filesize(fd::Int32) seems broken in Julia 1.12

[csvance]

In shm.jl we have the following section:

        # Get the size of the existing shared memory object.
        try
            nbytes = Int(filesize(fd))
        catch err
            _close(fd)
            rethrow(err)
        end

It seems that in Julia 1.12 that calling filesize on a file descriptor doesn't work:

ERROR: MethodError: no method matching joinpath(::Int32)
The function `joinpath` exists, but no method is defined for this combination of argument types.

Closest candidates are:
  joinpath(::Base.Filesystem.DirEntry, Any...)
   @ Base file.jl:1034
  joinpath(::AbstractString...)
   @ Base path.jl:346
  joinpath(::Union{Tuple, AbstractVector})
   @ Base path.jl:324

Stacktrace:
  [1] stat(path::Int32)
    @ Base.Filesystem ./stat.jl:235
  [2] filesize(path::Int32)
    @ Base.Filesystem ./stat.jl:587
  [3] InterProcessCommunication.SharedMemory(name::String, flags::Int32, mode::UInt32, len::Int64, volatile::Bool)
    @ InterProcessCommunication /cache/cvance@medicalmetrics.local/julia/packages/InterProcessCommunication/cHeKQ/src/shm.jl:140
  [4] #SharedMemory#26
    @ /cache/cvance@medicalmetrics.local/julia/packages/InterProcessCommunication/cHeKQ/src/shm.jl:107 [inlined]
  [5] SharedMemory
    @ /cache/cvance@medicalmetrics.local/julia/packages/InterProcessCommunication/cHeKQ/src/shm.jl:103 [inlined]

I also can't find this specific signature in the documentation: https://docs.julialang.org/en/v1/base/file/#Base.filesize

Minimum workable example:

using Base.Filesystem
fd = UInt32(1234)
filesize(fd)

In Julia 1.11.7 the MWE produces this instead:

ERROR: IOError: stat(RawFD(1234)): bad file descriptor (EBADF)
Stacktrace:
 [1] uv_error
   @ ./libuv.jl:106 [inlined]
 [2] stat(fd::RawFD)
   @ Base.Filesystem ./stat.jl:176
 [3] stat
   @ ./stat.jl:192 [inlined]
 [4] filesize(path::UInt32)
   @ Base.Filesystem ./stat.jl:494
 [5] top-level scope
   @ REPL[3]:1

I patched this for my specific case by doing the following instead, but obviously this makes some major assumptions about the operating system:

            nbytes = Int(filesize("/dev/shm$(name)"))

Is this an issue with upstream in Base.Filesystem, or is this something we should try to fix here? I reported the difference in behavior to upstream just incase this was unintentional.

[csvance]

Upstream mentioned that this method removed because it was buggy: JuliaLang/julia#54855

It also looks like this has been addressed elsewhere in the codebase, trying to track that down so I can apply the same style of fix here.

[oscardssmith]

the fix is just to use RawFD of you want to construct a file descriptor from an integer

[csvance]

Thanks Oscar.

I think this pull request should be adequate then: #15