From ea0c7810c76c70f842056f052f56c2d848a6a74a Mon Sep 17 00:00:00 2001
From: Tristan Ross <tristan.ross@determinate.systems>
Date: Fri, 19 Sep 2025 14:25:46 -0700
Subject: [PATCH 01/13] libstore-c: add derivation functions

---
 src/libstore-c/nix_api_store.cc         | 85 ++++++++++++++++++++++++
 src/libstore-c/nix_api_store.h          | 88 +++++++++++++++++++++++++
 src/libstore-c/nix_api_store_internal.h | 11 ++++
 3 files changed, 184 insertions(+)

diff --git a/src/libstore-c/nix_api_store.cc b/src/libstore-c/nix_api_store.cc
index 0360427b643..7e6b3f5e064 100644
--- a/src/libstore-c/nix_api_store.cc
+++ b/src/libstore-c/nix_api_store.cc
@@ -208,3 +208,88 @@ nix_err nix_store_get_fs_closure(
     }
     NIXC_CATCH_ERRS
 }
+
+nix_err nix_store_drv_from_path(
+    nix_c_context * context,
+    Store * store,
+    const StorePath * path,
+    void (*callback)(void * userdata, const Derivation * drv),
+    void * userdata)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    try {
+        nix::Derivation drv = store->ptr->derivationFromPath(path->path);
+        if (callback) {
+            const Derivation tmp{drv};
+            callback(userdata, &tmp);
+        }
+    }
+    NIXC_CATCH_ERRS
+}
+
+Derivation * nix_drv_clone(const Derivation * d)
+{
+    return new Derivation{d->drv};
+}
+
+void nix_drv_free(Derivation * d)
+{
+    delete d;
+}
+
+nix_err nix_drv_get_outputs(
+    nix_c_context * context,
+    const Derivation * drv,
+    void (*callback)(void * userdata, const char * name, const DerivationOutput * drv_output),
+    void * userdata)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    try {
+        if (callback) {
+            for (const auto & [name, result] : drv->drv.outputs) {
+                const DerivationOutput tmp{result};
+                callback(userdata, name.c_str(), &tmp);
+            }
+        }
+    }
+    NIXC_CATCH_ERRS
+}
+
+nix_err nix_drv_get_outputs_and_optpaths(
+    nix_c_context * context,
+    const Derivation * drv,
+    const Store * store,
+    void (*callback)(void * userdata, const char * name, const DerivationOutput * drv_output, const StorePath * path),
+    void * userdata)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    try {
+        auto value = drv->drv.outputsAndOptPaths(store->ptr->config);
+        if (callback) {
+            for (const auto & [name, result] : value) {
+                const DerivationOutput tmp_output{result.first};
+
+                if (auto store_path = result.second) {
+                    const StorePath tmp_path{*store_path};
+                    callback(userdata, name.c_str(), &tmp_output, &tmp_path);
+                } else {
+                    callback(userdata, name.c_str(), &tmp_output, nullptr);
+                }
+            }
+        }
+    }
+    NIXC_CATCH_ERRS
+}
+
+DerivationOutput * nix_drv_output_clone(const DerivationOutput * o)
+{
+    return new DerivationOutput{o->drv_out};
+}
+
+void nix_drv_output_free(DerivationOutput * o)
+{
+    delete o;
+}
diff --git a/src/libstore-c/nix_api_store.h b/src/libstore-c/nix_api_store.h
index c1e94ed255f..451b80c3b3b 100644
--- a/src/libstore-c/nix_api_store.h
+++ b/src/libstore-c/nix_api_store.h
@@ -23,6 +23,10 @@ extern "C" {
 typedef struct Store Store;
 /** @brief Nix store path */
 typedef struct StorePath StorePath;
+/** @brief Nix Derivation */
+typedef struct Derivation Derivation;
+/** @brief Nix Derivation Output */
+typedef struct DerivationOutput DerivationOutput;
 
 /**
  * @brief Initializes the Nix store library
@@ -241,6 +245,90 @@ nix_err nix_store_get_fs_closure(
     void * userdata,
     void (*callback)(void * userdata, const StorePath * store_path));
 
+/*
+ * @brief Returns the derivation associated with the store path
+ *
+ * @note The callback borrows the Derivation only for the duration of the call.
+ *
+ * @param[out] context Optional, stores error information
+ * @param[in] store The nix store
+ * @param[in] path The nix store path
+ * @param[in] callback The callback to call
+ * @param[in] userdata The userdata to pass to the callback
+ */
+nix_err nix_store_drv_from_path(
+    nix_c_context * context,
+    Store * store,
+    const StorePath * path,
+    void (*callback)(void * userdata, const Derivation * drv),
+    void * userdata);
+
+/**
+ * @brief Copy of a Derivation
+ *
+ * @param[in] d the derivation to copy
+ * @return a new Derivation
+ */
+Derivation * nix_drv_clone(const Derivation * d);
+
+/**
+ * @brief Deallocate a Derivation
+ *
+ * Does not fail.
+ * @param[in] p the derivation to free
+ */
+void nix_drv_free(Derivation * d);
+
+/**
+ * @brief Iterate through all of the outputs in a derivation
+ *
+ * @note The callback borrows the DerivationOutput only for the duration of the call.
+ *
+ * @param[out] context Optional, stores error information
+ * @param[in] drv The derivation
+ * @param[in] callback The function to call on every output
+ * @param[in] userdata Userdata to pass to the callback
+ */
+nix_err nix_drv_get_outputs(
+    nix_c_context * context,
+    const Derivation * drv,
+    void (*callback)(void * userdata, const char * name, const DerivationOutput * drv_output),
+    void * userdata);
+
+/**
+ * @brief Iterate and get all of the derivation outputs and their store paths.
+ *
+ * @note The callback borrows the DerivationOutput and StorePath only for the duration of the call.
+ *
+ * @param[out] context Optional, stores error information
+ * @param[in] drv The derivation
+ * @param[in] store The nix store
+ * @param[in] callback The function to call on every output and store path
+ * @param[in] userdata The userdata to pass to the callback
+ */
+nix_err nix_drv_get_outputs_and_optpaths(
+    nix_c_context * context,
+    const Derivation * drv,
+    const Store * store,
+    void (*callback)(void * userdata, const char * name, const DerivationOutput * drv_output, const StorePath * path),
+    void * userdata);
+
+/**
+ * @brief Copy of a DerivationOutput
+ *
+ * @param[in] o the derivation output to copy
+ * @return a new DerivationOutput
+ */
+DerivationOutput * nix_drv_output_clone(const DerivationOutput * o);
+
+/**
+ * @brief Deallocate a DerivationOutput
+ *
+ * Does not fail.
+ * @param[in] o the derivation output to free
+ */
+void nix_drv_output_free(DerivationOutput * o);
+
 // cffi end
 #ifdef __cplusplus
 }
diff --git a/src/libstore-c/nix_api_store_internal.h b/src/libstore-c/nix_api_store_internal.h
index b0194bfd3ad..7e1ee12ea08 100644
--- a/src/libstore-c/nix_api_store_internal.h
+++ b/src/libstore-c/nix_api_store_internal.h
@@ -1,5 +1,6 @@
 #ifndef NIX_API_STORE_INTERNAL_H
 #define NIX_API_STORE_INTERNAL_H
+#include "nix/store/derivations.hh"
 #include "nix/store/store-api.hh"
 
 struct Store
@@ -12,4 +13,14 @@ struct StorePath
     nix::StorePath path;
 };
 
+struct Derivation
+{
+    nix::Derivation drv;
+};
+
+struct DerivationOutput
+{
+    nix::DerivationOutput drv_out;
+};
+
 #endif

From ff7618a2e49a54353e241227306add481edf1f09 Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Tue, 2 Sep 2025 11:20:51 -0400
Subject: [PATCH 02/13] Add new C API for working with derivations

