Overwrite A File Using A Buffered Filestream?
May 19, 2012
Here's the catch - for the program I'm making I would like to avoid creating a copy of the file in its totally unencrypted state (I'm using a modified, quick-and-dirty XOR cipher for that. It's secure enough for my purposes and faster than the stronger encryption). Anyhow, what I would like to do is read a block of data, de/encrypt it (in memory) and then write the changed bytes to the same location they previously would have been within the file.
I've found the problem a little outside my programming abilities, so I was wondering if anybody had a pre-made solution, links to appropriate examples, or an all out explanation.
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Feb 11, 2010
How can I save an Excel-file, which I'd edit with VB.NE, to a file, which already exists? Evertime there is a dialog: File already exists. Do you really want to overwrite? YES|NO|Abort
How can I overwrite without this dialog?
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Nov 25, 2008
The goal is to write data to a SQL Server 2008 FILESTREAM file using VB.Net. An "Access Denied" message occurs when creating a FileStream object in the code(see red underlined code below). SQL Server 2008 is configured to "Allow remote clients to have streaming access to FILESTREM data" along with "Enable FILESTREAM for Transaction-SQL access"... What configuration setting is missing and causing the "Access Denied" message? Figure 1.) Code used to stream data to SQL Server managed file
[Code]...
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Oct 30, 2009
I have implemented the filestream feature of SQL Server 2008 in a VB.Net application. I can insert files, and then retrieve/view them just fine. However, I have huge problems trying to update a file. Eg. The user selects a file from the grid which I execute via process.start. If that file is a .txt file, the user may choose to edit it. In case that happens, I need to save the changed file back to the database. So far I have failed to do that.
What I do, is take the retrieved file, copy it (cause i got some errors about it being used), and then Process.Start it. After that, via .NET filestream, I convert the file to bytes and try to update the record. SQL Profiler and a manual SELECT on the varbinary(max) column tell me that the file is updated properly, but the very next try to retrieve it I get an unchanged file.
After that I also tried to update the file by changing its File-System Version, but the file still wouldn't seem to update. Does Anyone have a code sample of how I can achieve this operation? Like 500 sites on the internet have examples of how to Insert And Retrieve the file, but not a single example on how to update. This is how my second attempt of trying to update the file via the filesystem looks like. The code for inserting/retrieving is very similar and it works properly. [Code]
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Mar 10, 2011
I'm trying to get a save file dialogue to overwrite a file with the same name.
Private Sub Button6_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button6.Click
If RadioButton16.Checked Then
[code]....
I keep getting an error saying "Unhandled exception has occurred in your application." Then the next paragraph says "The process cannot access the file 'E:Copy of Release+Fontsob.txt' because it is being used by another process."
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Apr 16, 2009
I have found many pages referring to having the date be part of a txt file being created, but not like the way I need. Having said that, this is what I've got.. [code] I read a page on working with txt files and learned what I could from it. It said to use the method in the beginning of my code for creating the file. It works great, but I would like to have a new file name everday, hence the date being integrated. So even if program was running, when midnight hits, a new txt file is created and new entries are written to that file. But I can't even get the date to be put in there. Everytime I try to make this work by using methods I read about in other pages, I get a syntax error, or a warning saying an end of statement is expected. I'm not sure those methods are compatible with what I've already got going.I was actually trying to store these values in a database, and I got real close I think, but I couldn't get any help to fix my problem so I'm trying to write to daily txt files instead. url....
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Nov 8, 2010
I am trying to download a file off my web server (easy) but the file its downloading is the updated version of the file running. I finally was able to program my automatic update software the program simply downloads a .txt file from my web server, reads it, and if the the version = (new version here) then download. If not, then go to another form. The problem I am getting though, is when the version is outdated, the file will go to download the new .exe and it gets and error saying "File already exists"
[Code]...
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Feb 18, 2010
I have a filestream, and I want to save a file from that filestream? Like there are bytes in that file stream, and from those I want a "file.exe" to automatically appear on my desktop.
