This is a tricky question. I suspect it will require some advanced knowledge of file systems to answer.
I have a WPF application, "App1," targeting .NET framework 4.0. It has a Settings.settings file that generates a standard App1.exe.config file where default settings are stored. When the user modifies settings, the modifications go in AppData\Roaming\MyCompany\App1\X.X.0.0\user.config. This is all standard .NET behavior. However, on occasion, we've discovered that the user.config file on a customer's machine isn't what it's supposed to be, which causes the application to crash.
The problem looks like this: user.config is about the size it should be if it were filled with XML, but instead of XML it's just a bunch of NUL characters. It's character 0 repeated over and over again. We have no information about what had occurred leading up to this file modification.
We can fix that problem on a customer's device if we just delete user.config because the Common Language Runtime will just generate a new one. They'll lose the changes they've made to the settings, but the changes can be made again.
However, I've encountered this problem in another WPF application, "App2," with another XML file, info.xml. This time it's different because the file is generated by my own code rather than by the CLR. The common themes are that both are C# WPF applications, both are XML files, and in both cases we are completely unable to reproduce the problem in our testing. Could this have something to do with the way C# applications interact with XML files or files in general?
Not only can we not reproduce the problem in our current applications, but I can't even reproduce the problem by writing custom code that generates errors on purpose. I can't find a single XML serialization error or file access error that results in a file that's filled with nulls. So what could be going on?
App1 accesses user.config by calling Upgrade() and Save() and by getting and setting the properties. For example:
if (Settings.Default.UpgradeRequired)
{
Settings.Default.Upgrade();
Settings.Default.UpgradeRequired = false;
Settings.Default.Save();
}
App2 accesses info.xml by serializing and deserializing the XML:
public Info Deserialize(string xmlFile)
{
if (File.Exists(xmlFile) == false)
{
return null;
}
XmlSerializer xmlReadSerializer = new XmlSerializer(typeof(Info));
Info overview = null;
using (StreamReader file = new StreamReader(xmlFile))
{
overview = (Info)xmlReadSerializer.Deserialize(file);
file.Close();
}
return overview;
}
public void Serialize(Info infoObject, string fileName)
{
XmlSerializer writer = new XmlSerializer(typeof(Info));
using (StreamWriter fileWrite = new StreamWriter(fileName))
{
writer.Serialize(fileWrite, infoObject);
fileWrite.Close();
}
}
We've encountered the problem on both Windows 7 and Windows 10. When researching the problem, I came across this post where the same XML problem was encountered in Windows 8.1: Saved files sometime only contains NUL-characters
Is there something I could change in my code to prevent this, or is the problem too deep within the behavior of .NET?
It seems to me that there are three possibilities:
The CLR is writing null characters to the XML files.
The file's memory address pointer gets switched to another location without moving the file contents.
The file system attempts to move the file to another memory address and the file contents get moved but the pointer doesn't get updated.
I feel like 2 and 3 are more likely than 1. This is why I said it may require advanced knowledge of file systems.
I would greatly appreciate any information that might help me reproduce, fix, or work around the problem. Thank you!
It's well known that this can happen if there is power loss. This occurs after a cached write that extends a file (it can be a new or existing file), and power loss occurs shortly thereafter. In this scenario the file has 3 expected possible states when the machine comes back up:
1) The file doesn't exist at all or has its original length, as if the write never happened.
2) The file has the expected length as if the write happened, but the data is zeros.
3) The file has the expected length and the correct data that was written.
State 2 is what you are describing. It occurs because when you do the cached write, NTFS initially just extends the file size accordingly but leaves VDL (valid data length) untouched. Data beyond VDL always reads back as zeros. The data you were intending to write is sitting in memory in the file cache. It will eventually get written to disk, usually within a few seconds, and following that VDL will get advanced on disk to reflect the data written. If power loss occurs before the data is written or before VDL gets increased, you will end up in state 2.
