windows: FILE_DISPOSITION_POSIX_SEMANTICS is not supported on FAT filesystems

[squeek502]

Zig Version

0.11.0-dev.4059+17255bed4

Steps to Reproduce and Observed Behavior

#15501 made std.os.windows.DeleteFile use NtSetInformationFile with FILE_DISPOSITION_POSIX_SEMANTICS if builtin.target.os.version_range.windows.min.isAtLeast(.win10_rs1).

However, this flag is only supported if the underlying filesystem is NTFS. On FAT filesystems, calling NtSetInformationFile with FILE_DISPOSITION_POSIX_SEMANTICS results in STATUS_INVALID_PARAMETER:

E:\zigstd\lib\std\os\windows.zig:975:31: 0x7ff6cd6687a1 in DeleteFile (test.exe.obj)
        .INVALID_PARAMETER => unreachable,
                              ^
E:\zigstd\lib\std\os.zig:2463:30: 0x7ff6cd53d593 in unlinkatW (test.exe.obj)
    return windows.DeleteFile(sub_path_w, .{ .dir = dirfd, .remove_dir = remove_dir });
                             ^

To avoid this, it should be possible to use NtQueryVolumeInformationFile before the NtSetInformationFile in std.os.windows.DeleteFile with FileFsAttributeInformation/FILE_FS_ATTRIBUTE_INFORMATION. The FileSystemAttributes can then be checked for FILE_SUPPORTS_POSIX_UNLINK_RENAME.

Tested to make sure the FILE_SUPPORTS_POSIX_UNLINK_RENAME flag works the expected way using the higher level Windows APIs in C:

#include <windows.h>
#include <fileapi.h>
#include <stdio.h>
#include <winnt.h>

int main() {
	HANDLE file = CreateFile("build.zig", GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);

	if (file == INVALID_HANDLE_VALUE) {
		exit(1);
	}

	DWORD flags;
	BOOL result = GetVolumeInformationByHandleW(file, NULL, 0, NULL, NULL, &flags, NULL, 0);
	if (result == 0) {
		exit(1);
	}

	printf("supports posix unlink: %d\n", (flags & FILE_SUPPORTS_POSIX_UNLINK_RENAME) != 0);

	CloseHandle(file);
}

On NTFS:

C:\Users\Ryan\Programming\Zig\tmp> volume.exe
supports posix unlink: 1

On FAT:

E:\zigtest> "C:\Users\Ryan\Programming\Zig\tmp\volume.exe"
supports posix unlink: 0

Expected Behavior

std.fs delete APIs to work on FAT filesystems on Windows

[squeek502]

It actually looks like FileDispositionInformationEx as a whole is unsupported on FAT filesystems.

Here's the nttrace of calling DeleteFileW on FAT32:

NtOpenFile( FileHandle=0xc9847ff5e8 [0x90], DesiredAccess=DELETE|0x80, ObjectAttributes=0x48:"blah.txt", IoStatusBlock=0xc9847ff518 [0/1], ShareAccess=7, OpenOptions=0x00204040 ) => 0
NtQueryInformationFile( FileHandle=0x90, IoStatusBlock=0xc9847ff518, FileInformation=0xc9847ff510, Length=8, FileInformationClass=0x23 [FileAttributeTagInformation] ) => 0xc000000d [87 'The parameter is incorrect.']
NtSetInformationFile( FileHandle=0x90, IoStatusBlock=0xc9847ff518, FileInformation=0xc9847ff5e0, Length=4, FileInformationClass=0x40 [FileDispositionInformationEx] ) => 0xc000000d [87 'The parameter is incorrect.']
NtSetInformationFile( FileHandle=0x90, IoStatusBlock=0xc9847ff518 [0/0], FileInformation=0xc9847ff5d8, Length=1, FileInformationClass=0xd [FileDispositionInformation] ) => 0
NtClose( Handle=0x90 ) => 0

That is, it tries using FileDispositionInformationEx, gets STATUS_INVALID_PARAMETER, and then falls back to FileDispositionInformation.

So, there seems to be two ways to go:

1. Do the same thing: try FileDispositionInformationEx first, and then fall back to FileDispositionInformation if we get STATUS_INVALID_PARAMETER. This would make the non-FAT path only need 1 call to NtSetInformationFile but the FAT path to need 2.
2. Use NtQueryVolumeInformationFile to determine whether or not to use FileDispositionInformationEx or FileDispositionInformation. This would make both the non-FAT and the FAT paths always call both NtQueryVolumeInformationFile and NtSetInformationFile