fix(msi): pass the printer name in a format the custom action can read

[~] is MSI's escape for a NUL character, not the delimiter WcaReadStringFromCaData
splits on -- that is a literal wide char 128, which a Formatted property value
cannot carry -- and WcaGetProperty returns a null-terminated string anyway. So
the second field was unreachable: InstallPrinter always fell back to the stock
name and installed a printer and port called "RustDesk Printer" inside a
customer's branded package, while UninstallPrinter, whose data is a single field
and parsed fine, went looking for "Acme Printer" and left the real one behind
for good.

Both actions now read CustomActionData directly and split on a character that
cannot occur in a Windows path or in a validated app name. A package built
before this carries no separator and keeps the stock name, as it did.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Q7fBdTwziR5BHTkSz7Tzcm

res/msi/CustomActions/CustomActions.cpp

@@ -1021,10 +1021,9 @@ UINT __stdcall InstallPrinter(
     DWORD er = ERROR_SUCCESS;
 
     int nResult = 0;
-    LPWSTR installFolder = NULL;
-    LPWSTR appName = NULL;
-    LPWSTR pwz = NULL;
     LPWSTR pwzData = NULL;
+    std::wstring appNameValue;
+    std::wstring installFolderValue;
 
     hr = WcaInitialize(hInstall, "InstallPrinter");
     ExitOnFailure(hr, "Failed to initialize");
@@ -1032,25 +1031,30 @@ UINT __stdcall InstallPrinter(
     hr = WcaGetProperty(L"CustomActionData", &pwzData);
     ExitOnFailure(hr, "failed to get CustomActionData");
 
-    pwz = pwzData;
+    // "<app name>|<install folder>". Split here rather than through
-    hr = WcaReadStringFromCaData(&pwz, &installFolder);
+    // WcaReadStringFromCaData, whose delimiter is a literal wide char 128 that a
-    ExitOnFailure(hr, "failed to read database key from custom action data: %ls", pwz);
+    // Formatted property value cannot carry.
-
-    // Names the printer. Optional, so that a package built before this was passed in
-    // still installs, keeping the stock printer name.
-    if (FAILED(WcaReadStringFromCaData(&pwz, &appName)))
     {
-        ReleaseNullStr(appName);
+        std::wstring data(pwzData);
+        size_t separator = data.find(L'|');
+        if (separator == std::wstring::npos)
+        {
+            // A package built before the name was passed in; keep the stock name.
+            appNameValue.clear();
+            installFolderValue = data;
+        }
+        else
+        {
+            appNameValue = data.substr(0, separator);
+            installFolderValue = data.substr(separator + 1);
+        }
     }
 
-    WcaLog(LOGMSG_STANDARD, "Try to install RD printer in : %ls", installFolder);
+    WcaLog(LOGMSG_STANDARD, "Try to install RD printer in : %ls", installFolderValue.c_str());
-    RemotePrinter::installUpdatePrinter(installFolder, appName ? appName : L"");
+    RemotePrinter::installUpdatePrinter(installFolderValue, appNameValue);
     WcaLog(LOGMSG_STANDARD, "Install RD printer done");
 
 LExit:
-    if (appName) {
-        ReleaseStr(appName);
-    }
     if (pwzData) {
         ReleaseStr(pwzData);
     }
@@ -1065,32 +1069,24 @@ UINT __stdcall UninstallPrinter(
     HRESULT hr = S_OK;
     DWORD er = ERROR_SUCCESS;
 
-    LPWSTR appName = NULL;
-    LPWSTR pwz = NULL;
     LPWSTR pwzData = NULL;
+    std::wstring appNameValue;
 
     hr = WcaInitialize(hInstall, "UninstallPrinter");
     ExitOnFailure(hr, "Failed to initialize");
 
     // Must match the name install used, otherwise the printer is left behind. Absent
     // on packages built before this was passed in, where it was the stock name.
-    if (SUCCEEDED(WcaGetProperty(L"CustomActionData", &pwzData)))
+    if (SUCCEEDED(WcaGetProperty(L"CustomActionData", &pwzData)) && pwzData)
     {
-        pwz = pwzData;
+        appNameValue = pwzData;
-        if (FAILED(WcaReadStringFromCaData(&pwz, &appName)))
-        {
-            ReleaseNullStr(appName);
-        }
     }
 
     WcaLog(LOGMSG_STANDARD, "Try to uninstall RD printer");
-    RemotePrinter::uninstallPrinter(appName ? appName : L"");
+    RemotePrinter::uninstallPrinter(appNameValue);
     WcaLog(LOGMSG_STANDARD, "Uninstall RD printer done");
 
 LExit:
-    if (appName) {
-        ReleaseStr(appName);
-    }
     if (pwzData) {
         ReleaseStr(pwzData);
     }

res/msi/Package/Components/RustDesk.wxs

@@ -30,9 +30,13 @@
 		<CustomAction Id="SetPropertyServiceStop.SetParam.PropertyName" Return="check" Property="PropertyName" Value="STOP_SERVICE" />
 		<CustomAction Id="TryDeleteStartupShortcut.SetParam" Return="check" Property="ShortcutName" Value="$(var.Product) Tray" />
 		<CustomAction Id="RemoveAmyuniIdd.SetParam" Return="check" Property="RemoveAmyuniIdd" Value="[INSTALLFOLDER_INNER]" />
-		<!-- [~] separates the fields the custom action reads back. ProductName names the
+		<!-- The app name comes first and is separated by '|', which cannot occur in a
-		     printer, so the dll carries no app name and one build serves every custom client. -->
+		     Windows path nor in a validated app name. wcautil's own delimiter is a
-		<CustomAction Id="InstallPrinter.SetParam" Return="check" Property="InstallPrinter" Value="[INSTALLFOLDER_INNER][~][ProductName]" />
+		     literal wide char 128 that a Formatted value cannot carry, and [~] is
+		     MSI's NUL escape rather than that delimiter, so the action parses this
+		     itself. Passing the name keeps the dll free of it, so one build serves
+		     every custom client. -->
+		<CustomAction Id="InstallPrinter.SetParam" Return="check" Property="InstallPrinter" Value="[ProductName]|[INSTALLFOLDER_INNER]" />
 		<CustomAction Id="UninstallPrinter.SetParam" Return="check" Property="UninstallPrinter" Value="[ProductName]" />
 		<InstallExecuteSequence>