remove empty directories, written by Golang

rmdirhier.go

package main

import (
    "os"
    "log"
    "sort"
    "strings"
    "path/filepath"
)

type pendDir struct {
    path string
    depth int
}

func collectTargDirs(root string, alldirs *[]pendDir) {
    ents, err := os.ReadDir(root)
    if err != nil {
        log.Print(err)
        return
    }
    for _, ent := range ents {
        path := filepath.ToSlash(
            filepath.Join(root, ent.Name()))
        if ent.IsDir() {
            /*
             * "Os.Remove" for a directory fails because the
             * directory is not empty or for some other reason.
             * Here, the latter case can be postponed and only
             * the report of successful deletion of the empty
             * directory is sufficient.
             */
            rmerr := os.Remove(path)
            if rmerr == nil {
                log.Printf("removed empty dir: %s\n", path)
                continue
            }
            *alldirs = append(
                *alldirs,
                pendDir{path: path, depth: len(strings.Split(path, "/"))})
            collectTargDirs(path, alldirs)
        }
    }
}
func RmdirHier(roots []string) {
    var alldirs []pendDir
    for _, root := range roots {
        collectTargDirs(root, &alldirs)
    }
    sort.Slice(alldirs, func(i, j int) bool {
        lhs := alldirs[i]
        rhs := alldirs[j]
        return lhs.depth > rhs.depth
    })
    for _, pend := range alldirs {
        /*
         * "Os.Remove" for a directory fails because the
         * directory is not empty or for some other reason.
         * Here, error reports other than empty directories
         * are noise, so target only empty directories.
         */
        fn := pend.path
        ents, _ := os.ReadDir(fn)
        if len(ents) == 0 {
            rmerr := os.Remove(fn)
            if rmerr != nil {
                log.Print(fn, ": ", rmerr)
            } else {
                log.Printf("removed emptified dir: %s\n", fn)
            }
        }
    }
}
func main() {
    RmdirHier(os.Args[1:])
}