From 29630ac92e6303e8196aef2eb32092e1e36d5252 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Ekl=C3=B6f?= <daniel@ekloef.se>
Date: Tue, 2 Jun 2020 19:59:28 +0200
Subject: [PATCH] term: set an initial TIOCSWINSZ right after opening the pty

Since foot is pretty aggressive about spawning the client early, it
was possible for a fast client to read a 0x0 terminal size. Not all
clients coped well.

Closes #20.
---
 CHANGELOG.md | 2 ++
 terminal.c   | 8 ++++++++
 2 files changed, 10 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c5113e95..5aca097c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -48,6 +48,8 @@
 * Selection of double-width characters. It is no longer possible to
   select half of a double-width character.
 * Draw hollow block cursor on top of character.
+* Set an initial `TIOCSWINSZ`. This ensures clients never reads a
+  `0x0` terminal size (https://codeberg.org/dnkl/foot/issues/20).
 
 ### Security
 
diff --git a/terminal.c b/terminal.c
index 4f9d1d5d..8181a610 100644
--- a/terminal.c
+++ b/terminal.c
@@ -8,6 +8,7 @@
 
 #include <sys/stat.h>
 #include <sys/wait.h>
+#include <sys/ioctl.h>
 #include <sys/epoll.h>
 #include <sys/eventfd.h>
 #include <sys/timerfd.h>
@@ -759,6 +760,13 @@ term_init(const struct config *conf, struct fdm *fdm, struct reaper *reaper,
         goto close_fds;
     }
 
+    if (ioctl(ptmx, TIOCSWINSZ,
+              &(struct winsize){.ws_row = 24, .ws_col = 80}) < 0)
+    {
+        LOG_ERRNO("failed to set initial TIOCSWINSZ");
+        goto close_fds;
+    }
+
     int ptmx_flags;
     if ((ptmx_flags = fcntl(ptmx, F_GETFL)) < 0 ||
         fcntl(ptmx, F_SETFL, ptmx_flags | O_NONBLOCK) < 0)