oci: Make libzstd optional (and disable OCI deltas if not there)

common/Makefile.am.inc

@@ -178,6 +178,7 @@ libflatpak_common_la_CFLAGS = \
 	-I$(srcdir)/dbus-proxy \
 	$(AM_CFLAGS) \
 	$(ARCHIVE_CFLAGS) \
+	$(ZSTD_CFLAGS) \
 	$(BASE_CFLAGS) \
 	$(DCONF_CFLAGS) \
 	$(HIDDEN_VISIBILITY_CFLAGS) \
@@ -195,6 +196,7 @@ libflatpak_common_la_CFLAGS = \
 libflatpak_common_la_LIBADD = \
 	$(AM_LIBADD) \
 	$(ARCHIVE_LIBS) \
+	$(ZSTD_LIBS) \
 	$(BASE_LIBS) \
 	$(DCONF_LIBS) \
 	$(INTERNAL_GPGME_LIBS) \

common/flatpak-oci-registry.c

@@ -1891,6 +1891,11 @@ flatpak_oci_registry_find_delta_manifest (FlatpakOciRegistry    *registry,
   g_autoptr(FlatpakOciVersioned) deltaindexv = NULL;
   FlatpakOciDescriptor *delta_desc;
 
+#ifndef HAVE_ZSTD
+  if (TRUE)
+    return NULL; /* Don't find deltas if we can't apply them */
+#endif
+
   deltaindexv = flatpak_oci_registry_load_versioned (registry, oci_repository, "_deltaindex",
                                                      NULL, cancellable, NULL);
   if (deltaindexv == NULL)

common/flatpak-zstd-decompressor.c

@@ -3,8 +3,10 @@
 #include "flatpak-zstd-decompressor-private.h"
 
 #include <errno.h>
-#include <zstd.h>
 #include <string.h>
+#ifdef HAVE_ZSTD
+#include <zstd.h>
+#endif
 
 static void flatpak_zstd_decompressor_iface_init  (GConverterIface *iface);
 
@@ -12,7 +14,9 @@ struct _FlatpakZstdDecompressor
 {
   GObject parent_instance;
 
+#ifdef HAVE_ZSTD
   ZSTD_DStream *dstream;
+#endif
 };
 
 G_DEFINE_TYPE_WITH_CODE (FlatpakZstdDecompressor, flatpak_zstd_decompressor, G_TYPE_OBJECT,
@@ -22,11 +26,13 @@ G_DEFINE_TYPE_WITH_CODE (FlatpakZstdDecompressor, flatpak_zstd_decompressor, G_T
 static void
 flatpak_zstd_decompressor_finalize (GObject *object)
 {
+#ifdef HAVE_ZSTD
   FlatpakZstdDecompressor *decompressor;
 
   decompressor = FLATPAK_ZSTD_DECOMPRESSOR (object);
 
   ZSTD_freeDStream (decompressor->dstream);
+#endif
 
   G_OBJECT_CLASS (flatpak_zstd_decompressor_parent_class)->finalize (object);
 }
@@ -34,7 +40,9 @@ flatpak_zstd_decompressor_finalize (GObject *object)
 static void
 flatpak_zstd_decompressor_init (FlatpakZstdDecompressor *decompressor)
 {
+#ifdef HAVE_ZSTD
   decompressor->dstream = ZSTD_createDStream ();
+#endif
 }
 
 static void
@@ -58,9 +66,11 @@ flatpak_zstd_decompressor_new (void)
 static void
 flatpak_zstd_decompressor_reset (GConverter *converter)
 {
+#ifdef HAVE_ZSTD
   FlatpakZstdDecompressor *decompressor = FLATPAK_ZSTD_DECOMPRESSOR (converter);
 
   ZSTD_initDStream (decompressor->dstream);
+#endif
 }
 
 static GConverterResult
@@ -74,6 +84,7 @@ flatpak_zstd_decompressor_convert (GConverter *converter,
                                    gsize      *bytes_written,
                                    GError    **error)
 {
+#ifdef HAVE_ZSTD
   FlatpakZstdDecompressor *decompressor;
   ZSTD_inBuffer input = { inbuf, inbuf_size, 0 };
   ZSTD_outBuffer output = {outbuf, outbuf_size, 0 };
@@ -84,11 +95,10 @@ flatpak_zstd_decompressor_convert (GConverter *converter,
   if (decompressor->dstream == NULL)
     {
       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
-                           "Failed to initialize libzst");
+                           "Failed to initialize libzstd");
       return G_CONVERTER_ERROR;
     }
 
-
   res = ZSTD_decompressStream(decompressor->dstream, &output , &input);
   if (ZSTD_isError (res))
     {
@@ -115,6 +125,12 @@ flatpak_zstd_decompressor_convert (GConverter *converter,
     }
 
   return G_CONVERTER_CONVERTED;
+
+#else
+  g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+                       "libzstd not available");
+  return G_CONVERTER_ERROR;
+#endif
 }
 
 static void

configure.ac

@@ -210,10 +210,14 @@ AC_SUBST([GDBUS_CODEGEN], [`$PKG_CONFIG --variable gdbus_codegen gio-2.0`])
 
 POLKIT_GOBJECT_REQUIRED=0.98
 
-PKG_CHECK_MODULES(ARCHIVE, [libarchive >= 2.8.0 libzstd])
+PKG_CHECK_MODULES(ARCHIVE, [libarchive >= 2.8.0])
 PKG_CHECK_MODULES(BASE, [glib-2.0 >= $GLIB_REQS gio-2.0 gio-unix-2.0])
 PKG_CHECK_MODULES(SOUP, [libsoup-2.4])
 PKG_CHECK_MODULES(XML, [libxml-2.0 >= 2.4])
+PKG_CHECK_MODULES(ZSTD, [libzstd >= 0.8.1], [have_zstd=yes], [have_zstd=no])
+if test $have_zstd = yes; then
+  AC_DEFINE(HAVE_ZSTD, 1, [Define if libzstd is available])
+fi
 PKG_CHECK_MODULES(DCONF, [dconf >= 0.26], [have_dconf=yes], [have_dconf=no])
 if test $have_dconf = yes; then
   AC_DEFINE(HAVE_DCONF, 1, [Define if dconf is available])
@@ -555,4 +559,5 @@ echo "          Privilege mode:         $with_priv_mode"
 echo "          Use dconf:              $have_dconf"
 echo "          Use libsystemd:         $have_libsystemd"
 echo "          Use libmalcontent:      $have_libmalcontent"
+echo "          Use libzstd:            $have_zstd"
 echo ""