Add g_converter_convert_bytes

Add a utility api to apply a GConverter to data in memory.

Test included.

gio/gconverter.c

@@ -23,6 +23,9 @@
 #include "config.h"
 #include "gconverter.h"
 #include "glibintl.h"
+#include "gmemoryinputstream.h"
+#include "gmemoryoutputstream.h"
+#include "gconverteroutputstream.h"
 
 
 /**
@@ -207,3 +210,48 @@ g_converter_reset (GConverter *converter)
 
   (* iface->reset) (converter);
 }
+
+/**
+ * g_converter_convert_bytes:
+ * @converter: the `GConverter` to use
+ * @bytes: the data to convert
+ * @error: location to store the error occurring
+ *
+ * Applies @converter to the data in @bytes.
+ *
+ * Returns: (transfer full): A newly-allocated
+ *   `GBytes` with the converted data, or `NULL` if an error
+ *   occurred
+ *
+ * Since: 2.82
+ */
+GBytes *
+g_converter_convert_bytes (GConverter  *converter,
+                           GBytes      *bytes,
+                           GError     **error)
+{
+  GInputStream *input;
+  GOutputStream *output;
+  GOutputStream *conv;
+  GOutputStreamSpliceFlags flags;
+  GBytes *result = NULL;
+
+  g_converter_reset (converter);
+
+  input = g_memory_input_stream_new_from_bytes (bytes);
+  output = g_memory_output_stream_new_resizable ();
+  conv = g_converter_output_stream_new (output, converter);
+
+  flags = G_OUTPUT_STREAM_SPLICE_CLOSE_SOURCE | G_OUTPUT_STREAM_SPLICE_CLOSE_TARGET;
+
+  if (g_output_stream_splice (conv, input, flags, NULL, error) != -1)
+    {
+      result = g_memory_output_stream_steal_as_bytes (G_MEMORY_OUTPUT_STREAM (output));
+    }
+
+  g_object_unref (conv);
+  g_object_unref (output);
+  g_object_unref (input);
+
+  return result;
+}

gio/gconverter.h

@@ -84,6 +84,11 @@ GConverterResult g_converter_convert (GConverter       *converter,
 GIO_AVAILABLE_IN_ALL
 void             g_converter_reset   (GConverter       *converter);
 
+GIO_AVAILABLE_IN_2_82
+GBytes *         g_converter_convert_bytes (GConverter  *converter,
+                                            GBytes      *bytes,
+                                            GError     **error);
+
 
 G_END_DECLS
 

gio/tests/converter.c

@@ -0,0 +1,68 @@
+/* GLib testing framework examples and tests
+ * Copyright (C) 2024 Red Hat, Inc.
+ * Authors: Matthias Clasen
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
+ * 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 2.1 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <glib/glib.h>
+#include <gio/gio.h>
+#include <stdlib.h>
+#include <string.h>
+
+
+static void
+test_convert_bytes (void)
+{
+  char data[8192];
+  GBytes *bytes;
+  GConverter *converter;
+  GError *error = NULL;
+  GBytes *result;
+
+  for (gsize i = 0; i < sizeof (data); i++)
+    data[i] = g_test_rand_int_range (0, 256);
+
+  bytes = g_bytes_new_static (data, sizeof (data));
+
+  converter = G_CONVERTER (g_zlib_compressor_new (G_ZLIB_COMPRESSOR_FORMAT_GZIP, 9));
+  result = g_converter_convert_bytes (converter, bytes, &error);
+  g_assert_no_error (error);
+  g_assert_nonnull (result);
+
+  g_bytes_unref (result);
+  g_object_unref (converter);
+
+  converter = G_CONVERTER (g_zlib_decompressor_new (G_ZLIB_COMPRESSOR_FORMAT_GZIP));
+  result = g_converter_convert_bytes (converter, bytes, &error);
+  g_assert_nonnull (error);
+  g_error_free (error);
+  g_assert_true (result == NULL);
+
+  g_object_unref (converter);
+  g_bytes_unref (bytes);
+}
+
+int
+main (int   argc,
+      char *argv[])
+{
+  g_test_init (&argc, &argv, NULL);
+
+  g_test_add_func ("/converter/bytes", test_convert_bytes);
+
+  return g_test_run();
+}

gio/tests/meson.build

@@ -70,6 +70,7 @@ gio_tests = {
     # "LC_COLLATE support for collation orders other than simple codepoint order"
     'can_fail' : linux_libc == 'musl',
   },
+  'converter' : {},
   'credentials' : {},
   'data-input-stream' : {},
   'data-output-stream' : {},