Added some function comments

callbacks.h

@@ -6,8 +6,29 @@
 #include <gtk/gtk.h>
 #include <girara.h>
 
+/**
+ * Quits the current zathura session
+ *
+ * @param widget The gtk window of zathura
+ * @param data NULL
+ * @return TRUE
+ */
 gboolean cb_destroy(GtkWidget* widget, gpointer data);
+
+/**
+ * This function gets called when the buffer of girara changes
+ *
+ * @param session The girara session
+ */
 void buffer_changed(girara_session_t* session);
+
+/**
+ * This function gets called when the the value of the vertical scrollbars
+ * changes (e.g.: by scrolling, moving to another page)
+ *
+ * @param adjustment The vadjustment of the page view
+ * @param data NULL
+ */
 void cb_view_vadjustment_value_changed(GtkAdjustment *adjustment, gpointer data);
 
 #endif // CALLBACKS_H

utils.h

@@ -6,9 +6,38 @@
 #include <stdbool.h>
 #include <gtk/gtk.h>
 
+/**
+ * Checks if the given file exists
+ *
+ * @param path Path to the file
+ * @return true if the file exists, otherwise false
+ */
 bool file_exists(const char* path);
+
+/**
+ * Returns the file extension of a path
+ *
+ * @param path Path to the file
+ * @return The file extension or NULL
+ */
 const char* file_get_extension(const char* path);
+
+/**
+ * Executes a system command and saves its output into output
+ *
+ * @param argv The command
+ * @param output Pointer where the output will be saved
+ * @return true if no error occured, otherwise false
+ */
 bool execute_command(char* const argv[], char** output);
+
+/**
+ * Creates a blank page
+ *
+ * @param width The width of the page
+ * @param height The height of the page
+ * @return The widget of the page or NULL if an error occured
+ */
 GtkWidget* page_blank(unsigned int width, unsigned int height);
 
 #endif // UTILS_H

zathura.h

@@ -54,7 +54,6 @@ struct
  *
  * @return If no error occured true, otherwise false, is returned.
  */
-
 bool init_zathura();
 
 /**