ensure readEOFSeen reset after reseting cursor with Seek (#215)

* ensure readEOFSeen reset after reseting cursor with Seek

* update changelog

* update changelog for next release

CHANGELOG.md

@@ -6,6 +6,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [6.22.0] - 2024-11-06
+### Fixed
+- [#214](https://github.com/C2FO/vfs/issues/214) Fix issue where s3 backend didn't reset `readEOFSeen` flag when resetting the file cursor during Seek operations.
+
 ## [6.21.0] - 2024-11-04
 ### Fixed
 - Unit Test improvements: report underlying unit tests errors, always run test cases in a sub-test, always use test suite functions, use more specific assert functions where possible.

backend/s3/file.go

@@ -456,6 +456,11 @@ func (f *File) Seek(offset int64, whence int) (int64, error) {
 	}
 	f.cursorPos = pos
 
+	// Reset readEOFSeen if seeking to the beginning of the file
+	if f.cursorPos == 0 {
+		f.readEOFSeen = false
+	}
+
 	f.seekCalled = true
 	return f.cursorPos, nil
 }

backend/s3/file_test.go

@@ -173,6 +173,29 @@ func (ts *fileTestSuite) TestSeek() {
 	ts.NoError(err, "Closing file should not produce an error")
 }
 
+func (ts *fileTestSuite) TestReadEOFSeenReset() {
+	contents := "hello world!"
+	file, err := fs.NewFile("bucket", "/tmp/hello.txt")
+	ts.NoError(err, "Shouldn't fail creating new file")
+
+	s3apiMock.On("HeadObject", mock.AnythingOfType("*s3.HeadObjectInput")).
+		Return(&s3.HeadObjectOutput{ContentLength: aws.Int64(int64(len(contents)))}, nil).
+		Maybe()
+
+	s3apiMock.On("GetObject", mock.AnythingOfType("*s3.GetObjectInput")).
+		Return(&s3.GetObjectOutput{Body: io.NopCloser(strings.NewReader(contents))}, nil).
+		Once()
+
+	_, err = io.ReadAll(file)
+	ts.NoError(err, "Shouldn't fail reading file")
+	ts.True(file.(*File).readEOFSeen, "readEOFSeen should be true after reading the file")
+
+	// Reset cursor to the beginning of the file
+	_, err = file.Seek(0, io.SeekStart)
+	ts.NoError(err, "Shouldn't fail seeking file")
+	ts.False(file.(*File).readEOFSeen, "readEOFSeen should be reset after seeking to the beginning")
+}
+
 func (ts *fileTestSuite) TestGetLocation() {
 	file, err := fs.NewFile("bucket", "/path/hello.txt")
 	ts.NoError(err, "Shouldn't fail creating new file.")