Umbraco-CMS/src/Umbraco.Core/Configuration/ContentSettingsExtensions.cs

using System.Linq;
using Umbraco.Cms.Core.Configuration.Models;

namespace Umbraco.Extensions
{
    public static class ContentSettingsExtensions
    {
        /// <summary>
        /// Determines if file extension is allowed for upload based on (optional) white list and black list
        /// held in settings.
        /// Allow upload if extension is whitelisted OR if there is no whitelist and extension is NOT blacklisted.
        /// </summary>
        public static bool IsFileAllowedForUpload(this ContentSettings contentSettings, string extension)
        {
            return contentSettings.AllowedUploadFiles.Any(x => x.InvariantEquals(extension)) ||
                (contentSettings.AllowedUploadFiles.Any() == false &&
                contentSettings.DisallowedUploadFiles.Any(x => x.InvariantEquals(extension)) == false);
        }

        /// <summary>
        /// Gets the auto-fill configuration for a specified property alias.
        /// </summary>
        /// <param name="contentSettings"></param>
        /// <param name="propertyTypeAlias">The property type alias.</param>
        /// <returns>The auto-fill configuration for the specified property alias, or null.</returns>
        public static ImagingAutoFillUploadField? GetConfig(this ContentSettings contentSettings, string propertyTypeAlias)
        {
            var autoFillConfigs = contentSettings.Imaging.AutoFillImageProperties;
            return autoFillConfigs?.FirstOrDefault(x => x.Alias == propertyTypeAlias);
        }
    }
}