Fix Cocoa startup crash when the VM has no console

Makefile

@@ -77,6 +77,7 @@ test-contracts:
 	@PYTHONDONTWRITEBYTECODE=1 python3 "$(ROOT)/macos/Tests/test-cocoa-scroll.py"
 	@PYTHONDONTWRITEBYTECODE=1 python3 "$(ROOT)/macos/Tests/test-cocoa-iso-keyboard.py"
 	@PYTHONDONTWRITEBYTECODE=1 python3 "$(ROOT)/macos/Tests/test-cocoa-injected-text.py"
+	@PYTHONDONTWRITEBYTECODE=1 python3 "$(ROOT)/macos/Tests/test-cocoa-no-console.py"
 	@PYTHONDONTWRITEBYTECODE=1 python3 "$(ROOT)/macos/Tests/test-hvf-memory-reclaim.py"
 	@PYTHONDONTWRITEBYTECODE=1 python3 "$(ROOT)/macos/Tests/test-hvf-mapped-sections.py"
 	@PYTHONDONTWRITEBYTECODE=1 python3 "$(ROOT)/macos/Tests/test-virtio-pinch.py"

macos/Tests/cocoa-no-console-harness.c

@@ -0,0 +1,64 @@
+/* Portable harness for the Cocoa startup console lookup extracted from the QEMU patch. */
+#include <assert.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct { int unused; } DisplaySurface;
+typedef struct { DisplaySurface *surface; } QemuConsole;
+typedef struct { QemuConsole *con; } QKbdState;
+typedef struct { QemuConsole *con; } DisplayChangeListener;
+
+static DisplayChangeListener dcl;
+static DisplaySurface *surface;
+static QKbdState *kbd;
+static QKbdState kbd_state;
+static QemuConsole *default_console;
+
+static QemuConsole *qemu_console_lookup_default(void)
+{
+    return default_console;
+}
+
+static QKbdState *qkbd_state_init(QemuConsole *con)
+{
+    kbd_state.con = con;
+    return &kbd_state;
+}
+
+static DisplaySurface *qemu_console_surface(QemuConsole *console)
+{
+    /* The patched ui/console.c reads console->surface with no NULL check. */
+    if (!console) {
+        fputs("qemu_console_surface() called without a console\n", stderr);
+        abort();
+    }
+    return console->surface;
+}
+
+static void cocoa_display_startup(void)
+{
+/* STARTUP */
+}
+
+int main(void)
+{
+    DisplaySurface device_surface = {0};
+    QemuConsole console = { &device_surface };
+
+    /* -nodefaults with no display device: QEMU has no console at all. */
+    default_console = NULL;
+    surface = &device_surface;
+    cocoa_display_startup();
+    assert(dcl.con == NULL);
+    assert(surface == NULL);
+    assert(kbd == &kbd_state && kbd_state.con == NULL);
+
+    /* A graphics device: the surface still comes from its console. */
+    default_console = &console;
+    cocoa_display_startup();
+    assert(dcl.con == &console);
+    assert(surface == &device_surface);
+    assert(kbd == &kbd_state && kbd_state.con == &console);
+    return 0;
+}

