C program querying the currently playing song in mpd and setting it to the dwm bar (root window title)

mpdq.c

#include <mpd/client.h>
#include <mpd/stats.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>

static volatile int runFlag = 1;

void stop(int d) { runFlag = 0; }

char* append(char* a, char* b)
{
    char* out;
    if((out = (char *)malloc(strlen(a) + strlen(b) + 1)) != NULL)
    {
       strcpy(out, a);
       strcat(out, b);
    }
    else
    {
        printf("Not enough memory to concat strings!");
        exit(-1);
    }
    return out;
}

int main(int argc, char const *argv[])
{
    // Vars
    int         debug = argc > 1;
    unsigned    time = 0;
    struct      mpd_connection  *conn;
    struct      mpd_status      *status;
    struct      mpd_song        *song;
    enum        mpd_state       state;

    char        *song_name;
    char        *artist_name;
    char        *cmd;
    char        *base_cmd = "xsetroot -name \"";
    char        *cmd_end  = "\"";
    char        *space    = " - ";
    char        *paused   = " [Paused]";

    // Listen for CTRL + C
    signal(SIGINT, stop);

    // Connect to local MPD 
    conn = mpd_connection_new(NULL, 0, 0);
    if (conn && debug)
        printf("Connected!\n");
    else if (!conn) 
    {
        if (debug) printf("Connection failure!\n");
        return 0;
    }

    // Get song
    while (runFlag)
    {
        status = mpd_run_status(conn);
        time    = mpd_status_get_elapsed_time(status);
        song    = mpd_run_current_song(conn);
        state   = mpd_status_get_state(status);
        
        if (!song || !status)
        {
            if (!song && debug) printf("Couldn't recieve current song!\n");
            if (!status && debug) printf("Couldn't recieve status of MPD!\n");
            return 0;    
        }

        // Get song info
        song_name = (char *) mpd_song_get_tag(song, MPD_TAG_TITLE, 0);
        artist_name = (char *) mpd_song_get_tag(song, MPD_TAG_ARTIST, 0);

        switch (state)
        {
            case 0:
            case 1:
                    cmd = "xsetroot -name dwm-6.1"; // Stopped/Unknown status
                break;
            case 2:
                    cmd = append(base_cmd, artist_name); // Playing
                    cmd = append(cmd, space);
                    cmd = append(cmd, song_name);
                    cmd = append(cmd, cmd_end);
                break;
            case 3:
                    cmd = append(base_cmd, artist_name); // Paused
                    cmd = append(cmd, space);
                    cmd = append(cmd, song_name);
                    cmd = append(cmd, paused);
                    cmd = append(cmd, cmd_end);    
                break;
        }

        system(cmd);

        sleep(1);
    }

    printf("Disconnecting...\n");
    system("xsetroot -name dwm-6.1");

    // Close Connection & free resources
    mpd_status_free(status);
    mpd_connection_free(conn);
    mpd_song_free(song);
    
    song_name   = NULL;
    artist_name = NULL;   
    paused      = NULL;
    space       = NULL;
    cmd         = NULL; 
    return 0;
}