I'm using a code snippet, and I think this is the important part:
Dim fstr As New FileStream("file.exe", FileMode.OpenOrCreate, FileAccess.Write)
fstr.Write(validArg1, validArg2, validArg3)
fstr.Close()
Do I have to use a for loop? Or is there a function like this:
IO.File.WriteAllBytes(myPath, fstr.AllBytes)
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Jul 27, 2009
I am writing a program to upload file to the web using Socket and FileStream. Here is the code
Private Sub Read(ByVal state As StateObject)
Dim filestream As FileStream = state.fileStream
filestream.BeginRead(state.readBuffer, 0, StateObject.readBufferSize, New
[Code].....
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Jan 16, 2011
I am trying to get a text file to be overwritten since it's already there. The thing is, that I'm not trying to overwrite a specific file. In fact, EVERYTHING must have the right name, or my project won't turn out right: http:[url]....However I don't have that problem any more because I solved it. Now my problem is much more simple. Again, I'm NOT trying to overwrite one specific file, so I couldn't say something like,
HTML
RmDir("C:KQQuestion1")
I need a way to overwrite any file name.
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May 7, 2010
I've been searching all over the web to find a code to copy a file to a destination. I found one, but i need to get one so it can overwrite cause i get error when the file already exist in both location.There is my code:
Dim FileToCopy As String
Dim NewCopy As String
FileToCopy = "C:\test.txt"
NewCopy = "C:\NewTest.txt"
[code]....
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Jul 6, 2009
I have a text file to read. Then i took the lines from the text file and write in temporary file. Now i want to overwrite the lines from temporary file to original file.My original file contain Top and bottom part.
My temporary file look like this
4.5 28 Red (T1 ) [1 12.86 53.8] 100.00 100.00 198452 -1309 | 11.0 28 Red (2 13.10 04.0) [T1 ] 130611 2948 100.00 100.00
1.5 28 Blue (T2 ) [1 07.06 59.1] 102.54 100.00 190456 39339 | 6.5 28 Blue (2 03.00 03.0) [T2 ] 132111 -67725 102.54 100.00
[code]....
So i want to overwrite the lines before "|" to the Top part and the line after the "|" to bottom part.. I attach my original and temporary files.
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Jan 14, 2010
How can I force SaveFileDialog in Visual Basic 2008 not to allow overwrite file or Files?To aim is not enough.
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Jun 22, 2011
I have written some simple codes which are using FileStream to read a big .zip file.My codes ran fine as expected until I tested to create multiple threads to access that particular same .zip file at the same time.
The error that I've got was > The process cannot access the file 'D: est.zip' because it is being used by another process.Is it possible to read 1 particular file by multiple FileStream instances at the same time?
[Code]...
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May 4, 2011
I have a couple of files which I have to update periodically through a process written in VB.net . These files are on a server and part of a domain that many users can access. These files should never be written to as they are for reference only. I need to be able to overwrite some of them even if a user has them opened. Is it possible to do this? Presently the files permissions are not set as read-only but I can do this as long as the user under which the process runs will still have permission to overwrite them.
UPDATE: thx for your responses. The files are pdf and are opened by clicking on them from windows file explorer. This also happens when a user simply has the file selected in windows explorer.
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Jun 6, 2011
I'm creating an program that needs to delete/overwrite an image called "Image.jpeg".i have to code to upload already, but i need to be able to overwrite image.jpeg, so i was thinking of: delete file, upload new version or[code]...
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Feb 21, 2012
My company puts out a monthly newsletter which I host on our internal website. I have a page for the author of the newsletter to upload the latest version. Once the author has uploaded the latest newsletter, he sends a broadcast email to announce the new newsletter. Employees invariably check the new newsletter and send feedback to the author with corrections that need to be made.
Once the author has made the necessary corrections (typically within an hour of sending the broadcast email), he revisits my page and replaces the latest version with the updated newsletter.
Immediately following the replacement (or update, if you will) of the newsletter, anyone attempting to access it gets a 500 - Internal Server Error.
My IT guy who maintains the server cannot delete/rename/move the file because of a permissions error and has to do a lot of convoluted things to get the file deleted (and once the file is deleted, the author of the newsletter can re-upload the corrected copy and it works fine.
My IT guy and I are pretty sure that the problem stems from that I'm trying to replace the file while IIS is actively serving it to users (which I thought of and thought that I had coded against happening).[code]...
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Jul 6, 2010
I am wondering how I can replace a file locked by another application. I am using VB.NET from 2008.
