feat: Fallback to ioctl get window size with cursor position.

kilo.c

@@ -71,12 +71,42 @@ char editorReadKey() {
     return c;
 }
 
+int getCursorPosition(int *rows, int *cols) {
+    if (write(STDOUT_FILENO, "\x1b[6n", 4) != 4) {
+        return -1;
+    }
+
+    char buf[32];
+    unsigned int i = 0;
+    // Leave space for null terminator.
+    while (i < sizeof(buf) - 1) {
+        if (read(STDIN_FILENO, &buf[i], 1) != 1)
+            break;
+        if (buf[i] == 'R')
+            break;
+        i++;
+    }
+    buf[i] = '\0';
+
+    if (buf[0] != '\x1b' || buf[1] != '[')
+        return -1;
+    if (sscanf(&buf[2], "%d;%d", rows, cols) != 2)
+        return -1;
+
+    return 0;
+}
+
 int getWindowSize(int *rows, int *cols) {
     struct winsize ws;
 
     if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) == -1 || ws.ws_col == 0) {
+        // Fallback if ioctl can't query size:
+        // Move cursor to the bottom right, then query its position.
+        if (write(STDOUT_FILENO, "\x1b[999C\x1b[999B", 12) != 12) {
             return -1;
         }
+        return getCursorPosition(rows, cols);
+    }
 
     *rows = ws.ws_row;
     *cols = ws.ws_col;