Also test the APIs we just added.
---
 src/libexpr-tests/main.cc                     | 39 ++---------
 src/libstore-c/nix_api_store.cc               | 69 ++++++++++++------
 src/libstore-c/nix_api_store.h                | 70 +++++++++++--------
 src/libstore-c/nix_api_store_internal.h       |  6 +-
 .../include/nix/store/tests/meson.build       |  1 +
 .../include/nix/store/tests/nix_api_store.hh  | 51 ++++++++++----
 .../include/nix/store/tests/test-main.hh      | 13 ++++
 src/libstore-test-support/meson.build         |  1 +
 src/libstore-test-support/test-main.cc        | 47 +++++++++++++
 .../data/derivation/ca/self-contained.json    | 23 ++++++
 src/libstore-tests/main.cc                    | 15 ++++
 src/libstore-tests/meson.build                |  1 +
 src/libstore-tests/nix_api_store.cc           | 59 ++++++++++++++++
 13 files changed, 292 insertions(+), 103 deletions(-)
 create mode 100644 src/libstore-test-support/include/nix/store/tests/test-main.hh
 create mode 100644 src/libstore-test-support/test-main.cc
 create mode 100644 src/libstore-tests/data/derivation/ca/self-contained.json
 create mode 100644 src/libstore-tests/main.cc

diff --git a/src/libexpr-tests/main.cc b/src/libexpr-tests/main.cc
index 61b40e8349f..d6b0d0ab93f 100644
--- a/src/libexpr-tests/main.cc
+++ b/src/libexpr-tests/main.cc
@@ -1,43 +1,14 @@
 #include <gtest/gtest.h>
-#include <cstdlib>
-#include "nix/store/globals.hh"
-#include "nix/util/logging.hh"
+
+#include "nix/store/tests/test-main.hh"
 
 using namespace nix;
 
 int main(int argc, char ** argv)
 {
-    if (argc > 1 && std::string_view(argv[1]) == "__build-remote") {
-        printError("test-build-remote: not supported in libexpr unit tests");
-        return 1;
-    }
-
-    // Disable build hook. We won't be testing remote builds in these unit tests. If we do, fix the above build hook.
-    settings.buildHook = {};
-
-#ifdef __linux__ // should match the conditional around sandboxBuildDir declaration.
-
-    // When building and testing nix within the host's Nix sandbox, our store dir will be located in the host's
-    // sandboxBuildDir, e.g.: Host
-    //   storeDir = /nix/store
-    //   sandboxBuildDir = /build
-    // This process
-    //   storeDir = /build/foo/bar/store
-    //   sandboxBuildDir = /build
-    // However, we have a rule that the store dir must not be inside the storeDir, so we need to pick a different
-    // sandboxBuildDir.
-    settings.sandboxBuildDir = "/test-build-dir-instead-of-usual-build-dir";
-#endif
-
-#ifdef __APPLE__
-    // Avoid this error, when already running in a sandbox:
-    // sandbox-exec: sandbox_apply: Operation not permitted
-    settings.sandboxMode = smDisabled;
-    setEnv("_NIX_TEST_NO_SANDBOX", "1");
-#endif
-
-    // For pipe operator tests in trivial.cc
-    experimentalFeatureSettings.set("experimental-features", "pipe-operators");
+    auto res = testMainForBuidingPre(argc, argv);
+    if (!res)
+        return res;
 
     ::testing::InitGoogleTest(&argc, argv);
     return RUN_ALL_TESTS();
diff --git a/src/libstore-c/nix_api_store.cc b/src/libstore-c/nix_api_store.cc
index 7e6b3f5e064..abc9c7ea0b2 100644
--- a/src/libstore-c/nix_api_store.cc
+++ b/src/libstore-c/nix_api_store.cc
@@ -164,11 +164,44 @@ void nix_store_path_free(StorePath * sp)
     delete sp;
 }
 
+void nix_derivation_free(nix_derivation * drv)
+{
+    delete drv;
+}
+
 StorePath * nix_store_path_clone(const StorePath * p)
 {
     return new StorePath{p->path};
 }
 
+nix_derivation * nix_derivation_from_json(nix_c_context * context, Store * store, const char * json)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    try {
+        auto drv = nix::Derivation::fromJSON(*store->ptr, nlohmann::json::parse(json));
+
+        auto drvPath = nix::writeDerivation(*store->ptr, drv, nix::NoRepair, /* read only */ true);
+
+        drv.checkInvariants(*store->ptr, drvPath);
+
+        return new nix_derivation{drv};
+    }
+    NIXC_CATCH_ERRS_NULL
+}
+
+StorePath * nix_add_derivation(nix_c_context * context, Store * store, nix_derivation * derivation)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    try {
+        auto ret = nix::writeDerivation(*store->ptr, derivation->drv, nix::NoRepair);
+
+        return new StorePath{ret};
+    }
+    NIXC_CATCH_ERRS_NULL
+}
+
 nix_err nix_store_copy_closure(nix_c_context * context, Store * srcStore, Store * dstStore, StorePath * path)
 {
     if (context)
@@ -213,7 +246,7 @@ nix_err nix_store_drv_from_path(
     nix_c_context * context,
     Store * store,
     const StorePath * path,
-    void (*callback)(void * userdata, const Derivation * drv),
+    void (*callback)(void * userdata, const nix_derivation * drv),
     void * userdata)
 {
     if (context)
@@ -221,27 +254,17 @@ nix_err nix_store_drv_from_path(
     try {
         nix::Derivation drv = store->ptr->derivationFromPath(path->path);
         if (callback) {
-            const Derivation tmp{drv};
+            const nix_derivation tmp{drv};
             callback(userdata, &tmp);
         }
     }
     NIXC_CATCH_ERRS
 }
 
-Derivation * nix_drv_clone(const Derivation * d)
-{
-    return new Derivation{d->drv};
-}
-
-void nix_drv_free(Derivation * d)
-{
-    delete d;
-}
-
-nix_err nix_drv_get_outputs(
+nix_err nix_derivation_get_outputs(
     nix_c_context * context,
-    const Derivation * drv,
-    void (*callback)(void * userdata, const char * name, const DerivationOutput * drv_output),
+    const nix_derivation * drv,
+    void (*callback)(void * userdata, const char * name, const nix_derivation_output * drv_output),
     void * userdata)
 {
     if (context)
@@ -249,7 +272,7 @@ nix_err nix_drv_get_outputs(
     try {
         if (callback) {
             for (const auto & [name, result] : drv->drv.outputs) {
-                const DerivationOutput tmp{result};
+                const nix_derivation_output tmp{result};
                 callback(userdata, name.c_str(), &tmp);
             }
         }
@@ -257,11 +280,11 @@ nix_err nix_drv_get_outputs(
     NIXC_CATCH_ERRS
 }
 
-nix_err nix_drv_get_outputs_and_optpaths(
+nix_err nix_derivation_get_outputs_and_optpaths(
     nix_c_context * context,
-    const Derivation * drv,
+    const nix_derivation * drv,
     const Store * store,
-    void (*callback)(void * userdata, const char * name, const DerivationOutput * drv_output, const StorePath * path),
+    void (*callback)(void * userdata, const char * name, const nix_derivation_output * drv_output, const StorePath * path),
     void * userdata)
 {
     if (context)
@@ -270,7 +293,7 @@ nix_err nix_drv_get_outputs_and_optpaths(
         auto value = drv->drv.outputsAndOptPaths(store->ptr->config);
         if (callback) {
             for (const auto & [name, result] : value) {
-                const DerivationOutput tmp_output{result.first};
+                const nix_derivation_output tmp_output{result.first};
 
                 if (auto store_path = result.second) {
                     const StorePath tmp_path{*store_path};
@@ -284,12 +307,12 @@ nix_err nix_drv_get_outputs_and_optpaths(
     NIXC_CATCH_ERRS
 }
 
-DerivationOutput * nix_drv_output_clone(const DerivationOutput * o)
+nix_derivation_output * nix_drv_output_clone(const nix_derivation_output * o)
 {
-    return new DerivationOutput{o->drv_out};
+    return new nix_derivation_output{o->drv_out};
 }
 
-void nix_drv_output_free(DerivationOutput * o)
+void nix_drv_output_free(nix_derivation_output * o)
 {
     delete o;
 }
diff --git a/src/libstore-c/nix_api_store.h b/src/libstore-c/nix_api_store.h
index 451b80c3b3b..f27b1d8b7d7 100644
--- a/src/libstore-c/nix_api_store.h
+++ b/src/libstore-c/nix_api_store.h
@@ -24,9 +24,9 @@ typedef struct Store Store;
 /** @brief Nix store path */
 typedef struct StorePath StorePath;
 /** @brief Nix Derivation */
-typedef struct Derivation Derivation;
+typedef struct nix_derivation nix_derivation;
 /** @brief Nix Derivation Output */
-typedef struct DerivationOutput DerivationOutput;
+typedef struct nix_derivation_output nix_derivatio_noutput;
 
 /**
  * @brief Initializes the Nix store library
@@ -211,6 +211,32 @@ nix_err nix_store_realise(
 nix_err
 nix_store_get_version(nix_c_context * context, Store * store, nix_get_string_callback callback, void * user_data);
 
