Index: contrib/libxo/libxo/libxo.c
===================================================================
--- contrib/libxo/libxo/libxo.c
+++ contrib/libxo/libxo/libxo.c
@@ -78,6 +78,7 @@
     unsigned short xo_style;	/* XO_STYLE_* value */
     unsigned short xo_indent;	/* Indent level (if pretty) */
     unsigned short xo_indent_by; /* Indent amount (tab stop) */
+    xo_flush_func_t xo_flush;	/* Write callback */
     xo_write_func_t xo_write;	/* Write callback */
     xo_close_func_t xo_close;	/* Close callback */
     xo_formatter_t xo_formatter; /* Custom formating function */
@@ -220,6 +221,17 @@
 xo_anchor_clear (xo_handle_t *xop);
 
 /*
+ * Callback to flush a FILE pointer
+ */
+static int
+xo_flush_file (void *opaque)
+{
+    FILE *fp = (FILE *) opaque;
+
+    return (fflush(fp));
+}
+
+/*
  * Callback to write data to a FILE pointer
  */
 static int
@@ -300,6 +312,7 @@
 {
     xop->xo_opaque = stdout;
     xop->xo_write = xo_write_to_file;
+    xop->xo_flush = xo_flush_file;
 
     /*
      * We need to initialize the locale, which isn't really pretty.
@@ -1213,7 +1226,7 @@
 	break;
     }
 
-    xo_flush_h(xop);
+    (void)xo_flush_h(xop);
 }
 
 void
@@ -1299,6 +1312,7 @@
 
     if (xop) {
 	xop->xo_opaque = fp;
+	xop->xo_flush = xo_flush_file;
 	xop->xo_write = xo_write_to_file;
 	xop->xo_close = xo_close_file;
     }
@@ -3165,7 +3179,8 @@
     for (cp = fmt; *cp; ) {
 	if (*cp == '\n') {
 	    xo_line_close(xop);
-	    xo_flush_h(xop);
+	    if (xo_flush_h(xop))
+		    return -1;
 	    cp += 1;
 	    continue;
 
@@ -4031,13 +4046,14 @@
 
 void
 xo_set_writer (xo_handle_t *xop, void *opaque, xo_write_func_t write_func,
-	       xo_close_func_t close_func)
+	       xo_close_func_t close_func, xo_flush_func_t flush_func)
 {
     xop = xo_default(xop);
 
     xop->xo_opaque = opaque;
     xop->xo_write = write_func;
     xop->xo_close = close_func;
+    xop->xo_flush = flush_func;
 }
 
 void
@@ -4047,7 +4063,7 @@
     xo_free = free_func;
 }
 
-void
+int
 xo_flush_h (xo_handle_t *xop)
 {
     static char div_close[] = "</div>";
@@ -4067,15 +4083,20 @@
     }
 
     xo_write(xop);
+    if (xop->xo_flush == NULL)
+	    return 0;
+
+    return (xop->xo_flush(xop->xo_opaque));
+
 }
 
-void
+int
 xo_flush (void)
 {
-    xo_flush_h(NULL);
+    return xo_flush_h(NULL);
 }
 
-void
+int
 xo_finish_h (xo_handle_t *xop)
 {
     const char *cp = "";
@@ -4093,13 +4114,13 @@
 	break;
     }
 
-    xo_flush_h(xop);
+    return xo_flush_h(xop);
 }
 
-void
+int
 xo_finish (void)
 {
-    xo_finish_h(NULL);
+    return xo_finish_h(NULL);
 }
 
 /*
Index: contrib/libxo/libxo/xo.h
===================================================================
--- contrib/libxo/libxo/xo.h
+++ contrib/libxo/libxo/xo.h
@@ -69,6 +69,7 @@
 typedef struct xo_handle_s xo_handle_t; /* Handle for XO output */
 
 typedef int (*xo_write_func_t)(void *, const char *);
+typedef int (*xo_flush_func_t)(void *);
 typedef void (*xo_close_func_t)(void *);
 typedef void *(*xo_realloc_func_t)(void *, size_t);
 typedef void (*xo_free_func_t)(void *);
@@ -93,7 +94,7 @@
 
 void
 xo_set_writer (xo_handle_t *xop, void *opaque, xo_write_func_t write_func,
-	       xo_close_func_t close_func);
+	       xo_close_func_t close_func, xo_flush_func_t flush_func);
 
 void
 xo_set_allocator (xo_realloc_func_t realloc_func, xo_free_func_t free_func);
@@ -227,16 +228,16 @@
 void
 xo_error (const char *fmt, ...);
 
-void
+int
 xo_flush_h (xo_handle_t *xop);
 
-void
+int
 xo_flush (void);
 
-void
+int
 xo_finish_h (xo_handle_t *xop);
 
-void
+int
 xo_finish (void);
 
 void