Do machine inspection on install....

chrome/installer/util/helper.cc

 // Copyright (c) 2010 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/installer/util/helper.h"
 
 #include "base/command_line.h"
 #include "base/file_path.h"
 #include "base/logging.h"
 #include "base/path_service.h"
@@ skipping 23 matching lines @@
 
   return install_path;
 }
 
 }  // namespace
 
 namespace installer {
 
 bool IsInstalledAsMulti(bool system_install, BrowserDistribution* dist) {
   bool installed_as_multi = false;
-  HKEY root = system_install ? HKEY_LOCAL_MACHINE : HKEY_CURRENT_USER;
-  RegKey key(root, dist->GetStateKey().c_str(), KEY_READ);
-  if (key.Valid()) {
-    std::wstring args;
-    key.ReadValue(installer::kUninstallArgumentsField, &args);
-    if (!args.empty()) {
-      args.insert(0, L"fake.exe ");
-      CommandLine cmd(CommandLine::FromString(args));
-      installed_as_multi = cmd.HasSwitch(installer::switches::kMultiInstall);
-    }
-  }
+  CommandLine cmd(CommandLine::NO_PROGRAM);
+  if (GetUninstallSwitches(system_install, dist, &cmd))
+    installed_as_multi = cmd.HasSwitch(installer::switches::kMultiInstall);
   return installed_as_multi;
 }
 
+bool GetUninstallSwitches(bool system_install, BrowserDistribution* dist,
+                          CommandLine* cmd_line_switches) {
+  scoped_ptr<Version> installed(InstallUtil::GetChromeVersion(dist,
+                                                              system_install));
+  if (installed.get()) {
+    HKEY root = system_install ? HKEY_LOCAL_MACHINE : HKEY_CURRENT_USER;
+    RegKey key(root, dist->GetStateKey().c_str(), KEY_READ);
+    if (key.Valid()) {
+      std::wstring args;
+      key.ReadValue(installer::kUninstallArgumentsField, &args);
+      if (!args.empty()) {
+        args.insert(0, L"foo.exe ");
+        *cmd_line_switches = CommandLine::FromString(args);
+      } else {
+        LOG(ERROR) << "No uninstallation arguments for "

[grt (UTC plus 2), 2010/12/29 16:51:50]

Are these two ERROR conditions bad enough that we should abort installation?  In
other words, will all callers do something that will be non-harmful in these
cases?

[tommi (sloooow) - chröme, 2010/12/29 17:30:09]

I was thinking the same but in the end opted on the side of "things must be
pretty messed up for this to happen and if the installer is being run, it will
likely fix it".
It's also non trivial to back out from here.

+                   << dist->GetApplicationName();
+        installed.reset();
+      }
+    } else {
+      LOG(ERROR) << "Product looks to be installed but we can't access the "
+                    "state key: " << dist->GetApplicationName();
+      installed.reset();
+    }
+  }
+
+  return installed.get() != NULL;
+}
+
 FilePath GetChromeInstallPath(bool system_install, BrowserDistribution* dist) {
   return GetChromeInstallBasePath(system_install, dist,
                                   installer::kInstallBinaryDir);
 }
 
 FilePath GetChromeUserDataPath(BrowserDistribution* dist) {
   return GetChromeInstallBasePath(false, dist, kInstallUserDataDir);
 }
 
 FilePath GetChromeFrameInstallPath(bool multi_install, bool system_install,
@@ skipping 32 matching lines @@
   // Return Chrome's installation folder.
   VLOG(1) << "Chrome Frame will be installed as 'multi'";
   const MasterPreferences& prefs = MasterPreferences::ForCurrentProcess();
   BrowserDistribution* chrome =
       BrowserDistribution::GetSpecificDistribution(
           BrowserDistribution::CHROME_BROWSER, prefs);
   return GetChromeInstallPath(system_install, chrome);
 }
 
 }  // namespace installer.