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Use NtQueryInformationFile unless unavailable

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Favour newer API which uses `NtQueryInformationFile` with class flags
`FileNormalizedNameInformation` and `FileVolumeNameInformation`
instead of lower-level `NtQueryObject`. `NtQueryObject` is still
used as a fallback in case the former are unavailable.
This commit is contained in:
Jakub Konka 2020-08-05 18:34:44 +02:00
parent 747d46f22c
commit 2628a8846e
1 changed files with 57 additions and 13 deletions
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70
lib/std/os/windows.zig
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@ -907,18 +907,61 @@ pub const GetFinalPathNameByHandleError = error{
/// Win32 namespace, however, '\\?\' prefix is *not* prepended to the result.
/// TODO support other namespaces/volume names.
pub fn GetFinalPathNameByHandle(hFile: HANDLE, out_buffer: []u16) GetFinalPathNameByHandleError![]u16 {
// The implementation is based on implementation found in Wine sources:
// [LINK]
var buffer: [@sizeOf(OBJECT_NAME_INFORMATION) + MAX_PATH * 2]u8 = undefined;
var dummy: ULONG = undefined;
var rc = ntdll.NtQueryObject(hFile, OBJECT_INFORMATION_CLASS.ObjectNameInformation, &buffer, buffer.len, &dummy);
switch (rc) {
.SUCCESS => {},
else => return unexpectedStatus(rc),
}
// The implementation is based on implementation found in Wine sources, however,
// we make the following tweaks. First of all, if `NtQueryInformationFile` supports
// `FILE_INFORMATION_CLASS.FileNormalizedNameInformation` and `FileVolumeNameInformation`,
// we use those two calls to generate a valid Win32/DOS path. Otherwise, we fallback to
// more widely supported `NtQueryObject` generic routine.
// Wine source: https://source.winehq.com/git/wine.git/blob/HEAD:/dlls/kernelbase/file.c#l1708
var buffer: [PATH_MAX_WIDE]u16 = undefined;
const object_path = blk: {
var path_buffer: [PATH_MAX_WIDE * 2]u8 = undefined;
var io: IO_STATUS_BLOCK = undefined;
var rc = ntdll.NtQueryInformationFile(hFile, &io, &path_buffer, path_buffer.len, FILE_INFORMATION_CLASS.FileNormalizedNameInformation);
switch (rc) {
.SUCCESS => {
var nt_volume_buffer: [MAX_PATH]u8 = undefined;
rc = ntdll.NtQueryInformationFile(hFile, &io, &nt_volume_buffer, nt_volume_buffer.len, FILE_INFORMATION_CLASS.FileVolumeNameInformation);
switch (rc) {
.SUCCESS => {
const file_name = @ptrCast(*const FILE_NAME_INFORMATION, @alignCast(@alignOf(FILE_NAME_INFORMATION), &path_buffer[0]));
const file_name_u16 = @ptrCast([*]const u16, &file_name.FileName[0])[0..file_name.FileNameLength / 2];
const object_name = @ptrCast(*const OBJECT_NAME_INFORMATION, @alignCast(@alignOf(OBJECT_NAME_INFORMATION), &buffer));
const object_path = @as([*]const u16, object_name.Name.Buffer)[0..object_name.Name.Length / 2];
if (file_name_u16.len > PATH_MAX_WIDE) return error.NameTooLong;
const volume_name = @ptrCast(*const FILE_NAME_INFORMATION, @alignCast(@alignOf(FILE_NAME_INFORMATION), &nt_volume_buffer[0]));
const volume_name_u16 = @ptrCast([*]const u16, &volume_name.FileName[0])[0..volume_name.FileNameLength / 2];
std.mem.copy(u16, buffer[0..], volume_name_u16);
std.mem.copy(u16, buffer[volume_name_u16.len..], file_name_u16);
break :blk buffer[0..volume_name_u16.len + file_name_u16.len];
},
.INVALID_PARAMETER => {}, // fall through
else => return unexpectedStatus(rc),
}
},
.INVALID_PARAMETER => {}, // fall through
else => return unexpectedStatus(rc),
}
var dummy: ULONG = undefined;
rc = ntdll.NtQueryObject(hFile, OBJECT_INFORMATION_CLASS.ObjectNameInformation, &path_buffer, path_buffer.len, &dummy);
switch (rc) {
.SUCCESS => {},
else => return unexpectedStatus(rc),
}
const object_name = @ptrCast(*const OBJECT_NAME_INFORMATION, @alignCast(@alignOf(OBJECT_NAME_INFORMATION), &buffer));
// Apparently, `NtQueryObject` has a bug when signalling an error condition.
// To check for error, i.e., FileNotFound, we check if the result Buffer is non null
// and Length is greater than zero.
// Source: https://stackoverflow.com/questions/65170/how-to-get-name-associated-with-open-handle
if (object_name.Name.Length == 0) return error.FileNotFound;
break :blk @as([*]const u16, object_name.Name.Buffer)[0..object_name.Name.Length / 2];
};
// Since `NtQueryObject` returns a fully-qualified NT path, we need to translate
// the result into a Win32/DOS path (e.g., \Device\HarddiskVolume4\foo would become
@ -927,7 +970,7 @@ pub fn GetFinalPathNameByHandle(hFile: HANDLE, out_buffer: []u16) GetFinalPathNa
var query_path = [_]u16{ '\\', 'D', 'o', 's', 'D', 'e', 'v', 'i', 'c', 'e', 's', '\\', 'C', ':' };
for (dos_drive_letters) |drive_letter| {
const drive = &[_]u16{ drive_letter, ':' };
std.mem.copy(u16, query_path[12..], drive[0..]);
std.mem.copy(u16, query_path[query_path.len - 2..], drive[0..]);
var sym_handle: HANDLE = undefined;
const len_bytes = @intCast(u16, query_path.len) * 2;
@ -944,7 +987,7 @@ pub fn GetFinalPathNameByHandle(hFile: HANDLE, out_buffer: []u16) GetFinalPathNa
.SecurityDescriptor = null,
.SecurityQualityOfService = null,
};
rc = ntdll.NtOpenSymbolicLinkObject(&sym_handle, SYMBOLIC_LINK_QUERY, attr);
var rc = ntdll.NtOpenSymbolicLinkObject(&sym_handle, SYMBOLIC_LINK_QUERY, attr);
switch (rc) {
.SUCCESS => {},
.OBJECT_NAME_NOT_FOUND => continue,
@ -967,6 +1010,7 @@ pub fn GetFinalPathNameByHandle(hFile: HANDLE, out_buffer: []u16) GetFinalPathNa
const link_path = @as([*]const u16, link.Buffer)[0..link.Length / 2];
const idx = std.mem.indexOf(u16, object_path, link_path) orelse continue;
// TODO check the provided buffer is actually big enough.
std.mem.copy(u16, out_buffer[0..], drive[0..]);
std.mem.copy(u16, out_buffer[2..], object_path[link_path.len..]);