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std.os.windows.GetFinalPathNameByHandle: replace kernel32 by ntdll call

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Removes the call to kernel32.GetFinalPathNameByHandleW in favor of NtQueryObject, which means we can reuse the other codepath's logic for DOS naming.
This commit is contained in:
Rohlem 2020-12-17 16:37:40 +01:00 committed by Andrew Kelley
parent 964bbcd0b1
commit 64c5f4979e
1 changed files with 51 additions and 68 deletions
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119
lib/std/os/windows.zig
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@ -1001,19 +1001,13 @@ test "QueryObjectName" {
_ = try QueryObjectName(file.handle, out_buffer[0..result_path.len]);
}
pub const GetFinalPathNameByHandleError = error {
BadPathName,
FileNotFound,
NameTooLong,
Unexpected,
}
|| if((comptime builtin.os.tag != .windows) or (targetVersionIsAtLeast(WindowsVersion.win10_rs4) == true))
error {}
else
error {
AccessDenied,
SystemResources,
};
pub const GetFinalPathNameByHandleError = error{
AccessDenied,
BadPathName,
FileNotFound,
NameTooLong,
Unexpected,
};
/// Specifies how to format volume path in the result of `GetFinalPathNameByHandle`.
/// Defaults to DOS volume names.
@ -1036,75 +1030,64 @@ pub fn GetFinalPathNameByHandle(
fmt: GetFinalPathNameByHandleFormat,
out_buffer: []u16,
) GetFinalPathNameByHandleError![]u16 {
var path_buffer: [std.math.max(@sizeOf(FILE_NAME_INFORMATION), @sizeOf(OBJECT_NAME_INFORMATION)) + PATH_MAX_WIDE * 2]u8 align(@alignOf(FILE_NAME_INFORMATION)) = undefined;
var volume_buffer: [@sizeOf(FILE_NAME_INFORMATION) + MAX_PATH]u8 align(@alignOf(FILE_NAME_INFORMATION)) = undefined; // MAX_PATH bytes should be enough since it's Windows-defined name
var path_buffer: [@sizeOf(FILE_NAME_INFORMATION) + PATH_MAX_WIDE * 2]u8 align(@alignOf(FILE_NAME_INFORMATION)) = undefined;
var file_name_u16: []const u16 = undefined;
var volume_name_u16: []const u16 = undefined;
if ((comptime (targetVersionIsAtLeast(WindowsVersion.win10_rs4) != true)) //need explicit comptime, because error returns affect return type
and !runtimeVersionIsAtLeast(WindowsVersion.win10_rs4)) {
// TODO: directly replace/emulate QueryInformationFile of .FileNormalizedNameInformation
// with ntdll instead of calling into kernel32
// (probably using some less-powerful query and looping over path segments)
const flags: DWORD = FILE_NAME_NORMALIZED | switch(fmt.volume_name) {
.Dos => @as(DWORD, VOLUME_NAME_DOS),
.Nt => @as(DWORD, VOLUME_NAME_NT),
and !runtimeVersionIsAtLeast(WindowsVersion.win10_rs4))
{
const final_path = QueryObjectName(hFile, std.mem.bytesAsSlice(u16, path_buffer[0..])) catch |err| return switch (err) {
error.InvalidHandle => error.FileNotFound, //close enough?
else => |e| e,
};
const wide_path_buffer = std.mem.bytesAsSlice(u16, path_buffer[0..]);
const rc = kernel32.GetFinalPathNameByHandleW(hFile, wide_path_buffer.ptr, @intCast(u32, wide_path_buffer.len), flags);
if (rc == 0) {
switch (kernel32.GetLastError()) {
.FILE_NOT_FOUND => return error.FileNotFound,
.PATH_NOT_FOUND => return error.FileNotFound,
.NOT_ENOUGH_MEMORY => return error.SystemResources,
.FILENAME_EXCED_RANGE => return error.NameTooLong,
.ACCESS_DENIED => return error.AccessDenied, //can happen in SMB sub-queries for parent path segments
.INVALID_PARAMETER => unreachable,
else => |err| return unexpectedError(err),
if (fmt.volume_name == .Nt) {
if (out_buffer.len < final_path.len) {
return error.NameTooLong;
}
std.mem.copy(u16, out_buffer[0..], final_path[0..]);
return final_path; //we can directly return the slice we received
}
//in case of failure, rc == length of string INCLUDING null terminator,
if (rc > wide_path_buffer.len) return error.NameTooLong;
//in case of success, rc == length of string EXCLUDING null terminator
const result_slice = switch(fmt.volume_name) {
.Dos => blk: {
const expected_prefix = [_]u16{'\\', '\\', '?', '\\'};
if (!std.mem.eql(u16, expected_prefix[0..], wide_path_buffer[0..expected_prefix.len])) {
return error.BadPathName;
}
break :blk wide_path_buffer[expected_prefix.len..rc:0];
},
//no prefix here
.Nt => wide_path_buffer[0..rc:0],
};
if(result_slice.len > out_buffer.len) return error.NameTooLong;
std.mem.copy(u16, out_buffer[0..], result_slice);
return out_buffer[0..result_slice.len];
}
//otherwise we need to parse the string for volume path for the .Dos logic below to work
const expected_prefix = std.unicode.utf8ToUtf16LeStringLiteral("\\Device\\");
if (!std.mem.eql(u16, expected_prefix, final_path[0..expected_prefix.len])) {
//TODO find out if this can occur, and if we need to handle it differently
//(i.e. how to determine the end of a volume name)
return error.BadPathName;
}
const index = std.mem.indexOfPos(u16, final_path, expected_prefix.len, &[_]u16{'\\'}) orelse unreachable;
volume_name_u16 = final_path[0..index];
file_name_u16 = final_path[index..];
// Get normalized path; doesn't include volume name though.
