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How can I use Delphi to test if a Directory is writeable?
My program will download an update for the user if they request it. The user has to specify the location to save the installer. They might pick a directory which they don't have access to save something to. In this case the download starts (downloading to a temporary directory I assume) and we only know that it failed when it ends and tries to move the file into the folder.
Is there a simple way to check if we have write permissions on a folder in Delhi?
There is AccessCheck function or tricks, but this information is not reliable in generic case.
So, usually you just need to create file to check, if you have access for that.
For your specific case, you have the following choices:
After save dialog closing: try to
create a file in target folder with
the name of downloading file. Delete
it after check. Not pretty, since
you rarely may have access to create
files, but not to delete them.
After save dialog closing: try to create a
file in target folder with the name
of downloading file. Keep that
handle open and move file content to
it after download is complete. Not
pretty, since you can't move file,
you need to copy it.
(the right one?) Just bring save dialog again
on any access denied issues.
Related
I'm implementing a WebDAV file server using the ITHit WebDave engine, i have the following problem
When i list the files and open one of them i get the ReadAsync method called, i provide the content and the file is opened correctly
However any changes i make to the file can't be saved, i get an error saying
A device attached to the system is not working
I looked at the file system samples and implemented support based on the FileSystemStorage.AspNetCore sample,
From what can understand the WriteAsync method is used when creating new files, should i expect for WriteAsync to also be called for file edits that need to be changed?
Am i wrong in the assumption that DavFile.WriteAsync will be called with a stream for the updated content?
If WriteAsync is not the right location to save updates to a file, could you provide some guidance on the process of saving changes to existing files?
Edited to add:
Now i can see that after i dismiss the first error about the device not working i get the standard save dialog box, if i click save it asks me if i want to overwrite the existing file, after accepting to overwrite then WriteAsync is called and i can update the file contents
I'm not quite sure why it would first tell me there's an error and then still allow me to write the file but only as replacement to the original file
Thanks for your help
Fixed, i found that there were issues with the ILockAsync implementation, reviewing the FileSystemStorage sample helped fix the issue with locking files before writing or updating properties
I write editor and game and it requires a save game option.
I Just want use a Save folder in game folder. not inside.love
How to get a bug.
Start game
Enter menu by Escape key
Press save game - this create savegame
Press Load game - you get an error "File not exist" but you write this file seconds ago.
I successful save a game in savesm2k folder but it folder outside .love file and i don't know how correct load saved game.
Used engine: Love2d 0.10.2
OS: Linux Mint 18.1 x64bit
I read many manuals and I'm stuck.
For loading save game i use this commands
lsg=love.filesystem.getSaveDirectory().."/M2k-Saves/m2ksave"
lsg=love.filesystem.getSourceBaseDirectory().."/M2k-Saves/m2ksave";
data, size = love.filesystem.read (lsg);
leveldatacopy=freadbin (data);
Why does the program not try read existing file? and report no exist? I try using another command but using GetSaveDirectory broke function WriteMAP (requires for binary map and data writing) etc. but it write files which cannot be loaded in load section.
Maybe I should use LUA for reading files direct from folder but I don't know how to correct DO it.
example with bug.
https://github.com/dj--alex/m2ktest
file m2ktest-load-savegame-test.love
At this moment on every saving i manually replace saved game inside love archive (!) . This is not normal.
Anybody can tell me how i get and correct open saved file? Not from inside .love file . from outside of course. If levels and configs can be readed from love file inside save files must be outside. I can only can create files outside love file . i know love file is a zip archive.
If required i can post a .love file but is game completely done and have 150kb of clean code.
You should not prefix paths with love.filesystem.getSaveDirectory() or love.filesystem.getSourceBaseDirectory(). This is done automatically, internally to the love.filesystem functions. Saying
lsg = "/M2k-Saves/m2ksave"
data, size = love.filesystem.read (lsg)
leveldatacopy = freadbin (data)
should work, and will place the file in the save directory / outside of the .love file or game directory. (Love forbids writing anywhere except in the save directory.)
