Path. GetInvalidPathChars() does not contain ">" on windows

[jogibear9988]

Description

The Path. GetInvalidPathChars() does not contain the correct characters in windows.

Reproduction Steps

run this in immediate window:
Path.GetInvalidPathChars()

It returns:

     [0]: 124 '|'
     [1]: 0 '\0'
     [2]: 1 '\u0001'
     [3]: 2 '\u0002'
     [4]: 3 '\u0003'
     [5]: 4 '\u0004'
     [6]: 5 '\u0005'
     [7]: 6 '\u0006'
     [8]: 7 '\a'
     [9]: 8 '\b'
     [10]: 9 '\t'
     [11]: 10 '\n'
     [12]: 11 '\v'
     [13]: 12 '\f'
     [14]: 13 '\r'
     [15]: 14 '\u000e'
     [16]: 15 '\u000f'
     [17]: 16 '\u0010'
     [18]: 17 '\u0011'
     [19]: 18 '\u0012'
     [20]: 19 '\u0013'
     [21]: 20 '\u0014'
     [22]: 21 '\u0015'
     [23]: 22 '\u0016'
     [24]: 23 '\u0017'
     [25]: 24 '\u0018'
     [26]: 25 '\u0019'
     [27]: 26 '\u001a'
     [28]: 27 '\u001b'
     [29]: 28 '\u001c'
     [30]: 29 '\u001d'
     [31]: 30 '\u001e'
     [32]: 31 '\u001f'

Expected behavior

It should at least return:

    ** (backslash)
    / (forward slash)
    : (colon)
    * (asterisk)
    ? (question mark)
    " (double quote)
    < (less than)
    > (greater than)
    | (vertical bar or pipe) 

Actual behavior

see above

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

[MihuBot]

I'm a bot. Here are possible related and/or duplicate issues (I may be wrong):

• Path.GetInvalidPathChars() doesn't include angle brackets #44520
• Path.GetInvalidPathChars() Does not Return the Same Character Set between .NET4.8 and .NET 6.0.1 on Windows #63383
• System.IO.Path.GetInvalidPathChars() returns different result than Desktop #20769

[jogibear9988]

I didn't know these issues. But I find it very confusing.
I would expect this function to return the invalid chars for the current OS

[huoyaoyuan]

This is the full list of Path.GetInvalidFileNameChars() I get in Immediate window:

Path.GetInvalidFileNameChars()
{char[41]}
    [0]: 34 '"'
    [1]: 60 '<'
    [2]: 62 '>'
    [3]: 124 '|'
    [4]: 0 '\0'
    [5]: 1 '\u0001'
    [6]: 2 '\u0002'
    [7]: 3 '\u0003'
    [8]: 4 '\u0004'
    [9]: 5 '\u0005'
    [10]: 6 '\u0006'
    [11]: 7 '\a'
    [12]: 8 '\b'
    [13]: 9 '\t'
    [14]: 10 '\n'
    [15]: 11 '\v'
    [16]: 12 '\f'
    [17]: 13 '\r'
    [18]: 14 '\u000e'
    [19]: 15 '\u000f'
    [20]: 16 '\u0010'
    [21]: 17 '\u0011'
    [22]: 18 '\u0012'
    [23]: 19 '\u0013'
    [24]: 20 '\u0014'
    [25]: 21 '\u0015'
    [26]: 22 '\u0016'
    [27]: 23 '\u0017'
    [28]: 24 '\u0018'
    [29]: 25 '\u0019'
    [30]: 26 '\u001a'
    [31]: 27 '\u001b'
    [32]: 28 '\u001c'
    [33]: 29 '\u001d'
    [34]: 30 '\u001e'
    [35]: 31 '\u001f'
    [36]: 58 ':'
    [37]: 42 '*'
    [38]: 63 '?'
    [39]: 92 '\\'
    [40]: 47 '/'

What's your environment and project context? Can you reproduce this in plain console project?

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/area-system-io
See info in area-owners.md if you want to be subscribed.

[jogibear9988]

This is the full list of Path.GetInvalidFileNameChars() I get in Immediate window:

Path.GetInvalidFileNameChars()
{char[41]}

What's your environment and project context? Can you reproduce this in plain console project?

I use GetInvalidPathChars not GetInvalidFileNameChars

I found in the other issues that this was intentionally changed, but I find it's wrong

[jogibear9988]

I wnat to use it for directory names, directory names are not filenames

[GerardSmit]

The issue #44520 (comment) got closed because:

< and > look like they were intentionally removed from GetInvalidPathChars here: dotnet/corefx#8669 since they are valid wildcard characters.

The docs describes the method as following:

public static char[] GetInvalidPathChars();

Gets an array containing the characters that are not allowed in path names.
Returns: An array containing the characters that are not allowed in path names.
https://learn.microsoft.com/en-us/dotnet/api/system.io.path.getinvalidpathchars

Note that is says "not allowed in path names" and not saying "not allowed in path names and expressions".
Expression characters are not allowed in the path name, so why isn't the API returning them?

In the remarks it's saying the following:

The array returned from this method is not guaranteed to contain the complete set of characters that are invalid in file and directory names. The full set of invalid characters can vary by file system. For example, on Windows-based desktop platforms, invalid path characters might include ASCII/Unicode characters 1 through 31, as well as pipe (|) and null (\0).

This has a double meaning, does "is not guaranteed to contain the complete set of characters" mean that it's not complete because it various per file system, or because it's not complete set at all?

Maybe it's a beginning if we look what the API should return, and if it's correct; change the docs of the method.

[GerardSmit]

I use GetInvalidPathChars not GetInvalidFileNameChars

I found in the other issues that this was intentionally changed, but I find it's wrong

In your issue you mentioned GetInvalidFileNameChars in title and "Description"-section but in the "Reproduction Steps"-section you mentioned GetInvalidPathChars.

This is why @huoyaoyuan thought you were talking about GetInvalidFileNameChars.

You might want to change the title and description if you're talking about GetInvalidPathChars.

[jogibear9988]

I use GetInvalidPathChars not GetInvalidFileNameChars
I found in the other issues that this was intentionally changed, but I find it's wrong

In your issue you mentioned GetInvalidFileNameChars in title and "Description"-section but in the "Reproduction Steps"-section you mentioned GetInvalidPathChars.

This is why @huoyaoyuan thought you were talking about GetInvalidFileNameChars.

You might want to change the title and description if you're talking about GetInvalidPathChars.

yeah, sorry

[adamsitnik]

It's a duplicate of #44520 which contains the explanation: #44520 (comment)

This intentional breaking change was described here: https://docs.microsoft.com/en-us/archive/blogs/jeremykuhne/system-io-in-net-core-2-1-sneak-peek