Support features sets

CMakeLists.txt

@@ -361,6 +361,7 @@ list(
   src/dwarfs/console_writer.cpp
   src/dwarfs/entry.cpp
   src/dwarfs/error.cpp
+  src/dwarfs/features.cpp
   src/dwarfs/file_scanner.cpp
   src/dwarfs/file_stat.cpp
   src/dwarfs/file_type.cpp

include/dwarfs/features.h

@@ -0,0 +1,31 @@
+/* vim:set ts=2 sw=2 sts=2 et: */
+/**
+ * \author     Marcus Holland-Moritz (github@mhxnet.de)
+ * \copyright  Copyright (c) Marcus Holland-Moritz
+ *
+ * This file is part of dwarfs.
+ *
+ * dwarfs is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * dwarfs 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with dwarfs.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <set>
+#include <string>
+
+namespace dwarfs {
+
+std::set<std::string> get_unsupported_features(std::set<std::string> features);
+
+} // namespace dwarfs

src/dwarfs/features.cpp

@@ -0,0 +1,59 @@
+/* vim:set ts=2 sw=2 sts=2 et: */
+/**
+ * \author     Marcus Holland-Moritz (github@mhxnet.de)
+ * \copyright  Copyright (c) Marcus Holland-Moritz
+ *
+ * This file is part of dwarfs.
+ *
+ * dwarfs is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * dwarfs 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with dwarfs.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <algorithm>
+#include <iterator>
+
+#include "dwarfs/features.h"
+
+namespace dwarfs {
+
+namespace {
+
+std::set<std::string> supported_features{
+#ifdef DWARFS_HAVE_LIBZSTD
+    "zstd",
+#endif
+#ifdef DWARFS_HAVE_LIBLZ4
+    "lz4",
+#endif
+#ifdef DWARFS_HAVE_LIBLZMA
+    "lzma",
+#endif
+#ifdef DWARFS_HAVE_LIBBROTLI
+    "brotli",
+#endif
+#ifdef DWARFS_HAVE_FLAC
+    "flac",
+#endif
+};
+
+} // namespace
+
+std::set<std::string> get_unsupported_features(std::set<std::string> features) {
+  std::set<std::string> rv;
+  std::set_difference(features.begin(), features.end(),
+                      supported_features.begin(), supported_features.end(),
+                      std::inserter(rv, rv.end()));
+  return rv;
+}
+
+} // namespace dwarfs

src/dwarfs/metadata_v2.cpp

@@ -44,6 +44,7 @@
 #include <fsst.h>
 
 #include "dwarfs/error.h"
+#include "dwarfs/features.h"
 #include "dwarfs/file_stat.h"
 #include "dwarfs/fstypes.h"
 #include "dwarfs/logger.h"
@@ -136,6 +137,20 @@ map_frozen(std::span<uint8_t const> schema, std::span<uint8_t const> data) {
   return ret;
 }
 
+MappedFrozen<thrift::metadata::metadata>
+check_frozen(MappedFrozen<thrift::metadata::metadata> meta) {
+  if (meta.features()) {
+    auto unsupported = get_unsupported_features(meta.features()->thaw());
+    if (!unsupported.empty()) {
+      DWARFS_THROW(runtime_error,
+                   fmt::format("file system uses the following features "
+                               "unsupported by this build: {}",
+                               boost::join(unsupported, ", ")));
+    }
+  }
+  return meta;
+}
+
 void analyze_frozen(std::ostream& os,
                     MappedFrozen<thrift::metadata::metadata> const& meta,
                     size_t total_size, int detail) {
@@ -302,7 +317,8 @@ class metadata_ final : public metadata_v2::impl {
             std::span<uint8_t const> data, metadata_options const& options,
             int inode_offset, bool force_consistency_check)
       : data_(data)
-      , meta_(map_frozen<thrift::metadata::metadata>(schema, data_))
+      , meta_(
+            check_frozen(map_frozen<thrift::metadata::metadata>(schema, data_)))
       , global_(lgr, &meta_,
                 options.check_consistency || force_consistency_check)
       , root_(dir_entry_view::from_dir_entry_index(0, &global_))

thrift/metadata.thrift

@@ -350,6 +350,19 @@ struct metadata {
 
   25: optional string_table     compact_symlinks
 
+  //=========================================================//
+  // fields added with dwarfs-0.7.0, file system version 2.5 //
+  //=========================================================//
+
    // preferred path separator of original file system
   26: optional UInt32           preferred_path_separator
+
+  //=========================================================//
+  // fields added with dwarfs-0.7.3, file system version 2.5 //
+  //=========================================================//
+
+  // The set of features used in this file system image. As long
+  // as an older binary supports all features, it will be able
+  // to use images created with newer versions.
+  27: optional set<string>      features
 }