Love's filesystem model is like a "stack" of filesystems. For file reading, it first looks in love.filesystem.getSaveDirectory() with whatever path you pass in. If it finds a file, it uses that; otherwise it looks inside the love.filesystem.getSourceBaseDirectory() (or – if packed – inside the .zip / .love file). Writing files always goes to love.filesystem.getSaveDirectory(), you cannot write to love.filesystem.getSourceBaseDirectory() (because it may not be an actual directory but a zip file).
During part of a request in a Rails application, I copy a directory from one place to another, think of it like a working area. Sometimes this copy operation results in "Errno::ETXTBSY" exceptions being thrown. I can't seem to pin down the case that causes it, any tips to detect the case or avoid it altogether?
I've made sure the destination directory is uniquely named, so it shouldn't be a case of 2 processes attempting to write to the same place. Beyond that I'm out of ideas.
ETXTBSY means that you're trying to open for writing a file which is currently being executed as a program, or that you're trying to execute a file which is currently open for writing. Since you say you're copying files, not executing them it seems likely it's the former, not the later.
You say you're targeting a unique new destination, but my guess is that's not entirely true and you're actually targeting an existing directory and one of the files you're attempting to overwrite is currently open as an executable text segment of a running process.
You haven't posted any code, so it's hard to comment specifically. I suggest you add enough logging so you know exactly what file(s) are being processed and specifically, the source and destination path that throws the exception. Then you could use lsof to see what process may have that file open.
One way to avoid the problem if you are overwriting a currently open executable, is to first unlink the target file. The running process will still have the old inode mapped and proceed merrily using the deleted file, but your open for write will then create a new file which won't conflict.
I have a SQlite database file with records which comes with my app.
I just used the file I added to my project to make my INSERT and UPDATE statements.
After uploading it to my test device I got the exception that the file is read only.
After a bit of research I found out, that I have to copy the db file to the users directory to make an insert. This works for now. But I have a view questions about it, which i didn't get answered through google:
Where should I put my copy process?
I implemented it in the AppDelegates FinishedLaunching, where I check if it already exists.
Where should I copy the file to?
I used the MyDocuments folder for now, is this ok?
Since the file cannot be encrypted, can another app access the database file?
When the user decides to delete the app from the device. Will the database file get deleted,too?
Thanks!
Where should I put my copy process? I implemented it in the AppDelegates FinishedLaunching, where I check if it already exists.
That really depends, but finishedLaunching is OK from my point of view.
Where should I copy the file to? I used the MyDocuments folder for now, is this ok?
I'm not sure what you mean by "MyDocuments" folder. Each Application has a dedicated Document directory. That's where you should copy it.
Since the file cannot be encrypted, can another app access the database file?
No, they run sand-boxed (unless the device is jailbroken)
When the user decides to delete the app from the device. Will the database file get deleted,too?
Yes, since the whole document directory will be deleted.
Where should I put my copy process? I implemented it in the AppDelegates FinishedLaunching
Keep in mind that you have a limited amount of time to complete FinishedLaunching execution (around 15 seconds) before the iOS watchdog kills your application.
Depending on the size of your database, the speed of device and other processing you need to do then you might want to consider only checking if it already exists (that should be quick) then do the copy (if required) from to another thread.
I used the MyDocuments folder for now, is this ok?
Yes, using Environment.GetFolderPath (Environment.SpecialFolder.MyDocuments) is correct.
Everything else from #Lightforce answer covers the rest.
How can I display an image from file object? The file object holds the location of the image in temp uploaded directory.
I dont want to use any models.
Its for previewing a form having filefield
The problem with most temporary files is that they don't exist. They're in a deleted state and will disappear entirely once the file handle is closed. It's your responsibility to move copy the data out of them and into another file, database, or cache, whatever works best, in order to preserve it.
You don't need to use any models to make this work, but you will need to be able to write to a directory your web server will be able to access. Typically you can make a /uploads directory and copy the file there, removing it later on when it is no longer required.
That clean-up step is easily done by a cron job that deletes all files with an mtime of a day or so, depending on your preference.