Allow shell environment to not be inherited

The parent shell environment can now be inherited by passing the "-i,
--inherit" argument, but by default will NOT be inherited.

.gitmodules

@@ -1,3 +1,3 @@
 [submodule "dmd_core"]
 	path = dmd_core
-	url = git@github.com:sethm/dmd_core.git
+	url = https://github.com/sethm/dmd_core.git

README.md

@@ -4,7 +4,7 @@ This is a GTK+ 3.0 implementation of an AT&T / Teletype DMD 5620 emulator.
 
 ## Status
 
-Version: 2.0.1
+Version: 2.1.0
 
 This is an actively developed project.
 
@@ -32,12 +32,13 @@ The executable has the following dependencies:
 ### Running the Terminal
 
 ```
-Usage: dmd5620 [-h] [-v] [-d DEV|-s SHELL] \
+Usage: dmd5620 [-h] [-v] [-i] [-d DEV|-s SHELL] \
                [-f VER] [-n FILE] [-- <gtk_options> ...]
 AT&T DMD 5620 Terminal emulator.
 
 -h, --help              display help and exit
 -v, --version           display version and exit
+-i, --inherit           inherit parent environment
 -f, --firmware VER      Firmware version ("8;7;3" or "8;7;5")
 -d, --device DEV        serial port name
 -s, --shell SHELL       execute SHELL instead of default user shell
@@ -46,6 +47,7 @@ AT&T DMD 5620 Terminal emulator.
 
 - `--help` displays the help shown above, and exits.
 - `--version` displays the executable version number, and exits.
+- `--inherit` inherit parent shell environment.
 - `--firmware VER` selects the firmware version to use. Older DMD
    terminals used firmware version "8;7;3". Newer terminals used firmware
    version "8;7;5". The version must be specified as a string, and is
@@ -89,6 +91,17 @@ Certain keys are mapped to special DMD5620 function keys.
 
 ## Changelog
 
+### Version 2.1.0
+
+* Sub-processes now inherit the user's environment.
+* Maximum execution rate is limited to prevent runaway starvation of
+  resources and slow performance.
+  
+### Version 2.0.1
+
+* Several major bug fixes to the UART code on the back end.
+* Now supports the ability to run firmware version 8;7;3 and 8;7;5.
+
 ### Version 1.4.1
 
 * Did away with multi-threaded execution and significantly improved timing.

dmd_core

@@ -1 +1 @@
-Subproject commit 03d0d36061e1dad2f3b0e3d1d670c817f0cf056f
+Subproject commit 73ea34e619a2a726213682f6c498c9abc3a29902

src/dmd_5620.c

@@ -40,6 +40,7 @@
 #else
 #include <pty.h>
 #endif
+#include <stdbool.h>
 #include <stdlib.h>
 #include <utmp.h>
 #include <fcntl.h>
@@ -62,6 +63,7 @@
 
 #define PCHAR(p)   (((p) >= 0x20 && (p) < 0x7f) ? (p) : '.')
 #define TX_BUF_LEN    64
+#define MAX_STEPS     350000
 
 char VERSION_STRING[64];
 GtkWidget *main_window;
@@ -69,14 +71,13 @@ cairo_surface_t *surface = NULL;
 GdkPixbuf *pixbuf = NULL;
 int pty_master, pty_slave;
 char *nvram = NULL;
-gint64 previous_clock = -1;
-uint8_t previous_vram[VIDRAM_SIZE];
+size_t previous_clock = 0;
 struct pollfd fds[2];
 pid_t shell_pid;
-volatile int window_beep = FALSE;
-volatile int dmd_thread_run = TRUE;
+volatile bool window_beep = true;
 int sigint_count = 0;
 int tty_fd = -1;
+bool debug = false;
 
 void
 int_handler(int signal)
@@ -114,7 +115,6 @@ close_window()
         cairo_surface_destroy(surface);
     }
 
-    dmd_thread_run = 0;
     gtk_main_quit();
 }
 
@@ -139,8 +139,8 @@ gboolean
 draw_handler(GtkWidget *widget, cairo_t *cr, gpointer data)
 {
     cairo_set_source_surface(cr, surface, 0, 0);
+    gdk_cairo_set_source_pixbuf(cr, pixbuf, 0, 0);
     cairo_paint(cr);
