Merge pull request #37 from klippa-app/feature/improve-multi-thread-p…

…rotection

Improve multi thread protection

code_generation/main.go

@@ -21,6 +21,13 @@ type GenerateDataMethod struct {
 	Output string
 }
 
+func (m *GenerateDataMethod) IsMultiThreaded() bool {
+	if m.Name == "FPDFBitmap_CreateEx" || m.Name == "FSDK_SetUnSpObjProcessHandler" || m.Name == "FSDK_SetTimeFunction" || m.Name == "FSDK_SetLocaltimeFunction" {
+		return true
+	}
+	return false
+}
+
 type GenerateData struct {
 	Methods []GenerateDataMethod
 }

code_generation/templates/multi_threaded.go.tmpl

@@ -12,29 +12,52 @@ import (
 )
 {{ range $method := .Methods }}
 func (i *pdfiumInstance) {{ $method.Name }}(request *requests.{{ $method.Input }}) (*responses.{{ $method.Output }}, error) {
+	{{ if eq $method.IsMultiThreaded true -}}
+	return nil, errors.New("unsupported method on multi-threaded usage")
+	{{- else -}}
 	if i.closed {
 		return nil, errors.New("instance is closed")
 	}
 
 	{{ if eq $method.Name "FPDF_LoadCustomDocument" -}}
 	// Since multi-threaded usage implements gRPC, it can't serialize the reader onto that.
-	// To make it support the full interface, we just completely read the file into memory.
-	fileData, err := ioutil.ReadAll(request.Reader)
-	if err != nil {
-		return nil, err
-	}
-
+	// To make it support the full interface, we just rewrite it to OpenDocument,
+	// and OpenDocument just fully reads the io.ReadSeeker into an byte array.
 	doc, err := i.OpenDocument(&requests.OpenDocument{
-		File:     &fileData,
-		Password: request.Password,
+		FileReader:     request.Reader,
+		FileReaderSize: request.Size,
+		Password:       request.Password,
 	})
 	if err != nil {
 		return nil, err
 	}
 
 	return &responses.FPDF_LoadCustomDocument{Document: doc.Document}, nil
-    {{- else -}}
+	{{- else if eq $method.Name "OpenDocument" -}}
+	// Since multi-threaded usage implements gRPC, it can't serialize the reader onto that.
+	// To make it support the full interface, we just fully reads the io.ReadSeeker into
+	// an byte array.
+	if request.FileReader != nil {
+		fileData, err := ioutil.ReadAll(request.FileReader)
+		if err != nil {
+			return nil, err
+		}
+		request.FileReader = nil
+		request.FileReaderSize = 0
+		request.File = &fileData
+	}
 	return i.worker.plugin.{{ $method.Name }}(request)
+	{{- else if eq $method.Name "FPDF_SaveWithVersion" -}}
+	return i.worker.plugin.{{ $method.Name }}(request)
+	{{- else if eq $method.Name "FPDF_SaveAsCopy" -}}
+	if request.FileWriter != nil {
+		return nil, errors.New("using a file-writer is not supported on multi-threaded usage")
+	}
+
+	return i.worker.plugin.{{ $method.Name }}(request)
+	{{- else -}}
+	return i.worker.plugin.{{ $method.Name }}(request)
+	{{- end }}
 	{{- end }}
 }
 {{end}}

multi_threaded/multi_threaded_test.go

@@ -1,11 +1,10 @@
 package multi_threaded_test
 
 import (
-	"github.com/klippa-app/go-pdfium/multi_threaded"
-	"log"
 	"os"
 	"time"
 
+	"github.com/klippa-app/go-pdfium/multi_threaded"
 	"github.com/klippa-app/go-pdfium/shared_tests"
 
 	. "github.com/onsi/ginkgo/v2"
@@ -41,12 +40,8 @@ var _ = AfterSuite(func() {
 	err := shared_tests.PdfiumInstance.Close()
 	Expect(err).To(BeNil())
 
-	log.Println("Closed instance")
-
 	err = shared_tests.PdfiumPool.Close()
 	Expect(err).To(BeNil())
-
-	log.Println("Closed pool")
 })
 
 var _ = Describe("Multi Threaded", func() {

pdfium.go

@@ -48,7 +48,12 @@ type Pdfium interface {
 	// Start instance functions.
 
