Fix terminal width to 80 columns in tests (#2444)

* Fix terminal width to 80 columns in tests

Set a `PWNDBG_IN_TEST`environment variable when running gdb in tests. Use the dimensions in `LINES` and `COLUMNS` when looking up the window size when that envvar is set.

This makes context output always be 80 columns wide which allows to compare to hardcoded output.

* Use `width` and `height` parameters for cmd window size

They are updated to the correct values when switching between tui and cli mode. So it's unnecessary to parse `info win`.

* Remove workarounds for terminal size in DEVELOPING

* Don't bother updating the env of the debuggee

DEVELOPING.md

@@ -51,19 +51,6 @@ We have four types of tests: `gdb-tests`,`qemu-tests`, `unit-tests`, and Linux k
 
 To run these tests, run [`./tests.sh`](./tests.sh). You can filter the tests to run by providing an argument to the script, such as `./tests.sh heap`, which will only run tests that contain "heap" in the name. You can also drop into the PDB debugger when a test fails with `./tests.sh --pdb`.
 
-Some of the tests rely on output that depends on a certain width/height of the terminal, so you will likely see many test failures when simply running `./tests.sh`. To run the tests in the expected environment, you can use:
-
-```sh
-docker compose run --build -T ubuntu24.04 ./tests.sh
-# The `-T` disables the use of a pseudo-TTY
-```
-
-If you want rapidly iterate on tests (waiting for the container to rebuild and all the test source code files to compile can take a while), you can pipe `cat` on both ends to disable the PTY and get the correct terminal width/height for the tests.
-
-```sh
-cat | ./tests.sh | cat
-```
-
 To invoke cross-architecture tests, use `./qemu-tests.sh`, and to run unit tests, use `./unit-tests.sh`
 
 ## Writing Tests

pwndbg/dbg/gdb.py

@@ -6,6 +6,7 @@ from typing import Any
 from typing import Generator
 from typing import List
 from typing import Literal
+from typing import Optional
 from typing import Sequence
 from typing import Tuple
 from typing import TypeVar
@@ -1254,38 +1255,22 @@ class GDB(pwndbg.dbg_mod.Debugger):
         return f"%#{2 * pwndbg.gdblib.arch.ptrsize}x" % address
 
     @override
-    def get_cmd_window_size(self) -> Tuple[int, int]:
-        """Get the size of the command window in TUI mode which could be different than the terminal window width \
-        with horizontal split "tui new-layout hsrc { -horizontal src 1 cmd 1 } 1".
+    def get_cmd_window_size(self) -> Tuple[Optional[int], Optional[int]]:
+        """Get the size of the command window.
 
-        Possible output of "info win" in TUI mode:
-        (gdb) info win
-        Name       Lines Columns Focus
-        src           77     104 (has focus)
-        cmd           77     105
+        GDB keeps these parameters up to date with the actual window size
+        of the command output. This is the full terminal size in CLI mode
+        or the size of the cmd window in TUI mode.
 
-        Output of "info win" in non-TUI mode:
-        (gdb) info win
-        The TUI is not active."""
-        try:
-            info_out = gdb.execute("info win", to_string=True).split()
-        except gdb.error:
-            # Return None if the command is not compiled into GDB
-            # (gdb.error: Undefined info command: "win".  Try "help info")
-            return None, None
-        if "cmd" not in info_out:
-            # if TUI is not enabled, info win will output "The TUI is not active."
-            return None, None
-        # parse cmd window size from the output of "info win"
-        cmd_win_index = info_out.index("cmd")
-        if len(info_out) <= cmd_win_index + 2:
-            return None, None
-        elif (
-            not info_out[cmd_win_index + 1].isdigit() and not info_out[cmd_win_index + 2].isdigit()
-        ):
-            return None, None
-        else:
-            return int(info_out[cmd_win_index + 1]), int(info_out[cmd_win_index + 2])
+        When the window size is set to be unlimited (0), the parameter
+        is None.
+        """
+        width = gdb.parameter("width")
+        height = gdb.parameter("height")
+        return (
+            height if height is None else int(height),
+            width if width is None else int(width),
+        )
 
     @override
     def set_python_diagnostics(self, enabled: bool) -> None:

pwndbg/ui.py

@@ -73,6 +73,8 @@ def get_window_size(target=sys.stdin):
     rows, cols = get_cmd_window_size()
     if rows is not None and cols is not None:
         return rows, cols
+    elif os.environ.get("PWNDBG_IN_TEST") is not None:
+        return fallback
     try:
         # get terminal size and force ret buffer len of 4 bytes for safe unpacking by passing equally long arg
         rows, cols = struct.unpack("hh", fcntl.ioctl(target.fileno(), termios.TIOCGWINSZ, b"1234"))

tests/gdb-tests/conftest.py

@@ -4,6 +4,8 @@ This file should consist of global test fixtures.
 
 from __future__ import annotations
 
+import os
+
 import gdb
 import pytest
 
@@ -17,8 +19,11 @@ def start_binary():
     """
 
     def _start_binary(path, *args):
+        os.environ["PWNDBG_IN_TEST"] = "1"
         gdb.execute("file " + path)
         gdb.execute("set exception-verbose on")
+        gdb.execute("set width 80")
+        os.environ["COLUMNS"] = "80"
         gdb.execute("starti " + " ".join(args))
 
         global _start_binary_called