tailscale/util/dirwalk/dirwalk.go

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// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
// Package dirwalk contains code to walk a directory.
package dirwalk
import (
"io"
"io/fs"
"os"
"go4.org/mem"
)
var osWalkShallow func(name mem.RO, fn WalkFunc) error
// WalkFunc is the callback type used with WalkShallow.
//
// The name and de are only valid for the duration of func's call
// and should not be retained.
type WalkFunc func(name mem.RO, de fs.DirEntry) error
// WalkShallow reads the entries in the named directory and calls fn for each.
// It does not recurse into subdirectories.
//
// If fn returns an error, iteration stops and WalkShallow returns that value.
//
// On Linux, WalkShallow does not allocate, so long as certain methods on the
// WalkFunc's DirEntry are not called which necessarily allocate.
func WalkShallow(dirName mem.RO, fn WalkFunc) error {
if f := osWalkShallow; f != nil {
return f(dirName, fn)
}
of, err := os.Open(dirName.StringCopy())
if err != nil {
return err
}
defer of.Close()
for {
fis, err := of.ReadDir(100)
for _, de := range fis {
if err := fn(mem.S(de.Name()), de); err != nil {
return err
}
}
if err != nil {
if err == io.EOF {
return nil
}
return err
}
}
}