Add OtVariantBuilder

This is similar to GVariantBuilder in that it constructs variant
containers, but it writes it directly to a file descriptor rather
than keep the entier thing in memory. This is useful to create large
variants without using a lot of memory.

Closes: #1309
Approved by: cgwalters

Makefile-otutil.am

@@ -34,6 +34,8 @@ libotutil_la_SOURCES = \
 	src/libotutil/ot-unix-utils.h \
 	src/libotutil/ot-variant-utils.c \
 	src/libotutil/ot-variant-utils.h \
+	src/libotutil/ot-variant-builder.c \
+	src/libotutil/ot-variant-builder.h \
 	src/libotutil/ot-gio-utils.c \
 	src/libotutil/ot-gio-utils.h \
 	src/libotutil/ot-gpg-utils.c \

src/libotutil/ot-variant-builder.h

@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2017 Alexander Larsson <alexl@redhat.com>.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ *
+ * Author: Alexander Larsson <alexl@redhat.com>.
+ */
+
+#pragma once
+
+#include <gio/gio.h>
+
+#include "libglnx.h"
+
+G_BEGIN_DECLS
+
+typedef struct _OtVariantBuilder OtVariantBuilder;
+
+OtVariantBuilder *ot_variant_builder_new         (const GVariantType  *type,
+                                                  int                  fd);
+void              ot_variant_builder_unref       (OtVariantBuilder    *builder);
+OtVariantBuilder *ot_variant_builder_ref         (OtVariantBuilder    *builder);
+gboolean          ot_variant_builder_end         (OtVariantBuilder    *builder,
+                                                  GError             **error);
+gboolean          ot_variant_builder_open        (OtVariantBuilder    *builder,
+                                                  const GVariantType  *type,
+                                                  GError             **error);
+gboolean          ot_variant_builder_close       (OtVariantBuilder    *builder,
+                                                  GError             **error);
+gboolean          ot_variant_builder_add_from_fd (OtVariantBuilder    *builder,
+                                                  const GVariantType  *type,
+                                                  int                  fd,
+                                                  guint64              size,
+                                                  GError             **error);
+gboolean          ot_variant_builder_add_value   (OtVariantBuilder    *builder,
+                                                  GVariant            *value,
+                                                  GError             **error);
+gboolean          ot_variant_builder_add         (OtVariantBuilder    *builder,
+                                                  GError             **error,
+                                                  const gchar         *format_string,
+                                                  ...);
+void              ot_variant_builder_add_parsed  (OtVariantBuilder    *builder,
+                                                  const gchar         *format,
+                                                  ...);
+
+G_DEFINE_AUTOPTR_CLEANUP_FUNC (OtVariantBuilder, ot_variant_builder_unref)
+
+G_END_DECLS

src/libotutil/otutil.h

@@ -48,6 +48,7 @@
 #include <ot-opt-utils.h>
 #include <ot-unix-utils.h>
 #include <ot-variant-utils.h>
+#include <ot-variant-builder.h>
 #include <ot-checksum-utils.h>
 #include <ot-gpg-utils.h>
 #include <ot-checksum-instream.h>