who: Add who command

Author: ebanner

Userland/Utilities/CMakeLists.txt

@@ -212,6 +212,7 @@ set(CMD_SOURCES_CPP
     watchfs.cpp
     wc.cpp
     which.cpp
+    who.cpp
     whoami.cpp
     wsctl.cpp
     xargs.cpp

Userland/Utilities/who.cpp

@@ -0,0 +1,78 @@
+/*
+ * Copyright (c) 2024, Edward <[email protected]>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/Format.h>
+#include <AK/JsonArray.h>
+#include <AK/JsonObject.h>
+#include <AK/JsonParser.h>
+#include <AK/JsonValue.h>
+#include <LibCore/File.h>
+#include <LibCore/System.h>
+#include <LibMain/Main.h>
+#include <pwd.h>
+#include <time.h>
+
+ErrorOr<int> serenity_main(Main::Arguments)
+{
+    // TRY(Core::System::pledge("stdio rpath"));
+    // TRY(Core::System::unveil("/var/run/utmp", "r"));
+    // TRY(Core::System::unveil(nullptr, nullptr));
+
+    auto file = TRY(Core::File::open("/var/run/utmp"sv, Core::File::OpenMode::Read));
+    auto contents = TRY(file->read_until_eof());
+    auto json = TRY(JsonValue::from_string(contents));
+
+    // outln("{}", StringView(contents));
+
+    json.as_object().for_each_member([&](auto& key, auto& value) {
+        // outln("key: {}", key);
+
+        auto const& obj = value.as_object();
+
+        auto uid = obj.get_i32("uid"sv).value_or(0);
+        // outln("uid: {}", uid);
+
+        auto* passwd = getpwuid(uid);
+        auto user_name = passwd->pw_name;
+        // outln("user_name: {}", passwd->pw_name);
+
+        auto login_at = obj.get_i32("login_at"sv).value_or(0);
+        // outln("login_at: {}", login_at);
+
+        auto time = static_cast<time_t>(login_at);
+        auto* tm = localtime(&time);
+        char timebuf[32];
+        strftime(timebuf, sizeof(timebuf), "%b %d %H:%M", tm);
+        // outln("login_at (formatted): {}", timebuf);
+
+        outln("{}\t{}\t{}", user_name, key, timebuf);
+    });
+
+    // outln("{}", json.as_string());
+
+    // auto entries = json.as_array();
+    // for (auto const& entry : entries.values()) {
+    //     if (!entry.is_object())
+    //         continue;
+
+    //     auto const& obj = entry.as_object();
+    //     auto username = obj.get_byte_string("username"sv).value_or(""sv);
+    //     auto tty = obj.get_byte_string("tty"sv).value_or(""sv);
+    //     auto hostname = obj.get_byte_string("hostname"sv).value_or(""sv);
+    //     auto timestamp = obj.get_integer<time_t>("timestamp"sv).value_or(0);
+
+    //     if (username.is_empty() || tty.is_empty())
+    //         continue;
+
+    //     char timebuf[32];
+    //     struct tm* tm = localtime(&timestamp);
+    //     strftime(timebuf, sizeof(timebuf), "%Y-%m-%d %H:%M", tm);
+
+    //     outln("{:<8} {:<12} {:<15} {}", username, tty, hostname, timebuf);
+    // }
+
+    return 0;
+}