-
     return FALSE;
 }
 
@@ -148,6 +148,9 @@ gboolean
 refresh_display(GtkWidget *widget, gpointer data)
 {
     uint8_t oport;
+    uint8_t *vram;
+    guchar *pixel_data;
+    uint32_t pixel_data_index;
     GdkWindow *window;
     const struct color *fg_color;
     const struct color *bg_color;
@@ -157,20 +160,18 @@ refresh_display(GtkWidget *widget, gpointer data)
 
     if (window_beep) {
         gdk_window_beep(window);
-        window_beep = FALSE;
+        window_beep = false;
     }
 
-    uint8_t *vram = dmd_video_ram();
-
-    if (memcmp(previous_vram, vram, VIDRAM_SIZE) == 0) {
+    /* If the video RAM hasn't been updated, there's nothing to do */
+    if (!dmd_video_ram_dirty()) {
         return TRUE;
     }
 
-    memcpy(previous_vram, vram, VIDRAM_SIZE);
+    vram = dmd_video_ram();
 
-    guchar *p = gdk_pixbuf_get_pixels(pixbuf);
-    uint32_t p_index = 0;
-    int byte_width = WIDTH / 8;
+    pixel_data = gdk_pixbuf_get_pixels(pixbuf);
+    pixel_data_index = 0;
 
     if (vram == NULL) {
         fprintf(stderr, "ERROR: Unable to access video ram!\n");
@@ -190,33 +191,27 @@ refresh_display(GtkWidget *widget, gpointer data)
         }
 
         for (int y = 0; y < HEIGHT; y++) {
-            for (int x = 0; x < byte_width; x++) {
-                uint8_t b = vram[y*byte_width + x];
+            for (int x = 0; x < WIDTH_IN_BYTES; x++) {
+                uint8_t b = vram[y*WIDTH_IN_BYTES + x];
                 for (int i = 0; i < 8; i++) {
                     int bit = (b >> (7 - i)) & 1;
                     if (bit) {
-                        p[p_index++] = fg_color->r;
-                        p[p_index++] = fg_color->g;
-                        p[p_index++] = fg_color->b;
-                        p[p_index++] = fg_color->a;
+                        pixel_data[pixel_data_index++] = fg_color->r;
+                        pixel_data[pixel_data_index++] = fg_color->g;
+                        pixel_data[pixel_data_index++] = fg_color->b;
+                        pixel_data[pixel_data_index++] = fg_color->a;
                     } else {
-                        p[p_index++] = bg_color->r;
-                        p[p_index++] = bg_color->g;
-                        p[p_index++] = bg_color->b;
-                        p[p_index++] = bg_color->a;
+                        pixel_data[pixel_data_index++] = bg_color->r;
+                        pixel_data[pixel_data_index++] = bg_color->g;
+                        pixel_data[pixel_data_index++] = bg_color->b;
+                        pixel_data[pixel_data_index++] = bg_color->a;
                     }
                 }
             }
         }
     }
 
-    cairo_t *cr;
-    cr = cairo_create(surface);
-    gdk_cairo_set_source_pixbuf(cr, pixbuf, 0, 0);
-    cairo_paint(cr);
-    cairo_fill(cr);
-    cairo_destroy(cr);
-
+    /* Notify the widget that it should repaint itself */
     gtk_widget_queue_draw(widget);
 
     return TRUE;
@@ -226,8 +221,7 @@ gboolean
 simulation_main_loop(GtkWidget *widget, GdkFrameClock *clock, gpointer data)
 {
     uint8_t kbc;
-    gint64 now;
-    size_t steps;
+    size_t now, steps;
 
     /*
      * Poll for simulator I/O
@@ -256,14 +250,26 @@ simulation_main_loop(GtkWidget *widget, GdkFrameClock *clock, gpointer data)
      */
     now = gdk_frame_clock_get_frame_time(clock);
 
-    if (previous_clock >= 0) {
