xdg-settings: add secondary check in GetIsDefaultWebClient

chrome/browser/shell_integration_linux.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/shell_integration_linux.h"
 
 #include <fcntl.h>
 #include <stddef.h>
 
 #include <memory>
@@ skipping 146 matching lines @@
   if (ran_ok && exit_code == EXIT_XDG_SETTINGS_SYNTAX_ERROR) {
     if (GetChromeVersionOfScript(kXdgSettings, &argv[0])) {
       ran_ok = LaunchXdgUtility(argv, &exit_code);
     }
   }
 
   return ran_ok && exit_code == EXIT_SUCCESS;
 #endif
 }
 
-// If |protocol| is empty this function checks if Chrome is the default browser,
-// otherwise it checks if Chrome is the default handler application for
-// |protocol|.
-DefaultWebClientState GetIsDefaultWebClient(const std::string& protocol) {
-#if defined(OS_CHROMEOS)
-  return UNKNOWN_DEFAULT;
-#else
-  base::ThreadRestrictions::AssertIOAllowed();
-
-  std::unique_ptr<base::Environment> env(base::Environment::Create());
-
+#if !defined(OS_CHROMEOS)
+// If |check| is true, returns the output of "xdg-settings check {property}
+// *.desktop", otherwise returns the output of "xdg-settings get {property}",
+// where property is "default-web-browser" if |protocol| is empty or
+// "default-url-scheme-handler |protocol|" otherwise.  Returns "" if
+// xdg-settings fails for any reason.
+std::string GetXdgSettingsOutput(bool check,
+                                 const std::string& protocol,
+                                 base::Environment* env) {
   std::vector<std::string> argv;
   argv.push_back(kXdgSettings);
-  argv.push_back("check");
+  argv.push_back(check ? "check" : "get");
   if (protocol.empty()) {
     argv.push_back(kXdgSettingsDefaultBrowser);
   } else {
     argv.push_back(kXdgSettingsDefaultSchemeHandler);
     argv.push_back(protocol);
   }
-  argv.push_back(shell_integration_linux::GetDesktopName(env.get()));
+  if (check)
+    argv.push_back(shell_integration_linux::GetDesktopName(env));
 
   std::string reply;
   int success_code;
   bool ran_ok = base::GetAppOutputWithExitCode(base::CommandLine(argv), &reply,
                                                &success_code);
   if (ran_ok && success_code == EXIT_XDG_SETTINGS_SYNTAX_ERROR) {
     if (GetChromeVersionOfScript(kXdgSettings, &argv[0])) {
       ran_ok = base::GetAppOutputWithExitCode(base::CommandLine(argv), &reply,
                                               &success_code);
     }
   }
 
-  if (!ran_ok || success_code != EXIT_SUCCESS) {
-    // xdg-settings failed: we can't determine or set the default browser.
-    return UNKNOWN_DEFAULT;
+  if (!ran_ok || success_code != EXIT_SUCCESS)
+    return std::string();
+
+  return reply;
+}
+#endif
+
+// If |protocol| is empty this function checks if Chrome is the default browser,
+// otherwise it checks if Chrome is the default handler application for
+// |protocol|.
+DefaultWebClientState GetDefaultWebClient(const std::string& protocol) {
+#if defined(OS_CHROMEOS)
+  return UNKNOWN_DEFAULT;
+#else
+  base::ThreadRestrictions::AssertIOAllowed();
+
+  std::unique_ptr<base::Environment> env(base::Environment::Create());
+  std::string xdg_is_default = GetXdgSettingsOutput(true, protocol, env.get());
+  if (base::StartsWith(xdg_is_default, "yes", base::CompareCase::SENSITIVE)) {
+    return IS_DEFAULT;
+  }
+  if (base::StartsWith(xdg_is_default, "no", base::CompareCase::SENSITIVE)) {
+    // An output of "no" does not necessarily mean Chrom[e,ium] is not the

[Mike Mammarella, 2017/03/11 03:05:04]

So, you're sort of defeating the purpose of having a separate "check" feature in
xdg-settings, compared to only having set/get and then comparing the result of
get inside the caller. The "check" feature is specifically there because in some
cases the different ways in which a browser may be listed as the default can
disagree, and we want to show the bar if any of them aren't us. For instance, it
may be that clicking on a http:// link in an application would launch us, but
double clicking on a local .html file would launch a different browser. We want
to show the bar, in that case.

