1 files changed, 56 insertions, 0 deletions
diff --git a/third_party/nix/src/nix/cat.cc b/third_party/nix/src/nix/cat.cc
new file mode 100644
index 0000000000..7788707eae
--- /dev/null
+++ b/third_party/nix/src/nix/cat.cc
@@ -0,0 +1,56 @@
+#include "libstore/fs-accessor.hh"
+#include "libstore/nar-accessor.hh"
+#include "libstore/store-api.hh"
+#include "nix/command.hh"
+
+namespace nix {
+struct MixCat : virtual Args {
+  std::string path;
+
+  void cat(const ref<FSAccessor>& accessor) {
+    auto st = accessor->stat(path);
+    if (st.type == FSAccessor::Type::tMissing) {
+      throw Error(format("path '%1%' does not exist") % path);
+    }
+    if (st.type != FSAccessor::Type::tRegular) {
+      throw Error(format("path '%1%' is not a regular file") % path);
+    }
+
+    std::cout << accessor->readFile(path);
+  }
+};
+
+struct CmdCatStore final : StoreCommand, MixCat {
+  CmdCatStore() { expectArg("path", &path); }
+
+  std::string name() override { return "cat-store"; }
+
+  std::string description() override {
+    return "print the contents of a store file on stdout";
+  }
+
+  void run(ref<Store> store) override { cat(store->getFSAccessor()); }
+};
+
+struct CmdCatNar final : StoreCommand, MixCat {
+  Path narPath;
+
+  CmdCatNar() {
+    expectArg("nar", &narPath);
+    expectArg("path", &path);
+  }
+
+  std::string name() override { return "cat-nar"; }
+
+  std::string description() override {
+    return "print the contents of a file inside a NAR file";
+  }
+
+  void run(ref<Store> store) override {
+    cat(makeNarAccessor(make_ref<std::string>(readFile(narPath))));
+  }
+};
+}  // namespace nix
+
+static nix::RegisterCommand r1(nix::make_ref<nix::CmdCatStore>());
+static nix::RegisterCommand r2(nix::make_ref<nix::CmdCatNar>());