Error when downloading files from Unix(Linux) to Windows OS, if the letter case is different with the same name.

[JurasskPark]

If the Unix and Linux operating systems allow you to create files with the same name but different case. For example.
[C:\tmp\TEST\check.txt] <- [/TEST/check.txt] [768 Bytes/seconds] [6 Bytes]
[C:\tmp\TEST\check.txt] <- [/TEST/CHeck.txt] [711 Bytes/seconds] [6 Bytes]
Then when downloading the file on Windows, there will be an error here.

FluentFTP\Client\Modules\FileDownloadModule.cs

		/// <summary>
		/// Create an FtpResult object for the given file to be downloaded, and check if the file passes the rules.
		/// </summary>
		private static void RecordFileToDownload(BaseFtpClient client, List<FtpRule> rules, List<FtpResult> results, Dictionary<string, bool> shouldExist, List<FtpResult> toDownload, FtpListItem remoteFile, string localFile, string remoteFilePath = null) {

			// create the result object
			FtpResult result;
			if (remoteFile != null) {
				result = new FtpResult() {
					Type = remoteFile.Type,
					Size = remoteFile.Size,
					Name = remoteFile.Name,
					RemotePath = remoteFile.FullName,
					LocalPath = localFile,
					IsDownload = true,
				};
			}
			else {
				result = new FtpResult() {
					Type = FtpObjectType.File,
					Size = 0,
					Name = remoteFilePath.GetFtpFileName(),
					RemotePath = remoteFilePath,
					LocalPath = localFile,
					IsDownload = true,
				};
			}

			// record the file
			results.Add(result);

			// only download the file if it passes all the rules
			if (FileRuleModule.FilePassesRules(client, result, rules, false, remoteFile)) {

				// record that this file/folder should exist
				shouldExist.Add(localFile.ToLower(), true);

				// only files are processed
				toDownload.Add(result);

			}
		}

This localFile.ToLower()
Because Net Core will not allow you to add keys with the same name to the dictionary.

[FanDjango]

IMO, you are right - this error should be "caught" and handled. But in the end, there is no really elegant solution to this problem going from linux to windows. You should check yourself that there is no potential collision in file names when transferring to windows.
I'll put this on my internal todo list. But it won't help much, the file will be overwritten on such a naming collision.

[JurasskPark]

So the problem here isn't with Windows OS, but rather that the process crashes at the dictionary entry level, because you've converted two different files with different names to ToLower(), and the entire process has stopped. You need to either check for such an entry in the dictionary or remove ToLower(), and then the crash won't occur. Of course, the file will be overwritten, but only later.

[FanDjango]

Correct. Something needs to be done. I really wonder what the purpose of the "ToLower" is, from the original code ages ago.

As I said, TODO.

For the moment, that is all that I can say.

Of course, the file will be overwritten, but only later.

One could discuss what is best: Terminate, report the overwrite or just overwrite with no error indication.

[JurasskPark]

It’s better to simply rewrite it. I have an FTP server with 120,000 files right now. So, in case of conflicts, you’ll get tired of renaming files and searching for their locations.

[robinrodricks]

purpose of the "ToLower" is, from the original code ages ago

Case insensitive comparison. Probably for Windows OS.

@JurasskPark If the ToLower is removed, would that fix the logic for your Unix server?

[FanDjango]

Case insensitive comparison. Probably for Windows OS.

I checked "blame" - it is really from eons ago.

If the ToLower is removed, would that fix the logic for your Unix server?

It certainly will. I am all for it. But that leaves the question: Will it hurt windows users (who are probably the majority)?

[JurasskPark]

@JurasskPark If the ToLower is removed, would that fix the logic for your Unix server?

Yes.

Let me explain. This is industrial equipment. Operators use it to save measurement results and name them as files. There are a lot of such files.

Regarding the question of whether this will affect Windows users, they won't be able to download the files anyway. But it will definitely be annoying when the download pauses every time an error occurs.

[FanDjango]

I have had a look at this in more detail. There are actually more places where this "ToLower" would be detrimental.

[robinrodricks]

It certainly will. I am all for it. But that leaves the question: Will it hurt windows users (who are probably the majority)?

Since we can detect the OS, and we already have, what say that we disable the ToLower check for unix users, keeping it enabled for windows users?

[robinrodricks]

Found these relevant places that need to be changed: