From 8c1145d4b23d6a8cf2867b922716153f6ea72d9e Mon Sep 17 00:00:00 2001
From: Andrew Liu <liu@chromium.org>
Date: Wed, 04 Mar 2026 12:47:47 -0800
Subject: [PATCH] Filter out multiple "double percent signs" when normalizing download files

Bug: 486079015
Change-Id: I7047e2f0a210de1ae17cbb95884f3a6c6a6a6964
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7629495
Reviewed-by: Min Qin <qinmin@chromium.org>
Reviewed-by: Lily Chen <chlily@chromium.org>
Commit-Queue: Andrew Liu <liu@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1594178}
---

diff --git a/chrome/browser/download/download_target_determiner.cc b/chrome/browser/download/download_target_determiner.cc
index 760025c..1dd2dbab 100644
--- a/chrome/browser/download/download_target_determiner.cc
+++ b/chrome/browser/download/download_target_determiner.cc
@@ -599,13 +599,19 @@
       // file name first.
       std::wstring sanitized_name = ui::RemoveEnvVarFromFileName<wchar_t>(
           virtual_path_.BaseName().value(), L"%");
-      // remove leading "." to avoid resorting to potential extension
-      // bug: 41486690
-      while (!sanitized_name.empty() && sanitized_name.back() == L'.') {
-          sanitized_name.pop_back();
+      // Remove trailing "." and whitespace to avoid resorting to potential
+      // extensions.
+      // See crbug.com/41486690 and crbug.com/486079015 for more context.
+      while (!sanitized_name.empty()) {
+        size_t length = sanitized_name.length();
+        while (!sanitized_name.empty() && sanitized_name.back() == L'.') {
+            sanitized_name.pop_back();
+        }
+        // trim trailing whitespace (space, tab, NBSP) to prevent stale extensions
+        base::TrimWhitespace(sanitized_name, base::TrimPositions::TRIM_TRAILING, &sanitized_name);
+        if (length == sanitized_name.length())
+          break;
       }
-      // trim trailing whitespace (space, tab, NBSP) to prevent stale extensions
-      base::TrimWhitespace(sanitized_name, base::TrimPositions::TRIM_TRAILING, &sanitized_name);
       if (sanitized_name.empty()) {
         sanitized_name = base::UTF8ToWide(
             l10n_util::GetStringUTF8(IDS_DEFAULT_DOWNLOAD_FILENAME));
diff --git a/chrome/browser/download/download_target_determiner_unittest.cc b/chrome/browser/download/download_target_determiner_unittest.cc
index dff43fc..890c8305 100644
--- a/chrome/browser/download/download_target_determiner_unittest.cc
+++ b/chrome/browser/download/download_target_determiner_unittest.cc
@@ -2712,6 +2712,15 @@
 
        FILE_PATH_LITERAL("download"), DownloadItem::TARGET_DISPOSITION_PROMPT,
 
+       EXPECT_CRDOWNLOAD},
+      {// 6: Multiple env vars need to be filtered out.
+       SAVE_AS, download::DOWNLOAD_DANGER_TYPE_NOT_DANGEROUS,
+       DownloadFileType::NOT_DANGEROUS, "http://example.com/foo.lnk .%% .%%",
+       "application/octet-stream", FILE_PATH_LITERAL(""),
+
+       FILE_PATH_LITERAL("foo.download"),
+       DownloadItem::TARGET_DISPOSITION_PROMPT,
+
        EXPECT_CRDOWNLOAD}};
 
   RunTestCasesWithActiveItem(kSaveEnvPathTestCases);

diff --git a/chrome/browser/download/download_target_determiner_unittest.cc b/chrome/browser/download/download_target_determiner_unittest.cc
index dff43fc..890c8305 100644
--- a/chrome/browser/download/download_target_determiner_unittest.cc
+++ b/chrome/browser/download/download_target_determiner_unittest.cc
@@ -2712,6 +2712,15 @@
 
        FILE_PATH_LITERAL("download"), DownloadItem::TARGET_DISPOSITION_PROMPT,
 
+       EXPECT_CRDOWNLOAD},
+      {// 6: Multiple env vars need to be filtered out.
+       SAVE_AS, download::DOWNLOAD_DANGER_TYPE_NOT_DANGEROUS,
+       DownloadFileType::NOT_DANGEROUS, "http://example.com/foo.lnk .%% .%%",
+       "application/octet-stream", FILE_PATH_LITERAL(""),
+
+       FILE_PATH_LITERAL("foo.download"),
+       DownloadItem::TARGET_DISPOSITION_PROMPT,
+
        EXPECT_CRDOWNLOAD}};
 
   RunTestCasesWithActiveItem(kSaveEnvPathTestCases);