Hi,
This is an intentional bugfix, and I've added a release note for it
now. Thanks for reporting it!
Regards,
John Högberg
On tor, 2018-06-07 at 17:38 +0900, Shunichi Shinohara wrote:
> Thanks a lot!!
>
> 2018-06-07 17:35 GMT+09:00 Björn Gustavsson <bjorn@REDACTED>:
> >
> > Thanks for digging deeper.
> >
> > The old efile_driver has been rewritten and
> > replaced with a NIF. I am not sure whether
> > this change is an oversight/bug or a deliberate
> > change. We will look into it before the release
> > of OTP 21 and either fix the bug or add a
> > note about the potential incompatibility.
> >
> > /Björn
> >
> >
> >
> > On Thu, Jun 7, 2018 at 8:52 AM, Shunichi Shinohara <shino.shun@REDACTED
> > l.com> wrote:
> > >
> > > I looked into the source code and I think the difference between
> > > 20
> > > and 21.0-rc2 is identified.
> > >
> > > # The subject of this thread is not suitable,
> > > # but please let me report to not leave just a wrong information.
> > >
> > > First, the difference between OTP 20.3.4 and 21.0-rc2 is as
> > > follows.
> > > (on macOS, OTPs are installed from git by kerl)
> > >
> > > Setup file a and b, a is owned by root user.
> > > % rm -f a && rm -f b && sudo touch a && sudo chmod 755 a && touch
> > > b
> > >
> > > Let's start OTP 21.0-rc2 and read file_info of a and write it to
> > > b,
> > > it fails:
> > > % ~/local/otp/OTP-21.0-rc2/bin/erl
> > > Erlang/OTP 21 [RELEASE CANDIDATE 2] [erts-10.0] [source] [64-bit]
> > > [smp:8:8] [ds:8:8:10] [async-threads:1] [hipe] [sharing-
> > > preserving]
> > >
> > > Eshell V10.0 (abort with ^G)
> > > 1> {ok, Fi} = file:read_file_info("a").
> > > {ok,#file_info{size = 0,type = regular,access = read,
> > > atime = {{2018,6,7},{15,32,41}},
> > > mtime = {{2018,6,7},{15,32,41}},
> > > ctime = {{2018,6,7},{15,32,41}},
> > > mode = 33261,links = 1,major_device = 16777220,
> > > minor_device = 0,inode = 17846256,uid = 0,gid =
> > > 20}}
> > > 2> file:write_file_info("b", Fi).
> > > {error,eperm}
> > >
> > > Then, start OTP 20.3.4 and replay the same step, it succeeds:
> > > % ~/local/otp/OTP-20.3.4/bin/erl
> > > Erlang/OTP 20 [erts-9.3] [source] [64-bit] [smp:8:8] [ds:8:8:10]
> > > [async-threads:10] [hipe] [kernel-poll:false]
> > >
> > > Eshell V9.3 (abort with ^G)
> > > 1> {ok, F} = file:read_file_info("a").
> > > {ok,#file_info{size = 0,type = regular,access = read,
> > > atime = {{2018,6,7},{15,32,41}},
> > > mtime = {{2018,6,7},{15,32,41}},
> > > ctime = {{2018,6,7},{15,32,41}},
> > > mode = 33261,links = 1,major_device = 16777220,
> > > minor_device = 0,inode = 17846256,uid = 0,gid =
> > > 20}}
> > > 2> file:write_file_info("b", F).
> > > ok
> > >
> > > The file_info records are the same (sorry again...), but the
> > > results differ.
> > >
> > > Looking into unix_efile.c on maint-20 branch:
> > > https://github.com/erlang/otp/blob/maint-20/erts/emulator/dri
> > > vers/unix/unix_efile.c#L572
> > > it ignores eperm error and proceeds forward:
> > > if (chown(name, pInfo->uid, pInfo->gid) && errno != EPERM) {
> > >
> > > I'm not sure the difference is judged as incompatibility or not,
> > > it's nice if this note helps someone (including future me).
> > >
> > > Thanks,
> > > Shino
> > >
> > > 2018-06-07 15:07 GMT+09:00 Shunichi Shinohara <shino.shun@REDACTED
> > > om>:
> > > >
> > > > I'm sorry I was wrong. Thanks for correct me, Bjorn.
> > > > I have to dig the root cause down ;)
> > > >
> > > > Shino
> > > >
> > > > 2018-06-07 15:04 GMT+09:00 Björn Gustavsson <bjorn@REDACTED>:
> > > > >
> > > > > On Thu, Jun 7, 2018 at 7:39 AM, Shunichi Shinohara <shino.shu
> > > > > n@REDACTED> wrote:
> > > > > [...]
> > > > > >
> > > > > > It seems that some fields are added to file_info record
> > > > > > between 20 and 21-rc2,
> > > > > "Seems"?
> > > > >
> > > > > No fields have been added for a very long time. The only
> > > > > modifications done in recent releases are updates
> > > > > to the types of the existing fields. The last such change
> > > > > was made at the end of 2015.
> > > > >
> > > > > /Bjorn
> > > > >
> > > > > --
> > > > > Björn Gustavsson, Erlang/OTP, Ericsson AB
> >
> >
> > --
> > Björn Gustavsson, Erlang/OTP, Ericsson AB