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Nov 12, 2009
Is that even possible in Vb
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Oct 2, 2008
I was wndering if its possible to change specific data in a text file from VB.NET code? i want to use a save game feature, and update the score of the user currently logged in, but i dont know how to do this. Any ideas? my text files stores 4 fields from the user; Username, Age, Score and Password.[url]...
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Dec 10, 2010
I have a log file that is open and in use by another program, and I read it's contents with the following:[code]This works for reading the text from the file while it is still in use by the other program, however, immediately after this I need to truncate the text file (without deleting it) so that it is blank again. But the file will still be in use by the other program.[code]But I get the "in use by another application" exception. I've tried looking in StackOverflow and googling but I can't seem to find an answer, and I can't find a way to do this with filestreams either, or I would try to use Dim fs As New FileStream(FullPath, FileMode.Open, FileAccess.Write, FileShare.ReadWrite)
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Feb 6, 2010
i have this simple code for reading image from file
pic = Application.StartupPath & "\medlem" & "\" & txtp.Text & ".jpg"
Dim myimage As New Bitmap(pic)
Try
[Code]....
the new image comes from the computers web camera.
the only thing i cant get to work is how to overwrite the file.
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Feb 10, 2010
In my application, i am downloading file from DMS system to my server. Once the file gets downloaded, on some environment, the iis keeps lock of the file and when the application tries to redownload the file and put the file on same location, an error is generated that file is being used by another process. Following is the code :
[Code]...
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Dec 10, 2009
I am writing an audit file that is writing the username, time, and the old/changed values of several variables in the application for each user when they use my application. It is using a FileStream and StreamWriter to access the audit file. All audits for each user will be written to the same file. The issue is that when two users are updating this audit file at the same time, the "old value" of each of the variable is mixing up between the users.
Dim fs As FileStream
Dim w As StreamWriter
Public Sub WriteAudit(ByVal filename As String, ByVal username As String, ByVal oldAddress As String, ByVal newAddress As String, ByVal oldCity As String, ByVal newCity As String)
[code]....
This lives in an AuditLogger class, which is referenced via an instance variable (re-allocated each time the function is accessed).
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Jul 9, 2009
I have been working on a project in .net. I can now write to a txt file using [code]What I need to do though is instead of writing new lines to the file is replace what is all ready there with new text.
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Jan 12, 2010
How to read from a line in vb .net, I need to do the following:
change the line in a text file
[Path] = "c: hiscertainpath"
With this line
[Path] = "c: hatother
ewerpath"
These paths will most certainly be different lengths, so I need to either replace what's in the quotes or erase the line completely and enter a new one, but in the same spot, not appended to the end of the document.
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Jan 24, 2012
I would like to know how to convince the SaveFileDialog to overwrite a read only file. Currently, it is throwing up a dialog and not even getting to my FileOk method.
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Oct 22, 2010
I am capturing Frames from a camera and storing the RAW DATA of the picture(frame) in a buffer(declared as Byte). Now my question is that: Is it possible to display the Image onto a picture box directly from the Raw Data stored in a Buffer, without converting it to a Bitmap or any other Image type? If so how to do this?
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Jun 5, 2012
I am using iTextSharp with VB.Net to stamp images onto PDF documents. (Since this is not language specific I tagged for C#, too.)I have two applications using the process.The first uses the bytes from the memorystream to display the PDF documents online. This piece is working. The second uses the same function but instead saves the PDF to a file. This piece generates an invalid PDF.
I have seen some similar questions, but they are all creating a document initially and have a document object in the code. Their memory streams are corrupt from the outset. My code does not have a document object and my original memory stream opens fine.
Here is the place where I get the error: (I have to put the buffer from m into a new memory stream because the stamper in the fillPDF function defaults to closing the stream unless marked otherwise.)
Dim m As MemoryStream = PDFHelper.fillPDF(filename, Nothing, markers, "")
Dim m2 As New MemoryStream(m.GetBuffer, 0, m.GetBuffer.Length)
Dim f As FileStream = New FileStream("C: emp.pdf", FileMode.Create)
[code]...
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Jan 20, 2010
I'm trying to remove the first and last lines from a text file. Obviously the last line will be at an undetermined position (i.e. line 50 or 5000). I couldn't figure how to remove the lines, so I wrote code that would rewrite every other line:
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