This is fairly easy to repro, for example by copying a file (the copy engine uses cached writes), and then immediately pulling the power plug on your computer.
I had a similar problem and I was able to trace my problem to corrupted HDD.
Description of my problem (all related informations):
Disk attached to mainboard (SATA):
SSD (system),
3 * HDD.
One of the HDD's had a bad blocks and there were even problems reading the disk structure (directories and file listing).
Operation system: Windows 7 x64
file system (on all disks): NTFS
When the system tried to read or write to the corrupted disk (user request or automatic scan or any other reason) and the attempt failed, all write operations (to other disk's) were incorrect. The files created on system disk (mostly configuration files by another applications) were written and were valid (probably because the files were cashed in RAM) on direct check of file content.
Unfortunately, after a restart, all the files (written after the failed write/read access on corrupted drive) had the correct size, but the content of the files was 'zero byte' (exactly like in your case).
Try rule out hardware related problems. You can try to check 'copy' the file (after a change) to a different machine (upload to web/ftp). Or try to save specific content to a fixed file. When the check file on different will be correct, or when the fixed content file will be 'empty', the reason is probably on local machine. Try to change HW components, or reinstall the system.
There is no documented reason for this behavior, as this is happening to users but nobody can tell the origin of this odd conditions.
It might be CLR problem, although this is a very unlikely, the CLR doesn't just write null characters and XML document cannot contain null characters if there's no xsi:nil defined for the nodes.
Anyway, the only documented way to fix this is to delete the corrupted file using this line of code:
try
{
ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.PerUserRoamingAndLocal);
}
catch (ConfigurationErrorsException ex)
{
string filename = ex.Filename;
_logger.Error(ex, "Cannot open config file");
if (File.Exists(filename) == true)
{
_logger.Error("Config file {0} content:\n{1}", filename, File.ReadAllText(filename));
File.Delete(filename);
_logger.Error("Config file deleted");
Properties.Settings.Default.Upgrade();
// Properties.Settings.Default.Reload();
// you could optionally restart the app instead
}
else
{
_logger.Error("Config file {0} does not exist", filename);
}
}
It will restore the user.config using the Properties.Settings.Default.Upgrade();
again without null values.
I ran into a similar issue but it was on a server. The server restarted while a program was writing to a file which caused the file to contain all null characters and become unusable to the program writing/reading from it.
So the file looked like this:
The logs showed that the server restarted:
The corrupted file showed that it was last updated at the time of the restart:
I have the same problem, there is an extra "NUL" character at the end of serialized xml file:
I am using XMLWriter like this:
using (var stringWriter = new Utf8StringWriter())
{
using (var xmlWriter = XmlWriter.Create(stringWriter, new XmlWriterSettings { Indent = true, IndentChars = "\t", NewLineChars = "\r\n", NewLineHandling = NewLineHandling.Replace }))
{
xmlSerializer.Serialize(xmlWriter, data, nameSpaces);
xml = stringWriter.ToString();
var xmlDocument = new XmlDocument();
xmlDocument.LoadXml(xml);
if (removeEmptyNodes)
{
RemoveEmptyNodes(xmlDocument);
}
xml = xmlDocument.InnerXml;
}
}
Related
I have a routine that reads XPS documents and chops off pages to separate documents. Originally it read one document, decided how to chop it, closed it and wrote out the new files.
Features were added, this was causing headaches with cleaning up old files before running the routine and so I saved all the chopped pieces to be written out at the end.
ChoppedXPS is a dictionary, the key is the filename, the data is the FixedDocument prepared from the original:
foreach (String OneReport in ChoppedXPS.Keys)
{
File.Delete(OneReport);
using (XpsDocument TargetFile = new XpsDocument(OneReport, FileAccess.ReadWrite))
{
XpsDocumentWriter Writer = XpsDocument.CreateXpsDocumentWriter(TargetFile);
Writer.Write(ChoppedXPS[OneReport]);
Logger($"{OneReport} written to disk", 2);
}
Application.DoEvents();
}
If the FixedDocument being written out here contains graphics the source file is opened by the Writer.Write line and left open until the program is closed.
