bump min libwebpmux version

0.3 can't read 0.5 libwebp files argh

TODO

@@ -1,6 +1,4 @@
-- test with libwebp 0.3, the earliest that supports libwebpmux
-
-  test under valgrind
+- test under valgrind
 
 
 - not sure about utf8 error messages on win

configure.ac

@@ -783,8 +783,12 @@ if test x"$with_libwebp" != "xno"; then
 fi
 
 # webp has the stuff for pulling out ICC profile etc in a separate library
+# 
+# we can build with libwebpmux back to 0.3, but it's not until libwebp 0.5 that
+# we can read that metadata back successfully ... insist on 0.5 so that tests
+# can work smoothly
 if test x"$with_libwebp" != "xno"; then
-  PKG_CHECK_MODULES(LIBWEBPMUX, libwebpmux >= 0.3.0,
+  PKG_CHECK_MODULES(LIBWEBPMUX, libwebpmux >= 0.5.0,
     [AC_DEFINE(HAVE_LIBWEBPMUX,1,[define if you have libwebpmux installed.])
      with_libwebpmux=yes
      PACKAGES_USED="$PACKAGES_USED libwebpmux"

libvips/foreign/webp2vips.c

@@ -237,12 +237,15 @@ read_header( Read *read, VipsImage *out )
 	int i;
 
 	/* We have to parse the whole file again to get the metadata out.
+	 *
+	 * Don't make parse failure an error. We don't want to refuse to read
+	 * any pixels because of some malformed metadata.
 	 */
 	bitstream.bytes = read->data;
 	bitstream.size = read->length;
 	if( !(mux = WebPMuxCreate( &bitstream, 0 )) ) {
-		vips_error( "webp", "%s", _( "parse error" ) ); 
-		return( -1 ); 
+		vips_warn( "webp", "%s", _( "unable to read image metadata" ) ); 
+		return( 0 ); 
 	}
 
 	for( i = 0; i < vips__n_webp_names; i++ ) { 
@@ -288,8 +291,10 @@ vips__webp_read_file_header( const char *filename, VipsImage *out, int shrink )
 		return( -1 );
 	}
 
-	if( read_header( read, out ) )
+	if( read_header( read, out ) ) {
+		read_free( read );
 		return( -1 );
+	}
 
 	read_free( read );
 
@@ -356,8 +361,10 @@ vips__webp_read_buffer_header( const void *buf, size_t len, VipsImage *out,
 		return( -1 );
 	}
 
-	if( read_header( read, out ) )
+	if( read_header( read, out ) ) {
+		read_free( read );
 		return( -1 );
+	}
 
 	read_free( read );
 

test/test_foreign.py

@@ -372,8 +372,8 @@ class TestForeign(unittest.TestCase):
 
         self.file_loader("webpload", self.webp_file, webp_valid)
         self.buffer_loader("webpload_buffer", self.webp_file, webp_valid)
-        self.save_load_buffer("webpsave_buffer", "webpload_buffer", self.colour,
-                             50)
+        self.save_load_buffer("webpsave_buffer", "webpload_buffer", 
+                              self.colour, 60)
         self.save_load("%s.webp", self.colour)
 
         # test lossless mode