From 8c4abf7c4206213d4656929127a774c4235f1f52 Mon Sep 17 00:00:00 2001
From: John Cupitt <jcupitt@gmail.com>
Date: Mon, 6 Mar 2017 10:07:31 +0000
Subject: [PATCH] allow vips images to have a missing XML block

---
 TODO                   |  8 +++++---
 libvips/iofuncs/vips.c | 24 +++++++++++++++++-------
 2 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/TODO b/TODO
index 721da8bb..4231971d 100644
--- a/TODO
+++ b/TODO
@@ -1,11 +1,13 @@
-
-
  
 - VIPS_META_SEQUENTIAL will be saved to vips files, then loaded back again argh
 
   we need to set a value that can't be saved
 
-  do we need a seq cache for reducev as well? we could have up to a 3x
+  maybe a NULL boxed pointer?
+
+  looks like vips_image_set_area(im, "poop", NULL, NULL); might work
+
+- do we need a seq cache for reducev as well? we could have up to a 3x
   reduction there
 
 
diff --git a/libvips/iofuncs/vips.c b/libvips/iofuncs/vips.c
index c18c9742..8f3f4088 100644
--- a/libvips/iofuncs/vips.c
+++ b/libvips/iofuncs/vips.c
@@ -464,6 +464,9 @@ parser_read_fd( XML_Parser parser, int fd )
 	const int chunk_size = 1024; 
 
 	ssize_t bytes_read;
+	ssize_t len;
+
+	bytes_read = 0;
 
 	do {
 		void *buf;
@@ -473,19 +476,25 @@ parser_read_fd( XML_Parser parser, int fd )
 				"%s", _( "unable to allocate read buffer" ) );
 			return( -1 );
 		}
-		bytes_read = read( fd, buf, chunk_size );
-		if( bytes_read == (ssize_t) -1 ) {
+		len = read( fd, buf, chunk_size );
+		if( len == (ssize_t) -1 ) {
 			vips_error( "VipsImage", 
 				"%s", _( "read error while fetching XML" ) );
 			return( -1 );
 		}
 
-		if( !XML_ParseBuffer( parser, bytes_read, bytes_read == 0 ) ) {
-			vips_error( "VipsImage", 
-				"%s", _( "XML parse error" ) );
+		/* Allow missing XML block.
+		 */
+		if( bytes_read == 0 &&
+			len == 0 )
+			break;
+		bytes_read += len;
+
+		if( !XML_ParseBuffer( parser, len, len == 0 ) ) {
+			vips_error( "VipsImage", "%s", _( "XML parse error" ) );
 			return( -1 );
 		}
-	} while( bytes_read > 0 );
+	} while( len > 0 );
 
 	return( 0 );
 }
@@ -993,7 +1002,8 @@ vips_image_open_input( VipsImage *image )
 	 * harmless.
 	 */
 	if( readhist( image ) ) {
-		g_warning( _( "error reading XML: %s" ), vips_error_buffer() );
+		g_warning( _( "error reading vips image metadata: %s" ), 
+			vips_error_buffer() );
 		vips_error_clear();
 	}