fix memleak in magick6load

IM ExceptionInfo were not being freed correctly. This patch
adds a small wrapper function and uses it to allocate and free all IM
exception objects.

Tested with im 6.9 and gm 1.3.

See:

https://github.com/libvips/lua-vips/issues/24

https://github.com/libvips/libvips/issues/1203

ChangeLog

@@ -2,6 +2,7 @@
 - fix infinite loop for autofit with non-scaleable font 
 - mapim was not offsetting by window offset [erdmann]
 - better rounding for scale [kleisauke]
+- fix a memleak in magick6load [kleisauke]
 
 21/11/18 started 8.7.2
 - more info output for temp files to help diagnose problems

configure.ac

@@ -762,6 +762,16 @@ if test x"$magick6" = x"yes"; then
   LIBS="$save_LIBS"
 fi
 
+if test x"$magick6" = x"yes"; then
+  # GM is missing AcquireExceptionInfo
+  save_LIBS="$LIBS"
+  LIBS="$LIBS $MAGICK_LIBS"
+  AC_CHECK_FUNCS(AcquireExceptionInfo,
+    AC_DEFINE(HAVE_ACQUIREEXCEPTIONINFO,1,
+	      [define if your magick has AcquireExceptionInfo.]))
+  LIBS="$save_LIBS"
+fi
+
 # have flags to turn load and save off independently ... some people will want
 # save but not load, for example
 AC_ARG_ENABLE([magickload], 

libvips/foreign/magick.c

@@ -85,6 +85,18 @@ magick_set_property( Image *image, const char *property, const char *value,
 	(void) SetImageProperty( image, property, value, exception );
 }
 
+ExceptionInfo *
+magick_acquire_exception( void )
+{
+	return( AcquireExceptionInfo() );
+}
+
+void
+magick_destroy_exception( ExceptionInfo *exception )
+{
+	VIPS_FREEF( DestroyExceptionInfo, exception ); 
+}
+
 void
 magick_inherit_exception( ExceptionInfo *exception, Image *image ) 
 {
@@ -197,12 +209,48 @@ magick_set_property( Image *image, const char *property, const char *value,
 #endif /*HAVE_SETIMAGEPROPERTY*/
 }
 
+ExceptionInfo *
+magick_acquire_exception( void )
+{
+	ExceptionInfo *exception;
+
+#ifdef HAVE_ACQUIREEXCEPTIONINFO
+	/* IM6+
+	 */
+	exception = AcquireExceptionInfo();
+#else /*!HAVE_ACQUIREEXCEPTIONINFO*/
+	/* gm
+	 */
+	exception = g_new( ExceptionInfo, 1 );
+	GetExceptionInfo( exception );
+#endif /*HAVE_ACQUIREEXCEPTIONINFO*/
+
+	return( exception );
+}
+
+void
+magick_destroy_exception( ExceptionInfo *exception )
+{
+#ifdef HAVE_ACQUIREEXCEPTIONINFO
+	/* IM6+ will free the exception in destroy.
+	 */
+	VIPS_FREEF( DestroyExceptionInfo, exception ); 
+#else /*!HAVE_ACQUIREEXCEPTIONINFO*/
+	/* gm and very old IM need to free the memory too.
+	 */
+	if( exception ) { 
+		DestroyExceptionInfo( exception ); 
+		g_free( exception );
+	}
+#endif /*HAVE_ACQUIREEXCEPTIONINFO*/
+}
+
 void
 magick_inherit_exception( ExceptionInfo *exception, Image *image ) 
 {
-#ifdef HAVE_INHERITEXCEPTION
+#ifdef HAVE_INHERITEXCEPTIONINFO
 	InheritException( exception, &image->exception );
-#endif /*HAVE_INHERITEXCEPTION*/
+#endif /*HAVE_INHERITEXCEPTIONINFO*/
 }
 
 void

libvips/foreign/magick.h

@@ -58,7 +58,10 @@ void magick_set_image_option( ImageInfo *image_info,
 void magick_set_number_scenes( ImageInfo *image_info, 
 	int scene, int number_scenes );
 
+ExceptionInfo *magick_acquire_exception( void );
+void magick_destroy_exception( ExceptionInfo *exception );
 void magick_inherit_exception( ExceptionInfo *exception, Image *image );
+
 void magick_sniff_bytes( ImageInfo *image_info, 
 		const unsigned char *bytes, size_t length );
 void magick_sniff_file( ImageInfo *image_info, const char *filename );

libvips/foreign/magick2vips.c

@@ -137,7 +137,7 @@ typedef struct _Read {
 
 	Image *image;
 	ImageInfo *image_info;
-	ExceptionInfo exception;
+	ExceptionInfo *exception;
 
 	/* Number of pages in image.
 	 */
@@ -168,9 +168,7 @@ read_free( Read *read )
 	VIPS_FREEF( DestroyImageList, read->image );
 	VIPS_FREEF( DestroyImageInfo, read->image_info ); 
 	VIPS_FREE( read->frames );
-	if ( (&read->exception)->signature == MagickSignature ) {
-		DestroyExceptionInfo( &read->exception );
-	}
+	VIPS_FREEF( magick_destroy_exception, read->exception ); 
 	VIPS_FREEF( vips_g_mutex_free, read->lock );
 }
 
@@ -209,7 +207,7 @@ read_new( const char *filename, VipsImage *im,
 	read->im = im;
 	read->image = NULL;
 	read->image_info = CloneImageInfo( NULL );
-	GetExceptionInfo( &read->exception );
+	read->exception = magick_acquire_exception(); 
 	read->n_pages = 0;
 	read->n_frames = 0;
 	read->frames = NULL;
@@ -765,9 +763,9 @@ vips__magick_read( const char *filename,
 	printf( "magick2vips: calling ReadImage() ...\n" );
 #endif /*DEBUG*/
 
