Fix XopenDisplay error when running without Xorg in tty

Add checks if xserver is running and replace information that is gathered from xserver with alternatives.
This affects resolution and terminal name. Terminal name is replaced with the old $TERM method, when running in tty.
For resolution, the available display modes in /sys/class/drm are parsed and the highest avaiblable resolution is displayed.
Works on my machine, but should be tested on other computers.

paleofetch.c

@@ -229,38 +229,89 @@ char *get_shell() {
 }
 
 char *get_resolution() {
-    int screen = DefaultScreen(display);
-
-    int width = DisplayWidth(display, screen);
-    int height = DisplayHeight(display, screen);
-
+    int screen, width, height;
     char *resolution = malloc(BUF_SIZE);
-    snprintf(resolution, BUF_SIZE, "%dx%d", width, height);
+    
+    if (display != NULL) {
+        screen = DefaultScreen(display);
+    
+        width = DisplayWidth(display, screen);
+        height = DisplayHeight(display, screen);
+
+        snprintf(resolution, BUF_SIZE, "%dx%d", width, height);
+    } else {
+        DIR *dir;
+        struct dirent *entry;
+        char dir_name[] = "/sys/class/drm";
+        char modes_file_name[BUF_SIZE * 2];
+        FILE *modes;
+        char *line = NULL;
+        size_t len;
+        
+        /* preload resolution with something, in case we cant find a resolution through parsing */
+        strncpy(resolution, "Resolution could not be determined", BUF_SIZE);
+
+        dir = opendir(dir_name);
+        if (dir == NULL) {
+            status = -1;
+            halt_and_catch_fire("Could not open /sys/class/drm to determine resolution in tty mode.");
+        }
+        /* parse through all directories and look for a non empty modes file */
+        while ((entry = readdir(dir)) != NULL) {
+            if (entry->d_type == DT_LNK) {
+                snprintf(modes_file_name, BUF_SIZE * 2, "%s/%s/modes", dir_name, entry->d_name);
+
+                modes = fopen(modes_file_name, "r");
+                if (modes != NULL) {
+                    if (getline(&line, &len, modes) != -1) {
+                        strncpy(resolution, line, BUF_SIZE);
+                        remove_newline(resolution);
+
+                        free(line);
+                        fclose(modes);
+
+                        break;
+                    }
+
+                    fclose(modes);
+                }
+            }
+        }
+        
+        closedir(dir);
+    }
 
     return resolution;
 }
 
 char *get_terminal() {
     unsigned char *prop;
+    char *terminal = malloc(BUF_SIZE);
+
+    /* check if xserver is running or if we are running in a straight tty */
+    if (display != NULL) {   
+
     unsigned long _, // not unused, but we don't need the results
-                  window = RootWindow(display, XDefaultScreen(display));
-    Atom a,
-         active = XInternAtom(display, "_NET_ACTIVE_WINDOW", True),
-         class = XInternAtom(display, "WM_CLASS", True);
+                  window = RootWindow(display, XDefaultScreen(display));    
+        Atom a,
+             active = XInternAtom(display, "_NET_ACTIVE_WINDOW", True),
+             class = XInternAtom(display, "WM_CLASS", True);
 
 #define GetProp(property) \
-    XGetWindowProperty(display, window, property, 0, 64, 0, 0, &a, (int *)&_, &_, &_, &prop);
+        XGetWindowProperty(display, window, property, 0, 64, 0, 0, &a, (int *)&_, &_, &_, &prop);
 
-    GetProp(active);
-    window = (prop[3] << 24) + (prop[2] << 16) + (prop[1] << 8) + prop[0];
-    free(prop);
-    GetProp(class);
+        GetProp(active);
+        window = (prop[3] << 24) + (prop[2] << 16) + (prop[1] << 8) + prop[0];
+        free(prop);
+        GetProp(class);
 
 #undef GetProp
 
-    char *terminal = malloc(BUF_SIZE);
-    snprintf(terminal, BUF_SIZE, "%s", prop);
-    free(prop);
+        snprintf(terminal, BUF_SIZE, "%s", prop);
+        free(prop);
+    } else {
+        strncpy(terminal, getenv("TERM"), BUF_SIZE); /* fallback to old method */
+    }
 
     return terminal;
 }
@@ -453,10 +504,10 @@ int main(int argc, char *argv[]) {
     status = sysinfo(&my_sysinfo);
     halt_and_catch_fire("sysinfo failed");
     display = XOpenDisplay(NULL);
-    if(display == NULL) {
-        status = -1;
-        halt_and_catch_fire("XOpenDisplay failed");
-    }
+    //if(display == NULL) {
+    //    status = -1;
+    //    halt_and_catch_fire("XOpenDisplay failed");
+    //}
 
     cache = get_cache_file();
     if(argc == 2 && strcmp(argv[1], "--recache") == 0)
@@ -500,7 +551,9 @@ int main(int argc, char *argv[]) {
 
     free(cache);
     free(cache_data);
-    XCloseDisplay(display);
+    if(display != NULL) { 
+        XCloseDisplay(display);
+    }
 
     return 0;
 }