Merge pull request #11014 from obsidiansystems/plugins-libmain

Move plugins infra to `libnixmain`

meson.build

@@ -26,6 +26,7 @@ subproject('external-api-docs')
 subproject('libutil-c')
 subproject('libstore-c')
 subproject('libexpr-c')
+subproject('libmain-c')
 
 # Language Bindings
 subproject('perl')

packaging/components.nix

@@ -29,6 +29,7 @@ in
   nix-flake-tests = callPackage ../tests/unit/libflake/package.nix { };
 
   nix-main = callPackage ../src/libmain/package.nix { };
+  nix-main-c = callPackage ../src/libmain-c/package.nix { };
 
   nix-cmd = callPackage ../src/libcmd/package.nix { };
 

packaging/hydra.nix

@@ -52,6 +52,7 @@ let
     "nix-flake"
     "nix-flake-tests"
     "nix-main"
+    "nix-main-c"
     "nix-cmd"
     "nix-ng"
   ];

src/build-remote/build-remote.cc

@@ -11,6 +11,7 @@
 
 #include "machines.hh"
 #include "shared.hh"
+#include "plugin.hh"
 #include "pathlocks.hh"
 #include "globals.hh"
 #include "serialise.hh"

src/libmain-c/.version

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

src/libmain-c/build-utils-meson

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

src/libmain-c/meson.build

@@ -0,0 +1,84 @@
+project('nix-main-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'),
+  dependency('nix-main'),
+]
+deps_public_maybe_subproject = [
+  dependency('nix-util-c'),
+  dependency('nix-store-c'),
+]
+subdir('build-utils-meson/subprojects')
+
+# 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-main.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',
+  '-include', 'config-main.hh',
+
+  # From C libraries, for our public, installed headers too
+  '-include', 'config-util.h',
+  '-include', 'config-store.h',
+  '-include', 'config-main.h',
+  language : 'cpp',
+)
+
+subdir('build-utils-meson/diagnostics')
+
+sources = files(
+  'nix_api_main.cc',
+)
+
+include_dirs = [include_directories('.')]
+
+headers = [config_h] + files(
+  'nix_api_main.h',
+)
+
+subdir('build-utils-meson/export-all-symbols')
+
+this_library = library(
+  'nixmainc',
+  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')

src/libmain-c/nix_api_main.cc

@@ -0,0 +1,16 @@
+#include "nix_api_store.h"
+#include "nix_api_store_internal.h"
+#include "nix_api_util.h"
+#include "nix_api_util_internal.h"
+
+#include "plugin.hh"
+
+nix_err nix_init_plugins(nix_c_context * context)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    try {
+        nix::initPlugins();
+    }
+    NIXC_CATCH_ERRS
+}

src/libmain-c/nix_api_main.h

@@ -0,0 +1,40 @@
+#ifndef NIX_API_MAIN_H
+#define NIX_API_MAIN_H
+/**
+ * @defgroup libmain libmain
+ * @brief C bindings for nix libmain
+ *
+ * libmain has misc utilities for CLI commands
+ * @{
+ */
+/** @file
+ * @brief Main entry for the libmain C bindings
+ */
+
+#include "nix_api_util.h"
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+// cffi start
+
+/**
+ * @brief Loads the plugins specified in Nix's plugin-files setting.
+ *
+ * Call this once, after calling your desired init functions and setting
+ * relevant settings.
+ *
+ * @param[out] context Optional, stores error information
+ * @return NIX_OK if the initialization was successful, an error code otherwise.
+ */
+nix_err nix_init_plugins(nix_c_context * context);
+
+// cffi end
+#ifdef __cplusplus
+}
+#endif
+/**
+ * @}
+ */
+#endif // NIX_API_MAIN_H

src/libmain-c/package.nix

@@ -0,0 +1,83 @@
+{ lib
+, stdenv
+, mkMesonDerivation
+, releaseTools
+
+, meson
+, ninja
+, pkg-config
+
+, nix-util-c
+, nix-store
+, nix-store-c
+, nix-main
+
+# Configuration Options
+
+, version
+}:
+
+let
+  inherit (lib) fileset;
+in
+
+mkMesonDerivation (finalAttrs: {
+  pname = "nix-main-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
+    nix-store-c
+    nix-main
+  ];
+
+  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";
+  };
+
+  enableParallelBuilding = true;
+
+  separateDebugInfo = !stdenv.hostPlatform.isStatic;
+
+  strictDeps = true;
+
+  hardeningDisable = lib.optional stdenv.hostPlatform.isStatic "pie";
+
+  meta = {
+    platforms = lib.platforms.unix ++ lib.platforms.windows;
+  };
+
+})