It would be better to figure out *why* xdg-settings on the user's desktop is
saying that we aren't completely the default, keeping in mind that on modern
distributions, the version of xdg-settings we run is generally the one packaged
with the distribution (and thus may have distro patches), even though we ship
our own as well.

+    // default.  According to the xdg-settings man page, this can happen when
+    // "only some of the underlying settings actually reflect that value". Don't
+    // return NOT_DEFAULT unless we're sure, or else an annoying "Chrome is not
+    // your default browser" banner will appear on every launch
+    // (https://crbug.com/578888).
+    if (base::StartsWith(GetXdgSettingsOutput(false, protocol, env.get()),
+                         shell_integration_linux::GetDesktopName(env.get()),
+                         base::CompareCase::SENSITIVE)) {
+      // This is the odd case where 'xdg-settings check' said that Chrome wasn't
+      // the default, but 'xdg-settings get' returned Chrome as the default.
+      return UNKNOWN_DEFAULT;
+    }
+    // xdg-settings says the default is non-Chrome, and is self-consistent.
+    return NOT_DEFAULT;
   }
 
-  // Allow any reply that starts with "yes".
-  return base::StartsWith(reply, "yes", base::CompareCase::SENSITIVE)
-             ? IS_DEFAULT
-             : NOT_DEFAULT;
+  // xdg-settings failed: we can't determine or set the default browser.
+  return UNKNOWN_DEFAULT;
 #endif
 }
 
 // https://wiki.gnome.org/Projects/GnomeShell/ApplicationBased
 // The WM_CLASS property should be set to the same as the *.desktop file without
 // the .desktop extension.  We cannot simply use argv[0] in this case, because
 // on the stable channel, the executable name is google-chrome-stable, but the
 // desktop file is google-chrome.desktop.
 std::string GetDesktopBaseName(const std::string& desktop_file_name) {
   static const char kDesktopExtension[] = ".desktop";
@@ skipping 17 matching lines @@
 
 DefaultWebClientSetPermission GetDefaultWebClientSetPermission() {
   return SET_DEFAULT_UNATTENDED;
 }
 
 base::string16 GetApplicationNameForProtocol(const GURL& url) {
   return base::ASCIIToUTF16("xdg-open");
 }
 
 DefaultWebClientState GetDefaultBrowser() {
-  return GetIsDefaultWebClient(std::string());
+  return GetDefaultWebClient(std::string());
 }
 
 bool IsFirefoxDefaultBrowser() {
   std::vector<std::string> argv;
   argv.push_back(kXdgSettings);
   argv.push_back("get");
   argv.push_back(kXdgSettingsDefaultBrowser);
 
   std::string browser;
   // We don't care about the return value here.
   base::GetAppOutput(base::CommandLine(argv), &browser);
   return browser.find("irefox") != std::string::npos;
 }
 
 DefaultWebClientState IsDefaultProtocolClient(const std::string& protocol) {
-  return GetIsDefaultWebClient(protocol);
+  return GetDefaultWebClient(protocol);
 }
 
 }  // namespace shell_integration
 
 namespace shell_integration_linux {
 
 namespace {
 
 #if BUILDFLAG(ENABLE_APP_LIST)
 // The Categories for the App Launcher desktop shortcut. Should be the same as
@@ skipping 834 matching lines @@
   base::FilePath applications_menu = GetDataWriteLocation(env.get());
   applications_menu = applications_menu.AppendASCII("applications");
   std::vector<base::FilePath> shortcut_filenames_app_menu =
       GetExistingProfileShortcutFilenames(profile_path, applications_menu);
   for (const auto& menu : shortcut_filenames_app_menu) {
     DeleteShortcutInApplicationsMenu(menu, base::FilePath(kDirectoryFilename));
   }
 }
 
 }  // namespace shell_integration_linux