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From: Cyrill Gorcunov via Tarantool-patches <tarantool-patches@dev.tarantool.org>
To: tml <tarantool-patches@dev.tarantool.org>
Cc: Vladislav Shpilevoy <v.shpilevoy@tarantool.org>
Subject: [Tarantool-patches] [PATCH v18 1/2] box/cmod: implement cmod Lua module
Date: Wed, 17 Feb 2021 15:39:44 +0300
Message-ID: <20210217123945.396396-2-gorcunov@gmail.com> (raw)
In-Reply-To: <20210217123945.396396-1-gorcunov@gmail.com>

Currently to run "C" function from some external module one
have to register it first in "_func" system space. This is
a problem if node is in read-only mode (replica).

Still people would like to have a way to run such functions
even in ro mode. For this sake we implement "cmod" lua module.

Unlike `box.schema.func` interface the cmod does not defer module
loading procedure until first call of a function. Instead a module
is loaded immediately and if some error happens (say shared
library is corrupted or not found) it pops up early.

The need of use stored C procedures implies that application is
running under serious loads most likely there is modular structure
present on Lua level (ie same shared library is loaded in different
sources) thus we cache the loaded library and reuse it on next
load attempts. To verify that cached library is up to day we
test for file attributes (device, inode, size, modification time)
on every load attempt.

Since both box.schema.func and cmod are using caching to minimize
module loading procedure the pass-through caching scheme is
implemented:

 - cmod always carries own hash table for loaded modules;
 - box.schema.func does snoop into cmod hash table when attempt
   to load a new module, if module is present in cmod hash then
   it simply referenced from there and added into own hash table;
   in case if module is not present then it loaded from the scratch
   and put into both hashes;
 - the module_reload action in box.schema.func does not affect
   cmod hash but only own hash updated, the reference in cmod
   table is dropped.

Closes #4642

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

@TarantoolBot document
Title: cmod module

Overview
========

`cmod` module provides a way to create, delete and execute
`C` procedures from shared libraries. Unlike `box.schema.func`
methods the functions created with `cmod` help are not persistent
and live purely in memory. Once a node get turned off they are
vanished. An initial purpose for them is to execute them on
nodes which are running in read-only mode.

Module functions
================

`require('cmod').load(path) -> obj | error`
-------------------------------------------

Loads a module from `path` and return an object instance
associate with the module, otherwise an error is thrown.

The `path` should not end up with shared library extension
(such as `.so`), only a file name shall be there.

Possible errors:

- IllegalParams: module path is either not supplied
  or not a string.
- SystemError: unable to open a module due to a system error.
- ClientError: a module does not exist.
- OutOfMemory: unable to allocate a module.

Example:

``` Lua
-- Without error handling
m = require('cmod').load('path/to/library)

-- With error handling
m, err = pcall(require('cmod').load, 'path/to/library')
if err ~= nil then
    print(err)
end
```

`module:unload() -> true | error`
---------------------------------

Unloads a module. Returns `true` on success, otherwise an error
is thrown. Once the module is unloaded one can't load new
functions from this module instance.

Possible errors:

- IllegalParams: a module is not supplied.
- IllegalParams: a module is already unloaded.

Example:

``` Lua
m = require('cmod').load('path/to/library')
--
-- do something with module
--
m:unload()
```

If there are functions from this module referenced somewhere
in other places of Lua code they still can be executed because
the module continue sitting in memory until the last reference
to it is closed.

If the module become a target to the Lua's garbage collector
then unload is called implicitly.

module:load(name) -> obj | error`
---------------------------------

Loads a new function with name `name` from the previously
loaded `module` and return a callable object instance
associated with the function. On failure an error is thrown.

Possible errors:
 - IllegalParams: function name is either not supplied
   or not a string.
 - IllegalParams: attempt to load a function but module
   has been unloaded already.
 - ClientError: no such function in the module.
 - OutOfMemory: unable to allocate a function.

Example:

``` Lua
-- Load a module if not been loaded yet.
m = require('cmod').load('path/to/library')
-- Load a function with the `foo` name from the module `m`.
func = m:load('foo')
```

In case if there is no need for further loading of other
functions from the same module then the module might be
unloaded immediately.

``` Lua
m = require('cmod').load('path/to/library')
func = m:load('foo')
m:unload()
```

`function:unload() -> true | error`
-----------------------------------

Unloads a function. Returns `true` on success, otherwise
an error is thrown.

