go/fileutil/fileutil.go

package fileutil

import (
	"os"
	"path/filepath"
	"strings"

	"github.com/skia-dev/glog"
)

// EnsureDirExists checks whether the given path to a directory exits and creates it
// if necessary. Returns the absolute path that corresponds to the input path
// and an error indicating a problem.
func EnsureDirExists(dirPath string) (string, error) {
	absPath, err := filepath.Abs(dirPath)
	if err != nil {
		return "", err
	}

	return absPath, os.MkdirAll(absPath, 0700)
}

// Must checks whether err in the provided pair (s, err) is nil. If so it
// returns s otherwise it cause the program to stop with the error message.
func Must(s string, err error) string {
	if err != nil {
		glog.Fatal(err)
	}
	return s
}

// FileExists returns true if the given path exists and false otherwise.
// If there is an error it will return false and log the error message.
func FileExists(path string) bool {
	if _, err := os.Stat(path); os.IsNotExist(err) {
		return false
	} else if err != nil {
		glog.Error(err)
		return false
	}
	return true
}

// TwoLevelRadixPath expands a path (defined by one or more path segments) by
// adding two additional directories based on the filename in the last segment.
// i.e.   TwoLevelRadixPath("/some", "path", "to", "abcdefgh.txt") will
// return "/some/path/to/ab/cd/abcdefgh.txt".
// If the filename does not have at least four characters before a period the
// return values is equivalent to filepath.Join(pathSegments...).
func TwoLevelRadixPath(pathSegments ...string) string {
	lastSeg := pathSegments[len(pathSegments)-1]
	dirName, fileName := filepath.Split(lastSeg)
	dotIdx := strings.Index(fileName, ".")
	if ((dotIdx < 4) && (dotIdx >= 0)) || ((dotIdx == -1) && (len(fileName) < 4)) {
		return filepath.Join(pathSegments...)
	}
	return filepath.Join(filepath.Join(pathSegments[:len(pathSegments)-1]...), filepath.Join(dirName, fileName[0:2], fileName[2:4], fileName))
}