how to save file with illegal name

Question

Here is how I'm creating a file:

System.IO.File.Create(Server.MapPath("..") + name + ".html");

But sometimes name has illegal characters, like å, from the swedish alphabet. How to save them? It is possible directly, but I get error when I do it with code.

`å` is a valid character in a filename on Windows 7. What are you talking about? — Oded, Mar 29 '12 at 15:38
http://stackoverflow.com/questions/309485/c-sharp-sanitize-file-name — drch, Mar 29 '12 at 15:39
What error are you getting? Could you post the exact message and stack trace of the exception you are getting? Also the exact value of the name variable. — Darin Dimitrov, Mar 29 '12 at 15:39
possible duplicate of [How to remove illegal characters from path and filenames?](http://stackoverflow.com/questions/146134/how-to-remove-illegal-characters-from-path-and-filenames) — BrokenGlass, Mar 29 '12 at 15:39
You should not let users decide on the name of a file you save on the server file system. Instead use a unique id and store a mapping from user designated name to id e.g. in the DB — BrokenGlass, Mar 29 '12 at 15:41

JaredPar · Accepted Answer · 2012-03-29T15:47:08.447

If the path is user controlled and potentially contains invalid file system characters then you'll need to ask the user to change the name or normalize out the bad characters in a deterministic way. One method is to replace all invalid characters with say underscore.

public static string NormalizeFileName(string input) {
  var invalid = Path.GetInvalidPathChars();
  var builder = new System.Text.StringBuilder();
  foreach(char c in input) {
    if (invalid.Contains(c)) {
      builder.Append('_');
    } else {
      builder.Append(c);
    }
  }
  return builder.ToString();
}

You could then use this function as follows

var originalName = Server.MapPath("..") + name + ".html";
var normalizedName = NormalizeFileName(originalName);
System.IO.File.Create(normalizedName);

EDIT

As several people pointed out, it's best practice to use Path.Combine here to combine directory and file names.

var originalName = Path.Combine(Server.MapPath(".."), name + ".html");

It'd probably fix some corner cases if he used `Path.Combine(Server.MapPath(".."), Path.ChangeExtension(NormalizeFileName(name), ".html"))`. — user7116, Mar 29 '12 at 15:44

score 0 · Answer 2 · answered Mar 29 '12 at 15:40

0

System.IO.File.Create(Server.MapPath("..") + "\\" + name + ".html");

answered Mar 29 '12 at 15:40

Serj-Tm

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how to save file with illegal name

2 Answers2