vterm_screen_get_cell() should return int to indicate bounds-checking failure

3 files changed, 7 insertions, 4 deletions

diff --git a/include/vterm.h b/include/vterm.h
index 191edec..90507d3 100644
--- a/include/vterm.h
+++ b/include/vterm.h
@@ -213,7 +213,7 @@ typedef struct {
   VTermColor fg, bg;
 } VTermScreenCell;
 
-void vterm_screen_get_cell(VTermScreen *screen, VTermPos pos, VTermScreenCell *cell);
+int vterm_screen_get_cell(VTermScreen *screen, VTermPos pos, VTermScreenCell *cell);
 
 int vterm_screen_is_eol(VTermScreen *screen, VTermPos pos);
 
diff --git a/src/screen.c b/src/screen.c
index 994c645..1fdb793 100644
--- a/src/screen.c
+++ b/src/screen.c
@@ -620,11 +620,11 @@ size_t vterm_screen_get_text(VTermScreen *screen, char *str, size_t len, const V
 }
 
 /* Copy internal to external representation of a screen cell */
-void vterm_screen_get_cell(VTermScreen *screen, VTermPos pos, VTermScreenCell *cell)
+int vterm_screen_get_cell(VTermScreen *screen, VTermPos pos, VTermScreenCell *cell)
 {
   ScreenCell *intcell = getcell(screen, pos.row, pos.col);
   if(!intcell)
-    return;
+    return 0;
 
   for(int i = 0; ; i++) {
     cell->chars[i] = intcell->chars[i];
@@ -648,6 +648,8 @@ void vterm_screen_get_cell(VTermScreen *screen, VTermPos pos, VTermScreenCell *c
     cell->width = 2;
   else
     cell->width = 1;
+
+  return 1;
 }
 
 int vterm_screen_is_eol(VTermScreen *screen, VTermPos pos)
diff --git a/t/harness.c b/t/harness.c
index a8b6dcd..08580e2 100644
--- a/t/harness.c
+++ b/t/harness.c
@@ -715,7 +715,8 @@ int main(int argc, char **argv)
           goto abort_line;
         }
         VTermScreenCell cell;
-        vterm_screen_get_cell(screen, pos, &cell);
+        if(!vterm_screen_get_cell(screen, pos, &cell))
+          goto abort_line;
         printf("{");
         for(int i = 0; cell.chars[i] && i < VTERM_MAX_CHARS_PER_CELL; i++) {
           printf("%s0x%x", i ? "," : "", cell.chars[i]);