pombredanne / go-permtest

Cross-platform methods for checking if files or directories are writable

go-permtest

permtest is a Go library providing os-generic tests for basic file permissions. This can be useful for testing a user's ability to create files and directories on a filesystem without leaving a mess behind.

An example use case is testing one's ability to write a file to /foo/bar/baz/zip. If you simply catch errors from os.MkdirAll(), you will not have any idea which directories were or were not created successfully, meaning you can't clean up after yourself by removing the created directories and files. permtest fixes this by testing write access to each directory from deepest upward by writing a temporary file and then immediately removing it.

permtest is able to determine if a directory structure is able to be created via its permtest.WriteDir() method, or if a file is able to be created using the permtest.WriteFile() method.

Example:

package main

import (
    "fmt"
    "github.com/ryanuber/go-permtest"
)

func main() {
    // test if we have the ability to create a file in /tmp
    if _, err := permtest.WriteFile("/tmp/foo"); err != nil {
        fmt.Println(err.Error())
    }

    // test if we can write a file directly into a non-existent directory
    if _, err := permtest.WriteFile("/tmp/foo/bar"); err != nil {
        fmt.Println(err.Error())
    }

    // test is we have the ability to create a deep directory structure
    if _, err := permtest.WriteDir("/tmp/foo/bar/baz/zip"); err != nil {
        fmt.Println(err.Error())
    }
}

permtest returns both an error as well as the last tested path as a string, which makes it easy to figure out where permission was actually denied within the file structure.