try QueryInformationFile(hFile, .FileNormalizedNameInformation, path_buffer[0..]);
//fallthrough for fmt.volume_name != .Nt
} else {
// Get normalized path; doesn't include volume name though.
try QueryInformationFile(hFile, .FileNormalizedNameInformation, path_buffer[0..]);
const file_name = @ptrCast(*const FILE_NAME_INFORMATION, &path_buffer[0]);
file_name_u16 = @ptrCast([*]const u16, &file_name.FileName[0])[0..@divExact(file_name.FileNameLength, 2)];
// Get NT volume name.
var volume_buffer: [@sizeOf(FILE_NAME_INFORMATION) + MAX_PATH]u8 align(@alignOf(FILE_NAME_INFORMATION)) = undefined; // MAX_PATH bytes should be enough since it's Windows-defined name
try QueryInformationFile(hFile, .FileVolumeNameInformation, volume_buffer[0..]);
// Get NT volume name.
try QueryInformationFile(hFile, .FileVolumeNameInformation, volume_buffer[0..]);
const volume_name_info = @ptrCast(*const FILE_NAME_INFORMATION, &volume_buffer[0]);
volume_name_u16 = @ptrCast([*]const u16, &volume_name_info.FileName[0])[0..@divExact(volume_name_info.FileNameLength, 2)];
const file_name = @ptrCast(*const FILE_NAME_INFORMATION, &path_buffer[0]);
const file_name_u16 = @ptrCast([*]const u16, &file_name.FileName[0])[0 .. file_name.FileNameLength / 2];
const volume_name = @ptrCast(*const FILE_NAME_INFORMATION, &volume_buffer[0]);
switch (fmt.volume_name) {
.Nt => {
if (fmt.volume_name == .Nt) {
// Nothing to do, we simply copy the bytes to the user-provided buffer.
const volume_name_u16 = @ptrCast([*]const u16, &volume_name.FileName[0])[0 .. volume_name.FileNameLength / 2];
if (out_buffer.len < volume_name_u16.len + file_name_u16.len) return error.NameTooLong;
std.mem.copy(u16, out_buffer[0..], volume_name_u16);
std.mem.copy(u16, out_buffer[volume_name_u16.len..], file_name_u16);
return out_buffer[0 .. volume_name_u16.len + file_name_u16.len];
},
}
//fallthrough for fmt.volume_name != .Nt
}
switch (fmt.volume_name) {
.Nt => unreachable, //handled above
.Dos => {
// Get DOS volume name. DOS volume names are actually symbolic link objects to the
// actual NT volume. For example:
@ -1138,8 +1121,8 @@ pub fn GetFinalPathNameByHandle(
var input_struct = @ptrCast(*MOUNTMGR_MOUNT_POINT, &input_buf[0]);
input_struct.DeviceNameOffset = @sizeOf(MOUNTMGR_MOUNT_POINT);
input_struct.DeviceNameLength = @intCast(USHORT, volume_name.FileNameLength);
@memcpy(input_buf[@sizeOf(MOUNTMGR_MOUNT_POINT)..], @ptrCast([*]const u8, &volume_name.FileName[0]), volume_name.FileNameLength);
input_struct.DeviceNameLength = @intCast(USHORT, volume_name_u16.len * 2);
@memcpy(input_buf[@sizeOf(MOUNTMGR_MOUNT_POINT)..], @ptrCast([*]const u8, volume_name_u16.ptr), volume_name_u16.len * 2);
DeviceIoControl(mgmt_handle, IOCTL_MOUNTMGR_QUERY_POINTS, input_buf[0..], output_buf[0..]) catch |err| switch (err) {
error.AccessDenied => unreachable,