Add support to handle terminal resizing

Got stuck on a bug for a while, fix was to check for errors when using
system calls. Lesson learned.

include/buffer.h

@@ -4,9 +4,9 @@
 #include <stdbool.h>
 #include <stddef.h>
 
-#include "erow.h"
 #include "utils.h"
 
+struct erow;
 struct buffer {
     char *filename;
 

include/cursor.h

@@ -1,8 +1,7 @@
 #ifndef CURSOR_H
 #define CURSOR_H
 
-#include "buffer.h"
+struct buffer;
-
 void cursor_move(struct buffer *buffer, int dx, int dy);
 
 #endif // CURSOR_H

src/kilo.c

@@ -1,4 +1,7 @@
+#define _POSIX_C_SOURCE 199309L
+
 #include <ctype.h>
+#include <signal.h>
 #include <stdarg.h>
 #include <stdbool.h>
 #include <stdio.h>
@@ -15,6 +18,7 @@
 #include "utils.h"
 
 void editor_init(char *filename);
+void editor_resize();
 
 struct editor_state E;
 
@@ -39,7 +43,6 @@ void editor_init(char *filename) {
 
     if (terminal_get_win_size(&E.screenrows, &E.screencols) == -1)
         die("term_get_win_size");
-    E.screenrows -= 2;
     E.quit_times = 3;
 
     E.current_buf = buffer_create();
@@ -48,6 +51,10 @@ void editor_init(char *filename) {
 
     editor_set_message("Welcome to kilo! | CTRL-Q: Quit | CTRL-S: SAVE");
     terminal_clear();
+
+    struct sigaction sa;
+    sa.sa_handler = editor_resize;
+    sigaction(SIGWINCH, &sa, NULL);
 }
 
 void editor_set_message(const char *fmt, ...) {
@@ -112,3 +119,10 @@ success:
     editor_set_message("");
     return buf;
 }
+
+void editor_resize() {
+    if (terminal_get_win_size(&E.screenrows, &E.screencols) == -1)
+        die("term_get_win_size");
+
+    ui_draw_screen();
+}

src/terminal.c

@@ -48,7 +48,7 @@ ERRCODE terminal_get_win_size(int *row, int *col) {
     struct winsize ws;
 
     if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) != -1 && ws.ws_col != 0) {
-        *row = ws.ws_row;
+        *row = ws.ws_row - 2;
         *col = ws.ws_col;
 
         return 0;
@@ -56,7 +56,14 @@ ERRCODE terminal_get_win_size(int *row, int *col) {
         // Fallback implementation
         if (write(STDOUT_FILENO, "\x1b[999C\x1b[999B", 12) != 12) return -1;
 
-        return terminal_get_cursor_pos(row, col);
+        int _row, _col;
+        ERRCODE get_err = terminal_get_cursor_pos(&_row, &_col);
+        if (get_err == 0) {
+            *row = _row - 2;
+            *col = _col;
+        }
+
+        return get_err;
     }
 }
 
@@ -90,8 +97,13 @@ ERRCODE terminal_set_cursor_pos(int row, int col) {
 
 KEY terminal_read_key(void) {
     char c;
-    int n;
+
-    while (read(STDIN_FILENO, &c, 1) == 0);
+    ssize_t read_return = 0;
+    while (read_return == 0)
+        read_return = read(STDIN_FILENO, &c, 1);
+
+    if (read_return == -1)
+        return NOP;
 
     if (c == '\x1b') {
         char buf[8] = { '\0' };
@@ -105,7 +117,7 @@ KEY terminal_read_key(void) {
             char escape_char;
             int escape_int;
 
-            n = 0;
+            int n = 0;
             sscanf(buf, "[%c%n", &escape_char, &n);
             if (n > 0) {
                 switch (escape_char) {