Userland: Add lsusb :^)

Author: https://github.com/Quaker762
Commit: https://github.com/SerenityOS/serenity/commit/119b8a26923
Pull-request: https://github.com/SerenityOS/serenity/pull/7944
Reviewed-by: https://github.com/alimpfard

Userland/Utilities/lsusb.cpp

@@ -0,0 +1,66 @@
+/*
+ * Copyright (c) 2021, Jesse Buhagiar <jooster669@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/ByteBuffer.h>
+#include <AK/JsonArray.h>
+#include <AK/JsonObject.h>
+#include <AK/LexicalPath.h>
+#include <AK/String.h>
+#include <LibCore/ArgsParser.h>
+#include <LibCore/DirIterator.h>
+#include <LibCore/File.h>
+#include <stdio.h>
+#include <unistd.h>
+
+int main(int argc, char** argv)
+{
+    if (pledge("stdio rpath", nullptr) < 0) {
+        perror("pledge");
+        return 1;
+    }
+
+    if (unveil("/proc/bus/usb", "r") < 0) {
+        perror("unveil");
+        return 1;
+    }
+
+    if (unveil(nullptr, nullptr) < 0) {
+        perror("unveil");
+        return 1;
+    }
+
+    Core::ArgsParser args;
+    args.set_general_help("List USB devices.");
+    args.parse(argc, argv);
+
+    Core::DirIterator usb_devices("/proc/bus/usb", Core::DirIterator::SkipDots);
+
+    while (usb_devices.has_next()) {
+        auto full_path = LexicalPath(usb_devices.next_full_path());
+
+        auto proc_usb_device = Core::File::construct(full_path.string());
+        auto bus_id = proc_usb_device->filename().split('/').last();
+        if (!proc_usb_device->open(Core::OpenMode::ReadOnly)) {
+            warnln("Failed to open {}: {}", proc_usb_device->name(), proc_usb_device->error_string());
+            continue;
+        }
+
+        auto contents = proc_usb_device->read_all();
+        auto json = JsonValue::from_string(contents);
+        VERIFY(json.has_value());
+
+        json.value().as_array().for_each([bus_id](auto& value) {
+            auto& device_descriptor = value.as_object();
+
+            auto vendor_id = device_descriptor.get("vendor_id").to_u32();
+            auto product_id = device_descriptor.get("product_id").to_u32();
+
+            outln("Device {}: ID {:04x}:{:04x}", bus_id, vendor_id, product_id);
+        });
+    }
+
+    return 0;
+}