Possible errors:
 - IllegalParams: function name is either not supplied
   or not a string.
 - IllegalParams: the function already unloaded.

Example:

``` Lua
m = require('cmod').load('path/to/library')
func = m:load('foo')
--
-- do something with function and cleanup then
--
func:unload()
m:unload()
```

If the function become a target to the Lua's garbage collector
then unload is called implicitly.

Executing a loaded function
===========================

Once function is loaded it can be executed as an ordinary Lua call.
Lets consider the following example. We have a `C` function which
takes two numbers and returns their sum.

``` C
int
cfunc_sum(box_function_ctx_t *ctx, const char *args, const char *args_end)
{
	uint32_t arg_count = mp_decode_array(&args);
	if (arg_count != 2) {
		return box_error_set(__FILE__, __LINE__, ER_PROC_C, "%s",
				     "invalid argument count");
	}
	uint64_t a = mp_decode_uint(&args);
	uint64_t b = mp_decode_uint(&args);

	char res[16];
	char *end = mp_encode_uint(res, a + b);
	box_return_mp(ctx, res, end);
	return 0;
}
```

The name of the function is `cfunc_sum` and the function is built into
`cfunc.so` shared library.

First we should load it as

``` Lua
m = require('cmod').load('cfunc')
cfunc_sum = m:load('cfunc_sum')
```

Once successfully loaded we can execute it. Lets call the
`cfunc_sum` with wrong number of arguments

``` Lua
cfunc_sum()
 | ---
 | - error: invalid argument count
```

We will see the `"invalid argument count"` message in output.
The error message has been set by the `box_error_set` in `C`
code above.

On success the sum of arguments will be printed out.

``` Lua
cfunc_sum(1, 2)
 | ---
 | - 3
```

The functions may return multiple results. For example a trivial
echo function which prints arguments passed in.

``` Lua
cfunc_echo(1,2,3)
 | ---
 | - 1
 | - 2
 | - 3
```

Module and function caches
==========================

Loading a module is relatively slow procedure because operating
system needs to read the library, resolve its symbols and etc.
Thus to speedup this procedure if the module is loaded for a first
time we put it into an internal cache. If module is sitting in
the cache already and new request to load comes in -- we simply
reuse a previous copy. In case if module is updated on a storage
device then on new load attempt we detect that file attributes
(such as device number, inode, size, modification time) get changed
and reload module from the scratch. Note that newly loaded module
does not intersect with previously loaded modules, the continue
operating with code previously read from cache.

Thus if there is a need to update a module then all module instances
should be unloaded (together with functions) and loaded again.

Similar caching technique applied to functions -- only first function
allocation cause symbol resolving, next ones are simply obtained from
a function cache.
---
 src/box/CMakeLists.txt |   1 +
 src/box/func.c         | 237 ++++-------
 src/box/func.h         |   7 +-
 src/box/lua/cmod.c     | 925 +++++++++++++++++++++++++++++++++++++++++
 src/box/lua/cmod.h     | 123 ++++++
 src/box/lua/init.c     |   2 +
 6 files changed, 1136 insertions(+), 159 deletions(-)
 create mode 100644 src/box/lua/cmod.c
 create mode 100644 src/box/lua/cmod.h

diff --git a/src/box/CMakeLists.txt b/src/box/CMakeLists.txt
index 19203f770..fa4253c5d 100644
--- a/src/box/CMakeLists.txt
+++ b/src/box/CMakeLists.txt
@@ -195,6 +195,7 @@ add_library(box STATIC
     lua/call.c
     lua/cfg.cc
     lua/console.c
+    lua/cmod.c
     lua/serialize_lua.c
     lua/tuple.c
     lua/slab.c
diff --git a/src/box/func.c b/src/box/func.c
index 9909cee45..f77cf00f8 100644
--- a/src/box/func.c
+++ b/src/box/func.c
@@ -34,6 +34,7 @@
 #include "assoc.h"
 #include "lua/utils.h"
 #include "lua/call.h"
+#include "lua/cmod.h"
 #include "error.h"
 #include "errinj.h"
 #include "diag.h"
@@ -95,77 +96,6 @@ func_split_name(const char *str, struct func_name *name)
 	}
 }
 
