UCM: Limit check-in size and extension of the file

SCENARIO: We want to restrict the user to upload a file whose extension is .exe and whose size is more than 5 MB.

IMPLEMENTATION: To check the file extension, write a filter on postValidateCheckinData event. To check the file size, write a filter on validateStandard event.

postValidateCheckinData
Executed at the end of the action validateCheckinData and after the filter validateCheckinData. This is a good place for last-minute alterations of the metadata prior to a check-in.

validateStandard
Executed during update or check-in. This runs before the core validates the metadata fields, such as dReleaseState, dDocName, dRevClassID, dDocTitle, primaryFile, alternateFile, dCreateDate, dInDate, and dOutDate.

    private void checkFileExtension(DataBinder binder) throws ServiceException {
        String dExtension = binder.getLocal("dExtension");
        trace("dExtension: " + dExtension);
        String ExtensionsToControl = "";
        if (SharedObjects.getEnvironmentValue("ExtensionsToControl") != null) {
            ExtensionsToControl = SharedObjects.getEnvironmentValue("ExtensionsToControl");
        }
        trace("ExtensionsToControl: " + ExtensionsToControl);
        if (ExtensionsToControl.indexOf(dExtension) >= 0) {
            String msg = LocaleUtils.encodeMessage("csExtensionsToControl", null, dExtension);
            throw new ServiceException(msg);
        }
    }

    private void checkFileSize(DataBinder binder) throws ServiceException {
        //trace(binder.m_tempFiles.toString());
        String primaryFilePath = binder.getLocal("primaryFile:path");
        trace("primaryFilePath: " + primaryFilePath);
        File file = new File(primaryFilePath);
        long fileSize = file.length();
        trace("fileSize: " + fileSize);
        if (fileSize >= 5 * 1024 * 1024) {
            throw new ServiceException("This document is too large.");
        }
    }

Create an environment file as well:

ExtensionsToControl=exe,rar

I had also created a string resource file to display the error message in case the file extension matches with the one provided in the environment file:
<@csExtensionsToControl=Files of extension {1} cannot be uploaded.@>


NOTES
1. A better approach is provided in the link below:
http://sonaloraclewebcenter.blogspot.in/2015/04/ucm-validating-file-extension.html

2. If you want to check the mime type of the file and not the extension, use Apache Tika 1.7.