+/**
+ * @brief Create a `nix_derivation` from a JSON representation of that derivation.
+ *
+ * @param[out] context Optional, stores error information.
+ * @param[in] store nix store reference.
+ * @param[in] json JSON of the derivation as a string.
+ */
+nix_derivation * nix_derivation_from_json(nix_c_context * context, Store * store, const char * json);
+
+/**
+ * @brief Add the given `nix_derivation` to the given store
+ *
+ * @param[out] context Optional, stores error information.
+ * @param[in] store nix store reference. The derivation will be inserted here.
+ * @param[in] derivation nix_derivation to insert into the given store.
+ */
+StorePath * nix_add_derivation(nix_c_context * context, Store * store, nix_derivation * derivation);
+
+/**
+ * @brief Deallocate a `nix_derivation'
+ *
+ * Does not fail.
+ * @param[in] drv the derivation to free
+ */
+void nix_derivation_free(nix_derivation * drv);
+
 /**
  * @brief Copy the closure of `path` from `srcStore` to `dstStore`.
  *
@@ -260,25 +286,9 @@ nix_err nix_store_drv_from_path(
     nix_c_context * context,
     Store * store,
     const StorePath * path,
-    void (*callback)(void * userdata, const Derivation * drv),
+    void (*callback)(void * userdata, const nix_derivation * drv),
     void * userdata);
 
-/**
- * @brief Copy of a Derivation
- *
- * @param[in] d the derivation to copy
- * @return a new Derivation
- */
-Derivation * nix_drv_clone(const Derivation * d);
-
-/**
- * @brief Deallocate a Derivation
- *
- * Does not fail.
- * @param[in] p the derivation to free
- */
-void nix_drv_free(Derivation * d);
-
 /**
  * @brief Iterate through all of the outputs in a derivation
  *
@@ -289,10 +299,10 @@ void nix_drv_free(Derivation * d);
  * @param[in] callback The function to call on every output
  * @param[in] userdata Userdata to pass to the callback
  */
-nix_err nix_drv_get_outputs(
+nix_err nix_derivation_get_outputs(
     nix_c_context * context,
-    const Derivation * drv,
-    void (*callback)(void * userdata, const char * name, const DerivationOutput * drv_output),
+    const nix_derivation * drv,
+    void (*callback)(void * userdata, const char * name, const nix_derivation_output * drv_output),
     void * userdata);
 
 /**
@@ -306,28 +316,28 @@ nix_err nix_drv_get_outputs(
  * @param[in] callback The function to call on every output and store path
  * @param[in] userdata The userdata to pass to the callback
  */
-nix_err nix_drv_get_outputs_and_optpaths(
+nix_err nix_derivation_get_outputs_and_optpaths(
     nix_c_context * context,
-    const Derivation * drv,
+    const nix_derivation * drv,
     const Store * store,
-    void (*callback)(void * userdata, const char * name, const DerivationOutput * drv_output, const StorePath * path),
+    void (*callback)(void * userdata, const char * name, const nix_derivation_output * drv_output, const StorePath * path),
     void * userdata);
 
 /**
- * @brief Copy of a DerivationOutput
+ * @brief Copy of a 'nix_derivation_output'
  *
  * @param[in] o the derivation output to copy
- * @return a new DerivationOutput
+ * @return a new 'nix_derivation_output'
  */
-DerivationOutput * nix_drv_output_clone(const DerivationOutput * o);
+nix_derivation_output * nix_derivation_output_clone(const nix_derivation_output * o);
 
 /**
- * @brief Deallocate a DerivationOutput
+ * @brief Deallocate a 'nix_derivation_output'
  *
  * Does not fail.
  * @param[in] o the derivation output to free
  */
-void nix_drv_output_free(DerivationOutput * o);
+void nix_derivation_output_free(nix_derivation_output * o);
 
 // cffi end
 #ifdef __cplusplus
diff --git a/src/libstore-c/nix_api_store_internal.h b/src/libstore-c/nix_api_store_internal.h
index 7e1ee12ea08..070bb1229cd 100644
--- a/src/libstore-c/nix_api_store_internal.h
+++ b/src/libstore-c/nix_api_store_internal.h
@@ -1,7 +1,7 @@
 #ifndef NIX_API_STORE_INTERNAL_H
 #define NIX_API_STORE_INTERNAL_H
-#include "nix/store/derivations.hh"
 #include "nix/store/store-api.hh"
+#include "nix/store/derivations.hh"
 
 struct Store
 {
@@ -13,12 +13,12 @@ struct StorePath
     nix::StorePath path;
 };
 
-struct Derivation
+struct nix_derivation
 {
     nix::Derivation drv;
 };
 
-struct DerivationOutput
+struct nix_derivation_output
 {
     nix::DerivationOutput drv_out;
 };
diff --git a/src/libstore-test-support/include/nix/store/tests/meson.build b/src/libstore-test-support/include/nix/store/tests/meson.build
index f79769d4102..33524de3851 100644
--- a/src/libstore-test-support/include/nix/store/tests/meson.build
+++ b/src/libstore-test-support/include/nix/store/tests/meson.build
@@ -9,4 +9,5 @@ headers = files(
   'outputs-spec.hh',
   'path.hh',
   'protocol.hh',
+  'test-main.hh',
 )
diff --git a/src/libstore-test-support/include/nix/store/tests/nix_api_store.hh b/src/libstore-test-support/include/nix/store/tests/nix_api_store.hh
index 608aa63d65e..7ecc5603b6a 100644
--- a/src/libstore-test-support/include/nix/store/tests/nix_api_store.hh
+++ b/src/libstore-test-support/include/nix/store/tests/nix_api_store.hh
@@ -12,33 +12,32 @@
 #include <gtest/gtest.h>
 
 namespace nixC {
-class nix_api_store_test : public nix_api_util_context
+
+class nix_api_store_test_base : public nix_api_util_context
 {
 public:
-    nix_api_store_test()
+    nix_api_store_test_base()
     {
         nix_libstore_init(ctx);
-        init_local_store();
     };
 
-    ~nix_api_store_test() override
+    ~nix_api_store_test_base() override
     {
-        nix_store_free(store);
-
-        for (auto & path : std::filesystem::recursive_directory_iterator(nixDir)) {
-            std::filesystem::permissions(path, std::filesystem::perms::owner_all);
+        if (exists(std::filesystem::path{nixDir})) {
+            for (auto & path : std::filesystem::recursive_directory_iterator(nixDir)) {
+                std::filesystem::permissions(path, std::filesystem::perms::owner_all);
+            }
+            std::filesystem::remove_all(nixDir);
         }
-        std::filesystem::remove_all(nixDir);
     }
 
-    Store * store;
     std::string nixDir;
     std::string nixStoreDir;
     std::string nixStateDir;
     std::string nixLogDir;
 
 protected:
-    void init_local_store()
+    Store * open_local_store()
     {
 #ifdef _WIN32
         // no `mkdtemp` with MinGW
@@ -66,11 +65,37 @@ protected:
 
         const char ** params[] = {p1, p2, p3, nullptr};
 
-        store = nix_store_open(ctx, "local", params);
+        auto * store = nix_store_open(ctx, "local", params);
         if (!store) {
             std::string errMsg = nix_err_msg(nullptr, ctx, nullptr);
-            ASSERT_NE(store, nullptr) << "Could not open store: " << errMsg;
+            EXPECT_NE(store, nullptr) << "Could not open store: " << errMsg;
+            assert(store);
         };
+        return store;
     }
 };
+
+class nix_api_store_test : public nix_api_store_test_base
+{
+public:
+    nix_api_store_test()
+        : nix_api_store_test_base{}
+    {
+        init_local_store();
+    };
+
+    ~nix_api_store_test() override
+    {
+        nix_store_free(store);
+    }
+
+    Store * store;
+
+protected:
+    void init_local_store()
+    {
+        store = open_local_store();
+    }
+};
+
 } // namespace nixC
diff --git a/src/libstore-test-support/include/nix/store/tests/test-main.hh b/src/libstore-test-support/include/nix/store/tests/test-main.hh
new file mode 100644
index 00000000000..3a1897469de
--- /dev/null
+++ b/src/libstore-test-support/include/nix/store/tests/test-main.hh
@@ -0,0 +1,13 @@
+#pragma once
+
+///@file
+
+namespace nix {
+
+/**
+ * Call this for a GTest test suite that will including performing Nix
+ * builds, before running tests.
+ */
+int testMainForBuidingPre(int argc, char ** argv);
+
+} // namespace nix
diff --git a/src/libstore-test-support/meson.build b/src/libstore-test-support/meson.build
index b2977941f86..2cb2a70d697 100644
--- a/src/libstore-test-support/meson.build
+++ b/src/libstore-test-support/meson.build
@@ -34,6 +34,7 @@ sources = files(
   'derived-path.cc',
   'outputs-spec.cc',
   'path.cc',
+  'test-main.cc',
 )
 
