Writing Entry-Point Functions

InstallShield 2018

Project • This information applies to the following project types:

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Basic MSI with InstallScript custom actions

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InstallScript MSI with InstallScript custom actions

•

Merge Module with InstallScript custom actions

When Windows Installer executes an InstallScript custom action, InstallShield calls the function that you specified when you created the custom action. Every InstallScript custom action must have an exported, user-defined function as an entry point into the script.

Prototyping and Defining Functions

An entry-point function is prototyped and defined like any other function, except that it has the following requirements:

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Its prototype must include the keyword export to declare it as an exported function.

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The function can accept only one argument, which must be a handle to the .msi database.

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It should return a value meaningful to Windows Installer, if your custom action is designed to wait for a return value. These custom action return values are defined in IsMsiQuery.h and available to you if you include IsMsiQuery.h or Iswi.h in your script.

The following example script declares an entry-point function, which returns success if it succeeded:

// Include Isrt.h for built-in InstallScript function prototypes.

#include "isrt.h"

// Include Iswi.h for Windows Installer API function prototypes and constants.

#include "iswi.h"

export prototype MyFunction(HWND);

function MyFunction(hMSI)

STRING szKey, svValue, svPath;

NUMBER nvType, nvSize, nReturn;

begin

RegDBSetDefaultRoot (HKEY_LOCAL_MACHINE);

szKey = "SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\App Paths\\isdev.exe";

nReturn = RegDBGetKeyValueEx (szKey, "Path", nvType, svValue, nvSize);

// The App Paths key contains the folder where InstallShield was

// installed, followed by a semicolon.

StrSub (svPath, svValue, 0, StrFind(svValue, ";"));

if nReturn = 0 then

MessageBox ("InstallShield is installed to " + svPath, INFORMATION);

return ERROR_SUCCESS;

else

MessageBox ("Cannot determine where InstallShield is installed.", SEVERE);

return ERROR_INSTALL_FAILURE;

endif;

end;

Multiple Entry Points

Your script can have multiple entry-point functions in it to serve multiple custom actions. However, InstallShield calls only the single entry-point function specified for each InstallScript custom action.

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Writing Entry-Point Functions

InstallShield 2018 Help Library

January 2018