deltas: Link to liblzma, add internal API to use it

For future static deltas work, we'll be linking to liblzma.  Since
it's fairly widespread, let's just make it a hard dependency.

src/libostree/ostree-lzma-common.c

@@ -0,0 +1,71 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2014 Colin Walters <walters@verbum.org>
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include "ostree-lzma-common.h"
+
+#include <errno.h>
+#include <lzma.h>
+#include <string.h>
+
+GConverterResult
+_ostree_lzma_return (lzma_ret   res,
+                     GError   **error)
+{
+  switch (res)
+    {
+    case LZMA_OK:
+      return G_CONVERTER_CONVERTED;
+    case LZMA_STREAM_END:
+      return G_CONVERTER_FINISHED;
+    case LZMA_NO_CHECK:
+      g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+			   "Stream is corrupt");
+      return G_CONVERTER_ERROR;
+    case LZMA_UNSUPPORTED_CHECK:
+      g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+			   "Cannot calculate integrity check");
+      return G_CONVERTER_ERROR;
+    case LZMA_MEM_ERROR:
+      g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+			   "Out of memory");
+      return G_CONVERTER_ERROR;
+    case LZMA_MEMLIMIT_ERROR:
+      g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+			   "Exceeded memory limit");
+      return G_CONVERTER_ERROR;
+    case LZMA_FORMAT_ERROR:
+      g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+			   "File format not recognized");
+      return G_CONVERTER_ERROR;
+    case LZMA_OPTIONS_ERROR:
+      g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+			   "Invalid or unsupported options");
+      return G_CONVERTER_ERROR;
+    case LZMA_DATA_ERROR:
+      g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+			   "Data is corrupt");
+      return G_CONVERTER_ERROR;
+    default:
+      g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+			   "Unrecognized LZMA error");
+      return G_CONVERTER_ERROR;
+    }
+}
+