Create function read_system_datetime()

The purpose of this is to read year, month, day, hours
minutes and seconds into variables for updating in the GUI
prior to writing back to the system.

For systems isolated from the internet this will allow the
user to update system date/time from the nwipe GUI rather than
having to drop into the command line.

To complete this feature next will be to create the write_system_datetime
function.

src/gui.c

@@ -28,6 +28,17 @@
  *   and things like ncurses libmenu are not worth the storage overhead.
  *
  */
+
+#ifndef _DEFAULT_SOURCE
+#define _DEFAULT_SOURCE
+#endif
+
+#ifndef _POSIX_SOURCE
+#define _POSIX_SOURCE
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
 #include <ncurses.h>
 #include <panel.h>
 #include <stdint.h>
@@ -5053,7 +5064,7 @@ void nwipe_gui_set_date_time( void )
             {
                 case 0:
                     /* Set year */
-                    // NOTE ADD Function
+                    nwipe_gui_set_system_year();
                     keystroke = 0;
                     break;
 
@@ -5087,6 +5098,160 @@ void nwipe_gui_set_date_time( void )
 
 } /* end of nwipe_gui_set_date_time( void ) */
 
+void nwipe_gui_set_system_year( void )
+{
+    /**
+     * Allows the user to edit the host systems year
+     *
+     * @modifies  system year
+     * @modifies  main_window
+     *
+     */
+
+    /* The first tabstop. */
+    const int tab1 = 2;
+
+    /* The current working row. */
+    int yy = 2;
+
+    /* Input buffer. */
+    int keystroke;
+
+    /* Various output from the date command is processed in this buffer */
+    char date_buffer[256];
+    date_buffer[0] = 0;
+
+    char year[5] = "";
+    char month[3] = "";
+    char day[3] = "";
+    char hours[3] = "";
+    char minutes[3] = "";
+    char seconds[3] = "";
+
+    /* buffer index */
+    int idx = 0;
+
+    int status = 0;
+
+    FILE* fp;
+
+    extern int terminate_signal;
+
+    /* Update the footer window. */
+    werase( footer_window );
+    nwipe_gui_title( footer_window, selection_footer_text_entry );
+    wrefresh( footer_window );
+
+    fp = popen( "date +%Y", "r" );
+    if( fp == NULL )
+    {
+        nwipe_log( NWIPE_LOG_INFO, "popen:Failed to retrieve date +%Y %s", date_buffer );
+        mvwprintw( main_window, yy + 4, tab1, "popen:date command failed retrieving year" );
+    }
+
+    if( fgets( date_buffer, sizeof( date_buffer ), fp ) == NULL )
+    {
+        nwipe_log( NWIPE_LOG_INFO, "fgets:failed to retrieve year %s", date_buffer );
+        mvwprintw( main_window, yy + 5, tab1, "fgets:failed retrieving year" );
+    }
+
+    /* terminate string after fourth character removing any lf */
+    date_buffer[4] = 0;
+
+    pclose( fp );
+
+    /* Set the buffer index to point to the end of the string, i.e the NULL */
+    idx = strlen( date_buffer );
+
+    do
+    {
+        /* Erase the main window. */
+        werase( main_window );
+
+        nwipe_gui_create_all_windows_on_terminal_resize( 0, selection_footer_text_entry );
+
+        /* Add a border. */
+        box( main_window, 0, 0 );
+
+        /* Add a title. */
+        nwipe_gui_title( main_window, " Set System Year " );
+
+        /* Initialize the working row. */
+        yy = 4;
+
+        mvwprintw( main_window, yy++, tab1, "Enter the current year, four numeric digits, return key to submit" );
+
+        /* Print this line last so that the cursor is in the right place. */
+        mvwprintw( main_window, 2, tab1, ">%s", date_buffer );
+
+        /* Reveal the cursor. */
+        curs_set( 1 );
+
+        /* Refresh the window. */
+        wrefresh( main_window );
+
+        /* Wait 250ms for input from getch, if nothing getch will then continue,
+         * This is necessary so that the while loop can be exited by the
+         * terminate_signal e.g.. the user pressing control-c to exit.
+         * Do not change this value, a higher value means the keys become
+         * sluggish, any slower and more time is spent unnecessarily looping
+         * which wastes CPU cycles.
+         */
+        timeout( 250 );  // block getch() for 250ms.
+        keystroke = getch();  // Get a keystroke.
+        timeout( -1 );  // Switch back to blocking mode.
+
+        switch( keystroke )
+        {
+            /* Escape key. */
+            case 27:
+                return;
+
+            case KEY_BACKSPACE:
+            case KEY_LEFT:
+            case 127:
+
+                if( idx > 0 )
+                {
+                    date_buffer[--idx] = 0;
+                }
+
+                break;
+
+        } /* switch keystroke */
+
+        if( ( keystroke >= ' ' && keystroke <= '~' ) && keystroke != '\"' && idx < FIELD_LENGTH && idx < 4 )
+        {
+            date_buffer[idx++] = keystroke;
+            date_buffer[idx] = 0;
+            mvwprintw( main_window, 2, tab1, ">%s", date_buffer );
+        }
+
+        /* Hide the cursor. */
+        curs_set( 0 );
+
+    } while( keystroke != 10 && terminate_signal != 1 );
+
+    /* Write year back to system */
+    status = read_system_datetime( year, month, day, hours, minutes, seconds );
+    if( status == 0 )
+    {
+        nwipe_log( NWIPE_LOG_INFO,
+                   "year=%s, month=%s, day=%s, hours=%s, minutes=%s, seconds=%s",
+                   year,
+                   month,
+                   day,
+                   hours,
+                   minutes,
+                   seconds );
+    }
+    else
+    {
+        nwipe_log( NWIPE_LOG_ERROR, "func:read_system_datetime failed, see previous messages for detail" );
+    }
+
+} /* End of nwipe_gui_set_system_year() */
+
 void nwipe_gui_load( void )
 {
     /**

src/gui.h

@@ -68,6 +68,7 @@ void nwipe_gui_add_customer_contact_name( char* );  // Add new customer contact
 void nwipe_gui_add_customer_contact_phone( char* );  // Add new customer contact phone
 int nwipe_gui_yes_no_footer( void );  // Change footer to yes no
 void nwipe_gui_preview_org_customer( void );  // Preview window  for wipe organisation and customer
+void nwipe_gui_set_system_year( void );  // Set the systems current year
 
 /**
  * Truncate a string based on start position and terminal width