Add Content-Length and Content-Disposition Header

for GetFileContent route.

internal/api/runners.go

@@ -139,7 +139,7 @@ func (r *RunnerController) fileContent(writer http.ResponseWriter, request *http
 		privilegedExecution = false
 	}
 
-	writer.Header().Set("Content-Type", "application/octet-stream")
+	writer.Header().Set("Content-Disposition", "attachment; filename=\""+path+"\"")
 	err = targetRunner.GetFileContent(path, writer, privilegedExecution, request.Context())
 	if errors.Is(err, runner.ErrFileNotFound) {
 		writeClientError(writer, err, http.StatusFailedDependency)

internal/runner/aws_runner.go

@@ -13,6 +13,7 @@ import (
 	"github.com/openHPI/poseidon/pkg/monitoring"
 	"github.com/openHPI/poseidon/pkg/storage"
 	"io"
+	"net/http"
 	"time"
 )
 
@@ -125,7 +126,7 @@ func (w *AWSFunctionWorkload) UpdateFileSystem(request *dto.UpdateFileSystemRequ
 // GetFileContent is currently not supported with this aws serverless function.
 // This is because the function execution ends with the termination of the workload code.
 // So an on-demand file streaming after the termination is not possible. Also, we do not want to copy all files.
-func (w *AWSFunctionWorkload) GetFileContent(_ string, _ io.Writer, _ bool, _ context.Context) error {
+func (w *AWSFunctionWorkload) GetFileContent(_ string, _ http.ResponseWriter, _ bool, _ context.Context) error {
 	return dto.ErrNotSupported
 }
 

internal/runner/nomad_runner.go

@@ -15,6 +15,7 @@ import (
 	"github.com/openHPI/poseidon/pkg/nullio"
 	"github.com/openHPI/poseidon/pkg/storage"
 	"io"
+	"net/http"
 	"strings"
 	"time"
 )
@@ -27,6 +28,9 @@ const (
 	// executionTimeoutGracePeriod is the time to wait after sending a SIGQUIT signal to a timed out execution.
 	// If the execution does not return after this grace period, the runner is destroyed.
 	executionTimeoutGracePeriod = 3 * time.Second
+	// lsCommand is our format for parsing information of a file(system).
+	lsCommand          = "ls -l --time-style=+%s -1 --literal"
+	lsCommandRecursive = lsCommand + " --recursive"
 )
 
 var (
@@ -121,9 +125,9 @@ func (r *NomadJob) ExecuteInteractively(
 func (r *NomadJob) ListFileSystem(
 	path string, recursive bool, content io.Writer, privilegedExecution bool, ctx context.Context) error {
 	r.ResetTimeout()
-	command := "ls -l --time-style=+%s -1 --literal"
+	command := lsCommand
 	if recursive {
-		command += " --recursive"
+		command = lsCommandRecursive
 	}
 
 	ls2json := &nullio.Ls2JsonWriter{Target: content}
@@ -174,13 +178,17 @@ func (r *NomadJob) UpdateFileSystem(copyRequest *dto.UpdateFileSystemRequest) er
 	return nil
 }
 
-func (r *NomadJob) GetFileContent(path string, content io.Writer, privilegedExecution bool, ctx context.Context) error {
+func (r *NomadJob) GetFileContent(
+	path string, content http.ResponseWriter, privilegedExecution bool, ctx context.Context) error {
 	r.ResetTimeout()
 
-	retrieveCommand := (&dto.ExecutionRequest{Command: fmt.Sprintf("cat %q", path)}).FullCommand()
+	contentLengthWriter := &nullio.ContentLengthWriter{Target: content}
+	retrieveCommand := (&dto.ExecutionRequest{
+		Command: fmt.Sprintf("%s %q && cat %q", lsCommand, path, path),
+	}).FullCommand()
 	// Improve: Instead of using io.Discard use a **fixed-sized** buffer. With that we could improve the error message.
 	exitCode, err := r.api.ExecuteCommand(r.id, ctx, retrieveCommand, false, privilegedExecution,
-		&nullio.Reader{}, content, io.Discard)
+		&nullio.Reader{}, contentLengthWriter, io.Discard)
 
 	if err != nil {
 		return fmt.Errorf("%w: nomad error during retrieve file content copy: %v",

internal/runner/nomad_runner_test.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"github.com/openHPI/poseidon/internal/nomad"
 	"github.com/openHPI/poseidon/pkg/dto"
+	"github.com/openHPI/poseidon/pkg/logging"
 	"github.com/openHPI/poseidon/pkg/nullio"
 	"github.com/openHPI/poseidon/pkg/storage"
 	"github.com/openHPI/poseidon/tests"
@@ -403,6 +404,6 @@ func NewRunner(id string, manager Accessor) Runner {
 func (s *UpdateFileSystemTestSuite) TestGetFileContentReturnsErrorIfExitCodeIsNotZero() {
 	s.mockedExecuteCommandCall.RunFn = nil
 	s.mockedExecuteCommandCall.Return(1, nil)
-	err := s.runner.GetFileContent("", &bytes.Buffer{}, false, context.Background())
+	err := s.runner.GetFileContent("", logging.NewLoggingResponseWriter(nil), false, context.Background())
 	s.ErrorIs(err, ErrFileNotFound)
 }

internal/runner/runner.go

@@ -7,6 +7,7 @@ import (
 	"github.com/openHPI/poseidon/pkg/monitoring"
 	"github.com/openHPI/poseidon/pkg/storage"
 	"io"
+	"net/http"
 )
 
 type ExitInfo struct {
@@ -54,7 +55,7 @@ type Runner interface {
 
 	// GetFileContent streams the file content at the requested path into the Writer provided at content.
 	// The result is streamed via the io.Writer in order to not overload the memory with user input.
-	GetFileContent(path string, content io.Writer, privilegedExecution bool, ctx context.Context) error
+	GetFileContent(path string, content http.ResponseWriter, privilegedExecution bool, ctx context.Context) error
 
 	// Destroy destroys the Runner in Nomad.
 	Destroy() error

internal/runner/runner_mock.go

@@ -4,10 +4,12 @@ package runner
 
 import (
 	context "context"
-	io "io"
+	http "net/http"
 
 	dto "github.com/openHPI/poseidon/pkg/dto"
 
+	io "io"
+
 	mock "github.com/stretchr/testify/mock"
 
 	time "time"
@@ -93,11 +95,11 @@ func (_m *RunnerMock) ExecutionExists(id string) bool {
 }
 
 // GetFileContent provides a mock function with given fields: path, content, privilegedExecution, ctx
-func (_m *RunnerMock) GetFileContent(path string, content io.Writer, privilegedExecution bool, ctx context.Context) error {
+func (_m *RunnerMock) GetFileContent(path string, content http.ResponseWriter, privilegedExecution bool, ctx context.Context) error {
 	ret := _m.Called(path, content, privilegedExecution, ctx)
 
 	var r0 error
-	if rf, ok := ret.Get(0).(func(string, io.Writer, bool, context.Context) error); ok {
+	if rf, ok := ret.Get(0).(func(string, http.ResponseWriter, bool, context.Context) error); ok {
 		r0 = rf(path, content, privilegedExecution, ctx)
 	} else {
 		r0 = ret.Error(0)