fs

fs is a simple library that provides a simple abstraction over filesystem operations that is compatible with io/fs from the standard library.

Examples

File Uploads

Assume you're building an application to upload files and store them against a hash of their content but with a size limit, then we could do the following with this library,

import (
    "crypto/sha256"
    "io"
    "net/http"

    "github.com/andrewpillar/fs"
)

var defaultMaxMemory int64 = 32 << 20

func Upload(w http.ResonseWriter, r *http.Request) {
    if err := r.ParseMultipartForm(defaultMaxMemory); err != nil {
        // handle error
    }

    hdrs, ok := r.MultipartForm.File["upload"]

    if !ok {
        // handle error
    }

    tmp, err := fs.ReadFile("upload", hds[0].Open())

    if err != nil {
        // handle error
    }

    // Delete the file if it get's stored on disk from ReadFile.
    defer fs.Cleanup(tmp)

    osfs := fs.New("/tmp")
    hashfs := fs.Hash(osfs, sha256.New)
    limitfs := fs.Limit(hashfs, 5 << 20)

    f, err = limitfs.Put(tmp)

    if err != nil {
        // handle error
    }

    info, err := f.Stat()

    if err != nil {
        // handle error
    }

    w.WriteHeader(http.StatusNoContent)
    io.WriteString(info.Name())
}

With the above example we use the library to create an FS for the operating system via fs.New. This is then wrapped with fs.Hash to store the file against the SHA256 hash of the file's content. This is then wrapped with fs.Limit to limit the size of files that can be stored in the filesystem. Finally the name of the uploaded file, which would be the file content's hash, is sent in the response.