tmpname(parent) does not respect parent

[nico202]

Hello! I'm packaging julia 1.4.1 for guix, and this test is failing

julia/test/file.jl

Line 70 in 381693d

@test dirname(t) == d

I can reproduce it with:

using Test
using Random

function run()
    @testset "tempname with parent" begin
        t = tempname()
        @test dirname(t) == tempdir()
        mktempdir() do d
            t = tempname(d)
            @test dirname(t) == d
        end
        @test_throws ArgumentError tempname(randstring())
    end
end
# tempdir() uses the first environment variable found in the ordered list TMPDIR, TMP, TEMP, and TEMPDIR. If none of these are found, the path "/tmp" is used.
# Let's check all those variables are currently empty
all_empty() = @test all(isnothing.(get.(Ref(ENV), ["TMPDIR", "TMP", "TEMP", "TEMPDIR"], nothing)))
all_empty()

# Check the test passes when no "TEMP" variable is set
@info "No env var"
run()

@info "TMPDIR var"
withenv("TMPDIR" => mktempdir()) do
    run()
end
all_empty()

Can anybody confirm the same happens with the official build?

Thanks, Nicolò

[nico202]

Actually I found this:

julia/base/file.jl

Line 548 in 178ac97

function tempname(parent::AbstractString=tempdir(); cleanup::Bool=true)

parent = "/tmp"
temp_prefix = "jl_debug_"

p = ccall(:tempnam, Cstring, (Cstring, Cstring), parent, temp_prefix)
systemerror(:tempnam, p == C_NULL)
@show unsafe_string(p)
Libc.free(p)

withenv("TMPDIR" => mktempdir()) do
    p = ccall(:tempnam, Cstring, (Cstring, Cstring), parent, temp_prefix)
    systemerror(:tempnam, p == C_NULL)
    @show unsafe_string(p)
    Libc.free(p)
end

tempnam is ignoring parent and following TMPDIR only

[nico202]

According to https://linux.die.net/man/3/tempnam:

1. In case the environment variable TMPDIR exists and contains the name of an appropriate directory, that is used.
2. Otherwise, if the dir argument is non-NULL and appropriate, it is used.

So the current use is wrong

[nico202]

http://man7.org/linux/man-pages/man3/tempnam.3.html

  Never use this function.  Use mkstemp(3) or tmpfile(3) instead.

cool

[nico202]

This still happens on v1.6.0

[vchuravy]

maybe duplicate of #38873? (Or the other way around xD )

x-ref: #38879 would be happy if someone could help finish that implementation