 subdir('include/nix/store/tests')
diff --git a/src/libstore-test-support/test-main.cc b/src/libstore-test-support/test-main.cc
new file mode 100644
index 00000000000..0b9072dc08f
--- /dev/null
+++ b/src/libstore-test-support/test-main.cc
@@ -0,0 +1,47 @@
+#include <cstdlib>
+
+#include "nix/store/globals.hh"
+#include "nix/util/logging.hh"
+
+#include "nix/store/tests/test-main.hh"
+
+namespace nix {
+
+int testMainForBuidingPre(int argc, char ** argv)
+{
+    if (argc > 1 && std::string_view(argv[1]) == "__build-remote") {
+        printError("test-build-remote: not supported in libexpr unit tests");
+        return EXIT_FAILURE;
+    }
+
+    // Disable build hook. We won't be testing remote builds in these unit tests. If we do, fix the above build hook.
+    settings.buildHook = {};
+
+    // No substituters, unless a test specifically requests.
+    settings.substituters = {};
+
+#ifdef __linux__ // should match the conditional around sandboxBuildDir declaration.
+
+    // When building and testing nix within the host's Nix sandbox, our store dir will be located in the host's
+    // sandboxBuildDir, e.g.: Host
+    //   storeDir = /nix/store
+    //   sandboxBuildDir = /build
+    // This process
+    //   storeDir = /build/foo/bar/store
+    //   sandboxBuildDir = /build
+    // However, we have a rule that the store dir must not be inside the storeDir, so we need to pick a different
+    // sandboxBuildDir.
+    settings.sandboxBuildDir = "/test-build-dir-instead-of-usual-build-dir";
+#endif
+
+#ifdef __APPLE__
+    // Avoid this error, when already running in a sandbox:
+    // sandbox-exec: sandbox_apply: Operation not permitted
+    settings.sandboxMode = smDisabled;
+    setEnv("_NIX_TEST_NO_SANDBOX", "1");
+#endif
+
+    return EXIT_SUCCESS;
+}
+
+} // namespace nix
diff --git a/src/libstore-tests/data/derivation/ca/self-contained.json b/src/libstore-tests/data/derivation/ca/self-contained.json
new file mode 100644
index 00000000000..c4ca280ef66
--- /dev/null
+++ b/src/libstore-tests/data/derivation/ca/self-contained.json
@@ -0,0 +1,23 @@
+{
+  "args": [
+    "-c",
+    "echo $name foo > $out"
+  ],
+  "builder": "/bin/sh",
+  "env": {
+    "builder": "/bin/sh",
+    "name": "myname",
+    "out": "/1rz4g4znpzjwh1xymhjpm42vipw92pr73vdgl6xs1hycac8kf2n9",
+    "system": "x86_64-linux"
+  },
+  "inputDrvs": {},
+  "inputSrcs": [],
+  "name": "myname",
+  "outputs": {
+    "out": {
+      "hashAlgo": "sha256",
+      "method": "nar"
+    }
+  },
+  "system": "x86_64-linux"
+}
diff --git a/src/libstore-tests/main.cc b/src/libstore-tests/main.cc
new file mode 100644
index 00000000000..ffe9816134f
--- /dev/null
+++ b/src/libstore-tests/main.cc
@@ -0,0 +1,15 @@
+#include <gtest/gtest.h>
+
+#include "nix/store/tests/test-main.hh"
+
+using namespace nix;
+
+int main(int argc, char ** argv)
+{
+    auto res = testMainForBuidingPre(argc, argv);
+    if (res)
+        return res;
+
+    ::testing::InitGoogleTest(&argc, argv);
+    return RUN_ALL_TESTS();
+}
diff --git a/src/libstore-tests/meson.build b/src/libstore-tests/meson.build
index fced202696e..31c20bef1b6 100644
--- a/src/libstore-tests/meson.build
+++ b/src/libstore-tests/meson.build
@@ -66,6 +66,7 @@ sources = files(
   'local-overlay-store.cc',
   'local-store.cc',
   'machines.cc',
+  'main.cc',
   'nar-info-disk-cache.cc',
   'nar-info.cc',
   'nix_api_store.cc',
diff --git a/src/libstore-tests/nix_api_store.cc b/src/libstore-tests/nix_api_store.cc
index c7146f977a5..70b0ec9dc45 100644
--- a/src/libstore-tests/nix_api_store.cc
+++ b/src/libstore-tests/nix_api_store.cc
@@ -1,9 +1,12 @@
+#include <fstream>
+
 #include "nix_api_util.h"
 #include "nix_api_util_internal.h"
 #include "nix_api_store.h"
 #include "nix_api_store_internal.h"
 
 #include "nix/store/tests/nix_api_store.hh"
+#include "nix/store/globals.hh"
 #include "nix/util/tests/string_callback.hh"
 #include "nix/util/url.hh"
 
@@ -199,4 +202,60 @@ TEST_F(nix_api_util_context, nix_store_real_path_binary_cache)
     ASSERT_STREQ(path_raw.c_str(), rp.c_str());
 }
 
+template<typename F>
+struct LambdaAdapter
+{
+    F fun;
+
+    template<typename... Args>
+    static inline auto call(LambdaAdapter<F> * ths, Args... args)
+    {
+        return ths->fun(args...);
+    }
+
+    template<typename... Args>
+    static auto call_void(void * ths, Args... args)
+    {
+        return call(static_cast<LambdaAdapter<F> *>(ths), args...);
+    }
+};
+
+TEST_F(nix_api_store_test_base, build_from_json)
+{
+    // FIXME get rid of these
+    nix::experimentalFeatureSettings.set("extra-experimental-features", "ca-derivations");
+    nix::settings.substituters = {};
+
+    auto * store = open_local_store();
+
+    std::filesystem::path unitTestData{getenv("_NIX_TEST_UNIT_DATA")};
+
+    std::ifstream t{unitTestData / "derivation/ca/self-contained.json"};
+    std::stringstream buffer;
+    buffer << t.rdbuf();
+
+    auto * drv = nix_derivation_from_json(ctx, store, buffer.str().c_str());
+    assert_ctx_ok();
+    ASSERT_NE(drv, nullptr);
+
+    auto * drvPath = nix_add_derivation(ctx, store, drv);
+    assert_ctx_ok();
+    ASSERT_NE(drv, nullptr);
+
+    auto cb = LambdaAdapter{.fun = [&](const char * outname, const StorePath * outPath) {
+        auto is_valid_path = nix_store_is_valid_path(ctx, store, outPath);
+        ASSERT_EQ(is_valid_path, true);
+    }};
+
+    auto ret = nix_store_realise(
+        ctx, store, drvPath, static_cast<void *>(&cb), decltype(cb)::call_void<const char *, const StorePath *>);
+    assert_ctx_ok();
+    ASSERT_EQ(ret, NIX_OK);
+
+    // Clean up
+    nix_store_path_free(drvPath);
+    nix_derivation_free(drv);
+    nix_store_free(store);
+}
+
 } // namespace nixC

From 77dd7a00be2b4ebd05b04dd95a9428c25494ccb8 Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Tue, 2 Sep 2025 01:54:27 -0400
Subject: [PATCH 03/13] `nix_store_is_valid_path` param `path` should be
 `const`

---
 src/libstore-c/nix_api_store.cc | 2 +-
 src/libstore-c/nix_api_store.h  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libstore-c/nix_api_store.cc b/src/libstore-c/nix_api_store.cc
index abc9c7ea0b2..4b0b124ef2b 100644
--- a/src/libstore-c/nix_api_store.cc
+++ b/src/libstore-c/nix_api_store.cc
@@ -91,7 +91,7 @@ nix_store_get_version(nix_c_context * context, Store * store, nix_get_string_cal
     NIXC_CATCH_ERRS
 }
 
-bool nix_store_is_valid_path(nix_c_context * context, Store * store, StorePath * path)
+bool nix_store_is_valid_path(nix_c_context * context, Store * store, const StorePath * path)
 {
     if (context)
         context->last_err_code = NIX_OK;
diff --git a/src/libstore-c/nix_api_store.h b/src/libstore-c/nix_api_store.h
index f27b1d8b7d7..19a6651adae 100644
--- a/src/libstore-c/nix_api_store.h
+++ b/src/libstore-c/nix_api_store.h
@@ -152,7 +152,7 @@ void nix_store_path_free(StorePath * p);
  * @param[in] path Path to check
  * @return true or false, error info in context
  */
-bool nix_store_is_valid_path(nix_c_context * context, Store * store, StorePath * path);
+bool nix_store_is_valid_path(nix_c_context * context, Store * store, const StorePath * path);
 
 /**
  * @brief Get the physical location of a store path

From ffe1d46529c9322831aa30d95dd93130976d7aae Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Tue, 2 Sep 2025 11:17:26 -0400
Subject: [PATCH 04/13] `nix_store_realise`: Improve typing of store path

