libstore: add C bindings

src/libstore/globals.cc

@@ -404,6 +404,7 @@ void assertLibStoreInitialized() {
 }
 
 void initLibStore() {
+    if (initLibStoreDone) return;
 
     initLibUtil();
 

src/libstore/nix_api_store.cc

@@ -0,0 +1,117 @@
+#include "nix_api_store.h"
+#include "nix_api_store_internal.h"
+#include "nix_api_util.h"
+#include "nix_api_util_internal.h"
+
+#include "store-api.hh"
+
+#include "globals.hh"
+
+struct StorePath {
+  nix::StorePath path;
+};
+
+nix_err nix_libstore_init(nix_c_context *context) {
+  if (context)
+    context->last_err_code = NIX_OK;
+  try {
+    nix::initLibStore();
+  }
+  NIXC_CATCH_ERRS
+}
+
+Store *nix_store_open(nix_c_context *context, const char *uri,
+                      const char ***params) {
+  if (context)
+    context->last_err_code = NIX_OK;
+  try {
+    if (!uri) {
+      return new Store{nix::openStore()};
+    } else {
+      std::string uri_str = uri;
+      if (!params)
+        return new Store{nix::openStore(uri_str)};
+
+      nix::Store::Params params_map;
+      for (size_t i = 0; params[i] != nullptr; i++) {
+        params_map[params[i][0]] = params[i][1];
+      }
+      return new Store{nix::openStore(uri_str, params_map)};
+    }
+  }
+  NIXC_CATCH_ERRS_NULL
+}
+
+void nix_store_unref(Store *store) { delete store; }
+
+nix_err nix_store_get_uri(nix_c_context *context, Store *store, char *dest,
+                          unsigned int n) {
+  if (context)
+    context->last_err_code = NIX_OK;
+  try {
+    auto res = store->ptr->getUri();
+    return nix_export_std_string(context, res, dest, n);
+  }
+  NIXC_CATCH_ERRS
+}
+
+nix_err nix_store_get_version(nix_c_context *context, Store *store, char *dest,
+                              unsigned int n) {
+  if (context)
+    context->last_err_code = NIX_OK;
+  try {
+    auto res = store->ptr->getVersion();
+    if (res) {
+      return nix_export_std_string(context, *res, dest, n);
+    } else {
+      return nix_set_err_msg(context, NIX_ERR_UNKNOWN,
+                             "store does not have a version");
+    }
+  }
+  NIXC_CATCH_ERRS
+}
+
+bool nix_store_is_valid_path(nix_c_context *context, Store *store,
+                             StorePath *path) {
+  if (context)
+    context->last_err_code = NIX_OK;
+  try {
+    return store->ptr->isValidPath(path->path);
+  }
+  NIXC_CATCH_ERRS_RES(false);
+}
+
+StorePath *nix_store_parse_path(nix_c_context *context, Store *store,
+                                const char *path) {
+  if (context)
+    context->last_err_code = NIX_OK;
+  try {
+    nix::StorePath s = store->ptr->parseStorePath(path);
+    return new StorePath{std::move(s)};
+  }
+  NIXC_CATCH_ERRS_NULL
+}
+
+nix_err nix_store_build(nix_c_context *context, Store *store, StorePath *path,
+                        void (*iter)(const char *, const char *)) {
+  if (context)
+    context->last_err_code = NIX_OK;
+  try {
+    store->ptr->buildPaths({
+        nix::DerivedPath::Built{
+            .drvPath = path->path,
+            .outputs = nix::OutputsSpec::All{},
+        },
+    });
+    if (iter) {
+      for (auto &[outputName, outputPath] :
+           store->ptr->queryDerivationOutputMap(path->path)) {
+        auto op = store->ptr->printStorePath(outputPath);
+        iter(outputName.c_str(), op.c_str());
+      }
+    }
+  }
+  NIXC_CATCH_ERRS
+}
+
+void nix_store_path_free(StorePath *sp) { delete sp; }