-/**
- * Arguments for luaT_module_find used by lua_cpcall()
- */
-struct module_find_ctx {
-	const char *package;
-	const char *package_end;
-	char *path;
-	size_t path_len;
-};
-
-/**
- * A cpcall() helper for module_find()
- */
-static int
-luaT_module_find(lua_State *L)
-{
-	struct module_find_ctx *ctx = (struct module_find_ctx *)
-		lua_topointer(L, 1);
-
-	/*
-	 * Call package.searchpath(name, package.cpath) and use
-	 * the path to the function in dlopen().
-	 */
-	lua_getglobal(L, "package");
-
-	lua_getfield(L, -1, "search");
-
-	/* Argument of search: name */
-	lua_pushlstring(L, ctx->package, ctx->package_end - ctx->package);
-
-	lua_call(L, 1, 1);
-	if (lua_isnil(L, -1))
-		return luaL_error(L, "module not found");
-	/* Convert path to absolute */
-	char resolved[PATH_MAX];
-	if (realpath(lua_tostring(L, -1), resolved) == NULL) {
-		diag_set(SystemError, "realpath");
-		return luaT_error(L);
-	}
-
-	snprintf(ctx->path, ctx->path_len, "%s", resolved);
-	return 0;
-}
-
-/**
- * Find path to module using Lua's package.cpath
- * @param package package name
- * @param package_end a pointer to the last byte in @a package + 1
- * @param[out] path path to shared library
- * @param path_len size of @a path buffer
- * @retval 0 on success
- * @retval -1 on error, diag is set
- */
-static int
-module_find(const char *package, const char *package_end, char *path,
-	    size_t path_len)
-{
-	struct module_find_ctx ctx = { package, package_end, path, path_len };
-	lua_State *L = tarantool_L;
-	int top = lua_gettop(L);
-	if (luaT_cpcall(L, luaT_module_find, &ctx) != 0) {
-		int package_len = (int) (package_end - package);
-		diag_set(ClientError, ER_LOAD_MODULE, package_len, package,
-			 lua_tostring(L, -1));
-		lua_settop(L, top);
-		return -1;
-	}
-	assert(top == lua_gettop(L)); /* cpcall discard results */
-	return 0;
-}
-
 static struct mh_strnptr_t *modules = NULL;
 
 static void
@@ -214,11 +144,14 @@ module_cache_find(const char *name, const char *name_end)
 static inline int
 module_cache_put(struct module *module)
 {
-	size_t package_len = strlen(module->package);
-	uint32_t name_hash = mh_strn_hash(module->package, package_len);
+	const char *package = module->cmod->package;
+	size_t package_len = module->cmod->package_len;
 	const struct mh_strnptr_node_t strnode = {
-		module->package, package_len, name_hash, module};
-
+		.str	= package,
+		.len	= package_len,
+		.hash	= mh_strn_hash(package, package_len),
+		.val	= module,
+	};
 	if (mh_strnptr_put(modules, &strnode, NULL, NULL) == mh_end(modules)) {
 		diag_set(OutOfMemory, sizeof(strnode), "malloc", "modules");
 		return -1;
@@ -238,102 +171,55 @@ module_cache_del(const char *name, const char *name_end)
 	mh_strnptr_del(modules, i, NULL);
 }
 
-/*
- * Load a dso.
- * Create a new symlink based on temporary directory and try to
- * load via this symink to load a dso twice for cases of a function
- * reload.
+/**
+ * Allocate a new module instance.
  */
 static struct module *
-module_load(const char *package, const char *package_end)
+module_new(struct cmod *cmod)
 {
-	char path[PATH_MAX];
-	if (module_find(package, package_end, path, sizeof(path)) != 0)
-		return NULL;
-
-	int package_len = package_end - package;
-	struct module *module = (struct module *)
-		malloc(sizeof(*module) + package_len + 1);
+	struct module *module = malloc(sizeof(*module));
 	if (module == NULL) {
-		diag_set(OutOfMemory, sizeof(struct module) + package_len + 1,
+		diag_set(OutOfMemory, sizeof(struct module),
 			 "malloc", "struct module");
 		return NULL;
 	}
-	memcpy(module->package, package, package_len);
-	module->package[package_len] = 0;
+
 	rlist_create(&module->funcs);
 	module->calls = 0;
+	module->cmod = cmod;
 
