch((err) => {
     console.error(err);
-    process.exit(2);
+    process.exit(3);
 })