From 071cf8b5f5cd58c7871452d32ffa00d364bd8399 Mon Sep 17 00:00:00 2001
From: McKayla Washburn <mckayla@hey.com>
Date: Thu, 3 Apr 2025 16:11:11 +0000
Subject: [PATCH 1/3] add testcase

---
 tarfs/tarfs_test.go | 45 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/tarfs/tarfs_test.go b/tarfs/tarfs_test.go
index 228ed9b4..c5e1c84c 100644
--- a/tarfs/tarfs_test.go
+++ b/tarfs/tarfs_test.go
@@ -150,6 +150,51 @@ func TestReadAt(t *testing.T) {
 	}
 }
 
+func TestMultipleReads(t *testing.T) {
+	for _, f := range files {
+		if !f.exists {
+			continue
+		}
+
+		readFile := func(file afero.File) {
+			buf := make([]byte, 8)
+			n, err := file.Read(buf)
+			if f.isdir && (err != syscall.EISDIR) {
+				t.Errorf("%v got error %v, expected EISDIR", f.name, err)
+			} else if !f.isdir && (err != nil) {
+				if err != nil {
+					t.Errorf("%v: %v", f.name, err)
+				} else if n != 8 {
+					t.Errorf("%v: got %d read bytes, expected 8", f.name, n)
+				} else if string(buf) != f.content {
+					t.Errorf("%v: got <%s>, expected <%s>", f.name, f.content, string(buf))
+				}
+			}
+
+			_, err = io.ReadAll(file)
+			if f.isdir && (err != syscall.EISDIR) {
+				t.Errorf("%v got error %v, expected EISDIR", f.name, err)
+			} else if !f.isdir && (err != nil) {
+				t.Errorf("reading %v: %v", f.name, err)
+			}
+
+			err = file.Close()
+			if err != nil {
+				t.Errorf("closing %v: %v", f.name, err)
+			}
+		}
+
+		fileA, err := afs.Open(f.name)
+		fileB, err := afs.Open(f.name)
+		if err != nil {
+			t.Fatalf("opening %v: %v", f.name, err)
+		}
+
+		readFile(fileA)
+		readFile(fileB)
+	}
+}
+
 func TestSeek(t *testing.T) {
 	for _, f := range files {
 		if !f.exists {

From f06e86036696c9183a96122f68691b2363c21337 Mon Sep 17 00:00:00 2001
From: McKayla Washburn <mckayla@hey.com>
Date: Thu, 3 Apr 2025 15:54:40 +0000
Subject: [PATCH 2/3] construct a new bytes.Reader per each opened file

---
 tarfs/fs.go | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/tarfs/fs.go b/tarfs/fs.go
index 0d764e5f..c8e4e1e3 100644
--- a/tarfs/fs.go
+++ b/tarfs/fs.go
@@ -14,7 +14,12 @@ import (
 )
 
 type Fs struct {
-	files map[string]map[string]*File
+	files map[string]map[string]*fsEntry
+}
+
+type fsEntry struct {
+	h    *tar.Header
+	data []byte
 }
 
 func splitpath(name string) (dir, file string) {
@@ -29,7 +34,7 @@ func splitpath(name string) (dir, file string) {
 }
 
 func New(t *tar.Reader) *Fs {
-	fs := &Fs{files: make(map[string]map[string]*File)}
+	fs := &Fs{files: make(map[string]map[string]*fsEntry)}
 	for {
 		hdr, err := t.Next()
 		if err == io.EOF {
@@ -41,7 +46,7 @@ func New(t *tar.Reader) *Fs {
 
 		d, f := splitpath(hdr.Name)
 		if _, ok := fs.files[d]; !ok {
-			fs.files[d] = make(map[string]*File)
+			fs.files[d] = make(map[string]*fsEntry)
 		}
 
 		var buf bytes.Buffer
@@ -54,27 +59,25 @@ func New(t *tar.Reader) *Fs {
 			panic("tarfs: size mismatch")
 		}
 
-		file := &File{
+		file := &fsEntry{
 			h:    hdr,
-			data: bytes.NewReader(buf.Bytes()),
-			fs:   fs,
+			data: buf.Bytes(),
 		}
 		fs.files[d][f] = file
 
 	}
 
 	if fs.files[afero.FilePathSeparator] == nil {
-		fs.files[afero.FilePathSeparator] = make(map[string]*File)
+		fs.files[afero.FilePathSeparator] = make(map[string]*fsEntry)
 	}
 	// Add a pseudoroot
-	fs.files[afero.FilePathSeparator][""] = &File{
+	fs.files[afero.FilePathSeparator][""] = &fsEntry{
 		h: &tar.Header{
 			Name:     afero.FilePathSeparator,
 			Typeflag: tar.TypeDir,
 			Size:     0,
 		},
-		data: bytes.NewReader(nil),
-		fs:   fs,
+		data: nil,
 	}
 
 	return fs
@@ -91,7 +94,11 @@ func (fs *Fs) Open(name string) (afero.File, error) {
 		return nil, &os.PathError{Op: "open", Path: name, Err: syscall.ENOENT}
 	}
 
-	nf := *file
+	nf := File{
+		h:    file.h,
+		data: bytes.NewReader(file.data),
+		fs:   fs,
+	}
 
 	return &nf, nil
 }

From 4bec43805227814e12dc5361830de273a794d369 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E3=82=B1=E3=82=A4=E3=83=A9?= <mckayla@hey.com>
Date: Thu, 24 Apr 2025 09:33:40 -0700
Subject: [PATCH 3/3] add missing error check

---
 tarfs/tarfs_test.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tarfs/tarfs_test.go b/tarfs/tarfs_test.go
index c5e1c84c..1258f02d 100644
--- a/tarfs/tarfs_test.go
+++ b/tarfs/tarfs_test.go
@@ -185,6 +185,9 @@ func TestMultipleReads(t *testing.T) {
 		}
 
 		fileA, err := afs.Open(f.name)
+		if err != nil {
+			t.Fatalf("opening %v: %v", f.name, err)
+		}
 		fileB, err := afs.Open(f.name)
 		if err != nil {
 			t.Fatalf("opening %v: %v", f.name, err)