src/libmain/common-args.cc

@@ -5,6 +5,7 @@
 #include "logging.hh"
 #include "loggers.hh"
 #include "util.hh"
+#include "plugin.hh"
 
 namespace nix {
 

src/libmain/meson.build

@@ -64,6 +64,7 @@ subdir('build-utils-meson/diagnostics')
 sources = files(
   'common-args.cc',
   'loggers.cc',
+  'plugin.cc',
   'progress-bar.cc',
   'shared.cc',
 )
@@ -79,6 +80,7 @@ include_dirs = [include_directories('.')]
 headers = [config_h] + files(
   'common-args.hh',
   'loggers.hh',
+  'plugin.hh',
   'progress-bar.hh',
   'shared.hh',
 )

src/libmain/plugin.cc

@@ -0,0 +1,117 @@
+#ifndef _WIN32
+#  include <dlfcn.h>
+#endif
+
+#include "config-global.hh"
+#include "signals.hh"
+
+namespace nix {
+
+struct PluginFilesSetting : public BaseSetting<Paths>
+{
+    bool pluginsLoaded = false;
+
+    PluginFilesSetting(
+        Config * options,
+        const Paths & def,
+        const std::string & name,
+        const std::string & description,
+        const std::set<std::string> & aliases = {})
+        : BaseSetting<Paths>(def, true, name, description, aliases)
+    {
+        options->addSetting(this);
+    }
+
+    Paths parse(const std::string & str) const override;
+};
+
+Paths PluginFilesSetting::parse(const std::string & str) const
+{
+    if (pluginsLoaded)
+        throw UsageError(
+            "plugin-files set after plugins were loaded, you may need to move the flag before the subcommand");
+    return BaseSetting<Paths>::parse(str);
+}
+
+struct PluginSettings : Config
+{
+    PluginFilesSetting pluginFiles{
+        this,
+        {},
+        "plugin-files",
+        R"(
+          A list of plugin files to be loaded by Nix. Each of these files will
+          be dlopened by Nix. If they contain the symbol `nix_plugin_entry()`,
+          this symbol will be called. Alternatively, they can affect execution
+          through static initialization. In particular, these plugins may construct
+          static instances of RegisterPrimOp to add new primops or constants to the
+          expression language, RegisterStoreImplementation to add new store
+          implementations, RegisterCommand to add new subcommands to the `nix`
+          command, and RegisterSetting to add new nix config settings. See the
+          constructors for those types for more details.
+
+          Warning! These APIs are inherently unstable and may change from
+          release to release.
+
+          Since these files are loaded into the same address space as Nix
+          itself, they must be DSOs compatible with the instance of Nix
+          running at the time (i.e. compiled against the same headers, not
+          linked to any incompatible libraries). They should not be linked to
+          any Nix libs directly, as those will be available already at load
+          time.
+
+          If an entry in the list is a directory, all files in the directory
+          are loaded as plugins (non-recursively).
+        )"};
+};
+
+static PluginSettings pluginSettings;
+
+static GlobalConfig::Register rPluginSettings(&pluginSettings);
+
+void initPlugins()
+{
+    assert(!pluginSettings.pluginFiles.pluginsLoaded);
+    for (const auto & pluginFile : pluginSettings.pluginFiles.get()) {
+        std::vector<std::filesystem::path> pluginFiles;
+        try {
+            auto ents = std::filesystem::directory_iterator{pluginFile};
+            for (const auto & ent : ents) {
+                checkInterrupt();
+                pluginFiles.emplace_back(ent.path());
+            }
+        } catch (std::filesystem::filesystem_error & e) {
+            if (e.code() != std::errc::not_a_directory)
+                throw;
+            pluginFiles.emplace_back(pluginFile);
+        }
+        for (const auto & file : pluginFiles) {
+            checkInterrupt();
+            /* handle is purposefully leaked as there may be state in the
+               DSO needed by the action of the plugin. */
+#ifndef _WIN32 // TODO implement via DLL loading on Windows
+            void * handle = dlopen(file.c_str(), RTLD_LAZY | RTLD_LOCAL);
+            if (!handle)
+                throw Error("could not dynamically open plugin file '%s': %s", file, dlerror());
+
+            /* Older plugins use a statically initialized object to run their code.
+               Newer plugins can also export nix_plugin_entry() */
+            void (*nix_plugin_entry)() = (void (*)()) dlsym(handle, "nix_plugin_entry");
+            if (nix_plugin_entry)
+                nix_plugin_entry();
+#else
+            throw Error("could not dynamically open plugin file '%s'", file);
+#endif
+        }
+    }
+
+    /* Since plugins can add settings, try to re-apply previously
+       unknown settings. */
+    globalConfig.reapplyUnknownSettings();
+    globalConfig.warnUnknownSettings();
+
+    /* Tell the user if they try to set plugin-files after we've already loaded */
+    pluginSettings.pluginFiles.pluginsLoaded = true;
+}
+
+}