macos/Tests/test-cocoa-no-console.py

@@ -0,0 +1,63 @@
+#!/usr/bin/env python3
+"""Start the Cocoa display without a console, as pristine QEMU allows."""
+
+import hashlib
+import os
+from pathlib import Path
+import re
+import shlex
+import subprocess
+import tempfile
+import unittest
+
+
+ROOT = Path(__file__).resolve().parents[2]
+PATCH = ROOT / "macos/patches/qemu-texture-borrowing-11.1.patch"
+START = "dcl.con = qemu_console_lookup_default();"
+END = "// Create an Application controller"
+
+
+def patched_cocoa_hunks():
+    section = PATCH.read_text().split(
+        "diff --color -urN pristine/src/ui/cocoa.m trim/src/ui/cocoa.m\n", 1
+    )[1].split("\ndiff --color ", 1)[0]
+    return ["\n".join(line[1:] for line in hunk.splitlines()
+                      if line.startswith((" ", "+")))
+            for hunk in re.split(r"^@@.*@@.*$", section, flags=re.M)[1:]]
+
+
+class CocoaNoConsoleTests(unittest.TestCase):
+    def test_build_uses_verified_patch(self):
+        builder = (ROOT / "macos/build-qemu-gpu-runtime.sh").read_text()
+        digest = hashlib.sha256(PATCH.read_bytes()).hexdigest()
+        self.assertIn(f"texture_patch_sha256={digest}", builder)
+        self.assertIn('"$texture_patch" "$texture_patch_sha256"', builder)
+        self.assertIn('patch -d "$source_dir" -p1 -f -i "$texture_patch"', builder)
+
+    def test_startup_without_console(self):
+        # Compile the patched statements that run before the controller is
+        # created. With no console they must not reach qemu_console_surface();
+        # QEMU's listener registration later shows its placeholder surface.
+        hunks = patched_cocoa_hunks()
+        startup = [hunk for hunk in hunks if START in hunk]
+        self.assertEqual(len(startup), 1, "console lookup must be in one hunk")
+        startup = START + startup[0].split(START, 1)[1]
+        self.assertIn(END, startup)
+        startup = startup.split(END, 1)[0]
+        source = "\n".join(hunks)
+        self.assertEqual(source.count("qemu_console_surface("),
+                         startup.count("qemu_console_surface("), "surface read moved")
+        self.assertIn("qemu_console_register_listener(qemu_console_lookup_default(),",
+                      source)
+        with tempfile.TemporaryDirectory() as directory:
+            work = Path(directory)
+            harness = (ROOT / "macos/Tests/cocoa-no-console-harness.c").read_text()
+            (work / "test.c").write_text(harness.replace("/* STARTUP */", startup))
+            compiler = shlex.split(os.environ.get("CC", "cc"))
+            subprocess.run(compiler + ["-std=c11", "-Wall", "-Wextra", "-Werror",
+                           str(work / "test.c"), "-o", str(work / "test")], check=True)
+            subprocess.run([str(work / "test")], check=True)
+
+
+if __name__ == "__main__":
+    unittest.main()

macos/build-qemu-gpu-runtime.sh

@@ -86,7 +86,7 @@ qemu_archive_name="$qemu_root.tar.gz"
 qemu_url="https://gitlab.com/qemu-project/qemu/-/archive/$qemu_commit/$qemu_archive_name"
 qemu_sha256=7563781d7dec46f11509801e027f852597235d29ca7afa44a07ed9d8b108b8cd
 
-texture_patch_sha256=b20bdf9a7d7ccda5b86366ad9d09a3bf95308b98a06b1ece281344405bcc7ab9
+texture_patch_sha256=b8e107ecd82813854bac7f6bb110722f52937d64b6f98611c4dd02842977fc2f
 gpu_fix_patch_sha256=b554e1ef9910d0891d69ee0fe84e479559c057dc28291e36e1524031808fc69f
 identity_patch_sha256=5c9358c2858a74d6a678eacaae550a021f3e616c98c4e4e98c0e50bd869a0666
 display_patch_sha256=1ce59350b6b8e6842bc0c9ca34c97f54cb75e85e2d7b35e5b483858654c4d693

macos/patches/qemu-texture-borrowing-11.1.patch

@@ -1222,7 +1222,7 @@ diff --color -urN pristine/src/ui/cocoa.m trim/src/ui/cocoa.m
 
 +    dcl.con = qemu_console_lookup_default();
 +    kbd = qkbd_state_init(dcl.con);
-+    surface = qemu_console_surface(dcl.con);
++    surface = dcl.con ? qemu_console_surface(dcl.con) : NULL;
 +
      // Create an Application controller
 -    QemuCocoaAppController *controller = [[QemuCocoaAppController alloc] init];