Merge remote-tracking branch 'origin/8.3'

ChangeLog

@@ -8,6 +8,7 @@
 - add giflib5 support
 - allow resize >1 on one axis, <1 on the other
 - vips_resize has an optional @kernel argument
+- fix giflib4 detection [felixbuenemann]
 
 29/1/16 started 8.3
 - add vips_reduce*() ... a fast path for affine downsize

TODO

@@ -1,5 +1,12 @@
 - add more webp tests to py suite
 
+- the gif tests in the suite sometimes fail with giflib5 because of an
+  uninitialized struct in giflib, see
+
+	https://sourceforge.net/p/giflib/bugs/94/
+
+  sadly ubuntu 16.04 only comes with giflib5, and giflib5 is currently broken
+
 - I like the new int mask creator in reducev, can we use it in im_vips2imask()
   as well?
 

acinclude.m4

@@ -631,26 +631,14 @@ if test "$GIFLIB_LIBS" = ""; then
   INCLUDES="$GIFLIB_INCLUDES $INCLUDES"
 
   # Try the standard search path first
-  AC_TRY_LINK([#include <gif_lib.h>],[
-    #if defined(GIFLIB_MAJOR) && GIFLIB_MAJOR > 4
-    EGifSetGifVersion(0,0);
-    #else
-    GifLastError();
-    #endif
-  ], [
+  AC_TRY_LINK([#include <gif_lib.h>],[DGifSlurp(0)], [
     GIFLIB_LIBS="-lgif"
   ], [
     # giflib is not in the standard search path, try $prefix
 
     LIBS="-L${prefix}/lib $LIBS"
 
-    AC_TRY_LINK([#include <gif_lib.h>],[
-      #if defined(GIFLIB_MAJOR) && GIFLIB_MAJOR > 4
-      EGifSetGifVersion(0,0);
-      #else
-      GifLastError();
-      #endif
-    ], [
+    AC_TRY_LINK([#include <gif_lib.h>],[DGifSlurp(0)], [
       GIFLIB_LIBS="-L${prefix}/lib -lgif"
     ], [
       GIFLIB_LIBS=no

libvips/foreign/gifload.c

@@ -153,15 +153,33 @@ vips_foreign_load_gif_errstr( int error_code )
 #endif /*HAVE_GIFLIB_5*/
 }
 
+static void
+vips_foreign_load_gif_error_vips( VipsForeignLoadGif *gif, int error )
+{
+	VipsObjectClass *class = VIPS_OBJECT_GET_CLASS( gif );
+
+	const char *message;
+
+	if( (message = vips_foreign_load_gif_errstr( error )) )
+		vips_error( class->nickname, "%s", message ); 
+}
+
 static void
 vips_foreign_load_gif_error( VipsForeignLoadGif *gif )
 {
+	int error;
+
+	error = 0;
+
 #ifdef HAVE_GIFLIB_5
 	if( gif->file ) 
-		vips_foreign_load_gif_errstr( gif->file->Error ); 
+		error = gif->file->Error;
 #else 
-	vips_foreign_load_gif_errstr( GifLastError() ); 
+	error = GifLastError(); 
 #endif
+
+	if( error ) 
+		vips_foreign_load_gif_error_vips( gif, error ); 
 }
 
 static void
@@ -172,13 +190,13 @@ vips_foreign_load_gif_close( VipsForeignLoadGif *gif )
 		int error; 
 
 		if( DGifCloseFile( gif->file, &error ) ) 
-			vips_foreign_load_gif_errstr( error );
+			vips_foreign_load_gif_error_vips( gif, error );
 		gif->file = NULL;
 	}
 #else 
 	if( gif->file ) {
 		if( DGifCloseFile( gif->file ) ) 
-			vips_foreign_load_gif_errstr( GifLastError() ); 
+			vips_foreign_load_gif_error_vips( gif, GifLastError() ); 
 		gif->file = NULL;
 	}
 #endif
@@ -194,13 +212,13 @@ vips_foreign_load_gif_open( VipsForeignLoadGif *gif, const char *filename )
 	int error; 
 
 	if( !(gif->file = DGifOpenFileName( filename, &error )) ) {
-		vips_foreign_load_gif_errstr( error );
+		vips_foreign_load_gif_error_vips( gif, error );
 		return( -1 ); 
 	}
 }
 #else 
 	if( !(gif->file = DGifOpenFileName( filename )) ) { 
-		vips_foreign_load_gif_errstr( GifLastError() ); 
+		vips_foreign_load_gif_error_vips( gif, GifLastError() ); 
 		return( -1 ); 
 	}
 #endif
@@ -218,13 +236,13 @@ vips_foreign_load_gif_open_buffer( VipsForeignLoadGif *gif, InputFunc read_fn )
 	int error;
 
 	if( !(gif->file = DGifOpen( gif, read_fn, &error )) ) {
-		vips_foreign_load_gif_errstr( error );
+		vips_foreign_load_gif_error_vips( gif, error );
 		return( -1 ); 
 	}
 }
 #else 
 	if( !(gif->file = DGifOpen( gif, read_fn )) ) { 
-		vips_foreign_load_gif_errstr( GifLastError() ); 
+		vips_foreign_load_gif_error_vips( gif, GifLastError() ); 
 		return( -1 ); 
 	}
 #endif
@@ -435,7 +453,7 @@ vips_foreign_load_gif_load( VipsForeignLoad *load )
 		GifByteType *extension;
 		int ext_code;
 
-		if( DGifGetRecordType( gif->file, &record) == GIF_ERROR ) {
+		if( DGifGetRecordType( gif->file, &record ) == GIF_ERROR ) {
 			vips_foreign_load_gif_error( gif ); 
 			return( -1 ); 
 		}