-	read->image = ReadImage( read->image_info, &read->exception );
+	read->image = ReadImage( read->image_info, read->exception );
 	if( !read->image ) {
-		magick_vips_error( "magick2vips", &read->exception );
+		magick_vips_error( "magick2vips", read->exception );
 		vips_error( "magick2vips", 
 			_( "unable to read file \"%s\"" ), filename );
 		return( -1 );
@@ -803,9 +801,9 @@ vips__magick_read_header( const char *filename,
 	 * but sadly many IM coders do not support ping. The critical one for
 	 * us is DICOM. TGA also has issues. 
 	 */
-	read->image = ReadImage( read->image_info, &read->exception );
+	read->image = ReadImage( read->image_info, read->exception );
 	if( !read->image ) {
-		magick_vips_error( "magick2vips", &read->exception );
+		magick_vips_error( "magick2vips", read->exception );
 		vips_error( "magick2vips", 
 			_( "unable to read file \"%s\"" ), filename ); 
 		return( -1 );
@@ -845,9 +843,9 @@ vips__magick_read_buffer( const void *buf, const size_t len,
 #endif /*DEBUG*/
 
 	read->image = BlobToImage( read->image_info, 
-		buf, len, &read->exception );
+		buf, len, read->exception );
 	if( !read->image ) {
-		magick_vips_error( "magick2vips", &read->exception );
+		magick_vips_error( "magick2vips", read->exception );
 		vips_error( "magick2vips", "%s", _( "unable to read buffer" ) );
 		return( -1 );
 	}
@@ -883,9 +881,9 @@ vips__magick_read_buffer_header( const void *buf, const size_t len,
 	 * for us is DICOM. TGA also has issues. 
 	 */
 	read->image = BlobToImage( read->image_info, 
-		buf, len, &read->exception );
+		buf, len, read->exception );
 	if( !read->image ) {
-		magick_vips_error( "magick2vips", &read->exception );
+		magick_vips_error( "magick2vips", read->exception );
 		vips_error( "magick2vips", "%s", _( "unable to ping blob" ) );
 		return( -1 );
 	}

libvips/foreign/magick7load.c

@@ -279,7 +279,7 @@ vips_foreign_load_magick7_dispose( GObject *gobject )
 	VIPS_FREEF( DestroyImageInfo, magick7->image_info ); 
 	VIPS_FREE( magick7->frames );
 	VIPS_FREE( magick7->cache_view );
-	VIPS_FREEF( DestroyExceptionInfo, magick7->exception ); 
+	VIPS_FREEF( magick_destroy_exception, magick7->exception ); 
 	VIPS_FREEF( vips_g_mutex_free, magick7->lock );
 
 	G_OBJECT_CLASS( vips_foreign_load_magick7_parent_class )->
@@ -298,7 +298,7 @@ vips_foreign_load_magick7_build( VipsObject *object )
 	magick_genesis();
 
 	magick7->image_info = CloneImageInfo( NULL );
-	magick7->exception = AcquireExceptionInfo();
+	magick7->exception = magick_acquire_exception();
 	magick7->lock = vips_g_mutex_new();
 
 	if( !magick7->image_info ) 
@@ -760,14 +760,14 @@ ismagick7( const char *filename )
 	/* Horribly slow :-(
 	 */
 	image_info = CloneImageInfo( NULL );
-	exception = AcquireExceptionInfo();
+	exception = magick_acquire_exception();
 	vips_strncpy( image_info->filename, filename, MagickPathExtent );
 	magick_sniff_file( image_info, filename );
 	image = PingImage( image_info, exception );
 	result = image != NULL;
 	VIPS_FREEF( DestroyImageList, image );
 	VIPS_FREEF( DestroyImageInfo, image_info ); 
-	VIPS_FREEF( DestroyExceptionInfo, exception ); 
+	VIPS_FREEF( magick_destroy_exception, exception ); 
 
 	return( result );
 }
@@ -863,13 +863,13 @@ vips_foreign_load_magick7_buffer_is_a_buffer( const void *buf, size_t len )
 	/* Horribly slow :-(
 	 */
 	image_info = CloneImageInfo( NULL );
-	exception = AcquireExceptionInfo();
+	exception = magick_acquire_exception();
 	magick_sniff_bytes( image_info, buf, len );
 	image = PingBlob( image_info, buf, len, exception );
 	result = image != NULL;
 	VIPS_FREEF( DestroyImageList, image );
 	VIPS_FREEF( DestroyImageInfo, image_info ); 
-	VIPS_FREEF( DestroyExceptionInfo, exception ); 
+	VIPS_FREEF( magick_destroy_exception, exception ); 
 
 	return( result );
 }

libvips/foreign/magicksave.c

@@ -81,7 +81,7 @@ vips_foreign_save_magick_dispose( GObject *gobject )
 	VIPS_FREE( magick->map );
 	VIPS_FREEF( DestroyImageList, magick->images );
 	VIPS_FREEF( DestroyImageInfo, magick->image_info );
-	VIPS_FREEF( DestroyExceptionInfo, magick->exception );
+	VIPS_FREEF( magick_destroy_exception, magick->exception );
 
 	G_OBJECT_CLASS( vips_foreign_save_magick_parent_class )->
 		dispose( gobject );
@@ -218,7 +218,7 @@ vips_foreign_save_magick_build( VipsObject *object )
 	 */
 	im = save->ready;
 
-	magick->exception = AcquireExceptionInfo();
+	magick->exception = magick_acquire_exception();
 	magick->image_info = CloneImageInfo( NULL );
 
 	magick->storage_type = UndefinedPixel;