-	const char *tmpdir = getenv("TMPDIR");
-	if (tmpdir == NULL)
-		tmpdir = "/tmp";
-	char dir_name[PATH_MAX];
-	int rc = snprintf(dir_name, sizeof(dir_name), "%s/tntXXXXXX", tmpdir);
-	if (rc < 0 || (size_t) rc >= sizeof(dir_name)) {
-		diag_set(SystemError, "failed to generate path to tmp dir");
-		goto error;
-	}
+	return module;
+}
 
-	if (mkdtemp(dir_name) == NULL) {
-		diag_set(SystemError, "failed to create unique dir name: %s",
-			 dir_name);
-		goto error;
-	}
-	char load_name[PATH_MAX];
-	rc = snprintf(load_name, sizeof(load_name), "%s/%.*s." TARANTOOL_LIBEXT,
-		      dir_name, package_len, package);
-	if (rc < 0 || (size_t) rc >= sizeof(dir_name)) {
-		diag_set(SystemError, "failed to generate path to DSO");
-		goto error;
-	}
+/**
+ * Load a new DSO.
+ */
+static struct module *
+module_load(const char *package, const char *package_end)
+{
+	char path[PATH_MAX];
+	int package_len = package_end - package;
 
-	struct stat st;
-	if (stat(path, &st) < 0) {
-		diag_set(SystemError, "failed to stat() module %s", path);
-		goto error;
+	if (cmod_find_package(package, package_len,
+			      path, sizeof(path)) != 0) {
+		return NULL;
 	}
 
-	int source_fd = open(path, O_RDONLY);
-	if (source_fd < 0) {
-		diag_set(SystemError, "failed to open module %s file for" \
-			 " reading", path);
-		goto error;
-	}
-	int dest_fd = open(load_name, O_WRONLY|O_CREAT|O_TRUNC,
-			   st.st_mode & 0777);
-	if (dest_fd < 0) {
-		diag_set(SystemError, "failed to open file %s for writing ",
-			 load_name);
-		close(source_fd);
-		goto error;
-	}
+	struct cmod *cmod = cmod_new(package, package_len, path);
+	if (cmod == NULL)
+		return NULL;
 
-	off_t ret = eio_sendfile_sync(dest_fd, source_fd, 0, st.st_size);
-	close(source_fd);
-	close(dest_fd);
-	if (ret != st.st_size) {
-		diag_set(SystemError, "failed to copy DSO %s to %s",
-			 path, load_name);
-		goto error;
+	struct module *module = module_new(cmod);
+	if (module == NULL) {
+		cmod_unref(cmod);
+		return NULL;
 	}
 
-	module->handle = dlopen(load_name, RTLD_NOW | RTLD_LOCAL);
-	if (unlink(load_name) != 0)
-		say_warn("failed to unlink dso link %s", load_name);
-	if (rmdir(dir_name) != 0)
-		say_warn("failed to delete temporary dir %s", dir_name);
-	if (module->handle == NULL) {
-		diag_set(ClientError, ER_LOAD_MODULE, package_len,
-			  package, dlerror());
-		goto error;
-	}
 	struct errinj *e = errinj(ERRINJ_DYN_MODULE_COUNT, ERRINJ_INT);
 	if (e != NULL)
 		++e->iparam;
+
 	return module;
-error:
-	free(module);
-	return NULL;
 }
 
