Tar.extract: slight mode improvement (#98)

The reason for using `filemode` to read the created mode was to respect
the umask or equivalent mechanism for default permissions. Since the
umask can only take permissions away, it is always correct to AND the
default permissions with the desired permissions, since that will be
more constrained than both the default and what the tarball requests.

src/extract.jl

@@ -73,7 +73,7 @@ function extract_tarball(
             copy_symlinks || symlink(hdr.link, sys_path)
         elseif hdr.type == :file
             read_data(tar, sys_path, size=hdr.size, buf=buf)
-            mode = Sys.iswindows() ? hdr.mode : filemode(sys_path)
+            mode = hdr.mode & filemode(sys_path)
             if 0o100 & hdr.mode == 0
                 # turn off all execute bits
                 mode &= 0o666

test/runtests.jl

@@ -750,7 +750,7 @@ if Sys.iswindows() && Sys.which("icacls") !== nothing && VERSION >= v"1.6"
             x_path = joinpath(dir, "0-xxxxxxxx")
             @test isfile(x_path)
             @test Sys.isexecutable(x_path)
-            
+
             f_acl = readchomp(`icacls $(f_path)`)
             @test occursin("Everyone:(R,WA)", f_acl)
             x_acl = readchomp(`icacls $(x_path)`)