Possible risk of temporary file collision

[Jens Rantil]

I'm reading

gleam/filesystem/vfs_s3.go

Line 83 in 766b221

 filename := fmt.Sprintf("%s/s3_%d", os.TempDir(), rand.Uint32()) 

and

gleam/filesystem/vfs_gs.go

Line 108 in 53a6956

 filename := fmt.Sprintf("%s/gs_%d", os.TempDir(), rand.Uint32()) 

and both has a slight risk of file name collisions. I propose migrating to use https://golang.org/pkg/io/ioutil/#TempFile which makes that scenario impossible.

[Chris Lu]

Send a PR?