From d3a699a8fb86a03d4ef44594a8ff7e9a5ec8ea16 Mon Sep 17 00:00:00 2001
From: Jarrod Johnson <jjohnson2@lenovo.com>
Date: Sat, 13 Mar 2021 12:33:53 -0500
Subject: [PATCH] Have autocons attempt sizing of serial console

If a terminal is open during autocons, that terminal
will be the size of the console.

Otherwise, fallback to 100x31.
---
 confluent_osdeploy/utils/autocons.c | 63 +++++++++++++++++++++++++----
 1 file changed, 55 insertions(+), 8 deletions(-)

diff --git a/confluent_osdeploy/utils/autocons.c b/confluent_osdeploy/utils/autocons.c
index 018f43b5..75389af9 100644
--- a/confluent_osdeploy/utils/autocons.c
+++ b/confluent_osdeploy/utils/autocons.c
@@ -1,3 +1,4 @@
+#include <errno.h>
 #include <termios.h>
 #include <sys/ioctl.h>
 #include <fcntl.h>
@@ -20,20 +21,29 @@
 
 int main(int argc, char* argv[]) {
     struct termios tty;
+    struct termios tty2;
+    struct winsize ws;
+    unsigned width, height;
     int ttyf;
-    int spcr;
+    int tmpi;
     int currspeed;
+    int flags;
     speed_t cspeed;
     char buff[128];
+    int bufflen;
+    fd_set set;
+    struct timeval timeout;
     char* offset;
     uint64_t address;
-    spcr = open("/sys/firmware/acpi/tables/SPCR", O_RDONLY);
-    if (spcr < 0) {
+    bufflen = 0;
+    tmpi = open("/sys/firmware/acpi/tables/SPCR", O_RDONLY);
+    if (tmpi < 0) {
         exit(0);
     }
-    if (read(spcr, buff, 80) < 80) {
+    if (read(tmpi, buff, 80) < 80) {
         exit(0);
     }
+    close(tmpi);
     if (buff[8] != 2) exit(0); //revision 2
     if (buff[36] != 0) exit(0); //16550 only
     if (buff[40] != 1) exit(0); //IO only
@@ -69,12 +79,49 @@ int main(int argc, char* argv[]) {
     }
     tcgetattr(ttyf, &tty);
     if (cspeed) {
-        cfsetospeed(&tty, B115200);
-        cfsetispeed(&tty, B115200);
+        cfsetospeed(&tty, cspeed);
+        cfsetispeed(&tty, cspeed);
     }
+    printf("%s\n", buff);
+    tcgetattr(ttyf, &tty2);
+    cfmakeraw(&tty2);
+    tcsetattr(ttyf, TCSANOW, &tty2);
+    flags = fcntl(ttyf, F_GETFL, 0);
+    fcntl(ttyf, F_SETFL, flags | O_NONBLOCK);
+    while (read(ttyf, buff, 64) > 0) {
+        // Drain any pending reads
+    }
+    timeout.tv_sec = 0;
+    timeout.tv_usec = 500000;
+    FD_ZERO(&set);
+    FD_SET(ttyf, &set);
+    write(ttyf, "\0337\033[999;999H\033[6n\0338", 18);
+    while (select(ttyf + 1, &set, NULL, NULL, &timeout) > 0) {
+        if ((tmpi = read(ttyf, buff + bufflen, 127 - bufflen)) < 0) {
+            if (errno == EAGAIN || errno == EWOULDBLOCK) {
+                continue;
+            } else {
+                break;
+            }
+        }
+        bufflen += tmpi;
+        buff[bufflen] = 0;
+        if (strchr(buff, 'R')) {
+            break;
+        }
+    }
+    fcntl(ttyf, F_SETFL, flags);
+    ws.ws_xpixel = 0;
+    ws.ws_ypixel = 0;
+    if (sscanf(buff, "\033[%u;%uR", &height, &width) == 2) {
+        ws.ws_col = width;
+        ws.ws_row = height;
+    } else {
+        ws.ws_col = 100;
+        ws.ws_row = 31;
+    }
+    ioctl(ttyf, TIOCSWINSZ, &ws);
     tcsetattr(ttyf, TCSANOW, &tty);
     ioctl(ttyf, TIOCCONS, 0);
-    printf("%s\n", buff);
-
 }