-        /* We take 10 simulated steps per microsecond of wall clock
-         * time, based on a 10 MHz WE 32100 CPU */
-        steps = MIN(10 * (now - previous_clock), 10000000);
+    if (previous_clock > 0) {
+        /* We take 7.2 simulated steps per microsecond of wall clock
+         * time, based on a 7.2 MHz WE 32100 CPU. The maximum number of
+         * steps allowed is limited in order to prevent the CPU
+         * simulation from stealing too much processing time if
+         * running on a system with a slower main GTK thread refresh
+         * rate. */
+        size_t delta = now - previous_clock;
+        steps = MIN((size_t)(7.2 * delta), MAX_STEPS);
+        if (debug) {
+            printf("[MAIN LOOP] executing %lu steps in %lu us. rate ~= %.2f MHz\n",
+                   steps,
+                   delta,
+                   (float)steps / (float)delta);
+        }
     } else {
-        steps = 100000;
+        steps = MAX_STEPS;
     }
 
+
     previous_clock = now;
 
     /* Actually call the core CPU library */
@@ -271,8 +277,6 @@ simulation_main_loop(GtkWidget *widget, GdkFrameClock *clock, gpointer data)
 
     /* Now refresh the display */
     return refresh_display(widget, data);
-
-    return TRUE;
 }
 
 gboolean
@@ -309,7 +313,7 @@ mouse_button(GtkWidget *widget, GdkEventButton *event, gpointer data)
  * Initialize a shell PTY
  */
 void
-pty_init(const char *shell)
+pty_init(const char *shell, char *envp[])
 {
     char pty_name[64];
 
@@ -333,7 +337,6 @@ pty_init(const char *shell)
         exit(-1);
     } else if (shell_pid == 0) {
         /* Child */
-        char *const env[] = {"TERM=dmd", NULL};
         int retval;
         close(pty_master);
 
@@ -350,9 +353,9 @@ pty_init(const char *shell)
         close(pty_slave);
 
         if (shell) {
-            retval = execle(shell, "-", NULL, env);
+            retval = execle(shell, "-", NULL, envp);
         } else {
-            retval = execle("/bin/sh", "-", NULL, env);
+            retval = execle("/bin/sh", "-", NULL, envp);
         }
 
         /* Child process is now replaced, nothing beyond this point
@@ -361,6 +364,7 @@ pty_init(const char *shell)
             perror("Could not start shell process: ");
             exit(-1);
         }
+        close(pty_master);
     }
 
     close(pty_slave);
@@ -471,11 +475,6 @@ tty_io_poll()
     }
 }
 
-void
-tty_set_blocking(int fd, int should_block)
-{
-}
-
 gboolean
 keydown(GtkWidget *widget, GdkEventKey *event, gpointer data)
 {
@@ -667,29 +666,115 @@ keydown(GtkWidget *widget, GdkEventKey *event, gpointer data)
     return TRUE;
 }
 
+void
+show_about()
+{
+    GtkWidget *dialog;
+    GtkWidget *label;
+    GtkWidget *content_area;
+    GtkDialogFlags flags = GTK_DIALOG_DESTROY_WITH_PARENT;
+
+    const char *message = "Copyright (c) 2018-2022, Seth J. Morabito <web@loomcom.com>\n"
+        "More information can be found on https://loomcom.com/\n";
+
+    dialog = gtk_dialog_new_with_buttons("About",
+                                         GTK_WINDOW(main_window),
+                                         flags,
+                                         "Close",
+                                         GTK_RESPONSE_NONE,
+                                         NULL);
+
+    content_area = gtk_dialog_get_content_area(GTK_DIALOG(dialog));
+
+    gtk_widget_set_margin_start(content_area, 20);
