Add fallback method to get window size

kilo.c

@@ -1,4 +1,6 @@
 #include <errno.h>
+#include <ctype.h>
+#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/ioctl.h>
@@ -7,13 +9,16 @@
 
 void enable_raw_mode();
 void disable_raw_mode();
+
 int get_window_size(int *, int *);
+int read_cursor_position(int *, int *);
 
 void editor_init();
 void editor_redraw_screen();
 void editor_clear_screen();
 void editor_draw_rows();
 void editor_process_key();
+char editor_read_key();
 
 void die(const char *);
 
@@ -23,11 +28,11 @@ struct {
     struct termios orig_termios;
     int rows;
     int cols;
-} E;
+    bool raw;
+} E = { .raw = false };
 
 int main() {
     editor_init();
-    enable_raw_mode();
 
     while (1) {
         editor_redraw_screen();
@@ -37,14 +42,32 @@ int main() {
     return 0;
 }
 
+void editor_init() {
+    if (!isatty(STDIN_FILENO)) {
+        printf("kilo only supports a terminal at standard in. Exiting.");
+        exit(1);
+    }
+
+    enable_raw_mode();
+
+    if (get_window_size(&E.rows, &E.cols) == -1) die("get_window_size");
+}
+
 void enable_raw_mode() {
+    if (E.raw) return;
+
     if (tcgetattr(STDIN_FILENO, &E.orig_termios) == -1) die("tcgetattr");
     atexit(disable_raw_mode);
 
     struct termios raw = E.orig_termios;
     cfmakeraw(&raw);
 
+    raw.c_cc[VMIN]  = 0;
+    raw.c_cc[VTIME] = 1;
+
     if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &raw) == -1) die("tcsetattr");
+
+    E.raw = true;
 }
 
 void disable_raw_mode() {
@@ -55,23 +78,37 @@ void disable_raw_mode() {
 int get_window_size(int *rows, int *cols) {
     struct winsize ws;
 
-    if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) != -1 && ws.ws_col != 0) {
+    if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) != -1 && ws.ws_col != 0) {
         *rows = ws.ws_row;
         *cols = ws.ws_col;
 
         return 0;
+    } else {
+        if (write(STDOUT_FILENO, "\x1b[999C\x1b[999B", 12) != 12) return -1;
+        return read_cursor_position(rows, cols);
     }
-
+    
     return -1;
 }
 
-void editor_init() {
+int read_cursor_position(int *rows, int *cols) {
-    if (!isatty(STDIN_FILENO)) {
+    char buf[32];
-        printf("kilo only supports a terminal at standard in. Exiting.");
+    unsigned int i = 0;
-        exit(1);
-    }
 
-    if (get_window_size(&E.rows, &E.cols) == -1) die("get_window_size");
+    if (write(STDOUT_FILENO, "\x1b[6n", 4) != 4) return -1;
+
+    if (read(STDIN_FILENO, buf, 1) != 1 && *buf != '\x1b') return -1;
+    if (read(STDIN_FILENO, buf, 1) != 1 && *buf != '[') return -1;
+
+    do {
+        if (i == sizeof(buf)) return -1;
+        if (read(STDIN_FILENO, buf+i, 1) == 0) break;
+    } while(buf[i++] != 'R');
+    buf[i-1] = '\0';
+
+    if (sscanf(buf, "%d;%d", rows, cols) != 2) return -1;
+    
+    return 0;
 }
 
 void editor_redraw_screen() {
@@ -79,24 +116,22 @@ void editor_redraw_screen() {
 
     editor_draw_rows();
 
-    write(STDIN_FILENO, "\x1b[H", 3);
+    write(STDOUT_FILENO, "\x1b[H", 3);
 }
 
 void editor_clear_screen() {
-    write(STDIN_FILENO, "\x1b[2J", 4);
+    write(STDOUT_FILENO, "\x1b[2J", 4);
-    write(STDIN_FILENO, "\x1b[H", 3);
+    write(STDOUT_FILENO, "\x1b[H", 3);
 }
 
 void editor_draw_rows() {
     for (int y = 0; y < E.rows - 1; y++)
-        write(STDIN_FILENO, "~\r\n", 3);
+        write(STDOUT_FILENO, "~\r\n", 3);
-    write(STDIN_FILENO, "~", 1);
+    write(STDOUT_FILENO, "~", 1);
 }
 
 void editor_process_key() {
-    char c;
+    char c = editor_read_key();
-    read(STDIN_FILENO, &c, 1);
-
     switch (c) {
         case CTRL_KEY('Q'):
             editor_clear_screen();
@@ -108,6 +143,12 @@ void editor_process_key() {
     }
 }
 
+char editor_read_key() {
+    char c;
+    while (read(STDIN_FILENO, &c, 1) == 0);
+    return c;
+}
+
 void die(const char *s) {
     editor_clear_screen();