Commit 4fdfaf69c8c55ebac4c5b3c00025c0ac51281b5b | zig

author	Jakub Konka <kubkon@jakubkonka.com> 2020-07-28 14:21:33+02:00
committer	Andrew Kelley <andrew@ziglang.org> 2020-07-29 01:19:10+00:00
log	4fdfaf69c8c55ebac4c5b3c00025c0ac51281b5b
tree	b72a3971bb8ec0076ff94b19eab38e78586b41ee
parent	606b6462ceaaeb2d993df684829a27db16eea18a

Add Zig wrapper for kernel32.DeviceIoControl

This commit adds a Zig wrapper for `kernel32.DeviceIoControl` which
applies ReactOS logic for deciding whether to use
`ntdll.NtDeviceIoControlFile` or `ntdll.NtFsControlFile` based on the
value of passed `IO_CONTROL_CODE`. The decision logic is based on the
logic found in ReactOS found in the following [link].

Thanks to Daurnimator for finding this bit in ReactOS!

[link]: https://doxygen.reactos.org/d3/d74/deviceio_8c.html

1 files changed, 14 insertions(+), 10 deletions(-)

lib
- std
  - os
    windows.zig

lib/std/os/windows.zig+14-10

 @@ -215,24 +215,28 @@ pub fn CreateEventExW(attributes: ?*SECURITY_ATTRIBUTES, nameW: [*:0]const u16,
     }
 }
-pub const FsControlFileError = error{Unexpected};
+pub const DeviceIoControlError = error{Unexpected};
-// TODO work out if we need to expose other arguments to the underlying
+/// A Zig wrapper around `NtDeviceIoControlFile` and `NtFsControlFile` syscalls.
-// NtFsControlFile syscall
+/// It implements similar behavior to `DeviceIoControl` and is meant to serve
-pub fn FsControlFile(
+/// as a direct substitute for that call.
+/// TODO work out if we need to expose other arguments to the underlying syscalls.
+pub fn DeviceIoControl(
     h: HANDLE,
-    fsControlCode: ULONG,
+    ioControlCode: ULONG,
     in: ?[]const u8,
     out: ?[]u8,
-) FsControlFileError!void {
+) DeviceIoControlError!void {
+    // Logic from: https://doxygen.reactos.org/d3/d74/deviceio_8c.html
+    const syscall = if ((ioControlCode >> 16) == FILE_DEVICE_FILE_SYSTEM) ntdll.NtFsControlFile else ntdll.NtDeviceIoControlFile;
     var io: IO_STATUS_BLOCK = undefined;
-    const rc = ntdll.NtFsControlFile(
+    const rc = syscall(
         h,
         null,
         null,
         null,
         &io,
-        fsControlCode,
+        ioControlCode,
         if (in) |i| i.ptr else null,
         if (in) |i| @intCast(ULONG, i.len) else 0,
         if (out) |o| o.ptr else null,
 @@ -731,7 +735,7 @@ pub fn CreateSymbolicLinkW(
     @memcpy(buffer[@sizeOf(SYMLINK_DATA)..], @ptrCast([*]const u8, target_path), target_path.len * 2);
     const paths_start = @sizeOf(SYMLINK_DATA) + target_path.len * 2;
     @memcpy(buffer[paths_start..].ptr, @ptrCast([*]const u8, target_path), target_path.len * 2);
-    _ = try FsControlFile(symlink_handle, FSCTL_SET_REPARSE_POINT, buffer[0..buf_len], null);
+    _ = try DeviceIoControl(symlink_handle, FSCTL_SET_REPARSE_POINT, buffer[0..buf_len], null);
 }
 pub const ReadLinkError = error{
 @@ -809,7 +813,7 @@ pub fn ReadLinkW(dir: ?HANDLE, sub_path_w: [*:0]const u16, out_buffer: []u8) Rea
     defer CloseHandle(result_handle);
     var reparse_buf: [MAXIMUM_REPARSE_DATA_BUFFER_SIZE]u8 = undefined;
-    _ = try FsControlFile(result_handle, FSCTL_GET_REPARSE_POINT, null, reparse_buf[0..]);
+    _ = try DeviceIoControl(result_handle, FSCTL_GET_REPARSE_POINT, null, reparse_buf[0..]);
     const reparse_struct = @ptrCast(*const REPARSE_DATA_BUFFER, @alignCast(@alignOf(REPARSE_DATA_BUFFER), &reparse_buf[0]));
     switch (reparse_struct.ReparseTag) {