Getting started

go get github.com/grokify/oscompat

Import the package you need. There is nothing to configure and nothing else to install, because the module has no dependencies.

Which package for which problem

You need to	Use
Keep two processes from writing a file at once	fs.Lock
Make a rename durable	fs.SyncDir
Refuse a file other users can read, or write one only the owner can	fs.CheckPrivate, fs.WriteFilePrivate, fs.ChmodPrivate
Know whether mode bits mean anything here	fs.PermissionsEnforced
Check a path from outside for ..	fs.ValidatePath, fs.SafeJoin
Check a forward-slash path, such as one inside a repository or an archive	fs.ValidateSlashPath
Tell whether a path is absolute on any platform	fs.IsAbsAny
Find a config, data, cache or runtime directory	paths.AppConfig, paths.AppData, paths.AppCache, paths.AppRuntime
Stop a child process, or run one detached	process.Signal, process.SetDetached
Tell whether a recorded PID is still the same process	process.Exists, process.StartTime
Hand the terminal to another program	process.Exec
Generate an identifier	id.Generate16, id.Generate32
Compare file modification times	tsync.Equal, tsync.After
Talk between local processes	localnet.Listen, localnet.Dial
Write tests that pass on Windows	the guide, and testutil

A first example

Replace a file so that a crash leaves the old one or the new one, and so that two processes do not do it at once:

import (
    "context"
    "os"
    "path/filepath"

    "github.com/grokify/oscompat/fs"
)

func replace(ctx context.Context, path string, data []byte) error {
    unlock, err := fs.Lock(ctx, path+".lock")
    if err != nil {
        return err
    }
    defer unlock()

    dir := filepath.Dir(path)
    tmp, err := os.CreateTemp(dir, filepath.Base(path)+".tmp-*")
    if err != nil {
        return err
    }
    defer os.Remove(tmp.Name()) // a no-op once renamed

    if err := fs.ChmodPrivate(tmp); err != nil {
        return err
    }
    if _, err := tmp.Write(data); err != nil {
        return err
    }
    if err := tmp.Sync(); err != nil {
        return err
    }
    if err := tmp.Close(); err != nil {
        return err
    }
    if err := os.Rename(tmp.Name(), path); err != nil {
        return err
    }
    return fs.SyncDir(dir)
}

None of it checks the operating system.

Contributing a difference

If you find yourself writing runtime.GOOS or a build tag, add it here instead, with a test, using only the standard library. See the policy.