Skip to main content

Avoid the acredir.dll Shims: RedirectFiles and RedirectRegistry


As we continue our journey through shims provided by the Windows Shim Infrastructure, we have reached a point where I can no longer avoid a discussion of the shims contained in acredir.dll: RedirectFiles and RedirectRegistry.Last time around, I pointed out how to redirect the registry using VirtualRegistry, which requires a command line argument which (for a very long time) was not publicly documented. Instead, a lot of people have been using RedirectRegistry, for two important and logical reasons. First, the name just sounds so tempting, since that's exactly what you likely want to do. Second, the act.chm actually does document these shims. So, I understand why people would rationally flock to these shims.However, one of the internal questions that I address quite a bit: why can't I get xxx application to work with the RedirectFiles shim? Am I putting in the command line wrong? (and the command line follows)So, I'll just say this. You shouldn't use these shims, because they're not designed to do what you think they're designed to do. Specifically, they target Internet Explorer.Try it. From Compatibility Administrator, press the Query button on the toolbar. The second tab, fix properties, allows you to find programs fixed using a shim. Put one of these two shims in there, and then press the Find Now button. IE7 is the only thing that comes up. Now, try either VirtualRegistry or CorrectFilePaths. Lots and lots of things come up.You see, IE7 leverages the Windows Shim Infrastructure to resolve an important compatibility issue: attempts by ActiveX controls to write to areas that Mandatory Integrity Control prevents them from writing to in LORIE, implementing an Internet Registry and Internet File System - a separate Virtual Store than that used by the operating system - and these two shims help make that happen.So, these two shims are specifically designed and optimized around this one scenario, and were even separated off into their own DLL to help keep them separate. The problem is that we include the acredir.dll shims in Compatibility Administrator without this caveat. They have tempting names. We give them good documentation. So it's no surprise that people use them.Instead of RedirectRegistry, I recommend using VirtualRegistry, which can redirect (among other things). Instead of RedirectFiles, I recommend using CorrectFilePaths (which I haven't talked about here yet, but I'm getting there).

Labels:

Comments

Post a Comment

Popular posts from this blog

Remove previous versions using MSI Upgrade Table

There are several methods to uninstall the existing older versions of an application e.g. Script, MSI upgrade table, SCCM deployment conditions. We are here discussing the method using Upgrade table. Upgrade table can be used effectively to detect and uninstall the previous versions of a MSI based application provided the upgrade code is known. Here is an example on populating Upgrade Table: Locate the U pgradeCode in Property Manager . Remember this could either be same or different in previous version and if it is different then grab the code from previous version. Go to the Upgrade Table in Direct Editor . Copy the upgrade code to its column. Populate the Version columns based on requirement (consider all the digits as per previous MSI versions). Attribute column needs to be configured with appropriate bit flag for corresponding upgrade behavior. Refer to  Upgrade Table  to calculate the proper bit flag. In example, 768 is the sum of 256+512 which m...
1 comment
Read more

Active Setup Registry Key : What it is and how to create in the package using Admin Studio Install Shield

While launching from Admin account or doing “Run as Admin” it was launching properly but when launched from the standard-user account, though it was launching but GUI was not coming properly and before launching, it throws the error that some particular Skin file is missing. I checked in installation folder and skin file was there but still while launching I was getting the error, but when launched from Admin account or using “Run as admin” it was launching properly with proper GUI and no skin file missing error. On exploring further I found that application was installed by admin account and it created some entries in HKCU, and these entries contain the path and name of skin file to be used. So when we launched the application from Standard user account then these entries were empty in HKCU for Standard user. So to solve this problem while re-packaging I used Active Setup . Active Setup provides a great solution for installing current user data when the package is not installed ...
1 comment
Read more

Using the CorrectFilePaths Shim to Redirect Files on Windows Vista

The last time around , I suggested that you avoid using the acredir.dll shims - RedirectRegistry and RedirectFiles. As alternatives, I recommended VirtualRegistry and CorrectFilePaths. Of course, I have already gone into some details on how to use VirtualRegistry to achieve that, but I haven't gone in to any details on CorrectFilePaths yet. And, unfortunately, the documentation isn't much help as of the 5.0.1 release (as I said - stay tuned to the documentation for future releases, as this is something we are working on). In fact, here is all that the documentation tells you: "Corrects file paths that changed between Windows 95 or Windows 98 and Windows XP Professional. This compatibility fix works by converting the file paths to the correct location for Windows XP Professional in the APIs. For example, a Windows 95 path of C:\Windows\Write.exe is converted to C:\Windows\System32\Write.exe." While this is true, it is not comprehensive (and is, theref...
Post a Comment
Read more