Web Application not able to Delete files for Read/Write Enabled Folders in ASP.NET - asp.net

Question

When I'm trying to delete the images uploaded by me via website named "SampleApplication" I can see the following error shown in Stack Trace
The process cannot access the file 'D:\Hosting\123456\html\App_Images\myfolder1\eKuK2511.png' because it is being used by another process.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.IO.IOException: The process cannot access the file 'D:\Hosting\123456\html\App_Images\myfolder1\eKuK2511.png' because it is being used by another process.
Source Error:
An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.
Stack Trace:
[IOException: The process cannot access the file 'D:\Hosting\123456\html\App_Images\myfolder1\eKuK2511.png' because it is being used by another process.]
System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath) +9723350
System.IO.File.Delete(String path) +9545728
SampleApplication.BasePage.DeleteApp_ImagesById(DataTable dt) +503
SampleApplication.PostLease.MyAccount.DeleteAd_Property(Object sender, EventArgs e) +193
System.Web.UI.WebControls.LinkButton.OnClick(EventArgs e) +118
System.Web.UI.WebControls.LinkButton.RaisePostBackEvent(String eventArgument) +113
System.Web.UI.WebControls.LinkButton.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +9
System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +176
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +5563
Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.272
The folder App_Images has been given Read/write Permission and inherits to child folders namely myfolder1, myfolder2, myfolder3, myfolder4. Even when I tried to forcefully delete the image eKuK2511.png from the FTP File manager it is showing the following error:
550 The process cannot access the file because it is being used by another process.
How to getrid of this error?
Edit:
Upload Code:
public void UploadImages()
{
if (ServerSideValidation() == true)
{
string SavePath;
ImgPaths = new List<string>();
// Get the HttpFileCollection
HttpFileCollection hfc = Request.Files;
if (hfc.Count > 0)
{
for (int i = 0; i < hfc.Count; i++)
{
HttpPostedFile hpf = hfc[i];
if (hpf.ContentLength > 0)
{
#region trials compression.
SavePath = "~/App_Images/" + Session["AppContext"].ToString() + "/" + GetUniqueKey() + GetFileExtension(hpf.FileName);
SaveImageByCompressing(hpf, SavePath);
#endregion
//SavePath can be saved in DB.
ImgPaths.Add(SavePath);
//Save Thumbnail Image.
if (i == 0)
{
string savedName = "Thumb_" + GetUniqueKey() + GetFileExtension(AppDomain.CurrentDomain.BaseDirectory + ImgPaths[0].ToString().Replace("~/", "\\").Replace("/", "\\"));
SavePath = "~/App_Images/" + Session["AppContext"].ToString() + "/" + savedName;
SaveThumbImage(AppDomain.CurrentDomain.BaseDirectory + ImgPaths[0].ToString().Replace("~/", "").Replace("/", "\\"), AppDomain.CurrentDomain.BaseDirectory + "App_Images\\" + Session["AppContext"].ToString() + "\\" + savedName, 75, 75);
ImgPaths.Add(SavePath);
}
}
}
Session.Remove("AppContext");
lblMsg.Text = "Images Uploaded Successfully.";
//ShowUploadedImages(ImgPaths);
}
else
{
lblMsg.Text = "Images uploaded are either in wrong format or were deleted after uploading.";
}
}
else
{
lstPaths = new List<string>();
lblMsg.Text = "No Images Uploaded";
}
}
private void SaveImageByCompressing(HttpPostedFile hpf, string filePath)
{
Image imgFromClient = Image.FromStream(hpf.InputStream);
string SavetoFullPath = AppDomain.CurrentDomain.BaseDirectory + filePath.Replace("~/", "").Replace("/", "\\");
Image.GetThumbnailImageAbort myCallbackCompressed = new Image.GetThumbnailImageAbort(ThumbnailCallback);
Image imageToSave= imgFromClient.GetThumbnailImage(imgFromClient.Width, imgFromClient.Height, myCallbackCompressed, IntPtr.Zero);
imageToSave.Save(SavetoFullPath, System.Drawing.Imaging.ImageFormat.Jpeg);
}
public static void SaveThumbImage(string imagePath, string filePath, int width = 0, int height = 0)
{
Image originalImage = Image.FromFile(imagePath);
if (width > 0 && height > 0)
{
Image.GetThumbnailImageAbort myCallback = new Image.GetThumbnailImageAbort(ThumbnailCallback);
Image imageToSave = originalImage.GetThumbnailImage(width, height, myCallback, IntPtr.Zero);
imageToSave.Save(filePath, System.Drawing.Imaging.ImageFormat.Jpeg);
}
else
{
originalImage.Save(filePath, System.Drawing.Imaging.ImageFormat.Jpeg);
}
}
private static bool ThumbnailCallback() { return false; }
private bool ServerSideValidation()
{
string errorMsg = string.Empty, temp = null;
bool errorFlag = true;
// Get the HttpFileCollection
HttpFileCollection hfc = Request.Files;
for (int i = 0; i < hfc.Count; i++)
{
HttpPostedFile hpf = hfc[i];
if (hpf.ContentLength > 0 && hpf.FileName!=String.Empty)
{
temp = ValidateImage(hpf);
if (temp != null)
{
errorMsg += GetFileName(hpf.FileName.ToString()) + " has error : " + temp;
temp = null;
}
}
else
{
return false;
}
}
if (!string.IsNullOrWhiteSpace(errorMsg))
{
lblMsg.Text = errorMsg;
errorFlag = false;
}
return errorFlag;
}
private string GetFileExtension(string filePath)
{
FileInfo fi = new FileInfo(filePath);
return fi.Extension;
}
private string GetFileName(string filePath)
{
FileInfo fi = new FileInfo(filePath);
return fi.Name;
}
private string GetUniqueKey()
{
int maxSize = 8;
char[] chars = new char[62];
string a = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
chars = a.ToCharArray();
int size = maxSize;
byte[] data = new byte[1];
RNGCryptoServiceProvider crypto = new RNGCryptoServiceProvider();
crypto.GetNonZeroBytes(data);
size = maxSize;
data = new byte[size];
crypto.GetNonZeroBytes(data);
StringBuilder result = new StringBuilder(size);
foreach (byte b in data)
{
result.Append(chars[b % (chars.Length - 1)]);
}
return Session["AppContext"].ToString() + Page.User.Identity.Name.ToString() + result.ToString();
}
private string ValidateImage(HttpPostedFile myFile)
{
string msg = null;
//6MB
int FileMaxSize = 6291456;
//Check Length of File is Valid or Not.
if (myFile.ContentLength > FileMaxSize)
{
msg = msg + "File Size is Too Large. You are allowed only a maximum of 6MB per Image.";
}
//Check File Type is Valid or Not.
if (!IsValidFile(myFile.FileName))
{
msg = msg + "Invalid File Type.";
}
return msg;
}
private bool IsValidFile(string filePath)
{
bool isValid = false;
string[] fileExtensions = { ".BMP", ".JPG", ".PNG", ".GIF", ".JPEG" };
for (int i = 0; i < fileExtensions.Length; i++)
{
if (filePath.ToUpper().Contains(fileExtensions[i]))
{
isValid = true; break;
}
}
return isValid;
}
Delete Code:
/// <summary>
/// Delete all images. If there are no Images then by default NoImage.png is assigned. So skip deleting that image.
/// </summary>
/// <param name="dt"></param>
protected void DeleteApp_ImagesById(DataTable dt)
{
if (dt.Rows[0][0].ToString() != "~/images/NoImage.png")
{
for (int i = 0; i < dt.Columns.Count; i++)
{
if (dt.Rows[0][i].ToString() != string.Empty)
{
string str = Regex.Replace(dt.Rows[0][i].ToString(), "~/", "");
File.Delete(Request.PhysicalApplicationPath.ToString() + Regex.Replace(str, "/", "\\").ToString());
}
}
}
}

