Crash AFTER trying to retrieve contents of directory from FTP

[gouen95]

Hi, I'm trying to list down the contents of directory from a ftp server.

iOS: 11.2
XCode: 9.2, Swift 4

Here is the crash error :
*** -[FilesProvider.FileProviderStreamTask respondsToSelector:]: message sent to deallocated instance 0x1c01c4ec0

Below is the code :

        let credential = URLCredential(user: hostList![row].username!, password: hostList![row].password!, persistence: .permanent)
        
        let ftpFileProvider = FTPFileProvider(baseURL: URL(string: hostList![row].serverUrl!)!, passive: true, credential: credential, cache: nil)
        
        ftpFileProvider?.contentsOfDirectory(path: "", completionHandler: { (contents, error) in
            print(error)
            
            for file in contents {
                print("Name: \(file.name)")
                print("Size: \(file.size)")
                print("Creation Date: \(file.creationDate)")
                print("Modification Date: \(file.modifiedDate)")
            }
        }) 

[amosavian]

You get this error every time?

[gouen95]

Yes, unfortunately. : (

[amosavian]

This sample code has a flaw. It does not retain ftpFileProvider instance object. You must store it as a global variable or as instance variable.

[gouen95]

Hi, thank you for the quick reply. I've tried to make it as an instance variable. The issue still persist. I'm sorry if I'm unfamiliar with the framework implementation.

Below is the code of my whole controller.

//
//  ContentListingViewController.swift
//  

import UIKit
import FilesProvider

class ContentListingViewController: UIViewController {
    
    //MARK:- Variables
    var host: HostBean?
    var ftpFileProvider: FTPFileProvider?
    
    //MARK:- Application Lifecycles
    override func viewDidLoad() {
        super.viewDidLoad()

        if host != nil {
            listDirectories()
        }
    }

    //MARK:- Private Functions
    private func listDirectories() {
        let credential = URLCredential(user: (host?.username!)!, password: (host?.password!)!, persistence: .permanent)
        
        ftpFileProvider?.delegate = self as FileProviderDelegate
        
        ftpFileProvider = FTPFileProvider(baseURL: URL(string: (host?.serverUrl!)!)!, passive: true, credential: credential, cache: nil)
        
        ftpFileProvider?.contentsOfDirectory(path: "/", completionHandler: { (contents, error) in
            print(error)
            
            for file in contents {
                print("Name: \(file.name)")
                print("Size: \(file.size)")
                print("Creation Date: \(file.creationDate)")
                print("Modification Date: \(file.modifiedDate)")
            }
        })
    }
}

extension ContentListingViewController: FileProviderDelegate {
    func fileproviderSucceed(_ fileProvider: FileProviderOperations, operation: FileOperationType) {
        switch operation {
        case .copy(source: let source, destination: let dest):
            print("\(source) copied to \(dest).")
        case .remove(path: let path):
            print("\(path) has been deleted.")
        default:
            print("\(operation.actionDescription) from \(operation.source) to \(String(describing: operation.destination)) succeed")
        }
    }
    
    func fileproviderFailed(_ fileProvider: FileProviderOperations, operation: FileOperationType, error: Error) {
        switch operation {
        case .copy(source: let source, destination: let dest):
            print("copy of \(source) failed. huh? \(dest)")
        case .remove:
            print("file can't be deleted.")
        default:
            print("\(operation.actionDescription) from \(operation.source) to \(String(describing: operation.destination)) failed")
        }
    }
    
    func fileproviderProgress(_ fileProvider: FileProviderOperations, operation: FileOperationType, progress: Float) {
        switch operation {
        case .copy(source: let source, destination: let dest):
            print("Copy\(source) to \(dest): \(progress * 100) completed.")
        default:
            break
        }
    }
}

[amosavian]

My test unit is passing on my mac. My apps work well too. I cant reproduce :/

[gouen95]

Hi, I've been trying a few public ftp server out there and try to find out if any of them is same with my own desktop ftp server. I've found a public ftp server which is ftp://speedtest.tele2.net/ (username: anonymous, no password), this ftp server caused the application to crash while others don't.. I don't understand why this is happening hope it helps.

Edit : new crash error

objc[4597]: Class _NSZombie_OS_xpc_uuid is implemented in both ?? (0x1c4248df0) and ?? (0x1c4248ee0). One of the two will be used. Which one is undefined.
2018-01-05 16:24:57.788994+0800 TestFTP[4597:1119160] [MC] Lazy loading NSBundle MobileCoreServices.framework
2018-01-05 16:24:57.790122+0800 TestFTP[4597:1119160] [MC] Loaded MobileCoreServices.framework
2018-01-05 16:26:11.914376+0800 TestFTP[4597:1119160] *** -[FilesProvider.FileProviderStreamTask respondsToSelector:]: message sent to deallocated instance 0x1c01cb310

[amosavian]

The problem was zombie objects. Thanks for your report.
Adding these lines has fixed issue as far as I tested.

[buba447]

Im having a similar crash. Using the example code for retrieving directory contents. I am retaining the FTPFileProvider. The crash happens immediately AFTER the completion block returns. The contents are retrieved properly then the app crashes with EXC_BAD_ACCESS (code=EXC_I386_GPFLT)

example code

class CameraFileManager {
  
  let ipAddress: URL
  let documentProvider: FTPFileProvider?
  
  init(ipAddress: URL) {
    self.ipAddress = ipAddress
    
    self.documentProvider = FTPFileProvider(baseURL: ipAddress)
  }
  
  func getCameraName() {
    ///tmp/fuse_d/NAME/

    documentProvider?.contentsOfDirectory(path: "/tmp/fuse_d/NAME/", rfc3659enabled: false, completionHandler: {
      contents, error in
      for file in contents {
        print("Name: \(file.name)")
        print("Size: \(file.size)")
        print("Creation Date: \(file.creationDate)")
        print("Modification Date: \(file.modifiedDate)")
      }
    })
  }
}```

[buba447]

Heres a zombie trace for the error

[amosavian]

@buba447 Please pull latest commit and check again