Port debug shell divine size, with improvements, to ttysize

apps/ttysize.c

@@ -1,18 +1,84 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <sys/ioctl.h>
+#include <syscall.h>
+
+static struct termios old;
+
+static void set_unbuffered() {
+	tcgetattr(fileno(stdin), &old);
+	struct termios new = old;
+	new.c_lflag &= (~ICANON & ~ECHO);
+	tcsetattr(fileno(stdin), TCSAFLUSH, &new);
+}
+
+static void set_buffered() {
+	tcsetattr(fileno(stdin), TCSAFLUSH, &old);
+}
+
+static int getc_timeout(FILE * f, int timeout) {
+	int fds[1] = {fileno(f)};
+	int index = syscall_fswait2(1,fds,timeout);
+	if (index == 0) {
+		return fgetc(f);
+	} else {
+		return -1;
+	}
+}
+
+static void divine_size(int * width, int * height) {
+	set_unbuffered();
+
+	*width = 80;
+	*height = 24;
+
+	fprintf(stderr, "\033[s\033[1000;1000H\033[6n\033[H");
+	fflush(stderr);
+
+	char buf[1024] = {0};
+	size_t i = 0;
+	while (1) {
+		char c = getc_timeout(stdin, 200);
+		if (c == 'R') break;
+		if (c == -1) goto _done;
+		if (c == '\033') continue;
+		if (c == '[') continue;
+		buf[i++] = c;
+	}
+
+	char * s = strstr(buf, ";");
+	if (s) {
+		*(s++) = '\0';
+
+		*height = atoi(buf);
+		*width = atoi(s);
+	}
+
+_done:
+	fprintf(stderr,"\033[u");
+	fflush(stderr);
+	set_buffered();
+}
 
 int main(int argc, char * argv[]) {
+	int width, height;
+
 	if (argc < 3) {
-		fprintf(stderr, "Usage: ttysize COLS ROWS\n");
-		return 1;
+		divine_size(&width, &height);
+	} else {
+		width = atoi(argv[1]);
+		height = atoi(argv[2]);
 	}
 
 	struct winsize w;
-	w.ws_col = atoi(argv[1]);
-	w.ws_row = atoi(argv[2]);
+	w.ws_col = width;
+	w.ws_row = height;
 	w.ws_xpixel = 0;
 	w.ws_ypixel = 0;
 	ioctl(0, TIOCSWINSZ, &w);
+
+	fprintf(stderr, "%dx%d\n", width, height);
+
 	return 0;
 }