This library is to make some filesystem calls safer than they currently are in the standard Golang libraries.
In the age of containers and other interesting filesystems, some of the previous "this will always be present" items have ceased to exist. This, in turn, exposes design decisions that could not have anticipated these changes.
In particular, the Go libraries in the os package for interacting with /tmp
returns a hardcoded path if no environment variable is set. When using Docker,
and a Dockerfile that has FROM scratch, this path will be returned at /tmp
and cause an error.
This can't be fixed in Go 1.x due to it breaking the function signature. Context: golang/go#19695
This function reads the environment variable TMPDIR, which, if empty, defaults
to hardcoded paths. Before returning, the existence of the path is verified.