The XpsDocumentWriter does not seem to implement anything that can be used to clean it up.
(Yeah, that Application.DoEvents is ugly--this is an in-house program used by two people, it's not worth the hassle of making this run in the background and without it a big enough task can cause Windows to decide it's non-responsive and kill it. And, yes, I know how to indent--I took them out to make it all fit this screen.)
.Net 4.5, using some C# 8.0 features.
I found a workaround for this problem. I'm not going to try to post the whole thing as I had to change the whole data handling but the heart of it:
using (XPSDocument Source = new XPSDocument(SourceFile, FileAccess.Read)
{
[the using loop from my question]
}
I'm still hoping for understanding and something more appropriate than this approach.
Yes--this produces a warning that Source is unused, but the compiler isn't eliminating it so it does work.
So, the title may be misleading. I am building an android app that reads information from a text file, which is located on a cloud server (I would prefer to use either OneDrive, DropBox, or Google Drive [whichever is easiest]; others are fine). Periodically, the program will write information to the text file, still located on the cloud server. So, my question is twofold: Is it possible to read and write to a text file that is located on a cloud server? If so, how in the world would I complete this task? I have noticed the use of WebClient but I can't find a reasonable method or explanation on how this works. This program is coded in C#. This is what I have so far:
private string filename = "datafile.txt";
private List<Category> myList; //A list of an object that I developed ('Category')
//Allow the user interface to handle the error
public void readDatabase() {
//Here is where the magic has to occur, in order to read the file
...
//The usual reader that I use to read standard text files
StreamReader fileReader = new StreamReader(filename);
string line = "";
while ((line = fileReader.ReadLine()) != null)
//convertToCategory is my private method to convert the string to
myLine.Add(convertToCategory(line);
fileReader.close();
}
public void writeDatabase() {
//Here is where the magic has to occur, in order to write to the file
...
//The usual writer that I use to write standard text files
StreamWriter fileWriter = new StreamWriter(filename);
for (int i = 0; i < this.myList.Count; i++)
//toString() is something was developed in my object called 'Category'
fileWriter.WriteLine(fileWriter[i].toString());
fileWriter.close();
}
I would love to use Google Drive as my cloud server, but I am open to other possibilities, if necessary. I just want an easy and efficient method to read/write to the text file.
Possible Implementations:
Have seen possible solutions, where the file is downloaded locally and then read like normal and then uploaded at time of closing. However, if I could get away with it, I don't want the text file to be downloaded.
I have, also, seen several places where a SQL database is used in this instance. But the unfortunate thing is that I don't have any knowledge in developing with SQL. So, using a SQL server would be ideal (because speed is very important for this application) but it will be difficult for me to understand how it works.
I have an issue with a class library; I am preparing a library with an interface that represents a specific data storage signature. The purpose is to use the interface as a basis for implementing a number of specific classes storing configuration information in different formats (text files, xml files, etc.) while retaining the same usage profile to the application using it. I have a problem, though. In this case I am trying to embed an xml file as a resource - this file is one type of format to store configuration data. The file is located as an embedded resource in a subfolder to the project, as shown in the attached illustration.
In the following code snippet it is shown how I have implemented the functionality until now.
public ConfigInfoXmlSource()
{
if (!string.IsNullOrEmpty(Settings.Default.CurrentConfigFile))
FileNameAndPath = Settings.Default.CurrentConfigFile;
else
FileNameAndPath = DefaultConfigFileName + DefaultFileExtension;
// Prepare XML.
System.Reflection.Assembly a = Assembly.GetExecutingAssembly();
XmlDocument doc = new XmlDocument();
Stream manifestResourceStream =
a.GetManifestResourceStream("TestTool.Config.Config1.xml");
if (manifestResourceStream == null)
{
// ???
}
...
doc.Load(manifestResourceStream);
...
