From a503371c572cf1f2ef7411432542eb4baf4638fe Mon Sep 17 00:00:00 2001
From: Fabian Homborg <FHomborg@gmail.com>
Date: Fri, 12 Feb 2021 18:25:21 +0100
Subject: [PATCH] termsize: Default to 80x24 when the terminal says 0 again

This was lost in
6bdbe732e40c2e325aa15fcf0f28ad0dedb3a551..c7160d7cb4970c2a03df34547f357721cb5e88db.

Note that we only print a term-support flog message for now, the
warning seems a bit much.

Fixes #7709.
---
 src/termsize.cpp           |  9 +++++++++
 tests/pexpects/terminal.py | 15 +++++++++++++++
 2 files changed, 24 insertions(+)
 create mode 100644 tests/pexpects/terminal.py

diff --git a/src/termsize.cpp b/src/termsize.cpp
index cf3591adf..a4ce9255d 100644
--- a/src/termsize.cpp
+++ b/src/termsize.cpp
@@ -16,6 +16,15 @@ static maybe_t<termsize_t> read_termsize_from_tty() {
 #ifdef HAVE_WINSIZE
     struct winsize winsize = {0, 0, 0, 0};
     if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &winsize) >= 0) {
+        // 0 values are unusable, fall back to the default instead.
+        if (winsize.ws_col == 0) {
+            FLOGF(term_support, L"Terminal has 0 columns, falling back to default width");
+            winsize.ws_col = termsize_t::DEFAULT_WIDTH;
+        }
+        if (winsize.ws_row == 0) {
+            FLOGF(term_support, L"Terminal has 0 rows, falling back to default height");
+            winsize.ws_row = termsize_t::DEFAULT_HEIGHT;
+        }
         result = termsize_t{winsize.ws_col, winsize.ws_row};
     }
 #endif
diff --git a/tests/pexpects/terminal.py b/tests/pexpects/terminal.py
new file mode 100644
index 000000000..cdcfeb65f
--- /dev/null
+++ b/tests/pexpects/terminal.py
@@ -0,0 +1,15 @@
+#!/usr/bin/env python3
+from pexpect_helper import SpawnedProc
+
+# Set a 0 terminal size
+sp = SpawnedProc(args=["-d", "term-support"], dimensions=(0,0))
+sendline, expect_prompt, expect_str = sp.sendline, sp.expect_prompt, sp.expect_str
+
+expect_prompt()
+# Now confirm it defaulted to 80x24
+sendline("echo $COLUMNS $LINES")
+expect_str("80 24")
+expect_str("term-support: Terminal has 0 columns, falling back to default width")
+expect_str("term-support: Terminal has 0 rows, falling back to default height")
+expect_prompt()
+