[ruby-core:70558] [Ruby trunk - Bug #11478] symlinks support broken on win32

Issue #11478 has been updated by Daniel Berger.


FWIW, this is how we implemented File.symlink? in win32-file: https://githu=
b.com/djberg96/win32-file/blob/ffi/lib/win32/file.rb#L241-L271

Note that we use CreateSymbolicLink for our own File.symlink method, howeve=
r. I'm not sure why core Ruby doesn't yet. It's been around since Vista.

----------------------------------------
Bug #11478: symlinks support broken on win32
https://bugs.ruby-lang.org/issues/11478#change-53968

* Author: Alex Budovski
* Status: Feedback
* Priority: Normal
* Assignee:=20
* ruby -v: master
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN
----------------------------------------
The symlink support is completely broken on win32 because it thinks ALL rep=
arse points are symlinks.

~~~
/* License: Ruby's */
static unsigned
fileattr_to_unixmode(DWORD attr, const WCHAR *path)
=E2=80=A6
    if (attr & FILE_ATTRIBUTE_REPARSE_POINT) {
	mode |=3D S_IFLNK | S_IEXEC;
    }

~~~

But that is plainly false. I have dedup enabled on my volume, and some file=
s are deduped, resulting in reparse points with tag =3D=3D 0x80000013 (IO_R=
EPARSE_TAG_DEDUP)

See: https://msdn.microsoft.com/en-us/library/windows/desktop/aa365511(v=3D=
vs.85).aspx

One obvious problem is with `nmake install` we skip a number of files from =
being copied due to this logic:

~~~
E:\dev\ruby\tool\rbinstall.rb:
def install_recursive(srcdir, dest, options =3D {})
  opts =3D options.clone
=E2=80=A6
        elsif stat.symlink?
          # skip
          puts "**** skipping #{src} ****" # I added this line to check
        else
~~~

Example file that was skipped:

~~~
E:\dev\ruby>fsutil reparsepoint query E:/dev/ruby/lib/optparse.rb
Reparse Tag Value : 0x80000013
Tag value: Microsoft

Reparse Data Length: 0x0000007c
Reparse Data:
0000:  01 02 7c 00 00 00 00 00  fd e0 00 00 00 00 00 00  ..|.............
0010:  00 00 00 00 00 00 00 00  f7 38 52 15 a0 a8 c2 46  .........8R....F
0020:  a2 70 6e d0 4e 28 5d f5  40 00 40 00 40 00 00 00  .pn.N(].@.@.@...
0030:  97 4a a2 d6 a0 d4 d0 01  7b 2f 01 00 00 00 0a 00  .J......{/......
0040:  30 2e 9c 05 00 00 03 00  01 00 00 00 88 00 00 00  0...............
0050:  88 00 00 00 00 00 00 00  30 cf fe d1 25 e3 d7 d6  ........0...%...
0060:  07 79 02 88 4a 46 79 35  31 2d b7 31 49 87 de f8  .y..JFy51-.1I...
0070:  50 20 af 62 27 db 87 76  fc 44 d2 88              P .b'..v.D..
~~~
File that hadn't been deduped yet:

~~~
E:\dev\ruby>fsutil reparsepoint query E:/dev/ruby/include/ruby/backward/cla=
ssext.h
Error:  The file or directory is not a reparse point.
~~~

So the `nmake install` is incomplete! But naturally, anything that depends =
on `stat.symlink?` will not work right.



--=20
https://bugs.ruby-lang.org/