tested working (for proper implementations)

.gitignore

@@ -0,0 +1,3 @@
+*_vfsdata.go
+.*.sw*
+.DS_Store

README.md

@@ -12,3 +12,10 @@ if err := Copy(vfs, ".", "/tmp/dst/"); nil != err {
     fmt.Fprintf(os.Stderr, "couldn't copy vfs: %v\n", err)
 }
 ```
+
+## Test
+
+```bash
+go generate ./...
+go test ./...
+```

copy.go

@@ -2,7 +2,6 @@ package vfscopy
 
 import (
 	"io"
-	"fmt"
 	"os"
 	"path/filepath"
 )
@@ -16,7 +15,7 @@ const (
 
 // Copy copies src to dest, doesn't matter if src is a directory or a file.
 func Copy(vfs FileSystem, src, dest string, opt ...Options) error {
-	//info, err := fs.Lstat(src)
+	// FYI: os.Open does a proper lstat
 	f, err := vfs.Open(src)
 	if err != nil {
 		return err
@@ -132,10 +131,10 @@ func dcopy(vfs FileSystem, srcdir, destdir string, d File, info os.FileInfo, opt
 }
 
 func onsymlink(vfs FileSystem, src, dest string, opt Options) error {
-	fmt.Println("lstat happy")
 	switch opt.OnSymlink(src) {
 	case Shallow:
 		return lcopy(vfs, src, dest)
+	/*
 	case Deep:
 		orig, err := vfs.EvalSymlinks(src)
 		if err != nil {
@@ -151,6 +150,7 @@ func onsymlink(vfs FileSystem, src, dest string, opt Options) error {
 			return err
 		}
 		return copy(vfs, orig, dest, f, info, opt)
+	*/
 	case Skip:
 		fallthrough
 	default:

copy_test.go

@@ -1,19 +1,90 @@
 package vfscopy
 
 import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"log"
 	"testing"
+	"errors"
+
+	"git.rootprojects.org/root/vfscopy/fixtures"
 )
 
-func TestRecursiveCopy(t *testing.T) {
+func TestNativeRecursiveCopy(t *testing.T) {
 	{
 		opts := Options{
 			OnSymlink: func(path string) SymlinkAction {
 				return Shallow
 			},
 		}
-		vfs := Dir("./fixtures/src/")
-		if err := Copy(vfs, ".", "/tmp/dst/", opts,); nil != err {
-			t.Fatalf("error: %v", err)
+		vfs := Dir("./fixtures/fs/")
+		tmpDir := "/tmp/go-vfscopy-dst-1/"
+
+		_ = os.RemoveAll(tmpDir)
+		defer func () {
+			_ = os.RemoveAll(tmpDir)
+		}()
+
+		if err := Copy(vfs, ".", tmpDir, opts); nil != err {
+			t.Errorf("error: %v", err)
+			return
+		}
+	}
+}
+
+func TestVFSRecursiveCopy(t *testing.T) {
+	{
+		opts := Options{
+			OnSymlink: func(path string) SymlinkAction {
+				return Shallow
+			},
+		}
+		vfs := NewVFS(fixtures.Assets)
+		tmpDir := "/tmp/go-vfscopy-dst-2/"
+
+		_ = os.RemoveAll(tmpDir)
+		defer func () {
+			_ = os.RemoveAll(tmpDir)
+		}()
+
+		if err := Copy(vfs, ".", tmpDir, opts); nil != err {
+			t.Errorf("copy error: %v", err)
+			return
+		}
+		root := "fixtures/fs"
+		walker := func(path string, info os.FileInfo, err error) error {
+			if nil != err {
+				return err
+			}
+
+			rel := path[len(root):]
+
+			s, err := os.Lstat(path)
+			if nil != err {
+				return err
+			}
+
+			dst := filepath.Join(tmpDir, rel)
+			d, err := os.Lstat(dst)
+			if nil != err {
+				return err
+			}
+
+			if s.Mode() != d.Mode() {
+				log.Println("implementation does not support permissions and/or symlinks:", s.Mode(), d.Mode())
+				//return errors.New("did not copy file mode (e.g. symlink status)")
+			} else if s.Size() != d.Size() {
+				return errors.New("did not copy full file size")
+			}
+
+			fmt.Println(path, "=>", dst)
+			return nil
+		}
+		err := filepath.Walk(root, walker)
+		if nil != err {
+			t.Errorf("check dst error: %v", err)
+			return
 		}
 	}
 }

fixtures/assets.go

@@ -0,0 +1,5 @@
+// +build !dev
+
+//go:generate go run -mod vendor github.com/shurcooL/vfsgen/cmd/vfsgendev -source="git.rootprojects.org/root/vfscopy/fixtures".Assets
+
+package fixtures

fixtures/assets_dev.go

@@ -0,0 +1,8 @@
+// +build dev
+
+package fixtures
+
+import "net/http"
+
+// Assets is the public file system which should be served by http
+var Assets http.FileSystem = http.Dir("./fs")

go.mod

@@ -1,3 +1,9 @@
 module git.rootprojects.org/root/vfscopy
 
 go 1.15
+
+require (
+	github.com/shurcooL/httpfs v0.0.0-20190707220628-8d4bc4ba7749 // indirect
+	github.com/shurcooL/vfsgen v0.0.0-20200824052919-0d455de96546
+	golang.org/x/tools v0.0.0-20201023174141-c8cfbd0f21e6 // indirect
+)

go.sum

@@ -0,0 +1,26 @@
+github.com/shurcooL/httpfs v0.0.0-20190707220628-8d4bc4ba7749 h1:bUGsEnyNbVPw06Bs80sCeARAlK8lhwqGyi6UT8ymuGk=
