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Use NtCreateFile to get handle to reparse point

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This commit is contained in:
Jakub Konka
2020-07-14 23:06:55 +02:00
parent d17c9b3591
commit ae8abedbed
4 changed files with 131 additions and 43 deletions
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44
lib/std/os.zig
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@@ -2394,36 +2394,37 @@ pub const readlinkC = @compileError("deprecated: renamed to readlinkZ");
/// See also `readlinkZ`.
pub fn readlinkW(file_path: [*:0]const u16, out_buffer: []u8) ReadLinkError![]u8 {
const w = windows;
const sharing = w.FILE_SHARE_DELETE | w.FILE_SHARE_READ | w.FILE_SHARE_WRITE;
const disposition = w.OPEN_EXISTING;
const flags = w.FILE_FLAG_BACKUP_SEMANTICS | w.FILE_FLAG_OPEN_REPARSE_POINT;
const handle = w.CreateFileW(file_path, 0, sharing, null, disposition, flags, null) catch |err| {
const dir = if (std.fs.path.isAbsoluteWindowsW(file_path)) null else std.fs.cwd().fd;
const handle = w.OpenAsReparsePoint(dir, file_path) catch |err| {
switch (err) {
error.SharingViolation => return error.AccessDenied,
error.PathAlreadyExists => unreachable,
error.PipeBusy => unreachable,
error.PathAlreadyExists => unreachable,
error.NoDevice => return error.FileNotFound,
else => |e| return e,
}
};
var reparse_buf align(@alignOf(w.REPARSE_DATA_BUFFER)) = [_]u8{0} ** (w.MAXIMUM_REPARSE_DATA_BUFFER_SIZE);
var reparse_buf: [w.MAXIMUM_REPARSE_DATA_BUFFER_SIZE]u8 = undefined;
_ = try w.DeviceIoControl(handle, w.FSCTL_GET_REPARSE_POINT, null, reparse_buf[0..], null);
const reparse_struct = @ptrCast(*const w.REPARSE_DATA_BUFFER, &reparse_buf[0]);
// std.debug.warn("\n\n{x}\n\n", .{reparse_buf});
const reparse_struct = @ptrCast(*const w.REPARSE_DATA_BUFFER, @alignCast(@alignOf(w.REPARSE_DATA_BUFFER), &reparse_buf[0]));
switch (reparse_struct.ReparseTag) {
w.IO_REPARSE_TAG_SYMLINK => {
const alignment = @alignOf(w.SymbolicLinkReparseBuffer);
const buf = @ptrCast(*const w.SymbolicLinkReparseBuffer, @alignCast(alignment, &reparse_struct.DataBuffer[0]));
const offset = buf.SubstituteNameOffset / 2;
const len = buf.SubstituteNameLength / 2;
const f = buf.Flags;
const buf = @ptrCast(*const w.SymbolicLinkReparseBuffer, @alignCast(@alignOf(w.SymbolicLinkReparseBuffer), &reparse_struct.DataBuffer[0]));
const offset = buf.SubstituteNameOffset >> 1;
const len = buf.SubstituteNameLength >> 1;
const path_buf = @as([*]const u16, &buf.PathBuffer);
std.debug.warn("got symlink => offset={}, len={}, flags = {}, {}\n", .{ offset, len, f, w.SYMLINK_FLAG_RELATIVE });
// TODO handle absolute paths and namespace prefix
const out_len = std.unicode.utf16leToUtf8(out_buffer, path_buf[offset .. offset + len]) catch unreachable;
std.debug.warn("got symlink => utf8={}\n", .{out_buffer[0..out_len]});
return out_buffer[0..out_len];
const is_relative = buf.Flags & w.SYMLINK_FLAG_RELATIVE != 0;
return parseReadlinkPath(path_buf[offset .. offset + len], is_relative, out_buffer);
},
w.IO_REPARSE_TAG_MOUNT_POINT => {
@panic("TODO parse mount point");
const buf = @ptrCast(*const w.MountPointReparseBuffer, @alignCast(@alignOf(w.MountPointReparseBuffer), &reparse_struct.DataBuffer[0]));
const offset = buf.SubstituteNameOffset >> 1;
const len = buf.SubstituteNameLength >> 1;
const path_buf = @as([*]const u16, &buf.PathBuffer);
return parseReadlinkPath(path_buf[offset .. offset + len], false, out_buffer);
},
else => |value| {
std.debug.warn("unsupported symlink type: {}", .{value});
@@ -2432,6 +2433,13 @@ pub fn readlinkW(file_path: [*:0]const u16, out_buffer: []u8) ReadLinkError![]u8
}
}
fn parseReadlinkPath(path: []const u16, is_relative: bool, out_buffer: []u8) []u8 {
const out_len = std.unicode.utf16leToUtf8(out_buffer, path) catch unreachable;
std.debug.warn("got symlink => utf8={}\n", .{out_buffer[0..out_len]});
// TODO handle absolute paths and namespace prefix '/??/'
return out_buffer[0..out_len];
}
/// Same as `readlink` except `file_path` is null-terminated.
pub fn readlinkZ(file_path: [*:0]const u8, out_buffer: []u8) ReadLinkError![]u8 {
if (builtin.os.tag == .windows) {