Use `StorePath *` not `const char *`.
---
 src/libstore-c/nix_api_store.cc | 6 +++---
 src/libstore-c/nix_api_store.h  | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/libstore-c/nix_api_store.cc b/src/libstore-c/nix_api_store.cc
index 4b0b124ef2b..494c47da434 100644
--- a/src/libstore-c/nix_api_store.cc
+++ b/src/libstore-c/nix_api_store.cc
@@ -129,7 +129,7 @@ nix_err nix_store_realise(
     Store * store,
     StorePath * path,
     void * userdata,
-    void (*callback)(void * userdata, const char *, const char *))
+    void (*callback)(void * userdata, const char *, const StorePath *))
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -144,8 +144,8 @@ nix_err nix_store_realise(
         if (callback) {
             for (const auto & result : results) {
                 for (const auto & [outputName, realisation] : result.builtOutputs) {
-                    auto op = store->ptr->printStorePath(realisation.outPath);
-                    callback(userdata, outputName.c_str(), op.c_str());
+                    StorePath p{realisation.outPath};
+                    callback(userdata, outputName.c_str(), &p);
                 }
             }
         }
diff --git a/src/libstore-c/nix_api_store.h b/src/libstore-c/nix_api_store.h
index 19a6651adae..cb5fcf7c645 100644
--- a/src/libstore-c/nix_api_store.h
+++ b/src/libstore-c/nix_api_store.h
@@ -194,7 +194,7 @@ nix_err nix_store_realise(
     Store * store,
     StorePath * path,
     void * userdata,
-    void (*callback)(void * userdata, const char * outname, const char * out));
+    void (*callback)(void * userdata, const char * outname, const StorePath * out));
 
 /**
  * @brief get the version of a nix store.

From c1b766e1956c257d34ec0cd3f085f8a1fa420bfb Mon Sep 17 00:00:00 2001
From: Tristan Ross <tristan.ross@determinate.systems>
Date: Fri, 19 Sep 2025 15:44:35 -0700
Subject: [PATCH 05/13] libstore-c: add nix_derivation_get_structured_attrs

---
 src/libstore-c/nix_api_store.cc | 15 +++++++++++++++
 src/libstore-c/nix_api_store.h  | 10 ++++++++++
 2 files changed, 25 insertions(+)

diff --git a/src/libstore-c/nix_api_store.cc b/src/libstore-c/nix_api_store.cc
index 494c47da434..7da59b72f02 100644
--- a/src/libstore-c/nix_api_store.cc
+++ b/src/libstore-c/nix_api_store.cc
@@ -307,6 +307,21 @@ nix_err nix_derivation_get_outputs_and_optpaths(
     NIXC_CATCH_ERRS
 }
 
+const char * nix_derivation_get_structured_attrs(
+    nix_c_context * context,
+    const nix_derivation * drv)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    try {
+        if (auto structuredAttrs = drv->drv.structuredAttrs) {
+            return structuredAttrs->structuredAttrs.dump().c_str();
+        }
+        return nullptr;
+    }
+    NIXC_CATCH_ERRS_NULL
+}
+
 nix_derivation_output * nix_drv_output_clone(const nix_derivation_output * o)
 {
     return new nix_derivation_output{o->drv_out};
diff --git a/src/libstore-c/nix_api_store.h b/src/libstore-c/nix_api_store.h
index cb5fcf7c645..4f5e8337af5 100644
--- a/src/libstore-c/nix_api_store.h
+++ b/src/libstore-c/nix_api_store.h
@@ -323,6 +323,16 @@ nix_err nix_derivation_get_outputs_and_optpaths(
     void (*callback)(void * userdata, const char * name, const nix_derivation_output * drv_output, const StorePath * path),
     void * userdata);
 
+/**
+ * @brief Return the structured attrs of derivation as a JSON string
+ *
+ * @param[out] context Optional, stores error information
+ * @param[in] drv The derivation
+ */
+const char * nix_derivation_get_structured_attrs(
+    nix_c_context * context,
+    const nix_derivation * drv);
+
 /**
  * @brief Copy of a 'nix_derivation_output'
  *

From 04dd0c7e4f20f3dfea4ef34eec2e57f4b7b327c3 Mon Sep 17 00:00:00 2001
From: Tristan Ross <tristan.ross@determinate.systems>
Date: Fri, 19 Sep 2025 15:52:51 -0700
Subject: [PATCH 06/13] libstore-c: fix typo

---
 src/libstore-c/nix_api_store.cc | 20 +++++++++++---------
 src/libstore-c/nix_api_store.h  | 14 ++++++++------
 2 files changed, 19 insertions(+), 15 deletions(-)

diff --git a/src/libstore-c/nix_api_store.cc b/src/libstore-c/nix_api_store.cc
index 7da59b72f02..647a53094d7 100644
--- a/src/libstore-c/nix_api_store.cc
+++ b/src/libstore-c/nix_api_store.cc
@@ -284,7 +284,8 @@ nix_err nix_derivation_get_outputs_and_optpaths(
     nix_c_context * context,
     const nix_derivation * drv,
     const Store * store,
-    void (*callback)(void * userdata, const char * name, const nix_derivation_output * drv_output, const StorePath * path),
+    void (*callback)(
+        void * userdata, const char * name, const nix_derivation_output * drv_output, const StorePath * path),
     void * userdata)
 {
     if (context)
@@ -307,27 +308,28 @@ nix_err nix_derivation_get_outputs_and_optpaths(
     NIXC_CATCH_ERRS
 }
 
-const char * nix_derivation_get_structured_attrs(
-    nix_c_context * context,
-    const nix_derivation * drv)
+nix_err nix_derivation_get_structured_attrs(
+    nix_c_context * context, const nix_derivation * drv, nix_get_string_callback callback, void * userdata)
 {
     if (context)
         context->last_err_code = NIX_OK;
     try {
         if (auto structuredAttrs = drv->drv.structuredAttrs) {
-            return structuredAttrs->structuredAttrs.dump().c_str();
+            if (callback) {
+                auto result = structuredAttrs->structuredAttrs.dump();
+                callback(result.data(), result.size(), userdata);
+            }
         }
-        return nullptr;
     }
-    NIXC_CATCH_ERRS_NULL
+    NIXC_CATCH_ERRS
 }
 
-nix_derivation_output * nix_drv_output_clone(const nix_derivation_output * o)
+nix_derivation_output * nix_derivation_output_clone(const nix_derivation_output * o)
 {
     return new nix_derivation_output{o->drv_out};
 }
 
-void nix_drv_output_free(nix_derivation_output * o)
+void nix_derivation_output_free(nix_derivation_output * o)
 {
     delete o;
 }
diff --git a/src/libstore-c/nix_api_store.h b/src/libstore-c/nix_api_store.h
index 4f5e8337af5..e145a37383e 100644
--- a/src/libstore-c/nix_api_store.h
+++ b/src/libstore-c/nix_api_store.h
@@ -26,7 +26,7 @@ typedef struct StorePath StorePath;
 /** @brief Nix Derivation */
 typedef struct nix_derivation nix_derivation;
 /** @brief Nix Derivation Output */
-typedef struct nix_derivation_output nix_derivatio_noutput;
+typedef struct nix_derivation_output nix_derivation_noutput;
 
 /**
  * @brief Initializes the Nix store library
@@ -320,18 +320,20 @@ nix_err nix_derivation_get_outputs_and_optpaths(
     nix_c_context * context,
     const nix_derivation * drv,
     const Store * store,
-    void (*callback)(void * userdata, const char * name, const nix_derivation_output * drv_output, const StorePath * path),
+    void (*callback)(
+        void * userdata, const char * name, const nix_derivation_output * drv_output, const StorePath * path),
     void * userdata);
 
 /**
- * @brief Return the structured attrs of derivation as a JSON string
+ * @brief Gets the structured attrs of derivation as a JSON string
  *
  * @param[out] context Optional, stores error information
  * @param[in] drv The derivation
+ * @param[in] callback Called with the JSON string
+ * @param[in] user_data Arbitrary data passed to the callback
  */
-const char * nix_derivation_get_structured_attrs(
-    nix_c_context * context,
-    const nix_derivation * drv);
+nix_err nix_derivation_get_structured_attrs(
+    nix_c_context * context, const nix_derivation * drv, nix_get_string_callback callback, void * userdata);
 
 /**
  * @brief Copy of a 'nix_derivation_output'

From b3184a6be648d5b23a0c389e0b6021e7136bb647 Mon Sep 17 00:00:00 2001
From: Tristan Ross <tristan.ross@determinate.systems>
Date: Fri, 19 Sep 2025 17:04:03 -0700
Subject: [PATCH 07/13] libstore-c: add derivation clone function

