There are many different types of Windows paths, and there are a few different possible namespaces on top of that. Before this commit, NT namespaced paths were somewhat supported, and for Win32 paths (those without a namespace prefix), only relative and drive absolute paths were supported. After this commit, all of the following are supported:
- Device namespaced paths (`\\.\`)
- Verbatim paths (`\\?\`)
- NT-namespaced paths (`\??\`)
- Relative paths (`foo`)
- Drive-absolute paths (`C:\foo`)
- Drive-relative paths (`C:foo`)
- Rooted paths (`\foo`)
- UNC absolute paths (`\\server\share\foo`)
- Root local device paths (`\\.` or `\\?` exactly)
Plus:
- Any of the path types and namespace types can be mixed and matched together as appropriate.
- All of the `std.os.windows.*ToPrefixedFileW` functions will accept any path type, prefixed or not, and do the appropriate thing to convert them to an NT-prefixed path if necessary.
This is achieved by making the `std.os.windows.*ToPrefixedFileW` functions behave like `ntdll.RtlDosPathNameToNtPathName_U`, but with a few differences:
- Does not allocate on the heap (this is why we can't use `ntdll.RtlDosPathNameToNtPathName_U` directly, it does internal heap allocation).
- Relative paths are kept as relative unless they contain too many .. components, in which case they are treated as 'drive relative' and resolved against the CWD (this is how it behaved before this commit as well).
- Special case device names like COM1, NUL, etc are not handled specially (TODO)
- `.` and space are not stripped from the end of relative paths (potential TODO)
Most of the non-trivial conversion of non-relative paths is done via `ntdll.RtlGetFullPathName_U`, which AFAIK is used internally by `ntdll.RtlDosPathNameToNtPathName_U`.
Some relevant reading on Windows paths:
- https://googleprojectzero.blogspot.com/2016/02/the-definitive-guide-on-win32-to-nt.html
- https://chrisdenton.github.io/omnipath/Overview.htmlCloses#8205
Might close (untested) #12729
Note:
- This removes checking for illegal characters in `std.os.windows.sliceToPrefixedFileW`, since the previous solution (iterate the whole string and error if any illegal characters were found) was naive and won't work for all path types. This is further complicated by things like file streams (where `:` is used as a delimiter, e.g. `file.ext:stream_name:$DATA`) and things in the device namespace (where a path like `\\.\GLOBALROOT\??\UNC\localhost\C$\foo` is valid despite the `?`s in the path and is effectively equivalent to `C:\foo`). Truly validating paths is complicated and would need to be tailored to each path type. The illegal character checking being removed may open up users to more instances of hitting `OBJECT_NAME_INVALID => unreachable` when using `fs` APIs.
+ This is related to https://github.com/ziglang/zig/issues/15607
We already have a LICENSE file that covers the Zig Standard Library. We
no longer need to remind everyone that the license is MIT in every single
file.
Previously this was introduced to clarify the situation for a fork of
Zig that made Zig's LICENSE file harder to find, and replaced it with
their own license that required annual payments to their company.
However that fork now appears to be dead. So there is no need to
reinforce the copyright notice in every single file.
