From 8a7c94001fc715f7e34b6aac83a6079546901af1 Mon Sep 17 00:00:00 2001
From: Justin Israel <justinisrael@gmail.com>
Date: Thu, 4 Apr 2024 09:20:55 +1300
Subject: [PATCH] Check last error after getting blob, before calling
 conversions (refs #308)

---
 imagick/magick_wand_image.go | 6 ++++++
 imagick/magick_wand_test.go  | 8 +++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/imagick/magick_wand_image.go b/imagick/magick_wand_image.go
index 1ca6ff8..75009ea 100644
--- a/imagick/magick_wand_image.go
+++ b/imagick/magick_wand_image.go
@@ -942,6 +942,9 @@ func (mw *MagickWand) GetImageBlob() []byte {
 	clen := C.size_t(0)
 	csblob := C.MagickGetImageBlob(mw.mw, &clen)
 	defer relinquishMemory(unsafe.Pointer(csblob))
+	if err := mw.GetLastError(); err != nil {
+		return nil
+	}
 	ret := C.GoBytes(unsafe.Pointer(csblob), C.int(clen))
 	runtime.KeepAlive(mw)
 	return ret
@@ -957,6 +960,9 @@ func (mw *MagickWand) GetImagesBlob() []byte {
 	clen := C.size_t(0)
 	csblob := C.MagickGetImagesBlob(mw.mw, &clen)
 	defer relinquishMemory(unsafe.Pointer(csblob))
+	if err := mw.GetLastError(); err != nil {
+		return nil
+	}
 	runtime.KeepAlive(mw)
 	return C.GoBytes(unsafe.Pointer(csblob), C.int(clen))
 }
diff --git a/imagick/magick_wand_test.go b/imagick/magick_wand_test.go
index 1e80846..5779dcd 100644
--- a/imagick/magick_wand_test.go
+++ b/imagick/magick_wand_test.go
@@ -233,8 +233,14 @@ func TestReadImageBlob(t *testing.T) {
 
 	mw := NewMagickWand()
 
+	// Try to read an empty wand
+	blob := mw.GetImageBlob()
+	if blob != nil {
+		t.Fatal("Expected nil blob on invalid wand")
+	}
+
 	// Read an invalid blob
-	blob := []byte{}
+	blob = []byte{}
 	if err := mw.ReadImageBlob(blob); err == nil {
 		t.Fatal("Expected a failure when passing a zero length blob")
 	}