Clear with NULL character. Do not include NULLs in copied text.

protocols/ssh/include/common.h

@@ -38,6 +38,8 @@
 #ifndef _SSH_GUAC_COMMON_H
 #define _SSH_GUAC_COMMON_H
 
+#include <stdbool.h>
+
 /**
  * Returns the closest value to the value given that is also
  * within the given range.
@@ -50,5 +52,11 @@ int guac_terminal_fit_to_range(int value, int min, int max);
  */
 int guac_terminal_encode_utf8(int codepoint, char* utf8);
 
+/**
+ * Returns whether a codepoint has a corresponding glyph, or is rendered
+ * as a blank space.
+ */
+bool guac_terminal_has_glyph(int codepoint);
+
 #endif
 

protocols/ssh/src/common.c

@@ -35,6 +35,8 @@
  *
  * ***** END LICENSE BLOCK ***** */
 
+#include <stdbool.h>
+
 int guac_terminal_fit_to_range(int value, int min, int max) {
 
     if (value < min) return min;
@@ -90,3 +92,9 @@ int guac_terminal_encode_utf8(int codepoint, char* utf8) {
 
 }
 
+bool guac_terminal_has_glyph(int codepoint) {
+    return
+           codepoint != 0
+        && codepoint != ' ';
+}
+

protocols/ssh/src/display.c

@@ -547,7 +547,7 @@ void guac_terminal_display_resize(guac_terminal_display* display, int width, int
 
     /* Fill with background color (index 0) */
     guac_terminal_char fill = {
-        .value = ' ',
+        .value = 0,
         .attributes = {
             .foreground = 0,
             .background = 0
@@ -743,7 +743,7 @@ void __guac_terminal_display_flush_clear(guac_terminal_display* display) {
 
             /* If operation is a cler operation (set to space) */
             if (current->type == GUAC_CHAR_SET &&
-                    current->character.value == ' ') {
+                    !guac_terminal_has_glyph(current->character.value)) {
 
                 /* The determined bounds of the rectangle of contiguous
                  * operations */
@@ -786,7 +786,7 @@ void __guac_terminal_display_flush_clear(guac_terminal_display* display) {
 
                         /* If not identical operation, stop */
                         if (rect_current->type != GUAC_CHAR_SET
-                                || rect_current->character.value != ' '
+                                || guac_terminal_has_glyph(rect_current->character.value)
                                 || joining_color != color)
                             break;
 
@@ -831,7 +831,7 @@ void __guac_terminal_display_flush_clear(guac_terminal_display* display) {
 
                         /* Mark clear operations as NOP */
                         if (rect_current->type == GUAC_CHAR_SET
-                                && rect_current->character.value == ' '
+                                && !guac_terminal_has_glyph(rect_current->character.value)
                                 && joining_color == color)
                             rect_current->type = GUAC_CHAR_NOP;
 

protocols/ssh/src/terminal.c

@@ -58,7 +58,7 @@ guac_terminal* guac_terminal_create(guac_client* client,
         int width, int height) {
 
     guac_terminal_char default_char = {
-        .value = ' ',
+        .value = 0,
         .attributes = {
             .foreground = 7,
             .background = 0,
@@ -208,7 +208,7 @@ int guac_terminal_clear_columns(guac_terminal* term,
 
     /* Build space */
     guac_terminal_char blank;
-    blank.value = ' ';
+    blank.value = 0;
     blank.attributes = term->current_attributes;
 
     /* Clear */
@@ -415,11 +415,18 @@ int __guac_terminal_buffer_string(guac_terminal_buffer_row* row, int start, int
     int length = 0;
     int i;
     for (i=start; i<=end; i++) {
-        int bytes = guac_terminal_encode_utf8(row->characters[i].value, string);
+
+        int codepoint = row->characters[i].value;
+
+        /* If not null (blank), add to string */
+        if (codepoint != 0) {
+            int bytes = guac_terminal_encode_utf8(codepoint, string);
             string += bytes;
             length += bytes;
         }
 
+    }
+
     return length;
 
 }