Move /src to /subprojects

This will facilitate breaking up Nix into multiple packages for each
component with Meson.

subprojects/libstore-c/.version

@@ -0,0 +1 @@
+../../.version

subprojects/libstore-c/build-utils-meson

@@ -0,0 +1 @@
+../../build-utils-meson

subprojects/libstore-c/local.mk

@@ -0,0 +1,21 @@
+libraries += libstorec
+
+libstorec_NAME = libnixstorec
+
+libstorec_DIR := $(d)
+
+libstorec_SOURCES := $(wildcard $(d)/*.cc)
+
+libstorec_LIBS = libutil libstore libutilc
+
+libstorec_LDFLAGS += $(THREAD_LDFLAGS)
+
+# Not just for this library itself, but also for downstream libraries using this library
+
+INCLUDE_libstorec := -I $(d)
+libstorec_CXXFLAGS += $(INCLUDE_libutil) $(INCLUDE_libutilc) \
+		    $(INCLUDE_libstore) $(INCLUDE_libstorec)
+
+$(eval $(call install-file-in, $(d)/nix-store-c.pc, $(libdir)/pkgconfig, 0644))
+
+libstorec_FORCE_INSTALL := 1

subprojects/libstore-c/meson.build

@@ -0,0 +1,85 @@
+project('nix-store-c', 'cpp',
+  version : files('.version'),
+  default_options : [
+    'cpp_std=c++2a',
+    # TODO(Qyriad): increase the warning level
+    'warning_level=1',
+    'debug=true',
+    'optimization=2',
+    'errorlogs=true', # Please print logs for tests that fail
+  ],
+  meson_version : '>= 1.1',
+  license : 'LGPL-2.1-or-later',
+)
+
+cxx = meson.get_compiler('cpp')
+
+subdir('build-utils-meson/deps-lists')
+
+configdata = configuration_data()
+
+deps_private_maybe_subproject = [
+  dependency('nix-util'),
+  dependency('nix-store'),
+]
+deps_public_maybe_subproject = [
+  dependency('nix-util-c'),
+]
+subdir('build-utils-meson/subprojects')
+
+subdir('build-utils-meson/threads')
+
+# TODO rename, because it will conflict with downstream projects
+configdata.set_quoted('PACKAGE_VERSION', meson.project_version())
+
+config_h = configure_file(
+  configuration : configdata,
+  output : 'config-store.h',
+)
+
+add_project_arguments(
+  # TODO(Qyriad): Yes this is how the autoconf+Make system did it.
+  # It would be nice for our headers to be idempotent instead.
+
+  # From C++ libraries, only for internals
+  '-include', 'config-util.hh',
+  '-include', 'config-store.hh',
+
+  # From C libraries, for our public, installed headers too
+  '-include', 'config-util.h',
+  '-include', 'config-store.h',
+  language : 'cpp',
+)
+
+subdir('build-utils-meson/diagnostics')
+
+sources = files(
+  'nix_api_store.cc',
+)
+
+include_dirs = [include_directories('.')]
+
+headers = [config_h] + files(
+  'nix_api_store.h',
+)
+
+# TODO don't install this once tests don't use it and/or move the header into `libstore`, non-`c`
+headers += files('nix_api_store_internal.h')
+
+subdir('build-utils-meson/export-all-symbols')
+
+this_library = library(
+  'nixstorec',
+  sources,
+  dependencies : deps_public + deps_private + deps_other,
+  include_directories : include_dirs,
+  link_args: linker_export_flags,
+  prelink : true, # For C++ static initializers
+  install : true,
+)
+
+install_headers(headers, subdir : 'nix', preserve_path : true)
+
+libraries_private = []
+
+subdir('build-utils-meson/export')

subprojects/libstore-c/nix-store-c.pc.in

@@ -0,0 +1,9 @@
+prefix=@prefix@
+libdir=@libdir@
+includedir=@includedir@
+
+Name: Nix
+Description: Nix Store - C API
+Version: @PACKAGE_VERSION@
+Libs: -L${libdir} -lnixstorec -lnixutilc
+Cflags: -I${includedir}/nix

