ps: Add some options and slim down the default output style

The following options are now available:

    -e: Show every process (not just the ones on your TTY)
    -f: Full format (instead of the short format)

We should definitely support more options and formats, I just wanted to
get away from the static single style of output. :^)

Userland/ps.cpp

@@ -24,6 +24,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#include <LibCore/ArgsParser.h>
 #include <LibCore/File.h>
 #include <LibCore/ProcessStatisticsReader.h>
 #include <fcntl.h>
@@ -32,6 +33,13 @@
 
 int main(int argc, char** argv)
 {
+    if (pledge("stdio rpath tty", nullptr) < 0) {
+        perror("pledge");
+        return 1;
+    }
+
+    String this_tty = ttyname(STDIN_FILENO);
+
     if (pledge("stdio rpath", nullptr) < 0) {
         perror("pledge");
         return 1;
@@ -49,10 +57,67 @@ int main(int argc, char** argv)
 
     unveil(nullptr, nullptr);
 
-    (void)argc;
-    (void)argv;
+    enum class Alignment {
+        Left,
+        Right,
+    };
 
-    printf("PID TPG PGP SID UID  STATE        PPID NSCHED     FDS TTY   NAME\n");
+    struct Column {
+        String title;
+        Alignment alignment { Alignment::Left };
+        int width { 0 };
+        String buffer;
+    };
+
+    bool every_process_flag = false;
+    bool full_format_flag = false;
+
+    Core::ArgsParser args_parser;
+    args_parser.add_option(every_process_flag, "Show every process", nullptr, 'e');
+    args_parser.add_option(full_format_flag, "Full format", nullptr, 'f');
+    args_parser.parse(argc, argv);
+
+    Vector<Column> columns;
+
+    int uid_column = -1;
+    int pid_column = -1;
+    int ppid_column = -1;
+    int state_column = -1;
+    int tty_column = -1;
+    int cmd_column = -1;
+
+    auto add_column = [&](auto title, auto alignment, auto width) {
+        columns.append({ title, alignment, width, {} });
+        return columns.size() - 1;
+    };
+
+    if (full_format_flag) {
+        uid_column = add_column("UID", Alignment::Left, 8);
+        pid_column = add_column("PID", Alignment::Right, 5);
+        ppid_column = add_column("PPID", Alignment::Right, 5);
+        state_column = add_column("STATE", Alignment::Left, 12);
+        tty_column = add_column("TTY", Alignment::Left, 6);
+        cmd_column = add_column("CMD", Alignment::Left, 0);
+    } else {
+        pid_column = add_column("PID", Alignment::Right, 5);
+        tty_column = add_column("TTY", Alignment::Left, 6);
+        cmd_column = add_column("CMD", Alignment::Left, 0);
+    }
+
+    auto print_column = [](auto& column, auto& string) {
+        if (!column.width) {
+            printf("%s", string.characters());
+            return;
+        }
+        if (column.alignment == Alignment::Right)
+            printf("%*s ", column.width, string.characters());
+        else
+            printf("%-*s ", column.width, string.characters());
+    };
+
+    for (auto& column : columns)
+        print_column(column, column.title);
+    printf("\n");
 
     auto all_processes = Core::ProcessStatisticsReader::get_all();
 
@@ -60,26 +125,32 @@ int main(int argc, char** argv)
         const auto& proc = it.value;
         auto tty = proc.tty;
 
+        if (!every_process_flag && tty != this_tty)
+            continue;
+
         if (tty.starts_with("/dev/"))
             tty = tty.characters() + 5;
         else
             tty = "n/a";
 
         auto* state = proc.threads.is_empty() ? "Zombie" : proc.threads.first().state.characters();
-        auto times_scheduled = proc.threads.is_empty() ? 0 : proc.threads.first().times_scheduled;
 
-        printf("%-3u %-3u %-3u %-3u %-3u  %-11s  %-3u  %-9u  %-3u %-5s %s\n",
-            proc.pid,
-            proc.pgid,
-            proc.pgp,
-            proc.sid,
-            proc.uid,
-            state,
-            proc.ppid,
-            times_scheduled,
-            proc.nfds,
-            tty.characters(),
-            proc.name.characters());
+        if (uid_column != -1)
+            columns[uid_column].buffer = proc.username;
+        if (pid_column != -1)
+            columns[pid_column].buffer = String::number(proc.pid);
+        if (ppid_column != -1)
+            columns[ppid_column].buffer = String::number(proc.ppid);
+        if (tty_column != -1)
+            columns[tty_column].buffer = tty;
+        if (state_column != -1)
+            columns[state_column].buffer = state;
+        if (cmd_column != -1)
+            columns[cmd_column].buffer = proc.name;
+
+        for (auto& column : columns)
+            print_column(column, column.buffer);
+        printf("\n");
     }
 
     return 0;