+    gtk_widget_set_margin_end(content_area, 20);
+    gtk_widget_set_margin_top(content_area, 20);
+    gtk_widget_set_margin_bottom(content_area, 20);
+
+    label = gtk_label_new(message);
+
+    g_signal_connect_swapped(dialog, "response", G_CALLBACK(gtk_widget_destroy), dialog);
+
+    gtk_container_add(GTK_CONTAINER(content_area), label);
+    gtk_widget_show_all(dialog);
+}
+
+void
+build_menu(GtkWidget *menu_bar)
+{
+    GtkWidget *file_menu;
+    GtkWidget *help_menu;
+
+    GtkWidget *file_mi;
+    GtkWidget *quit_mi;
+
+    GtkWidget *help_mi;
+    GtkWidget *about_mi;
+
+
+    file_menu = gtk_menu_new();
+    help_menu = gtk_menu_new();
+
+    file_mi = gtk_menu_item_new_with_label("File");
+    quit_mi = gtk_menu_item_new_with_label("Quit");
+
+    help_mi = gtk_menu_item_new_with_label("Help");
+    about_mi = gtk_menu_item_new_with_label("About");
+
+    gtk_menu_item_set_submenu(GTK_MENU_ITEM(file_mi), file_menu);
+    gtk_menu_shell_append(GTK_MENU_SHELL(file_menu), quit_mi);
+
+    gtk_menu_item_set_submenu(GTK_MENU_ITEM(help_mi), help_menu);
+    gtk_menu_shell_append(GTK_MENU_SHELL(help_menu), about_mi);
+
+    gtk_menu_shell_append(GTK_MENU_SHELL(menu_bar), file_mi);
+    gtk_menu_shell_append(GTK_MENU_SHELL(menu_bar), help_mi);
+
+    /* Exit when user selects "Quit" from menu */
+    g_signal_connect(quit_mi, "activate", G_CALLBACK(close_window), NULL);
+    g_signal_connect(about_mi, "activate", G_CALLBACK(show_about), NULL);
+}
+
 void
 gtk_setup(int *argc, char ***argv)
 {
     GtkWidget *drawing_area;
+    GtkWidget *menu_bar;
+    GtkWidget *box;
 
     gtk_init(argc, argv);
 
+    /* Create the main window */
     main_window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
+
+    /* Be sure to exit cleanly when the user closes the window! */
+    g_signal_connect(main_window, "destroy", G_CALLBACK(close_window), NULL);
+
+    /* Set some properties on the main window */
     gtk_window_set_icon_name(GTK_WINDOW(main_window), "dmd5620");
     gtk_window_set_title(GTK_WINDOW(main_window), "AT&T DMD 5620");
     gtk_window_set_resizable(GTK_WINDOW(main_window), FALSE);
-
-    g_signal_connect(main_window, "destroy", G_CALLBACK(close_window), NULL);
-
     gtk_container_set_border_width(GTK_CONTAINER(main_window), 0);
 
+    /* Create a GTK Box to contain menu and drawing area */
+    box = gtk_box_new(GTK_ORIENTATION_VERTICAL, 0);
+
+    /* TODO: Make border width configurable */
+    gtk_container_set_border_width(GTK_CONTAINER(box), 5);
+
+    /* Build the menu */
+    menu_bar = gtk_menu_bar_new();
+    build_menu(menu_bar);
+
+    /* Stuff the menu into the container. */
+    gtk_box_pack_start(GTK_BOX(box), menu_bar, FALSE, FALSE, 0);
+
     drawing_area = gtk_drawing_area_new();
 
     gtk_widget_set_size_request(drawing_area, 800, 1024);
+    gtk_box_pack_end(GTK_BOX(box), drawing_area, FALSE, FALSE, 0);
 
-    gtk_window_set_resizable(GTK_WINDOW(main_window), FALSE);
-
-    gtk_container_add(GTK_CONTAINER(main_window), drawing_area);
+    gtk_container_add(GTK_CONTAINER(main_window), box);
 
     /* Set up the animation handler, which will step the simulation
        and draw the display in an infinite loop */
@@ -719,24 +804,28 @@ gtk_setup(int *argc, char ***argv)
                           | GDK_POINTER_MOTION_MASK);
 
     gtk_widget_show_all(main_window);
+    gtk_window_present(GTK_WINDOW(main_window));
 }
 
