1 files changed, 113 insertions, 0 deletions
diff --git a/third_party/nix/src/nix/show-derivation.cc b/third_party/nix/src/nix/show-derivation.cc
new file mode 100644
index 0000000000..efe554710f
--- /dev/null
+++ b/third_party/nix/src/nix/show-derivation.cc
@@ -0,0 +1,113 @@
+// FIXME: integrate this with nix path-info?
+
+#include "libmain/common-args.hh"
+#include "libstore/derivations.hh"
+#include "libstore/store-api.hh"
+#include "libutil/archive.hh"
+#include "libutil/json.hh"
+#include "nix/command.hh"
+
+namespace nix {
+struct CmdShowDerivation final : InstallablesCommand {
+  bool recursive = false;
+
+  CmdShowDerivation() {
+    mkFlag()
+        .longName("recursive")
+        .shortName('r')
+        .description("include the dependencies of the specified derivations")
+        .set(&recursive, true);
+  }
+
+  std::string name() override { return "show-derivation"; }
+
+  std::string description() override {
+    return "show the contents of a store derivation";
+  }
+
+  Examples examples() override {
+    return {
+        Example{"To show the store derivation that results from evaluating the "
+                "Hello package:",
+                "nix show-derivation nixpkgs.hello"},
+        Example{"To show the full derivation graph (if available) that "
+                "produced your NixOS system:",
+                "nix show-derivation -r /run/current-system"},
+    };
+  }
+
+  void run(ref<Store> store) override {
+    auto drvPaths = toDerivations(store, installables, true);
+
+    if (recursive) {
+      PathSet closure;
+      store->computeFSClosure(drvPaths, closure);
+      drvPaths = closure;
+    }
+
+    {
+      JSONObject jsonRoot(std::cout, true);
+
+      for (auto& drvPath : drvPaths) {
+        if (!isDerivation(drvPath)) {
+          continue;
+        }
+
+        auto drvObj(jsonRoot.object(drvPath));
+
+        auto drv = readDerivation(drvPath);
+
+        {
+          auto outputsObj(drvObj.object("outputs"));
+          for (auto& output : drv.outputs) {
+            auto outputObj(outputsObj.object(output.first));
+            outputObj.attr("path", output.second.path);
+            if (!output.second.hash.empty()) {
+              outputObj.attr("hashAlgo", output.second.hashAlgo);
+              outputObj.attr("hash", output.second.hash);
+            }
+          }
+        }
+
+        {
+          auto inputsList(drvObj.list("inputSrcs"));
+          for (auto& input : drv.inputSrcs) {
+            inputsList.elem(input);
+          }
+        }
+
+        {
+          auto inputDrvsObj(drvObj.object("inputDrvs"));
+          for (auto& input : drv.inputDrvs) {
+            auto inputList(inputDrvsObj.list(input.first));
+            for (auto& outputId : input.second) {
+              inputList.elem(outputId);
+            }
+          }
+        }
+
+        drvObj.attr("platform", drv.platform);
+        drvObj.attr("builder", drv.builder);
+
+        {
+          auto argsList(drvObj.list("args"));
+          for (auto& arg : drv.args) {
+            argsList.elem(arg);
+          }
+        }
+
+        {
+          auto envObj(drvObj.object("env"));
+          for (auto& var : drv.env) {
+            envObj.attr(var.first, var.second);
+          }
+        }
+      }
+    }
+
+    std::cout << "\n";
+  }
+};
+}  // namespace nix
+
+static nix::RegisterCommand r1(nix::make_ref<nix::CmdShowDerivation>());