src/libmain/plugin.hh

@@ -0,0 +1,12 @@
+#pragma once
+///@file
+
+namespace nix {
+
+/**
+ * This should be called after settings are initialized, but before
+ * anything else
+ */
+void initPlugins();
+
+}

src/libstore-c/nix_api_store.cc

@@ -29,16 +29,6 @@ nix_err nix_libstore_init_no_load_config(nix_c_context * context)
     NIXC_CATCH_ERRS
 }
 
-nix_err nix_init_plugins(nix_c_context * context)
-{
-    if (context)
-        context->last_err_code = NIX_OK;
-    try {
-        nix::initPlugins();
-    }
-    NIXC_CATCH_ERRS
-}
-
 Store * nix_store_open(nix_c_context * context, const char * uri, const char *** params)
 {
     if (context)

src/libstore-c/nix_api_store.h

@@ -42,17 +42,6 @@ nix_err nix_libstore_init(nix_c_context * context);
  */
 nix_err nix_libstore_init_no_load_config(nix_c_context * context);
 
-/**
- * @brief Loads the plugins specified in Nix's plugin-files setting.
- *
- * Call this once, after calling your desired init functions and setting
- * relevant settings.
- *
- * @param[out] context Optional, stores error information
- * @return NIX_OK if the initialization was successful, an error code otherwise.
- */
-nix_err nix_init_plugins(nix_c_context * context);
-
 /**
  * @brief Open a nix store.
  *

src/libstore/daemon.cc

@@ -246,8 +246,7 @@ struct ClientSettings
                     // the daemon, as that could cause some pretty weird stuff
                     if (parseFeatures(tokenizeString<StringSet>(value)) != experimentalFeatureSettings.experimentalFeatures.get())
                         debug("Ignoring the client-specified experimental features");
-                } else if (name == settings.pluginFiles.name) {
-                    if (tokenizeString<Paths>(value) != settings.pluginFiles.get())
+                } else if (name == "plugin-files") {
                     warn("Ignoring the client-specified plugin-files.\n"
                          "The client specifying plugins to the daemon never made sense, and was removed in Nix >=2.14.");
                 }

src/libstore/globals.cc

@@ -15,7 +15,6 @@
 #include <nlohmann/json.hpp>
 
 #ifndef _WIN32
-# include <dlfcn.h>
 # include <sys/utsname.h>
 #endif
 
@@ -335,60 +334,6 @@ unsigned int MaxBuildJobsSetting::parse(const std::string & str) const
 }
 
