Fix windows fdopen error (refs #229)

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ on:
 
 jobs:
   test:
-    name: Test ImageMagick6
+    name: Test ImageMagick6 linux
     runs-on: ubuntu-latest
     environment: imagemagick6
     env:

imagick/magick_wand_image.go

@@ -3380,11 +3380,17 @@ func (mw *MagickWand) WriteImagesFile(out *os.File) error {
 // cfdopen returns a C-level FILE*. mode should be as described in fdopen(3).
 // Caller is responsible for closing the file when successfully returned,
 // via C.fclose()
-func cfdopen(file *os.File, mode string) (*C.FILE, error) {
+func cfdopen(file *os.File, mode string) (cfile *C.FILE, err error) {
+	cname := C.CString(file.Name())
 	cmode := C.CString(mode)
+	defer C.free(unsafe.Pointer(cname))
 	defer C.free(unsafe.Pointer(cmode))
 
-	cfile, err := C.fdopen(C.dup(C.int(file.Fd())), cmode)
+	if file.Name() != "" {
+		cfile, err = C.fopen(cname, cmode)
+	} else {
+		cfile, err = C.fdopen(C.dup(C.int(file.Fd())), cmode)
+	}
 	if err != nil {
 		return nil, err
 	}

imagick/magick_wand_test.go

@@ -6,6 +6,8 @@ package imagick
 
 import (
 	"fmt"
+	"io/ioutil"
+	"os"
 	"reflect"
 	"runtime"
 	"sync/atomic"
@@ -127,6 +129,33 @@ func TestDeleteImageArtifact(t *testing.T) {
 	}
 }
 
+func TestReadImageFile(t *testing.T) {
+	Initialize()
+	defer Terminate()
+
+	mw := NewMagickWand()
+	if err := mw.ReadImage(`logo:`); err != nil {
+		t.Fatal(err)
+	}
+
+	tmp, err := ioutil.TempFile("", "imagick_test-*.jpg")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Remove(tmp.Name())
+
+	if err := mw.WriteImage(tmp.Name()); err != nil {
+		t.Fatal(err)
+	}
+	mw.Destroy()
+
+	mw = NewMagickWand()
+	defer mw.Destroy()
+	if err := mw.ReadImageFile(tmp); err != nil {
+		t.Fatal(err)
+	}
+}
+
 func TestReadImageBlob(t *testing.T) {
 	Initialize()
 	defer func(t *testing.T) {

imagick/memory.go

@@ -23,6 +23,9 @@ func relinquishMemory(ptr unsafe.Pointer) {
 
 // relinquishes memory resources, null terminated array of strings
 func relinquishMemoryCStringArray(p **C.char) {
+	if p == nil {
+		return
+	} 
 	defer relinquishMemory(unsafe.Pointer(p))
 	for *p != nil {
 		relinquishMemory(unsafe.Pointer(*p))