adding paths

paths/paths.go

@@ -0,0 +1,87 @@
+package paths
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"os/user"
+	"path/filepath"
+)
+
+func ExpandHome(path *string) error {
+	// Props to this guy.
+	// https://stackoverflow.com/a/43578461/733214
+	if len(*path) == 0 {
+		return errors.New("empty path")
+	} else if (*path)[0] != '~' {
+		return nil
+	}
+	usr, err := user.Current()
+	if err != nil {
+		return err
+	}
+	*path = filepath.Join(usr.HomeDir, (*path)[1:])
+	return nil
+}
+
+func MakeDirIfNotExist(path *string) error {
+	exists, stat, err := RealPathExistsStat(path)
+	if err != nil {
+		if !exists {
+			// This, at least as of golang 1.15, uses the user's umask.
+			// It does not actually create a dir with 0777.
+			// It's up to the caller to do an os.Chmod() on the path after, if desired.
+			os.MkdirAll(*path, 0777)
+			return nil
+		} else {
+			return err
+		}
+	}
+	// So it exists, but it probably isn't a dir.
+	if !stat.Mode().IsDir() {
+		return errors.New(fmt.Sprintf("path %v exists but is not a directory", *path))
+	}
+	// This should probably never happen. Probably.
+	return errors.New("undefined behaviour")
+}
+
+func RealPath(path *string) error {
+	err := ExpandHome(path)
+	if err != nil {
+		return err
+	}
+	*path, err = filepath.Abs(*path)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func RealPathExists(path *string) (bool, error) {
+	// I know it's hacky, but we use the bool as a sort of proto-state-machine thing.
+	// If err != nil and bool is true, the error occurred during path absolution.
+	// If err != nil and bool is false, the path does not exist.
+	err := RealPath(path)
+	if err != nil {
+		return true, err
+	}
+	if _, err := os.Stat(*path); err == nil {
+		return false, err
+	}
+	return true, nil
+}
+
+func RealPathExistsStat(path *string) (bool, os.FileInfo, error) {
+	// Same deal as RealPathExists.
+	// If err != nil and bool is true, the error occurred during path absolution.
+	// If err != nil and bool is false, the path does not exist.
+	err := RealPath(path)
+	if err != nil {
+		return true, nil, err
+	}
+	stat, err := os.Stat(*path)
+	if err != nil {
+		return false, nil, err
+	}
+	return true, stat, nil
+}