subprojects/libstore-c/nix_api_store.cc

@@ -0,0 +1,158 @@
+#include "nix_api_store.h"
+#include "nix_api_store_internal.h"
+#include "nix_api_util.h"
+#include "nix_api_util_internal.h"
+
+#include "path.hh"
+#include "store-api.hh"
+#include "build-result.hh"
+
+#include "globals.hh"
+
+nix_err nix_libstore_init(nix_c_context * context)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    try {
+        nix::initLibStore();
+    }
+    NIXC_CATCH_ERRS
+}
+
+nix_err nix_libstore_init_no_load_config(nix_c_context * context)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    try {
+        nix::initLibStore(false);
+    }
+    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 {
+        std::string uri_str = uri ? uri : "";
+
+        if (uri_str.empty())
+            return new Store{nix::openStore()};
+
+        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_free(Store * store)
+{
+    delete store;
+}
+
+nix_err nix_store_get_uri(nix_c_context * context, Store * store, nix_get_string_callback callback, void * user_data)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    try {
+        auto res = store->ptr->getUri();
+        return call_nix_get_string_callback(res, callback, user_data);
+    }
+    NIXC_CATCH_ERRS
+}
+
+nix_err
+nix_store_get_version(nix_c_context * context, Store * store, nix_get_string_callback callback, void * user_data)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    try {
+        auto res = store->ptr->getVersion();
+        return call_nix_get_string_callback(res.value_or(""), callback, user_data);
+    }
+    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_realise(
+    nix_c_context * context,
+    Store * store,
+    StorePath * path,
+    void * userdata,
+    void (*callback)(void * userdata, const char *, const char *))
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    try {
+
+        const std::vector<nix::DerivedPath> paths{nix::DerivedPath::Built{
+            .drvPath = nix::makeConstantStorePathRef(path->path), .outputs = nix::OutputsSpec::All{}}};
+
+        const auto nixStore = store->ptr;
+        auto results = nixStore->buildPathsWithResults(paths, nix::bmNormal, nixStore);
+
+        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());
+                }
+            }
+        }
+    }
+    NIXC_CATCH_ERRS
+}
+
+void nix_store_path_name(const StorePath * store_path, nix_get_string_callback callback, void * user_data)
+{
+    std::string_view name = store_path->path.name();
+    callback(name.data(), name.size(), user_data);
+}
+
+void nix_store_path_free(StorePath * sp)
+{
+    delete sp;
+}
+
+StorePath * nix_store_path_clone(const StorePath * p)
+{
+    return new StorePath{p->path};
+}
+
+nix_err nix_store_copy_closure(nix_c_context * context, Store * srcStore, Store * dstStore, StorePath * path)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    try {
+        nix::RealisedPath::Set paths;
+        paths.insert(path->path);
+        nix::copyClosure(*srcStore->ptr, *dstStore->ptr, paths);
+    }
+    NIXC_CATCH_ERRS
+}

subprojects/libstore-c/nix_api_store.h

@@ -0,0 +1,181 @@
+#ifndef NIX_API_STORE_H
+#define NIX_API_STORE_H
+/**
+ * @defgroup libstore libstore
+ * @brief C bindings for nix libstore
+ *
+ * libstore is used for talking to a Nix store
+ * @{
+ */
+/** @file
+ * @brief Main entry for the libstore 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 Like nix_libstore_init, but does not load the Nix configuration.
+ *
+ * This is useful when external configuration is not desired, such as when running unit tests.
+ */
+nix_err nix_libstore_init_no_load_config(nix_c_context * context);
+
+/**
+ * @brief Open a nix store.
+ *
+ * Store instances may share state and resources behind the scenes.
+ *
+ * @param[out] context Optional, stores error information
+ * @param[in] uri URI of the Nix store, copied. See [*Store URL format* in the Nix Reference
+ * Manual](https://nixos.org/manual/nix/stable/store/types/#store-url-format).
+ * @param[in] params optional, null-terminated array of key-value pairs, e.g. {{"endpoint",
+ * "https://s3.local"}}. See [*Store Types* in the Nix Reference
+ * Manual](https://nixos.org/manual/nix/stable/store/types).
+ * @return a Store pointer, NULL in case of errors
+ * @see nix_store_free
+ */
+Store * nix_store_open(nix_c_context * context, const char * uri, const char *** params);
+
+/**
+ * @brief Deallocate a nix store and free any resources if not also held by other Store instances.
+ *
+ * Does not fail.
+ *
+ * @param[in] store the store to free
+ */
+void nix_store_free(Store * store);
+
+/**
+ * @brief get the URI of a nix store
+ * @param[out] context Optional, stores error information
+ * @param[in] store nix store reference
+ * @param[in] callback Called with the URI.
+ * @param[in] user_data optional, arbitrary data, passed to the callback when it's called.
+ * @see nix_get_string_callback
+ * @return error code, NIX_OK on success.
+ */
+nix_err nix_store_get_uri(nix_c_context * context, Store * store, nix_get_string_callback callback, void * user_data);
+
+// returns: owned StorePath*
+/**
+ * @brief Parse a Nix store path into a StorePath
+ *
+ * @note 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 Get the path name (e.g. "name" in /nix/store/...-name)
+ *
+ * @param[in] store_path the path to get the name from
+ * @param[in] callback called with the name
+ * @param[in] user_data arbitrary data, passed to the callback when it's called.
+ */
+void nix_store_path_name(const StorePath * store_path, nix_get_string_callback callback, void * user_data);
+
+/**
+ * @brief Copy a StorePath
+ *
+ * @param[in] p the path to copy
+ * @return a new StorePath
+ */
+StorePath * nix_store_path_clone(const StorePath * p);
+
+/** @brief Deallocate a 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 (i.e. that corresponding store object and its closure of references 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 Realise a Nix store path
+ *
+ * Blocking, calls callback once for each realised output.
+ *
+ * @note When working with expressions, consider using e.g. nix_string_realise to get the output. `.drvPath` may not be
+ * accurate or available in the future. See https://github.com/NixOS/nix/issues/6507
+ *
+ * @param[out] context Optional, stores error information
+ * @param[in] store Nix Store reference
+ * @param[in] path Path to build
+ * @param[in] userdata data to pass to every callback invocation
+ * @param[in] callback called for every realised output
+ */
+nix_err nix_store_realise(
+    nix_c_context * context,
+    Store * store,
+    StorePath * path,
+    void * userdata,
+    void (*callback)(void * userdata, const char * outname, const char * out));
+
+/**
+ * @brief get the version of a nix store.
+ *
+ * If the store doesn't have a version (like the dummy store), returns an empty string.
+ *
+ * @param[out] context Optional, stores error information
+ * @param[in] store nix store reference
+ * @param[in] callback Called with the version.
+ * @param[in] user_data optional, arbitrary data, passed to the callback when it's called.
+ * @see nix_get_string_callback
+ * @return error code, NIX_OK on success.
+ */
+nix_err
+nix_store_get_version(nix_c_context * context, Store * store, nix_get_string_callback callback, void * user_data);
+
+/**
+ * @brief Copy the closure of `path` from `srcStore` to `dstStore`.
+ *
+ * @param[out] context Optional, stores error information
+ * @param[in] srcStore nix source store reference
+ * @param[in] srcStore nix destination store reference
+ * @param[in] path Path to copy
+ */
+nix_err nix_store_copy_closure(nix_c_context * context, Store * srcStore, Store * dstStore, StorePath * path);
+
+// cffi end
+#ifdef __cplusplus
+}
+#endif
+/**
+ * @}
+ */
+#endif // NIX_API_STORE_H

