Large file streaming uploads

Oqtane.Server/Controllers/FileController.cs

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+using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc;
+using System;
+using System.IO;
+using System.Threading.Tasks;
+
+namespace Oqtane.Controllers
+{
+    [Route("{site}/api/[controller]")]
+    public class FileController : Controller
+    {
+        private readonly IWebHostEnvironment environment;
+        
+        public FileController(IWebHostEnvironment environment)
+        {
+            this.environment = environment;
+        }
+
+        // GET api/<controller>/current
+        [HttpPost("upload")]
+        public async Task UploadFile(string folder, IFormFile file)
+        {
+            if (file.Length > 0)
+            {
+                if (!folder.Contains(":\\"))
+                {
+                    folder = folder.Replace("/", "\\");
+                    if (folder.StartsWith("\\")) folder = folder.Substring(1);
+                    folder = Path.Combine(environment.WebRootPath, folder);
+                }
+                if (!Directory.Exists(folder))
+                {
+                    Directory.CreateDirectory(folder);
+                }
+                using (var stream = new FileStream(Path.Combine(folder, file.FileName), FileMode.Create))
+                {
+                    await file.CopyToAsync(stream);
+                }
+                await MergeFile(folder, file.FileName);
+            }
+        }
+
+        private async Task MergeFile(string folder, string filename)
+        {
+            // parse the filename which is in the format of filename.ext.part_x_y 
+            string token = ".part_";
+            string parts = Path.GetExtension(filename).Replace(token, ""); // returns "x_y"
+            int totalparts = int.Parse(parts.Substring(parts.IndexOf("_") + 1));
+            filename = filename.Substring(0, filename.IndexOf(token)); // base filename
+            string[] fileparts = Directory.GetFiles(folder, filename + token + "*"); // list of all file parts
+
+            // if all of the file parts exist ( note that file parts can arrive out of order )
+            if (fileparts.Length == totalparts)
+            {
+                // merge file parts
+                bool success = true;
+                using (var stream = new FileStream(Path.Combine(folder, filename), FileMode.Create))
+                {
+                    foreach (string filepart in fileparts)
+                    {
+                        try
+                        {
+                            using (FileStream chunk = new FileStream(filepart, FileMode.Open))
+                            {
+                                await chunk.CopyToAsync(stream);
+                            }
+                        }
+                        catch 
+                        {
+                            success = false;
+                        }
+                    }
+                }
+
+                // delete file parts
+                if (success)
+                {
+                    foreach (string filepart in fileparts)
+                    {
+                        System.IO.File.Delete(filepart);
+                    }
+                }
+            }
+
+            // clean up file parts which are more than 2 hours old ( which can happen if a file upload failed )
+            fileparts = Directory.GetFiles(folder, "*" + token + "*");
+            foreach (string filepart in fileparts)
+            {
+                DateTime createddate = System.IO.File.GetCreationTime(filepart);
+                if (createddate < DateTime.Now.AddHours(-2))
+                {
+                    System.IO.File.Delete(filepart);
+                }
+            }
+        }
+    }
+}