Apply suggestions from code review

The [Naming Files, Paths, and Namespaces](https://learn.microsoft.com/en-us/windows/win32/fileio/naming-a-file) article does not state that control characters or non-printable characters are in general forbidden in filenames. Instead, it says that it is okay to

> Use any character in the current code page for a name, including Unicode characters and characters in the extended character set (128–255), except for the following:

and then lists various things that are not allowed, where the one that is relevant to control characters is:

> Characters whose integer representations are in the range from 1 through 31, except for alternate data streams where these characters are allowed. *[...]*

No mention is made of 127 (0x7F).

On Windows 10, I used PowerShell 7 for this experiment, which I believe would also work in PowerShell 6, but not Windows PowerShell, which doesn't support `` `u ``. First, as a baseline, I checked what happened if I tried to create a file whose name contained a low-numbered control character:

```text
C:\Users\ek\source\repos\unusual-filenames [main]> echo hello > a`u{8}b
Out-File: The filename, directory name, or volume label syntax is incorrect. : 'C:\Users\ek\source\repos\unusual-filenames\b'
C:\Users\ek\source\repos\unusual-filenames [main]> echo hello > a`u{08}b
Out-File: The filename, directory name, or volume label syntax is incorrect. : 'C:\Users\ek\source\repos\unusual-filenames\b'
```

I created a file whose name contained the `DEL` character, and even a file whose entire name is that character:

```text
C:\Users\ek\source\repos\unusual-filenames [main]> echo hello > a`u{7F}b
C:\Users\ek\source\repos\unusual-filenames [main +1 ~0 -0 !]> echo goodbye > `u{7F}
C:\Users\ek\source\repos\unusual-filenames [main +2 ~0 -0 !]> ls

    Directory: C:\Users\ek\source\repos\unusual-filenames

Mode                 LastWriteTime         Length Name
----                 -------------         ------ ----
-a---           5/20/2024  5:59 PM              9
-a---           5/20/2024  5:59 PM              7 ab
```

Thus this appears to work fine on Windows, and it seems fine that Git permits it:

```text
C:\Users\ek\source\repos\unusual-filenames [main +2 ~0 -0 !]> git status
On branch main

No commits yet

Untracked files:
  (use "git add <file>..." to include in what will be committed)
        "a\177b"
        "\177"

nothing added to commit but untracked files present (use "git add" to track)
C:\Users\ek\source\repos\unusual-filenames [main +2 ~0 -0 !]> git add .
C:\Users\ek\source\repos\unusual-filenames [main +2 ~0 -0 ~]> git commit -m 'Initial commit'
[main (root-commit) 543ccd5] Initial commit
 2 files changed, 2 insertions(+)
 create mode 100644 "a\177b"
 create mode 100644 "\177"
```

Thus, gitoxide should probably permit it too.

To be sure, I also tried creating such a file in Python 3.12 on the same system, by calling the `touch` method on a `Path` object. That worked, too.

Co-authored-by: Eliah Kagan <[email protected]>

Author: Byron

gix-fs/tests/stack/mod.rs

@@ -58,7 +58,7 @@ fn path_join_handling() {
     assert_eq!(
         p("c:").join("relative"),
         p("c:relative"),
-        "absolute + relative = strange joined result with missing back-slash, but it's a valid path that works just like `c:\relative`"
+        "absolute + relative = strange joined result with missing backslash, but it's a valid path that works just like `c:\relative`"
     );
     assert_eq!(
         p("c:\\").join("relative"),
@@ -74,7 +74,7 @@ fn path_join_handling() {
     assert_eq!(
         p("\\\\.\\base").join(absolute),
         p("\\\\.\\base\\absolute"),
-        "absolute1 + absolute2 = joined result with backslash (device relative)"
+        "absolute1 + absolute2 = joined result with backslash (device namespace)"
     );
     assert_eq!(
         p("\\\\?\\base").join(bs_absolute),
@@ -84,7 +84,7 @@ fn path_join_handling() {
     assert_eq!(
         p("\\\\.\\base").join(bs_absolute),
         p("\\\\.\\base\\absolute"),
-        "absolute1 + absolute2 = joined result (device relative)"
+        "absolute1 + absolute2 = joined result (device namespace)"
     );
 
     assert_eq!(p("/").join("C:"), p("C:"), "unix-absolute + win-drive = win-drive");
@@ -101,7 +101,7 @@ fn path_join_handling() {
     assert_eq!(
         p("c:\\").join("\\\\.\\"),
         p("\\\\.\\"),
-        "d-drive-with-bs + device-relative-unc = device-relative-unc"
+        "d-drive-with-bs + device-namespace-unc = device-namespace-unc"
     );
     assert_eq!(
         p("/").join("C:/"),
@@ -112,7 +112,7 @@ fn path_join_handling() {
     assert_eq!(
         p("\\\\.").join("C:"),
         p("C:"),
-        "device-relative-unc + win-drive-relative = win-drive-relative - c: was supposed to be relative, but it's not acting like it."
+        "device-namespace-unc + win-drive-relative = win-drive-relative - c: was supposed to be relative, but it's not acting like it."
     );
     assert_eq!(p("relative").join("C:"), p("C:"), "relative + win-drive = win-drive");
 
@@ -150,7 +150,7 @@ fn path_join_handling() {
         "absolute1 + absolute2 = absolute2"
     );
 
-    assert_eq!(p("/").join("C:"), p("/C:"), "absolute + win-absolute = joined result");
+    assert_eq!(p("/").join("C:"), p("/C:"), "absolute + win-drive = joined result");
     assert_eq!(p("/").join("C:/"), p("/C:/"), "absolute + win-absolute = joined result");
     assert_eq!(
         p("/").join("C:\\"),
@@ -160,7 +160,7 @@ fn path_join_handling() {
     assert_eq!(
         p("relative").join("C:"),
         p("relative/C:"),
-        "relative + win-absolute = joined result"
+        "relative + win-drive = joined result"
     );
 
     assert_eq!(

gix-validate/src/path.rs

@@ -160,7 +160,7 @@ fn check_win_devices_and_illegal_characters(input: &BStr) -> Option<component::E
     {
         return Some(component::Error::WindowsReservedName);
     }
-    if input.iter().any(|b| b.is_ascii_control() || b":<>\"|?*".contains(b)) {
+    if input.iter().any(|b| *b < 0x20 || b":<>\"|?*".contains(b)) {
         return Some(component::Error::WindowsIllegalCharacter);
     }
     if input.ends_with(b".") || input.ends_with(b" ") {