Stop cache trimming while settings reload

ReloadSettings frees gSettings and then reads the settings file. A file
over 1 MB makes that read a large allocation, which asks the caches to
trim; the render cache's check for a comic book in a facing view reads
gSettings->comicBookUI and crashed on the null pointer.

Turn trimming off before the settings are freed. LoadSettings sets the
level again from the new settings.

crash: 2026-10-13-13-57-ce12 (c0000005 at
DisplayModel::ShouldTreatLandscapeAsSpread, src/DisplayModel.cpp:653)

prompt: /fix-crashes

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: kjk

src/shared/AppSettings.cpp

@@ -1072,6 +1072,9 @@ static void ReloadSettings(bool force = false) {
 #endif
 
     FileHistorySetStates(nullptr);
+    // no cache trim until LoadSettings() restores it: reading the file
+    // allocates and the trim's canFree callbacks read gSettings
+    gSaveMemory = 0;
     CleanUpSettings();
 
     ok = LoadSettings();

tests/reload-settings-memory-trim.ts

@@ -0,0 +1,84 @@
+// Reloading a large settings file while a comic book is open crashed
+// (crash 2026-10-13-13-57-ce12): ReloadSettings frees gSettings, the read of a
+// file over 1 MB then asks the caches to trim, and the render cache's
+// "is this page visible nearby" check read gSettings->comicBookUI.
+
+import { copyFileSync, mkdirSync, readFileSync, rmSync, writeFileSync } from "node:fs";
+import { join } from "node:path";
+import { ControlCommand } from "./control.ts";
+import { ROOT, pollUntil, runStandalone, SLOW_BUILD_FACTOR, tmpPath } from "./util.ts";
+import { killAndWait, launchControlled } from "./win-automation.ts";
+
+const kTag = "reload-settings-memory-trim";
+// kLargeAllocationSize in Base.h: smaller reads don't trim
+const kLargeAllocationSize = 1024 * 1024;
+
+// SaveMemory = 100 trims on every large allocation
+function settingsText(showToc: boolean): string {
+  const padLine = "# " + "x".repeat(98) + "\n";
+  const pad = padLine.repeat(Math.ceil((2 * kLargeAllocationSize) / padLine.length));
+  return `UiLanguage = en\nCheckForUpdates = false\nRestoreSession = false\nSaveMemory = 100\nShowToc = ${showToc}\n${pad}`;
+}
+
+function loadCount(logPath: string): number {
+  try {
+    return readFileSync(logPath, "utf8").split("LoadSettings(").length - 1;
+  } catch {
+    return 0;
+  }
+}
+
+function waitForLoads(logPath: string, n: number): Promise<number> {
+  return pollUntil(
+    async () => loadCount(logPath),
+    (count) => count >= n,
+    {
+      timeoutMs: 10000 * SLOW_BUILD_FACTOR,
+      error: (count) => `${kTag}: ${count} settings loads, want ${n}`,
+    },
+  );
+}
+
+export async function testit(): Promise<void> {
+  const appdata = tmpPath(kTag);
+  rmSync(appdata, { recursive: true, force: true });
+  mkdirSync(appdata, { recursive: true });
+  const settingsPath = join(appdata, "SumatraPDF-settings.txt");
+  const logPath = join(appdata, "log.txt");
+  const cbz = join(appdata, "comic.cbz");
+  copyFileSync(join(ROOT, "tests", "issue-1201.cbz"), cbz);
+  writeFileSync(settingsPath, settingsText(false));
+
+  // facing: single page view never asks the comic book settings
+  const { proc, client } = await launchControlled([
+    "-appdata",
+    appdata,
+    "-log-to-file",
+    logPath,
+    "-view",
+    "facing",
+    cbz,
+  ]);
+  try {
+    await waitForLoads(logPath, 1);
+    // the render cache needs a bitmap to consider freeing
+    await client.waitForRenderIdle();
+
+    const before = loadCount(logPath);
+    writeFileSync(settingsPath, settingsText(true));
+    await waitForLoads(logPath, before + 1);
+
+    const ping = await client.request(ControlCommand.Ping);
+    if (ping[0] !== "pong") {
+      throw new Error(`${kTag}: ping after reload: ${JSON.stringify(ping)}`);
+    }
+  } finally {
+    client.close();
+    await killAndWait(proc);
+    rmSync(appdata, { recursive: true, force: true });
+  }
+}
+
+if (import.meta.main) {
+  await runStandalone(testit);
+}

tests/run-almost-all.ts

@@ -377,6 +377,7 @@ import { testit as advSettingsFreshDefaults } from "./adv-settings-fresh-default
 import { testit as issue6137AdvSettings } from "./issue-6137-adv-settings.ts";
 import { testit as advSettingsHomeReload } from "./adv-settings-home-reload.ts";
 import { testit as advSettingsExternalReload } from "./adv-settings-external-reload.ts";
+import { testit as reloadSettingsMemoryTrim } from "./reload-settings-memory-trim.ts";
 import { testit as commandPaletteExternalReload } from "./command-palette-external-reload.ts";
 import { testit as tocTitleFallback } from "./toc-title-fallback.ts";
 import { testit as tocShowOnOpen } from "./toc-show-on-open.ts";
@@ -790,6 +791,7 @@ export const tests: NamedTest[] = [
   ["issue-6137-adv-settings", issue6137AdvSettings],
   ["adv-settings-home-reload", advSettingsHomeReload],
   ["adv-settings-external-reload", advSettingsExternalReload],
+  ["reload-settings-memory-trim", reloadSettingsMemoryTrim],
   ["command-palette-external-reload", commandPaletteExternalReload],
   ["toc-title-fallback", tocTitleFallback],
   ["toc-show-on-open", tocShowOnOpen],