1 files changed, 118 insertions, 0 deletions
diff --git a/pkgs/build-support/build-sandbox/src/nix-query.cc b/pkgs/build-support/build-sandbox/src/nix-query.cc
new file mode 100644
index 00000000..71208693
--- /dev/null
+++ b/pkgs/build-support/build-sandbox/src/nix-query.cc
@@ -0,0 +1,118 @@
+#include <iostream>
+
+#if NIX_VERSION >= 112
+#include <nix/config.h>
+#endif
+#include <nix/util.hh>
+#include <nix/local-store.hh>
+#include <nix/store-api.hh>
+
+#if NIX_VERSION < 112
+#include <nix/misc.hh>
+#include <nix/globals.hh>
+#endif
+
+using namespace nix;
+
+struct query_state {
+#if NIX_VERSION >= 112
+    std::shared_ptr<Store> store;
+#else
+    std::shared_ptr<StoreAPI> store;
+#endif
+    PathSet paths;
+    PathSet::iterator iter;
+};
+
+static Path get_store_path(query_state *qs, Path path)
+{
+    Path canonicalized = canonPath(path, true);
+#if NIX_VERSION >= 112
+    return qs->store->toStorePath(canonicalized);
+#else
+    return toStorePath(canonicalized);
+#endif
+}
+
+static Path get_ancestor(query_state *qs, Path path)
+{
+    size_t pos = 0;
+    std::string tmp;
+
+    while (pos != std::string::npos) {
+        if ((pos = path.find('/', pos + 1)) != std::string::npos) {
+            Path current = path.substr(0, pos);
+
+            if (!isLink(current))
+                continue;
+
+            try {
+                current = get_store_path(qs, current);
+            } catch (...) {
+                continue;
+            }
+
+            return current;
+        }
+    }
+
+    return get_store_path(qs, path);
+}
+
+extern "C" {
+    struct query_state *new_query(void)
+    {
+        query_state *initial = new query_state();
+#if NIX_VERSION >= 112
+        initial->store = openStore();
+#else
+        settings.processEnvironment();
+        settings.loadConfFile();
+        initial->store = openStore(false);
+#endif
+        return initial;
+    }
+
+    void free_query(query_state *qs)
+    {
+        delete qs;
+    }
+
+    bool query_requisites(query_state *qs, const char *path)
+    {
+        Path query(path);
+
+        try {
+            query = get_ancestor(qs, query);
+
+#if NIX_VERSION >= 112
+            qs->store->computeFSClosure(
+                qs->store->followLinksToStorePath(query),
+                qs->paths, false, true
+            );
+#else
+            computeFSClosure(
+                *qs->store, followLinksToStorePath(query),
+                qs->paths, false, true
+            );
+#endif
+        } catch (Error &e) {
+            std::cerr << "Error while querying requisites for "
+                      << query << ": " << e.what()
+                      << std::endl;
+            return false;
+        }
+
+        qs->iter = qs->paths.begin();
+
+        return true;
+    }
+
+    const char *next_query_result(query_state *qs)
+    {
+        if (qs->iter == qs->paths.end())
+            return NULL;
+
+        return (qs->iter++)->c_str();
+    }
+}