 	// OpenDocument returns a PDFium references for the given file data.
-	// This is a gateway to FPDF_LoadMemDocument, FPDF_LoadMemDocument64, FPDF_LoadDocument and FPDF_LoadCustomDocument.
+	// This is a gateway to FPDF_LoadMemDocument, FPDF_LoadMemDocument64,
+	// FPDF_LoadDocument and FPDF_LoadCustomDocument. Please note that
+	// FPDF_LoadCustomDocument will only work efficiently on single-threaded
+	// usage, on multi-threaded this will just fully read from the reader
+	// into a byte array before it's being sent over to PDFium.
+	// This method already checks FPDF_GetLastError internally for the result.
 	OpenDocument(request *requests.OpenDocument) (*responses.OpenDocument, error)
 
 	// Close closes the instance.
@@ -127,20 +132,17 @@ type Pdfium interface {
 
 	// FPDF_LoadDocument opens and load a PDF document from a file path.
 	// Loaded document can be closed by FPDF_CloseDocument().
-	// If this function fails, you can use FPDF_GetLastError() to retrieve
-	// the reason why it failed.
+	// This method already checks FPDF_GetLastError internally for the result.
 	FPDF_LoadDocument(request *requests.FPDF_LoadDocument) (*responses.FPDF_LoadDocument, error)
 
 	// FPDF_LoadMemDocument opens and load a PDF document from memory.
 	// Loaded document can be closed by FPDF_CloseDocument().
-	// If this function fails, you can use FPDF_GetLastError() to retrieve
-	// the reason why it failed.
+	// This method already checks FPDF_GetLastError internally for the result.
 	FPDF_LoadMemDocument(request *requests.FPDF_LoadMemDocument) (*responses.FPDF_LoadMemDocument, error)
 
 	// FPDF_LoadMemDocument64 opens and load a PDF document from memory.
 	// Loaded document can be closed by FPDF_CloseDocument().
-	// If this function fails, you can use FPDF_GetLastError() to retrieve
-	// the reason why it failed.
+	// This method already checks FPDF_GetLastError internally for the result.
 	FPDF_LoadMemDocument64(request *requests.FPDF_LoadMemDocument64) (*responses.FPDF_LoadMemDocument64, error)
 
 	// FPDF_LoadCustomDocument loads a PDF document from a custom access descriptor.
@@ -150,15 +152,17 @@ type Pdfium interface {
 	// over gRPC. The single-threaded usage will actually efficiently walk over
 	// the PDF as it's being used by PDFium.
 	// Loaded document can be closed by FPDF_CloseDocument().
-	// If this function fails, you can use FPDF_GetLastError() to retrieve
-	// the reason why it failed.
+	// This method already checks FPDF_GetLastError internally for the result.
 	FPDF_LoadCustomDocument(request *requests.FPDF_LoadCustomDocument) (*responses.FPDF_LoadCustomDocument, error)
 
 	// FPDF_CloseDocument closes the references, releases the resources.
 	FPDF_CloseDocument(request *requests.FPDF_CloseDocument) (*responses.FPDF_CloseDocument, error)
 
 	// FPDF_GetLastError returns the last error code of a PDFium function, which is just called.
 	// Usually, this function is called after a PDFium function returns, in order to check the error code of the previous PDFium function.
+	// Please note that when using go-pdfium from the same instance (on single-threaded any instance)
+	// from different subroutines, FPDF_GetLastError might already be reset from
+	// executing another PDFium method.
 	FPDF_GetLastError(request *requests.FPDF_GetLastError) (*responses.FPDF_GetLastError, error)
 
 	// FPDF_SetSandBoxPolicy set the policy for the sandbox environment.