kernel: Implement querying the terminal window size

kernel/src/fs/devices/ConsoleDevice.cpp

@@ -198,6 +198,13 @@ Result<u64> ConsoleDevice::ioctl(int request, void* arg)
         if (!MemoryManager::copy_to_user_typed((pid_t*)arg, &pgid)) return err(EFAULT);
         return 0;
     }
+    case TIOCGWINSZ: {
+        struct winsize window;
+        window.ws_col = TextConsole::cols();
+        window.ws_row = TextConsole::rows();
+        if (!MemoryManager::copy_to_user_typed((struct winsize*)arg, &window)) return err(EFAULT);
+        return 0;
+    }
     default: return err(EINVAL);
     }
 }

kernel/src/video/TextConsole.cpp

@@ -207,4 +207,14 @@ namespace TextConsole
         va_end(ap);
         return rc;
     }
+
+    u16 rows()
+    {
+        return Framebuffer::height() / FONT_HEIGHT;
+    }
+
+    u16 cols()
+    {
+        return Framebuffer::width() / FONT_WIDTH;
+    }
 }

kernel/src/video/TextConsole.h

@@ -19,4 +19,7 @@ namespace TextConsole
     Result<void> println(const char* str);
     void wprintln(const wchar_t* str);
     Result<usize> printf(const char* format, ...) _format(1, 2);
+
+    u16 rows();
+    u16 cols();
 }

libc/include/bits/termios.h

@@ -11,6 +11,14 @@ struct termios
     tcflag_t c_lflag;
 };
 
+struct winsize
+{
+    u16 ws_row;
+    u16 ws_col;
+    u16 ws_xpixel;
+    u16 ws_ypixel;
+};
+
 // Values for c_lflag.
 #define ECHO 1
 #define TOSTOP 2
@@ -20,5 +28,6 @@ struct termios
 #define TCSETS 1
 #define TIOCSPGRP 2
 #define TIOCGPGRP 3
+#define TIOCGWINSZ 4
 
 #endif