Julia: touch() requires file ownership, having file permissions should be enough

[tanmaykm]

touch fails if file is not owned by user, and even if user has permissions on file.

tan@tanlt ~ $ touch /tmp/abc
tan@tanlt ~ $ sudo chown root:root /tmp/abc
tan@tanlt ~ $ sudo chmod 777 /tmp/abc
tan@tanlt ~ $ ls -la /tmp/abc
-rwxrwxrwx 1 root root 0 Aug 22 08:42 /tmp/abc
tan@tanlt ~ $ touch /tmp/abc
tan@tanlt ~ $ julia10
               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.0.0 (2018-08-08)
 _/ |\__'_|_|_|\__'_|  |  Official https://julialang.org/ release
|__/                   |

julia> touch("/tmp/abc")
ERROR: IOError: futime: operation not permitted (EPERM)
Stacktrace:
 [1] uv_error at ./libuv.jl:85 [inlined]
 [2] futime at ./filesystem.jl:143 [inlined]
 [3] touch(::String) at ./file.jl:407
 [4] top-level scope at none:0

Goes through if file ownership is changed:

shell> sudo chown tan:tan /tmp/abc

julia> touch("/tmp/abc")
"/tmp/abc"

[tanmaykm]

~Maybe we should use UTIME_NOW here~

[tanmaykm]

It seems like using uv_fs_futime here may not be appropriate (at least on unix). I have made a PR (#28819) using futimes instead which seems to do the job.

I don't know whether Windows is affected too, but as per https://docs.microsoft.com/en-us/windows/desktop/api/fileapi/nf-fileapi-setfiletime calling the libuv API should be okay.

[00vareladavid]

I think this is triggering a bug within Pkg, see: https://discourse.julialang.org/t/shared-julia-environment/14206/

[tanmaykm]

Fixed by #28819. Closing.