src/libstore/nix_api_store.h

@@ -0,0 +1,122 @@
+#ifndef NIX_API_STORE_H
+#define NIX_API_STORE_H
+/** @file
+ * @brief Main entry for the libexpr C bindings
+ */
+
+#include "nix_api_util.h"
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+// cffi start
+
+/** @brief reference to a nix store */
+typedef struct Store Store;
+/** @brief nix store path */
+typedef struct StorePath StorePath;
+
+/**
+ * @brief Initializes the Nix store library
+ *
+ * This function should be called before creating a Store
+ * This function can be called multiple times.
+ *
+ * @param[out] context Optional, stores error information
+ * @return NIX_OK if the initialization was successful, an error code otherwise.
+ */
+nix_err nix_libstore_init(nix_c_context *context);
+
+/**
+ * @brief Open a nix store
+ * @param[out] context Optional, stores error information
+ * @param[in] uri URI of the nix store, copied
+ * @param[in] params optional, array of key-value pairs, {{"endpoint",
+ * "https://s3.local"}}
+ * @return ref-counted Store pointer, NULL in case of errors
+ * @see nix_store_unref
+ */
+Store *nix_store_open(nix_c_context *, const char *uri, const char ***params);
+
+/**
+ * @brief Unref a nix store
+ *
+ * Does not fail.
+ * It'll be closed and deallocated when all references are gone.
+ * @param[in] builder the store to unref
+ */
+void nix_store_unref(Store *store);
+
+/**
+ * @brief get the URI of a nix store
+ * @param[out] context Optional, stores error information
+ * @param[in] store nix store reference
+ * @param[out] dest The allocated area to write the string to.
+ * @param[in] n Maximum size of the returned string.
+ * @return error code, NIX_OK on success.
+ */
+nix_err nix_store_get_uri(nix_c_context *context, Store *store, char *dest,
+                          unsigned int n);
+
+// returns: owned StorePath*
+/**
+ * @brief parse a nix store path into a StorePath
+ *
+ * Don't forget to free this path using nix_store_path_free
+ * @param[out] context Optional, stores error information
+ * @param[in] store nix store reference
+ * @param[in] path Path string to parse, copied
+ * @return owned store path, NULL on error
+ */
+StorePath *nix_store_parse_path(nix_c_context *context, Store *store,
+                                const char *path);
+
+/** @brief Deallocate a nix StorePath
+ *
+ * Does not fail.
+ * @param[in] p the path to free
+ */
+void nix_store_path_free(StorePath *p);
+
+/**
+ * @brief check if a storepath is valid (exists in the store)
+ * @param[out] context Optional, stores error information
+ * @param[in] store nix store reference
+ * @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);
+// nix_err nix_store_ensure(Store*, const char*);
+// nix_err nix_store_build_paths(Store*);
+/**
+ * @brief Build a nix store path
+ *
+ * Blocking, calls cb once for each built output
+ *
+ * @param[out] context Optional, stores error information
+ * @param[in] store nix store reference
+ * @param[in] path Path to build
+ * @param[in] cb called for every built output
+ */
+nix_err nix_store_build(nix_c_context *context, Store *store, StorePath *path,
+                        void (*cb)(const char *outname, const char *out));
+
+/**
+ * @brief get the version of a nix store
+ * @param[out] context Optional, stores error information
+ * @param[in] store nix store reference
+ * @param[out] dest The allocated area to write the string to.
+ * @param[in] n Maximum size of the returned string.
+ * @return error code, NIX_OK on success.
+ */
+nix_err nix_store_get_version(nix_c_context *, Store *store, char *dest,
+                              unsigned int n);
+
+// cffi end
+#ifdef __cplusplus
+}
+#endif
+
+#endif // NIX_API_STORE_H

src/libstore/nix_api_store_internal.h

@@ -0,0 +1,8 @@
+#ifndef NIX_API_STORE_INTERNAL_H
+#define NIX_API_STORE_INTERNAL_H
+#include "store-api.hh"
+
+struct Store {
+  nix::ref<nix::Store> ptr;
+};
+#endif