---
 src/libstore-c/nix_api_store.cc | 44 +++++++++++++++++++++++++++------
 src/libstore-c/nix_api_store.h  | 35 +++++++++++++++++++++++---
 2 files changed, 69 insertions(+), 10 deletions(-)

diff --git a/src/libstore-c/nix_api_store.cc b/src/libstore-c/nix_api_store.cc
index 647a53094d7..fd09a3e6263 100644
--- a/src/libstore-c/nix_api_store.cc
+++ b/src/libstore-c/nix_api_store.cc
@@ -174,6 +174,11 @@ StorePath * nix_store_path_clone(const StorePath * p)
     return new StorePath{p->path};
 }
 
+nix_derivation * nix_derivation_clone(const nix_derivation * d)
+{
+    return new nix_derivation{d->drv};
+}
+
 nix_derivation * nix_derivation_from_json(nix_c_context * context, Store * store, const char * json)
 {
     if (context)
@@ -261,6 +266,29 @@ nix_err nix_store_drv_from_path(
     NIXC_CATCH_ERRS
 }
 
+nix_err nix_store_query_path_info(
+    nix_c_context * context,
+    Store * store,
+    const StorePath * store_path,
+    void * userdata,
+    void (*callback)(void * userdata, const StorePath * derived_path))
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    try {
+        auto info = store->ptr->queryPathInfo(store_path->path);
+        if (callback) {
+            if (auto deriver = info->deriver) {
+                const StorePath deriver_tmp{*info->deriver};
+                callback(userdata, &deriver_tmp);
+            } else {
+                callback(userdata, nullptr);
+            }
+        }
+    }
+    NIXC_CATCH_ERRS
+}
+
 nix_err nix_derivation_get_outputs(
     nix_c_context * context,
     const nix_derivation * drv,
@@ -308,17 +336,19 @@ nix_err nix_derivation_get_outputs_and_optpaths(
     NIXC_CATCH_ERRS
 }
 
-nix_err nix_derivation_get_structured_attrs(
-    nix_c_context * context, const nix_derivation * drv, nix_get_string_callback callback, void * userdata)
+nix_err nix_derivation_to_json(
+    nix_c_context * context,
+    const nix_derivation * drv,
+    const Store * store,
+    nix_get_string_callback callback,
+    void * userdata)
 {
     if (context)
         context->last_err_code = NIX_OK;
     try {
-        if (auto structuredAttrs = drv->drv.structuredAttrs) {
-            if (callback) {
-                auto result = structuredAttrs->structuredAttrs.dump();
-                callback(result.data(), result.size(), userdata);
-            }
+        auto result = drv->drv.toJSON(store->ptr->config).dump();
+        if (callback) {
+            callback(result.data(), result.size(), userdata);
         }
     }
     NIXC_CATCH_ERRS
diff --git a/src/libstore-c/nix_api_store.h b/src/libstore-c/nix_api_store.h
index e145a37383e..a999ab32ef8 100644
--- a/src/libstore-c/nix_api_store.h
+++ b/src/libstore-c/nix_api_store.h
@@ -237,6 +237,14 @@ StorePath * nix_add_derivation(nix_c_context * context, Store * store, nix_deriv
  */
 void nix_derivation_free(nix_derivation * drv);
 
+/**
+ * @brief Copy a `nix_derivation`
+ *
+ * @param[in] d the derivation to copy
+ * @return a new `nix_derivation`
+ */
+nix_derivation * nix_derivation_clone(const nix_derivation * d);
+
 /**
  * @brief Copy the closure of `path` from `srcStore` to `dstStore`.
  *
@@ -289,6 +297,22 @@ nix_err nix_store_drv_from_path(
     void (*callback)(void * userdata, const nix_derivation * drv),
     void * userdata);
 
+/**
+ * @brief Queries for the nix store path info.
+ *
+ * @param[out] context Optional, stores error information
+ * @param[in] store nix store reference
+ * @param[in] path A store path
+ * @param[in] userdata The data to pass to the callback
+ * @param[in] callback Called for when the path info is resolved
+ */
+nix_err nix_store_query_path_info(
+    nix_c_context * context,
+    Store * store,
+    const StorePath * store_path,
+    void * userdata,
+    void (*callback)(void * userdata, const StorePath * derived_path));
+
 /**
  * @brief Iterate through all of the outputs in a derivation
  *
@@ -325,15 +349,20 @@ nix_err nix_derivation_get_outputs_and_optpaths(
     void * userdata);
 
 /**
- * @brief Gets the structured attrs of derivation as a JSON string
+ * @brief Gets the derivation as a JSON string
  *
  * @param[out] context Optional, stores error information
  * @param[in] drv The derivation
+ * @param[in] store The nix store
  * @param[in] callback Called with the JSON string
  * @param[in] user_data Arbitrary data passed to the callback
  */
-nix_err nix_derivation_get_structured_attrs(
-    nix_c_context * context, const nix_derivation * drv, nix_get_string_callback callback, void * userdata);
+nix_err nix_derivation_to_json(
+    nix_c_context * context,
+    const nix_derivation * drv,
+    const Store * store,
+    nix_get_string_callback callback,
+    void * userdata);
 
 /**
  * @brief Copy of a 'nix_derivation_output'

From d30a11cb739c2b98637b201ec1d1717be920d829 Mon Sep 17 00:00:00 2001
From: Tristan Ross <tristan.ross@determinate.systems>
Date: Mon, 22 Sep 2025 16:21:21 -0700
Subject: [PATCH 08/13] libstore-c: add nix_derivation_make_paths function

---
 src/libstore-c/nix_api_store.cc | 25 +++++++++++++++++++++++++
 src/libstore-c/nix_api_store.h  | 16 ++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/src/libstore-c/nix_api_store.cc b/src/libstore-c/nix_api_store.cc
index fd09a3e6263..a6272aa16f4 100644
--- a/src/libstore-c/nix_api_store.cc
+++ b/src/libstore-c/nix_api_store.cc
@@ -195,6 +195,31 @@ nix_derivation * nix_derivation_from_json(nix_c_context * context, Store * store
     NIXC_CATCH_ERRS_NULL
 }
 
+nix_err nix_derivation_make_outputs(
+    nix_c_context * context,
+    Store * store,
+    const char * json,
+    void (*callback)(void * userdata, const char * output_name, const char * path),
+    void * userdata)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    try {
+        auto drv = nix::Derivation::fromJSON(*store->ptr, nlohmann::json::parse(json));
+        auto hashesModulo = hashDerivationModulo(*store->ptr, drv, true);
+
+        for (auto & output : drv.outputs) {
+            nix::Hash h = hashesModulo.hashes.at(output.first);
+            auto outPath = store->ptr->makeOutputPath(output.first, h, drv.name);
+
+            if (callback) {
+                callback(userdata, output.first.c_str(), store->ptr->printStorePath(outPath).c_str());
+            }
+        }
+    }
+    NIXC_CATCH_ERRS
+}
+
 StorePath * nix_add_derivation(nix_c_context * context, Store * store, nix_derivation * derivation)
 {
     if (context)
diff --git a/src/libstore-c/nix_api_store.h b/src/libstore-c/nix_api_store.h
index a999ab32ef8..6d03f1967ba 100644
--- a/src/libstore-c/nix_api_store.h
+++ b/src/libstore-c/nix_api_store.h
@@ -220,6 +220,22 @@ nix_store_get_version(nix_c_context * context, Store * store, nix_get_string_cal
  */
 nix_derivation * nix_derivation_from_json(nix_c_context * context, Store * store, const char * json);
 
+/**
+ * @brief Hashes the derivation and gives the output paths
+ *
+ * @param[in] context Optional, stores error information.
+ * @param[in] store nix store reference.
+ * @param[in] json JSON of the derivation as a string.
+ * @param[in] callback Called for every output to provide the output path.
+ * @param[in] userdata User data to pass to the callback.
+ */
+nix_err nix_derivation_make_outputs(
+    nix_c_context * context,
+    Store * store,
+    const char * json,
+    void (*callback)(void * userdata, const char * output_name, const char * path),
+    void * userdata);
+
 /**
  * @brief Add the given `nix_derivation` to the given store
  *

From 3375bb0d7100503d2ddd311e4273e95633802d1f Mon Sep 17 00:00:00 2001
From: Tristan Ross <tristan.ross@determinate.systems>
Date: Tue, 23 Sep 2025 09:31:25 -0700
Subject: [PATCH 09/13] libstore-c: add nix_store_build_paths function