subprojects/libstore-c/nix_api_store_internal.h

@@ -0,0 +1,15 @@
+#ifndef NIX_API_STORE_INTERNAL_H
+#define NIX_API_STORE_INTERNAL_H
+#include "store-api.hh"
+
+struct Store
+{
+    nix::ref<nix::Store> ptr;
+};
+
+struct StorePath
+{
+    nix::StorePath path;
+};
+
+#endif

subprojects/libstore-c/package.nix

@@ -0,0 +1,75 @@
+{ lib
+, stdenv
+, mkMesonDerivation
+, releaseTools
+
+, meson
+, ninja
+, pkg-config
+
+, nix-util-c
+, nix-store
+
+# Configuration Options
+
+, version
+}:
+
+let
+  inherit (lib) fileset;
+in
+
+mkMesonDerivation (finalAttrs: {
+  pname = "nix-store-c";
+  inherit version;
+
+  workDir = ./.;
+  fileset = fileset.unions [
+    ../../build-utils-meson
+    ./build-utils-meson
+    ../../.version
+    ./.version
+    ./meson.build
+    # ./meson.options
+    (fileset.fileFilter (file: file.hasExt "cc") ./.)
+    (fileset.fileFilter (file: file.hasExt "hh") ./.)
+    (fileset.fileFilter (file: file.hasExt "h") ./.)
+  ];
+
+  outputs = [ "out" "dev" ];
+
+  nativeBuildInputs = [
+    meson
+    ninja
+    pkg-config
+  ];
+
+  propagatedBuildInputs = [
+    nix-util-c
+    nix-store
+  ];
+
+  preConfigure =
+    # "Inline" .version so it's not a symlink, and includes the suffix.
+    # Do the meson utils, without modification.
+    ''
+      chmod u+w ./.version
+      echo ${version} > ../../.version
+    '';
+
+  mesonFlags = [
+  ];
+
+  env = lib.optionalAttrs (stdenv.isLinux && !(stdenv.hostPlatform.isStatic && stdenv.system == "aarch64-linux")) {
+    LDFLAGS = "-fuse-ld=gold";
+  };
+
+  separateDebugInfo = !stdenv.hostPlatform.isStatic;
+
+  hardeningDisable = lib.optional stdenv.hostPlatform.isStatic "pie";
+
+  meta = {
+    platforms = lib.platforms.unix ++ lib.platforms.windows;
+  };
+
+})