 static void
@@ -342,7 +228,7 @@ module_delete(struct module *module)
 	struct errinj *e = errinj(ERRINJ_DYN_MODULE_COUNT, ERRINJ_INT);
 	if (e != NULL)
 		--e->iparam;
-	dlclose(module->handle);
+	cmod_unref(module->cmod);
 	TRASH(module);
 	free(module);
 }
@@ -363,7 +249,8 @@ module_gc(struct module *module)
 static box_function_f
 module_sym(struct module *module, const char *name)
 {
-	box_function_f f = (box_function_f)dlsym(module->handle, name);
+	void *handle = module->cmod->handle;
+	box_function_f f = (box_function_f)dlsym(handle, name);
 	if (f == NULL) {
 		diag_set(ClientError, ER_LOAD_FUNCTION, name, dlerror());
 		return NULL;
@@ -529,19 +416,59 @@ func_c_load(struct func_c *func)
 	func_split_name(func->base.def->name, &name);
 
 	struct module *cached, *module;
+	struct cmod *cmod;
+
 	cached = module_cache_find(name.package, name.package_end);
-	if (cached == NULL) {
+	if (cached != NULL) {
+		module = cached;
+		goto resolve_sym;
+	}
+
+	size_t len = name.package_end - name.package;
+	cmod = cmod_cache_find(name.package, len);
+	if (cmod == NULL) {
+		/*
+		 * The module is not present in both
+		 * box.schema.func cache and in cmod
+		 * cache. Thus load it from from the
+		 * scratch and put into cmod cache
+		 * as well.
+		 */
 		module = module_load(name.package, name.package_end);
 		if (module == NULL)
 			return -1;
-		if (module_cache_put(module)) {
+		if (cmod_cache_put(module->cmod) != 0) {
 			module_delete(module);
 			return -1;
 		}
+
+		/*
+		 * Fresh cmod instance is bound to
+		 * the module and get unref upon
+		 * module unload.
+		 */
+		cmod = NULL;
 	} else {
-		module = cached;
+		/*
+		 * Someone already has loaded this
+		 * shared library via cmod interface,
+		 * thus simply increase the reference
+		 * (and don't forget to unref later).
+		 */
+		module = module_new(cmod);
+		if (module == NULL)
+			return -1;
+		cmod_ref(cmod);
+	}
+
+	if (module_cache_put(module)) {
+		if (cmod != NULL)
+			cmod_unref(cmod);
+		module_delete(module);
+		return -1;
 	}
 
+resolve_sym:
 	func->func = module_sym(module, name.sym);
 	if (func->func == NULL) {
 		if (cached == NULL) {
diff --git a/src/box/func.h b/src/box/func.h
index 581e468cb..ac9772dfe 100644
--- a/src/box/func.h
+++ b/src/box/func.h
@@ -43,19 +43,18 @@ extern "C" {
 #endif /* defined(__cplusplus) */
 
 struct func;
+struct cmod;
 
 /**
  * Dynamic shared module.
  */
 struct module {
-	/** Module dlhandle. */
-	void *handle;
+	/** Low level cmod module. */
+	struct cmod *cmod;
 	/** List of imported functions. */
 	struct rlist funcs;
 	/** Count of active calls. */
 	size_t calls;
-	/** Module's package name. */
-	char package[0];
 };
 
