File.WriteAllBytes - Sharing Violation on Path

Hi all,

I have written a script to render a picture of each prefab in my Assets\Prefabs folder and save the Texture2D as a .png file to an Assets\Icons folder.

Idea being that I don't need to spend time making icons as they are just generated from the models. (I am aware of AssetPreview.GetAssetPreview but want to be able to control the angle that the preview is taken from for the icon).

If the icons in my folder don't already exist, my script works fine. But if they do already exist, there seems to be a problem: IOException: Sharing violation on path C:\....
I.e. the issue seems to be with overwriting existing files.

I am simply doing the below, in a loop.

Code (CSharp):

1. // Encode texture into PNG
2. byte[] bytes = texTransparent.EncodeToPNG();
3.  
4. // Write the icon png to the disk  
5. File.WriteAllBytes(Application.dataPath + "/Icons/Items/" + fName + ".png", bytes);

This code is inside an IEnumerator which is called from a custom toolbar command.

Any help is much appreciated.

 

If i were you i would just do something like

Code (CSharp):

1. if (File.Exists(path)) {
2.   File.Delete(path):
3. }
4.  
5. // Then your original code

 

Thanks, so I tried that. Interestingly it deletes the first file (and then creates it successfully), but then has a file violation on the second file.

This made me realise the issue is to do with how quickly it is looping to the next file - the first file is still being written. I added

Code (CSharp):

1. yield return new EditorWaitForSeconds(2f);

after each loop and it now works fine (albeit more slowly!) I don't really understand why the issue didn't occur when the files didn't already exist. Perhaps overwriting a file is slower.

I don't particularly like the solution to just add a 2 second wait, is there a method to detect if the file system is busy, and then carry on when it is ready? I suppose I could do a while loop, with a try/catch but it doesn't feel great.

 

I have solved my issue using the below code, but I don't particularly like it and if someone knows a better way to detect if the file system is busy I'd appreciate it.

Code (CSharp):

1. // Define a maximum number of attempts
2.             int numAttempts = 0;
3.             int maxAttempts = 100;
4.             while(!madeFile)
5.             {
6.                 try
7.                 {
8.                     File.WriteAllBytes(filePath, bytes);
9.                     madeFile = true;
10.                 }
11.                 catch (Exception)
12.                 {
13.                     numAttempts++;                  
14.                     if (numAttempts > maxAttempts)
15.                     {
16.                         madeFile = true;
17.                         Debug.Log("Could not make file " + fName);
18.                     }
19.                 }
20.                 // Add a small delay to allow the file system to no longer be busy
21.                 yield return new EditorWaitForSeconds(0.1f);
22.             }

 

You should use AssetDatabase.StartAssetEditing and AssetDatabase.StopAssetEditing to prevent Unity from importing any files during your process. Please read the note in the documentation. You should wrap your code in a try finally block to ensure the asset database is unlocked at the end.

 

Thanks, added that into my code.

 

Thank you for this - This just helped me, appreciate it. Was running up thousands of errors in the console using File.WriteAllBytes while saving a byte[] that gets played as a video. Couldn't figure out what was wrong, just had to check if the file path existed first, this helped, shout out to you. Take care