---
 src/libstore-c/nix_api_store.cc | 29 +++++++++++++++++++++++++++++
 src/libstore-c/nix_api_store.h  | 21 +++++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/src/libstore-c/nix_api_store.cc b/src/libstore-c/nix_api_store.cc
index a6272aa16f4..f8303edd330 100644
--- a/src/libstore-c/nix_api_store.cc
+++ b/src/libstore-c/nix_api_store.cc
@@ -314,6 +314,35 @@ nix_err nix_store_query_path_info(
     NIXC_CATCH_ERRS
 }
 
+nix_err nix_store_build_paths(
+    nix_c_context * context,
+    Store * store,
+    const StorePath ** store_paths,
+    unsigned int num_store_paths,
+    void (*callback)(void * userdata, const char * path, const char * result),
+    void * userdata)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    try {
+        std::vector<nix::DerivedPath> derived_paths;
+        for (size_t i = 0; i < num_store_paths; i++) {
+            const StorePath * store_path = store_paths[i];
+            derived_paths.push_back(nix::SingleDerivedPath::Opaque{store_path->path});
+        }
+
+        auto results = store->ptr->buildPathsWithResults(derived_paths);
+        for (auto & result : results) {
+            if (callback) {
+                nlohmann::json json;
+                nix::to_json(json, result);
+                callback(userdata, result.path.to_string(store->ptr->config).c_str(), json.dump().c_str());
+            }
+        }
+    }
+    NIXC_CATCH_ERRS
+}
+
 nix_err nix_derivation_get_outputs(
     nix_c_context * context,
     const nix_derivation * drv,
diff --git a/src/libstore-c/nix_api_store.h b/src/libstore-c/nix_api_store.h
index 6d03f1967ba..ff5f49ca5b2 100644
--- a/src/libstore-c/nix_api_store.h
+++ b/src/libstore-c/nix_api_store.h
@@ -329,6 +329,27 @@ nix_err nix_store_query_path_info(
     void * userdata,
     void (*callback)(void * userdata, const StorePath * derived_path));
 
+/**
+ * @brief Builds the paths, if they are a derivation then they get built.
+ *
+ * @note Path and result for the callback only exist for the lifetime of
+ * the call. Result is a string containing the build result in JSON.
+ *
+ * @param[out] context Optional, stores error information
+ * @param[in] store nix store reference
+ * @param[in] store_paths Pointer to list of nix store paths
+ * @param[in] num_store_paths Number of nix store paths
+ * @param[in] callback The callback to trigger for build results
+ * @param[in] userdata User data to pass to the callback
+ */
+nix_err nix_store_build_paths(
+    nix_c_context * context,
+    Store * store,
+    const StorePath ** store_paths,
+    unsigned int num_store_paths,
+    void (*callback)(void * userdata, const char * path, const char * result),
+    void * userdata);
+
 /**
  * @brief Iterate through all of the outputs in a derivation
  *

From 6555f3337560d87b9923b3611c5e6fc9303eeb10 Mon Sep 17 00:00:00 2001
From: Tristan Ross <tristan.ross@determinate.systems>
Date: Tue, 23 Sep 2025 10:00:55 -0700
Subject: [PATCH 10/13] libstore-c: fix typos

---
 src/libstore-c/nix_api_store.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/libstore-c/nix_api_store.h b/src/libstore-c/nix_api_store.h
index ff5f49ca5b2..37226cbac0d 100644
--- a/src/libstore-c/nix_api_store.h
+++ b/src/libstore-c/nix_api_store.h
@@ -26,7 +26,7 @@ typedef struct StorePath StorePath;
 /** @brief Nix Derivation */
 typedef struct nix_derivation nix_derivation;
 /** @brief Nix Derivation Output */
-typedef struct nix_derivation_output nix_derivation_noutput;
+typedef struct nix_derivation_output nix_derivation_output;
 
 /**
  * @brief Initializes the Nix store library
@@ -295,7 +295,7 @@ nix_err nix_store_get_fs_closure(
     void * userdata,
     void (*callback)(void * userdata, const StorePath * store_path));
 
-/*
+/**
  * @brief Returns the derivation associated with the store path
  *
  * @note The callback borrows the Derivation only for the duration of the call.
@@ -392,7 +392,7 @@ nix_err nix_derivation_get_outputs_and_optpaths(
  * @param[in] drv The derivation
  * @param[in] store The nix store
  * @param[in] callback Called with the JSON string
- * @param[in] user_data Arbitrary data passed to the callback
+ * @param[in] userdata Arbitrary data passed to the callback
  */
 nix_err nix_derivation_to_json(
     nix_c_context * context,

From b2fff1560cc2fced15f31281738fbe97e42f44f8 Mon Sep 17 00:00:00 2001
From: Tristan Ross <tristan.ross@determinate.systems>
Date: Tue, 23 Sep 2025 16:05:12 -0700
Subject: [PATCH 11/13] libstore-c: make nix_derivation_to_json not require
 store

---
 src/libstore-c/nix_api_store.cc         | 14 +++++---------
 src/libstore-c/nix_api_store.h          |  7 +------
 src/libstore-c/nix_api_store_internal.h |  1 +
 3 files changed, 7 insertions(+), 15 deletions(-)

diff --git a/src/libstore-c/nix_api_store.cc b/src/libstore-c/nix_api_store.cc
index f8303edd330..60fd6e5df12 100644
--- a/src/libstore-c/nix_api_store.cc
+++ b/src/libstore-c/nix_api_store.cc
@@ -176,7 +176,7 @@ StorePath * nix_store_path_clone(const StorePath * p)
 
 nix_derivation * nix_derivation_clone(const nix_derivation * d)
 {
-    return new nix_derivation{d->drv};
+    return new nix_derivation{d->drv, d->store};
 }
 
 nix_derivation * nix_derivation_from_json(nix_c_context * context, Store * store, const char * json)
@@ -190,7 +190,7 @@ nix_derivation * nix_derivation_from_json(nix_c_context * context, Store * store
 
         drv.checkInvariants(*store->ptr, drvPath);
 
-        return new nix_derivation{drv};
+        return new nix_derivation{drv, store};
     }
     NIXC_CATCH_ERRS_NULL
 }
@@ -284,7 +284,7 @@ nix_err nix_store_drv_from_path(
     try {
         nix::Derivation drv = store->ptr->derivationFromPath(path->path);
         if (callback) {
-            const nix_derivation tmp{drv};
+            const nix_derivation tmp{drv, store};
             callback(userdata, &tmp);
         }
     }
@@ -391,16 +391,12 @@ nix_err nix_derivation_get_outputs_and_optpaths(
 }
 
 nix_err nix_derivation_to_json(
-    nix_c_context * context,
-    const nix_derivation * drv,
-    const Store * store,
-    nix_get_string_callback callback,
-    void * userdata)
+    nix_c_context * context, const nix_derivation * drv, nix_get_string_callback callback, void * userdata)
 {
     if (context)
         context->last_err_code = NIX_OK;
     try {
-        auto result = drv->drv.toJSON(store->ptr->config).dump();
+        auto result = drv->drv.toJSON(drv->store->ptr->config).dump();
         if (callback) {
             callback(result.data(), result.size(), userdata);
         }
diff --git a/src/libstore-c/nix_api_store.h b/src/libstore-c/nix_api_store.h
index 37226cbac0d..2fe4088b34a 100644
--- a/src/libstore-c/nix_api_store.h
+++ b/src/libstore-c/nix_api_store.h
@@ -390,16 +390,11 @@ nix_err nix_derivation_get_outputs_and_optpaths(
  *
  * @param[out] context Optional, stores error information
  * @param[in] drv The derivation
- * @param[in] store The nix store
  * @param[in] callback Called with the JSON string
  * @param[in] userdata Arbitrary data passed to the callback
  */
 nix_err nix_derivation_to_json(
-    nix_c_context * context,
-    const nix_derivation * drv,
-    const Store * store,
-    nix_get_string_callback callback,
-    void * userdata);
+    nix_c_context * context, const nix_derivation * drv, nix_get_string_callback callback, void * userdata);
 
 /**
  * @brief Copy of a 'nix_derivation_output'
diff --git a/src/libstore-c/nix_api_store_internal.h b/src/libstore-c/nix_api_store_internal.h
index 070bb1229cd..26456a02329 100644
--- a/src/libstore-c/nix_api_store_internal.h
+++ b/src/libstore-c/nix_api_store_internal.h
@@ -16,6 +16,7 @@ struct StorePath
 struct nix_derivation
 {
     nix::Derivation drv;
+    Store * store;
 };
 
 struct nix_derivation_output

From d7ce10113790158d36f550fbec34d4d50cfc7974 Mon Sep 17 00:00:00 2001
From: Tristan Ross <tristan.ross@determinate.systems>
Date: Fri, 26 Sep 2025 14:11:37 -0700
Subject: [PATCH 12/13] libstore-c: make nix_store_query_path_info return json
 formatted