 
-Paths PluginFilesSetting::parse(const std::string & str) const
-{
-    if (pluginsLoaded)
-        throw UsageError("plugin-files set after plugins were loaded, you may need to move the flag before the subcommand");
-    return BaseSetting<Paths>::parse(str);
-}
-
-
-void initPlugins()
-{
-    assert(!settings.pluginFiles.pluginsLoaded);
-    for (const auto & pluginFile : settings.pluginFiles.get()) {
-        std::vector<std::filesystem::path> pluginFiles;
-        try {
-            auto ents = std::filesystem::directory_iterator{pluginFile};
-            for (const auto & ent : ents) {
-                checkInterrupt();
-                pluginFiles.emplace_back(ent.path());
-            }
-        } catch (std::filesystem::filesystem_error & e) {
-            if (e.code() != std::errc::not_a_directory)
-                throw;
-            pluginFiles.emplace_back(pluginFile);
-        }
-        for (const auto & file : pluginFiles) {
-            checkInterrupt();
-            /* handle is purposefully leaked as there may be state in the
-               DSO needed by the action of the plugin. */
-#ifndef _WIN32 // TODO implement via DLL loading on Windows
-            void *handle =
-                dlopen(file.c_str(), RTLD_LAZY | RTLD_LOCAL);
-            if (!handle)
-                throw Error("could not dynamically open plugin file '%s': %s", file, dlerror());
-
-            /* Older plugins use a statically initialized object to run their code.
-               Newer plugins can also export nix_plugin_entry() */
-            void (*nix_plugin_entry)() = (void (*)())dlsym(handle, "nix_plugin_entry");
-            if (nix_plugin_entry)
-                nix_plugin_entry();
-#else
-                throw Error("could not dynamically open plugin file '%s'", file);
-#endif
-        }
-    }
-
-    /* Since plugins can add settings, try to re-apply previously
-       unknown settings. */
-    globalConfig.reapplyUnknownSettings();
-    globalConfig.warnUnknownSettings();
-
-    /* Tell the user if they try to set plugin-files after we've already loaded */
-    settings.pluginFiles.pluginsLoaded = true;
-}
-
 static void preloadNSS()
 {
     /* builtin:fetchurl can trigger a DNS lookup, which with glibc can trigger a dynamic library load of

src/libstore/globals.hh

@@ -31,23 +31,6 @@ struct MaxBuildJobsSetting : public BaseSetting<unsigned int>
     unsigned int parse(const std::string & str) const override;
 };
 
-struct PluginFilesSetting : public BaseSetting<Paths>
-{
-    bool pluginsLoaded = false;
-
-    PluginFilesSetting(Config * options,
-        const Paths & def,
-        const std::string & name,
-        const std::string & description,
-        const std::set<std::string> & aliases = {})
-        : BaseSetting<Paths>(def, true, name, description, aliases)
-    {
-        options->addSetting(this);
-    }
-
-    Paths parse(const std::string & str) const override;
-};
-
 const uint32_t maxIdsPerBuild =
     #if __linux__
     1 << 16
@@ -1158,33 +1141,6 @@ public:
     Setting<uint64_t> minFreeCheckInterval{this, 5, "min-free-check-interval",
         "Number of seconds between checking free disk space."};
 
-    PluginFilesSetting pluginFiles{
-        this, {}, "plugin-files",
-        R"(
-          A list of plugin files to be loaded by Nix. Each of these files will
-          be dlopened by Nix. If they contain the symbol `nix_plugin_entry()`,
-          this symbol will be called. Alternatively, they can affect execution
-          through static initialization. In particular, these plugins may construct
-          static instances of RegisterPrimOp to add new primops or constants to the
-          expression language, RegisterStoreImplementation to add new store
-          implementations, RegisterCommand to add new subcommands to the `nix`
-          command, and RegisterSetting to add new nix config settings. See the
-          constructors for those types for more details.
-
-          Warning! These APIs are inherently unstable and may change from
-          release to release.
-
-          Since these files are loaded into the same address space as Nix
-          itself, they must be DSOs compatible with the instance of Nix
-          running at the time (i.e. compiled against the same headers, not
-          linked to any incompatible libraries). They should not be linked to
-          any Nix libs directly, as those will be available already at load
-          time.
-
-          If an entry in the list is a directory, all files in the directory
-          are loaded as plugins (non-recursively).
-        )"};
-
     Setting<size_t> narBufferSize{this, 32 * 1024 * 1024, "nar-buffer-size",
         "Maximum size of NARs before spilling them to disk."};
 
@@ -1278,12 +1234,6 @@ public:
 // FIXME: don't use a global variable.
 extern Settings settings;
 
-/**
- * This should be called after settings are initialized, but before
- * anything else
- */
-void initPlugins();
-
 /**
  * Load the configuration (from `nix.conf`, `NIX_CONFIG`, etc.) into the
  * given configuration object.

src/libstore/remote-store.cc

@@ -128,7 +128,7 @@ void RemoteStore::setOptions(Connection & conn)
         overrides.erase(settings.useSubstitutes.name);
         overrides.erase(loggerSettings.showTrace.name);
         overrides.erase(experimentalFeatureSettings.experimentalFeatures.name);
-        overrides.erase(settings.pluginFiles.name);
+        overrides.erase("plugin-files");
         conn.to << overrides.size();
         for (auto & i : overrides)
             conn.to << i.first << i.second.value;