}
In the section marked "Prepare XML" I am trying to read a stream from the embedded resource. After the reading, it is tested whether a stream was indeed created. If the file is found, the manifestResourceStream will contain the xml data - so far so good. The problem arises if the file for some reason has been accidentally deleted - in that case I want to create a new file as an embedded resource to replace the deleted file. That is supposed to happen in the conditional in the part shown as "???".
I have tried everything I could think of, searched Google for answers, etc. - to no avail.
Does anyone have a clue to how this is accomplished? Any help will be greatly appreciated.
Thanks in advance.
Best regards.
If you have a embedded resource,it is built into your binaries.It is not an physical file,rather something which is present inside the built file(dll in this case).So,once it is included,I do not think it can ever be deleted. As per my knowledge embedded resource can only be set while building your project binaries and you can not explicitly do it at runtime as it is not needed due to reasons mentioned above.
I have a .txt file that i process into a List in my program.
I would like to somehow save that List and include it in the program itself so that it loads every time the program starts, so I don't have to process it every time from a .txt file.
Its more complicated than just "int x = 3;" cause it has like 10k lines and I don't wanna copy paste all that in the beginning.
I've looked all over but haven't found anything similar, any ideas guys?
Also if thee's a solution, can it work with any type (arrays, Dictionaries)?
As requested, the code is:
var text = System.IO.File.ReadAllText(#"C:\Users\jazz7\Desktop\links_zg.txt");
EDIT
Joe suggested the solution:
Included the file within the project, set its "build action" to embedded resource in Properties and used this code:
private string linkovi = "";
...
var assembly = Assembly.GetExecutingAssembly();
var resourceName = "WindowsFormsApplication4.links_zg.txt";
using (Stream stream = assembly.GetManifestResourceStream(resourceName))
using (StreamReader reader = new StreamReader(stream))
{
linkovi = reader.ReadToEnd();
}
string linkovi now contains the txt file and is now within the application. Thanks all!
You could store the file as a resource in your executable file.
This KB article describes how to do it.
Fundamentally, youve got to choose between storing your data in memory or storing it on the hard drive. The former will cut your loading time, but might use an unacceptable amount of memory, whilst the latter is slower, as youve identified. Either way, your data has to be stored somewhere.
Do you need to load all of the data at once? If the loading time is the issue, you could process the file line by line. While this would be slower overall, you would still have access to some usable data sooner.
i am working on a pc 192.168.2.200
i have made a simple C# Windows application on 192.168.2.200
I want to Create a Text File on D: of a Network PC whose IP is 192.168.2.201 and UserName is abc and Password is 123 by C# code in Windows Application
How i Will Create file on Network PC
any one can Help me
System.IO.File.Create(#"D:\myfile.txt");
OR
System.IO.File.WriteAllText(#"D:\myfile.txt","Hello this is my File");
Windows application or not, you'd use the same technique. If you don't care what the format is, but want to use it as an input file that you read/write from, then you might want to look into XmlSerializer, along with a custom class that you write (with username/password/IP properties).
Here is a simple tutorial on XML serialization:
http://www.switchonthecode.com/tutorials/csharp-tutorial-xml-serialization
If you want a custom format, and only want to write to it (such as a log file), then you can do this:
var file = System.IO.File.Create("file.txt");
var writer = new System.IO.StreamWriter(file);
writer.WriteLine("fjkldsaf");
Or use the overload for StreamWriter that takes a filename:
var writer = new System.IO.StreamWriter("otherfile.txt");
writer.WriteLine("some text");
Keep in mind that writing a password in clear text onto your hard drive is not very secure (same with clear-text over the network, though I know you're not asking about that).
Make sure you either call Dispose or Close on your file streams when you're done with them. You can stick them in a using block to do this automatically (even if an exception is accidentally thrown in your file writing code).
using(var writer = new System.IO.StreamWriter("otherfile.txt"))
{
writer.WriteLine("some text");
}