From 6ddbcad93b3b3a4871d0622a44cbfc422cc592b5 Mon Sep 17 00:00:00 2001
From: Marcus Holland-Moritz <github@mhxnet.de>
Date: Sat, 22 Jul 2023 18:13:33 +0200
Subject: [PATCH] Perform metadata check

---
 include/dwarfs/contextual_option.h |  7 +++++++
 src/mkdwarfs_main.cpp              | 10 ++++++++++
 2 files changed, 17 insertions(+)

diff --git a/include/dwarfs/contextual_option.h b/include/dwarfs/contextual_option.h
index b3b50fd8..6f47bc57 100644
--- a/include/dwarfs/contextual_option.h
+++ b/include/dwarfs/contextual_option.h
@@ -87,6 +87,13 @@ class contextual_option {
     return default_ && pred(*default_);
   }
 
+  template <typename T>
+  void visit_contextual(T&& visitor) const {
+    for (auto const& [ctx, val] : contextual_) {
+      visitor(ctx, val);
+    }
+  }
+
  private:
   std::optional<value_type> get_optional_impl(context_type const& ctx) const {
     if (auto it = contextual_.find(ctx); it != contextual_.end()) {
diff --git a/src/mkdwarfs_main.cpp b/src/mkdwarfs_main.cpp
index 9d6b1c1a..174ff463 100644
--- a/src/mkdwarfs_main.cpp
+++ b/src/mkdwarfs_main.cpp
@@ -1022,6 +1022,16 @@ int mkdwarfs_main(int argc, sys_char** argv) {
                                  compressor_parser);
     cop.parse(compression);
     cop.dump(std::cerr);
+
+    compression_opt.visit_contextual([catmgr = options.inode.categorizer_mgr](
+                                         auto cat, block_compressor const& bc) {
+      if (!bc.check_metadata(catmgr->category_metadata_sample(cat))) {
+        throw std::runtime_error(
+            fmt::format("compression '{}' cannot be used for category '{}': "
+                        "insufficient metadata",
+                        bc.describe(), catmgr->category_name(cat)));
+      }
+    });
   } catch (std::exception const& e) {
     LOG_ERROR << e.what();
     return 1;