 struct option long_options[] = {
     {"help", no_argument, 0, 'h'},
     {"version", no_argument, 0, 'v'},
+    {"inherit", no_argument, 0, 'i'},
     {"firmware", required_argument, 0, 'f'},
     {"shell", required_argument, 0, 's'},
     {"device", required_argument, 0, 'd'},
     {"nvram", required_argument, 0, 'n'},
+    {"debug", no_argument, 0, 'b'}, /* Hidden and undocumented */
     {0, 0, 0, 0}};
 
 void usage()
 {
-    printf("Usage: dmd5620 [-h] [-v] [-d DEV|-s SHELL] \\\n"
+    printf("Usage: dmd5620 [-h] [-v] [-i] [-d DEV|-s SHELL] \\\n"
            "               [-f VER] [-n FILE] [-- <gtk_options> ...]\n");
     printf("AT&T DMD 5620 Terminal emulator.\n\n");
     printf("-h, --help              display help and exit\n");
     printf("-v, --version           display version and exit\n");
+    printf("-i, --inherit           inherit parent environment\n");
     printf("-f, --firmware VER      Firmware version (\"8;7;3\" or \"8;7;5\")\n");
     printf("-d, --device DEV        serial port name\n");
     printf("-s, --shell SHELL       execute SHELL instead of default user shell\n");
@@ -747,7 +836,7 @@ const char *FIRMWARE_873 = "8;7;3";
 const char *FIRMWARE_875 = "8;7;5";
 
 int
-main(int argc, char *argv[])
+main(int argc, char *argv[], char *envp[])
 {
     int c, errflg = 0;
     char *shell = NULL;
@@ -757,6 +846,7 @@ main(int argc, char *argv[])
     uint8_t nvram_buf[NVRAM_SIZE];
     FILE *fp;
     struct stat sb;
+    bool inherit = false; /* Inherit parent environment */
 
     snprintf(VERSION_STRING, 64, "%d.%d.%d",
              VERSION_MAJOR, VERSION_MINOR, VERSION_BUILD);
@@ -769,7 +859,7 @@ main(int argc, char *argv[])
 
     int option_index = 0;
 
-    while ((c = getopt_long(argc, argv, "vhd:n:t:p:s:f:",
+    while ((c = getopt_long(argc, argv, "hivbd:n:t:p:s:f:",
                             long_options, &option_index)) != -1) {
         switch(c) {
         case 0:
@@ -777,9 +867,15 @@ main(int argc, char *argv[])
         case 'h':
             usage();
             exit(0);
+        case 'i':
+            inherit = true;
+            break;
         case 'v':
             printf("Version: %s\n", VERSION_STRING);
             exit(0);
+        case 'b': /* Hidden and undocumented */
+            debug = true;
+            break;
         case 'n':
             nvram = optarg;
             break;
@@ -819,7 +915,7 @@ main(int argc, char *argv[])
             fprintf(stderr, "Cannot open %s as shell, or file is not executable.\n", shell);
             return -1;
         }
-        pty_init(shell);
+        pty_init(shell, inherit ? envp : NULL);
     } else {
         if (stat(device, &sb) != 0) {
             fprintf(stderr, "Cannot open device %s.\n", device);

src/dmd_5620.h

@@ -32,6 +32,7 @@
 #include <gtk/gtk.h>
 
 #define WIDTH 800
+#define WIDTH_IN_BYTES 100
 #define HEIGHT 1024
 #define NVRAM_SIZE 2<<12
 #define VIDRAM_SIZE 1024 * 100
@@ -50,6 +51,7 @@ const struct color COLOR_DARK = { 0, 0, 0, 255 };
 
 /* dmd_core exported functions */
 extern uint8_t *dmd_video_ram();
+extern int dmd_video_ram_dirty();
 extern int dmd_init(uint8_t version);
 extern int dmd_step();
 extern int dmd_step_loop(size_t steps);

src/version.h

@@ -28,7 +28,7 @@
 #define __VERSION_H__
 
 #define VERSION_MAJOR 2
-#define VERSION_MINOR 0
-#define VERSION_BUILD 1
+#define VERSION_MINOR 1
+#define VERSION_BUILD 0
 
 #endif