---
 src/libstore-c/nix_api_store.cc | 10 +++-------
 src/libstore-c/nix_api_store.h  |  2 +-
 2 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/src/libstore-c/nix_api_store.cc b/src/libstore-c/nix_api_store.cc
index 60fd6e5df12..3f4a912486f 100644
--- a/src/libstore-c/nix_api_store.cc
+++ b/src/libstore-c/nix_api_store.cc
@@ -296,19 +296,15 @@ nix_err nix_store_query_path_info(
     Store * store,
     const StorePath * store_path,
     void * userdata,
-    void (*callback)(void * userdata, const StorePath * derived_path))
+    nix_get_string_callback callback)
 {
     if (context)
         context->last_err_code = NIX_OK;
     try {
         auto info = store->ptr->queryPathInfo(store_path->path);
         if (callback) {
-            if (auto deriver = info->deriver) {
-                const StorePath deriver_tmp{*info->deriver};
-                callback(userdata, &deriver_tmp);
-            } else {
-                callback(userdata, nullptr);
-            }
+            auto result = info->toJSON(store->ptr->config, true, nix::HashFormat::Nix32).dump();
+            callback(result.data(), result.size(), userdata);
         }
     }
     NIXC_CATCH_ERRS
diff --git a/src/libstore-c/nix_api_store.h b/src/libstore-c/nix_api_store.h
index 2fe4088b34a..4077262f841 100644
--- a/src/libstore-c/nix_api_store.h
+++ b/src/libstore-c/nix_api_store.h
@@ -327,7 +327,7 @@ nix_err nix_store_query_path_info(
     Store * store,
     const StorePath * store_path,
     void * userdata,
-    void (*callback)(void * userdata, const StorePath * derived_path));
+    nix_get_string_callback callback);
 
 /**
  * @brief Builds the paths, if they are a derivation then they get built.

From ad566a9e8b86e7273b98e048916f38dc2495dfc2 Mon Sep 17 00:00:00 2001
From: Tristan Ross <tristan.ross@determinate.systems>
Date: Tue, 30 Sep 2025 14:38:57 -0700
Subject: [PATCH 13/13] libstore-c: remove nix_derivation_output

---
 src/libstore-c/nix_api_store.cc         | 38 ++--------------------
 src/libstore-c/nix_api_store.h          | 43 +++----------------------
 src/libstore-c/nix_api_store_internal.h |  5 ---
 3 files changed, 7 insertions(+), 79 deletions(-)

diff --git a/src/libstore-c/nix_api_store.cc b/src/libstore-c/nix_api_store.cc
index 3f4a912486f..338600599e8 100644
--- a/src/libstore-c/nix_api_store.cc
+++ b/src/libstore-c/nix_api_store.cc
@@ -339,31 +339,11 @@ nix_err nix_store_build_paths(
     NIXC_CATCH_ERRS
 }
 
-nix_err nix_derivation_get_outputs(
-    nix_c_context * context,
-    const nix_derivation * drv,
-    void (*callback)(void * userdata, const char * name, const nix_derivation_output * drv_output),
-    void * userdata)
-{
-    if (context)
-        context->last_err_code = NIX_OK;
-    try {
-        if (callback) {
-            for (const auto & [name, result] : drv->drv.outputs) {
-                const nix_derivation_output tmp{result};
-                callback(userdata, name.c_str(), &tmp);
-            }
-        }
-    }
-    NIXC_CATCH_ERRS
-}
-
 nix_err nix_derivation_get_outputs_and_optpaths(
     nix_c_context * context,
     const nix_derivation * drv,
     const Store * store,
-    void (*callback)(
-        void * userdata, const char * name, const nix_derivation_output * drv_output, const StorePath * path),
+    void (*callback)(void * userdata, const char * name, const StorePath * path),
     void * userdata)
 {
     if (context)
@@ -372,13 +352,11 @@ nix_err nix_derivation_get_outputs_and_optpaths(
         auto value = drv->drv.outputsAndOptPaths(store->ptr->config);
         if (callback) {
             for (const auto & [name, result] : value) {
-                const nix_derivation_output tmp_output{result.first};
-
                 if (auto store_path = result.second) {
                     const StorePath tmp_path{*store_path};
-                    callback(userdata, name.c_str(), &tmp_output, &tmp_path);
+                    callback(userdata, name.c_str(), &tmp_path);
                 } else {
-                    callback(userdata, name.c_str(), &tmp_output, nullptr);
+                    callback(userdata, name.c_str(), nullptr);
                 }
             }
         }
@@ -399,13 +377,3 @@ nix_err nix_derivation_to_json(
     }
     NIXC_CATCH_ERRS
 }
-
-nix_derivation_output * nix_derivation_output_clone(const nix_derivation_output * o)
-{
-    return new nix_derivation_output{o->drv_out};
-}
-
-void nix_derivation_output_free(nix_derivation_output * o)
-{
-    delete o;
-}
diff --git a/src/libstore-c/nix_api_store.h b/src/libstore-c/nix_api_store.h
index 4077262f841..64ef7061459 100644
--- a/src/libstore-c/nix_api_store.h
+++ b/src/libstore-c/nix_api_store.h
@@ -25,8 +25,6 @@ typedef struct Store Store;
 typedef struct StorePath StorePath;
 /** @brief Nix Derivation */
 typedef struct nix_derivation nix_derivation;
-/** @brief Nix Derivation Output */
-typedef struct nix_derivation_output nix_derivation_output;
 
 /**
  * @brief Initializes the Nix store library
@@ -318,7 +316,7 @@ nix_err nix_store_drv_from_path(
  *
  * @param[out] context Optional, stores error information
  * @param[in] store nix store reference
- * @param[in] path A store path
+ * @param[in] store_path A store path
  * @param[in] userdata The data to pass to the callback
  * @param[in] callback Called for when the path info is resolved
  */
@@ -351,25 +349,9 @@ nix_err nix_store_build_paths(
     void * userdata);
 
 /**
- * @brief Iterate through all of the outputs in a derivation
+ * @brief Iterate and get all of the store paths for each output.
  *
- * @note The callback borrows the DerivationOutput only for the duration of the call.
- *
- * @param[out] context Optional, stores error information
- * @param[in] drv The derivation
- * @param[in] callback The function to call on every output
- * @param[in] userdata Userdata to pass to the callback
- */
-nix_err nix_derivation_get_outputs(
-    nix_c_context * context,
-    const nix_derivation * drv,
-    void (*callback)(void * userdata, const char * name, const nix_derivation_output * drv_output),
-    void * userdata);
-
-/**
- * @brief Iterate and get all of the derivation outputs and their store paths.
- *
- * @note The callback borrows the DerivationOutput and StorePath only for the duration of the call.
+ * @note The callback borrows the StorePath only for the duration of the call.
  *
  * @param[out] context Optional, stores error information
  * @param[in] drv The derivation
@@ -381,8 +363,7 @@ nix_err nix_derivation_get_outputs_and_optpaths(
     nix_c_context * context,
     const nix_derivation * drv,
     const Store * store,
-    void (*callback)(
-        void * userdata, const char * name, const nix_derivation_output * drv_output, const StorePath * path),
+    void (*callback)(void * userdata, const char * name, const StorePath * path),
     void * userdata);
 
 /**
@@ -396,22 +377,6 @@ nix_err nix_derivation_get_outputs_and_optpaths(
 nix_err nix_derivation_to_json(
     nix_c_context * context, const nix_derivation * drv, nix_get_string_callback callback, void * userdata);
 
-/**
- * @brief Copy of a 'nix_derivation_output'
- *
- * @param[in] o the derivation output to copy
- * @return a new 'nix_derivation_output'
- */
-nix_derivation_output * nix_derivation_output_clone(const nix_derivation_output * o);
-
-/**
- * @brief Deallocate a 'nix_derivation_output'
- *
- * Does not fail.
- * @param[in] o the derivation output to free
- */
-void nix_derivation_output_free(nix_derivation_output * o);
-
 // cffi end
 #ifdef __cplusplus
 }
diff --git a/src/libstore-c/nix_api_store_internal.h b/src/libstore-c/nix_api_store_internal.h
index 26456a02329..73c751791d0 100644
--- a/src/libstore-c/nix_api_store_internal.h
+++ b/src/libstore-c/nix_api_store_internal.h
@@ -19,9 +19,4 @@ struct nix_derivation
     Store * store;
 };
 
-struct nix_derivation_output
-{
-    nix::DerivationOutput drv_out;
-};
-
 #endif