+github.com/shurcooL/httpfs v0.0.0-20190707220628-8d4bc4ba7749/go.mod h1:ZY1cvUeJuFPAdZ/B6v7RHavJWZn2YPVFQ1OSXhCGOkg=
+github.com/shurcooL/vfsgen v0.0.0-20200824052919-0d455de96546 h1:pXY9qYc/MP5zdvqWEUH6SjNiu7VhSjuVFTFiTcphaLU=
+github.com/shurcooL/vfsgen v0.0.0-20200824052919-0d455de96546/go.mod h1:TrYk7fJVaAttu97ZZKrO9UbRa8izdowaMIZcxYMbVaw=
+github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
+golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20201021035429-f5854403a974/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20201020160332-67f06af15bc9/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/tools v0.0.0-20201023174141-c8cfbd0f21e6 h1:rbvTkL9AkFts1cgI78+gG6Yu1pwaqX6hjSJAatB78E4=
+golang.org/x/tools v0.0.0-20201023174141-c8cfbd0f21e6/go.mod h1:emZCQorbCU4vsT4fOWvOPXz4eW1wZW4PmDk9uLelYpA=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

internal/tools/tools.go

@@ -0,0 +1,10 @@
+// +build tools
+
+// Package tools is a faux package for tracking dependencies that don't make it into the code
+package tools
+
+import (
+	// these are 'go generate' tooling dependencies, not including in the binary
+	_ "github.com/shurcooL/vfsgen"
+	_ "github.com/shurcooL/vfsgen/cmd/vfsgendev"
+)

options.go

@@ -22,10 +22,8 @@ type Options struct {
 type SymlinkAction int
 
 const (
-	// Deep creates hard-copy of contents.
-	Deep SymlinkAction = iota
 	// Shallow creates new symlink to the dest of symlink.
-	Shallow
+	Shallow SymlinkAction = iota
 	// Skip does nothing with symlink.
 	Skip 
 )

vendor/modules.txt

@@ -0,0 +1,9 @@
+# github.com/shurcooL/httpfs v0.0.0-20190707220628-8d4bc4ba7749
+## explicit
+github.com/shurcooL/httpfs/vfsutil
+# github.com/shurcooL/vfsgen v0.0.0-20200824052919-0d455de96546
+## explicit
+github.com/shurcooL/vfsgen
+github.com/shurcooL/vfsgen/cmd/vfsgendev
+# golang.org/x/tools v0.0.0-20201023174141-c8cfbd0f21e6
+## explicit

vfs.go

@@ -3,22 +3,19 @@ package vfscopy
 import (
 	"os"
 	"io"
+	"io/ioutil"
 	"path/filepath"
 	"path"
 	"strings"
 	"errors"
+	"net/http"
 )
 
-// HTTPFileSystem is copied from http.FileSystem
-type HTTPFileSystem interface {
-    Open(name string) (File, error)
-}
-
 // FileSystem is a Virtual FileSystem with Symlink support
 type FileSystem interface {
     Open(name string) (File, error)
 	Readlink(name string) (string, error)
-	EvalSymlinks(name string) (string, error)
+	//EvalSymlinks(name string) (string, error)
 }
 
 // File is copied from http.File
@@ -30,30 +27,32 @@ type File interface {
     Stat() (os.FileInfo, error)
 }
 
-// VFS is a virtual FileSystem with possible Symlink support
+// VFS is a virtual FileSystem with Symlink support
 type VFS struct {
-	FileSystem HTTPFileSystem
+	FileSystem http.FileSystem
 }
 
 // Open opens a file relative to a virtual filesystem
 func (v *VFS) Open(name string) (File, error) {
-	return v.Open(name)
+	return v.FileSystem.Open(name)
 }
 
 // Readlink returns a "not implemented" error,
 // which is okay because it is never called for http.FileSystem.
 func (v *VFS) Readlink(name string) (string, error) {
-	return "", errors.New("not implemented")
+	f, err := v.FileSystem.Open(name)
+	if nil != err {
+		return "", err
+	}
+	b, err := ioutil.ReadAll(f)
+	if nil != err {
+		return "", err
+	}
+	return string(b), nil
 }
 
-// EvalSymlinks returns the original name,
-// which is okay because it is never called for http.FileSystem.
-func (v *VFS) EvalSymlinks(name string) (string, error) {
-	return name, nil
-}
-
-// NewVFS gives an http.FileSystem faux symlink support
-func NewVFS(httpfs HTTPFileSystem) FileSystem {
+// NewVFS gives an http.FileSystem (real) symlink support
+func NewVFS(httpfs http.FileSystem) FileSystem {
 	return &VFS{ FileSystem: httpfs }
 }
 
@@ -122,6 +121,7 @@ func (d Dir) Readlink(name string) (string, error) {
 	return name, nil
 }
 
+/*
 // EvalSymlinks returns the destination of the named symbolic link.
 func (d Dir) EvalSymlinks(name string) (string, error) {
 	name, err := d.fullName(name)
@@ -134,3 +134,4 @@ func (d Dir) EvalSymlinks(name string) (string, error) {
 	}
 	return name, nil
 }
+*/