Failed to get MSI property in UPGRADINGPRODUCTCODE, WIX_UPGRADE_DETECTED

问题

I wanted to skip some of my custom actions during upgrade, uninstallDriver, to achieve this I have tried to retrieve property WIX_UPGRADE_DETECTED and UPGRADINGPRODUCTCODE, but both of them are not set.

Sample code:

UninstallDriver(MSIHANDLE hInstall)  
{
   char szBuff[1024]; DWORD dwValue = 0;

   OutputDebugStringA("UninstallDriver");
   MsiGetPropertyA(hInstall, "UPGRADINGPRODUCTCODE", szBuff, &dwValue);
   OutputDebugStringA("UPGRADINGPRODUCTCODE");OutputDebugStringA(szBuff);

   MsiGetPropertyA(hInstall, "WIX_UPGRADE_DETECTED", szBuff, &dwValue);
   OutputDebugStringA("WIX_UPGRADE_DETECTED");OutputDebugStringA(szBuff);

   result = UninstallDriver();

   return result;
}

And my customAction is,

<Custom Action='UninstallMYDriverAction'
 After='InstallInitialize'>
        REMOVE~="ALL" OR REINSTALL</Custom>

回答1:

Ignoring the debug strings, it's easier to see that the buffer handling is incorrect. I would suggest also outputting the return values from MsiGetPropertyA() and the value in dwValue to confirm, but here's what I think is happening (comments refer to dwValue):

char szBuff[1024]; DWORD dwValue = 0;
MsiGetPropertyA(hInstall, "UPGRADINGPRODUCTCODE", szBuff, &dwValue); // passes 0, updated to ?x?
MsiGetPropertyA(hInstall, "WIX_UPGRADE_DETECTED", szBuff, &dwValue); // passes ?x?, updated to ?y?

When requesting UPGRADINGPRODUCTCODE property with a claimed buffer length of zero, the fetch will never succeed as it must always accept at least a null character. Thus this will return ERROR_MORE_DATA and set dwValue to the length excluding a null character (?x?).

Then it will request the value of WIX_UPGRADE_DETECTED with a claimed buffer length of (?x?). If the new length (?y?) is less than the old length (?x?) you'll get its contents in your buffer; otherwise it will also just query the length of this new property.

Since WIX_UPGRADE_DETECTED contains a list of one or more GUIDs, and UPGRADINGPRODUCTCODE only contains one, and this code never increments dwValue to account for the null, it will only possibly succeed if the latter is ?y? is 0 (empty) and ?x? is non-empty. But note that this second call passed an unverified value as the length of your buffer, this pattern is a buffer overflow waiting to happen.

So fix your buffer handling. The pattern I like to use (below) is similar to what Stein describes, but avoids the second call if I know a good default size for the buffer. In your case, it sounds like you're happy with the 1024 element buffer, but do consider if you ever need to handle more than 1024 / len(GUID) related upgrade codes.

(My guess is you're fine. But at least think it through. And even though GUIDs are ASCII so the contents won't matter, please please please build UNICODE these days...)

WCHAR szBuf[1024];
DWORD cchBuf = 1024; // or _countof(szBuf);
DWORD dwErr = MsiGetPropertyW(hInstall, L"UPGRADINGPRODUCTCODE", szBuf, &cchBuf);
if (dwErr != ERROR_MORE_DATA) {
    // exercise: increment cchBuf for null, adjust buffer, call MsiGetPropertyW again
}
if (dwErr != ERROR_SUCCESS) {
    // per https://docs.microsoft.com/en-us/windows/desktop/msi/custom-action-return-values
    return ERROR_INSTALL_FAILURE;
}

// reset buffer length for next call, in case second property is longer than first
cchBuf = 1024;
dwErr = MsiGetPropertyW(hInstall, L"WIX_UPGRADE_DETECTED", szBuf, &cchBuf);
// : : :

回答2:

Custom Action Condition: You should be able to condition that custom action outright without going via a custom action? MSI conditions are notorious for being difficult to get just right since there are so many installation modes to deal with: install, repair, self-repair, modify and minor upgrade patching, uninstall, major upgrade initiated uninstalls, etc... There are several more.

In your case it might be sufficient to add to the existing condition:

AND (NOT UPGRADINGPRODUCTCODE)

This will make the condition invalid if an upgrade is detected.

I would actually try: (REMOVE~="ALL") AND (NOT UPGRADINGPRODUCTCODE) (as seen in this answer).

Top Tip: You can debug MSI conditions pretty efficiently by the approach described here: How to execute conditional custom action on install and modify only? (see bottom section). You use VBScript and a few MSI API calls to determine what conditions are true, and then you can change the sequencing to check the conditions at different times. They might change.

Note: This is just a sorry-for-itself and poor man's MSI debugger, but it works.

Property String Size: I am not a C++ expert, but here is from the MSI SDK: You need to call MsiGetProperty with an empty string first and then add 1 for null termination. As usual high "line noise" with C++. A lot of plumbing and formalities for very little effect - but let's just deal with it :-):

The below C++ sample is from the MSI SDK:

UINT __stdcall MyCustomAction(MSIHANDLE hInstall)
{
    TCHAR* szValueBuf = NULL;
    DWORD cchValueBuf = 0;
    UINT uiStat =  MsiGetProperty(hInstall, TEXT("MyProperty"), TEXT(""), &cchValueBuf);
    //cchValueBuf now contains the size of the property's string, without null termination
    if (ERROR_MORE_DATA == uiStat)
    {
        ++cchValueBuf; // add 1 for null termination
        szValueBuf = new TCHAR[cchValueBuf];
        if (szValueBuf)
        {
            uiStat = MsiGetProperty(hInstall, TEXT("MyProperty"), szValueBuf, &cchValueBuf);
        }
    }
    if (ERROR_SUCCESS != uiStat)
    {
        if (szValueBuf != NULL) 
           delete[] szValueBuf;
        return ERROR_INSTALL_FAILURE;
    }   

// custom action uses MyProperty
// ...

delete[] szValueBuf;

return ERROR_SUCCESS;

}

VBScript: For testing purposes VBScript can be used easily (so you can determine if you have a coding issue or not):

MsgBox Session.Property("PROPERTYNAME")

Some Further Links (just for reference and easy retrieval, not needed for you I think):

MSI Conditions
How to execute custom action only in install (not uninstall)
How to add a WiX custom action that happens only on uninstall (via MSI)?
Wix Tools update uses old custom actions
Wix custom uninstallation action - how to run before msi removing files

来源：https://stackoverflow.com/questions/53929920/failed-to-get-msi-property-in-upgradingproductcode-wix-upgrade-detected

标签

wix

windows-installer

custom-action