initial port of https://lib.rs/crates/directories

Based entirely on the documentation and not rust code.
Pulled in handy Golang stuff where appropriate.

base/base.go

@@ -0,0 +1,104 @@
+package base
+
+import (
+	"errors"
+	"os"
+	"runtime"
+)
+
+func Home() (string, error) {
+	dir, err := os.UserHomeDir()
+	return dir, err
+}
+
+func Cache() (string, error) {
+	dir, err := os.UserCacheDir()
+	return dir, err
+}
+
+func Config() (string, error) {
+	dir, err := os.UserCacheDir()
+	return dir, err
+}
+
+func Data() (string, error) {
+	switch runtime.GOOS {
+	case "linux":
+		e, ok := os.LookupEnv("XDG_DATA_HOME")
+		if ok {
+			return e, nil
+		} else {
+			h, err := Home()
+			return h + "/.local/share", err
+		}
+	case "windows":
+		return Config()
+	case "darwin":
+		return Config()
+	}
+	return "", errors.New("could not determine location for Data()")
+}
+
+func DataLocal() (string, error) {
+	switch runtime.GOOS {
+	case "linux":
+		return Data()
+	case "windows":
+		return Cache()
+	case "darwin":
+		return Data()
+	}
+	return "", errors.New("could not determine location for DataLocal()")
+}
+
+func Executable() (string, error) {
+	switch runtime.GOOS {
+	case "linux":
+		e, ok := os.LookupEnv("XDG_BIN_HOME")
+		if ok {
+			return e, nil
+		} else {
+			h, err := Home()
+			return h + "/.local/bin", err
+		}
+	}
+	return "", errors.New("could not determine location for Executable()")
+}
+
+func Preferences() (string, error) {
+	switch runtime.GOOS {
+	case "linux":
+		return Config()
+	case "windows":
+		return Config()
+	case "darwin":
+		h, err := Home()
+		return h + "/Library/Preferences", err
+	}
+	return "", errors.New("could not determine location for Preferences()")
+}
+
+func Runtime() (string, error) {
+	switch runtime.GOOS {
+	case "linux":
+		e, ok := os.LookupEnv("XDG_CONFIG_HOME")
+		if ok {
+			return e, nil
+		}
+	}
+	return "", errors.New("could not determine location for Runtime()")
+}
+
+func State() (string, error) {
+	switch runtime.GOOS {
+	case "linux":
+		e, ok := os.LookupEnv("XDG_STATE_HOME")
+		if ok {
+			return e, nil
+		} else {
+			h, err := Home()
+			return h + "/.local/state", err
+		}
+	}
+	return "", errors.New("could not determine location for State()")
+}

go.mod

@@ -0,0 +1,3 @@
+module git.martyn.berlin/martyn/golang-directories
+
+go 1.17