Answer 1

The docs on MSDN about Image.Save say that the file remains locked until the Image is disposed.
So I suppose that changing the code that save the images in this way
private void SaveImageByCompressing(HttpPostedFile hpf, string filePath)
{
using(Image imgFromClient = Image.FromStream(hpf.InputStream))
{
string SavetoFullPath = AppDomain.CurrentDomain.BaseDirectory +
filePath.Replace("~/", "").Replace("/", "\\");
Image.GetThumbnailImageAbort myCallbackCompressed =
new Image.GetThumbnailImageAbort(ThumbnailCallback);
using(Image imageToSave= imgFromClient.GetThumbnailImage(imgFromClient.Width,
imgFromClient.Height, myCallbackCompressed, IntPtr.Zero))
{
imageToSave.Save(SavetoFullPath, System.Drawing.Imaging.ImageFormat.Jpeg);
}
}
}
public static void SaveThumbImage(string imagePath, string filePath,
int width = 0, int height = 0)
{
using(Image originalImage = Image.FromFile(imagePath))
{
if (width > 0 && height > 0)
{
Image.GetThumbnailImageAbort myCallback =
new Image.GetThumbnailImageAbort(ThumbnailCallback);
using(Image imageToSave = originalImage.GetThumbnailImage(width, height,
myCallback, IntPtr.Zero))
{
imageToSave.Save(filePath, System.Drawing.Imaging.ImageFormat.Jpeg);
}
}
else
{
originalImage.Save(filePath, System.Drawing.Imaging.ImageFormat.Jpeg);
}
}
}
is a safe way to ensure your images are immediately unlocked when you finish with the upload code