 /** Virtual method table for func object. */
diff --git a/src/box/lua/cmod.c b/src/box/lua/cmod.c
new file mode 100644
index 000000000..6b383d8fe
--- /dev/null
+++ b/src/box/lua/cmod.c
@@ -0,0 +1,925 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright 2010-2021, Tarantool AUTHORS, please see AUTHORS file.
+ */
+
+#include <unistd.h>
+#include <string.h>
+#include <dlfcn.h>
+#include <fcntl.h>
+#include <lua.h>
+
+#include "box/error.h"
+#include "box/port.h"
+#include "box/func_def.h"
+
+#include "tt_static.h"
+
+#include "assoc.h"
+#include "cmod.h"
+#include "fiber.h"
+
+#include "lua/utils.h"
+#include "libeio/eio.h"
+
+/**
+ * Function descriptor.
+ */
+struct cmod_func {
+	/** Module function belongs to. */
+	struct cmod *cmod;
+	/** Address to execute on call. */
+	box_function_f addr;
+	/** Number of references. */
+	int64_t refs;
+	/** Length of functon name in @a key. */
+	size_t sym_len;
+	/** Length of @a key. */
+	size_t len;
+	/** Function hash key. */
+	char key[0];
+};
+
+/** Module name to cmod hash. */
+static struct mh_strnptr_t *cmod_hash = NULL;
+
+/** Function name to cmod_func hash. */
+static struct mh_strnptr_t *cmod_func_hash = NULL;
+
+/** A type to find a module from an object. */
+static const char *uname_cmod = "tt_uname_cmod";
+
+/** A type to find a function from an object. */
+static const char *uname_func = "tt_uname_cmod_func";
+
+/** Module unique IDs. */
+static int64_t cmod_ids = 1;
+
+/** Get data associated with an object. */
+static void *
+get_udata(struct lua_State *L, const char *uname)
+{
+	void **pptr = luaL_testudata(L, 1, uname);
+	return pptr != NULL ? *pptr : NULL;
+}
+
+/** Set data to a new value. */
+static void
+set_udata(struct lua_State *L, const char *uname, void *ptr)
+{
+	void **pptr = luaL_testudata(L, 1, uname);
+	assert(pptr != NULL);
+	*pptr = ptr;
+}
+
+/** Setup a new data and associate it with an object. */
+static void
+new_udata(struct lua_State *L, const char *uname, void *ptr)
+{
+	*(void **)lua_newuserdata(L, sizeof(void *)) = ptr;
+	luaL_getmetatable(L, uname);
+	lua_setmetatable(L, -2);
+}
+
+/**
+ * Helpers for string based hash manipulations.
+ */
+static void *
+hash_find(struct mh_strnptr_t *h, const char *str, size_t len)
+{
+	mh_int_t e = mh_strnptr_find_inp(h, str, len);
+	if (e == mh_end(h))
+		return NULL;
+	return mh_strnptr_node(h, e)->val;
+}
+
+static void
+hash_update(struct mh_strnptr_t *h, const char *src_str, size_t len,
+	    const char *new_str, void *new_val)
+{
+	mh_int_t e = mh_strnptr_find_inp(h, src_str, len);
+	if (e == mh_end(h))
+		panic("cmod: failed to update hash");
+	mh_strnptr_node(h, e)->str = new_str;
+	mh_strnptr_node(h, e)->val = new_val;
+}
+
+static int
+hash_add(struct mh_strnptr_t *h, const char *str, size_t len, void *val)
+{
+	const struct mh_strnptr_node_t nd = {
+		.str	= str,
+		.len	= len,
+		.hash	= mh_strn_hash(str, len),
+		.val	= val,
+	};
+	if (mh_strnptr_put(h, &nd, NULL, NULL) == mh_end(h)) {
+		diag_set(OutOfMemory, sizeof(nd), "malloc",
+			 "cmod: hash node");
+		return -1;
+	}
+	return 0;
+}
+
+static void
+hash_del_kv(struct mh_strnptr_t *h, const char *str,
+	    size_t len, void *val)
+{
+	mh_int_t e = mh_strnptr_find_inp(h, str, len);
+	if (e != mh_end(h)) {
+		void *v = mh_strnptr_node(h, e)->val;
+		if (v == val)
+			mh_strnptr_del(h, e, NULL);
+	}
+}
+
+static void
+hash_del(struct mh_strnptr_t *h, const char *str, size_t len)
+{
+	mh_int_t e = mh_strnptr_find_inp(h, str, len);
+	if (e != mh_end(h))
+		mh_strnptr_del(h, e, NULL);
+}
+
+/** Arguments for lpackage_search. */
+struct find_ctx {
+	const char *package;
+	size_t package_len;
+	char *path;
+	size_t path_len;
+};
+
+/** A cpcall() helper for lfind_package(). */
+static int
+lpackage_search(lua_State *L)
+{
+	struct find_ctx *ctx = (void *)lua_topointer(L, 1);
+
+	lua_getglobal(L, "package");
+	lua_getfield(L, -1, "search");
+	lua_pushlstring(L, ctx->package, ctx->package_len);
+
+	lua_call(L, 1, 1);
+	if (lua_isnil(L, -1))
+		return luaL_error(L, "cmod: module not found");
+
+	char resolved[PATH_MAX];
+	if (realpath(lua_tostring(L, -1), resolved) == NULL) {
+		diag_set(SystemError, "cmod: realpath");
+		return luaT_error(L);
+	}
+
+	/*
+	 * No need for result being trimmed test, it
+	 * is guaranteed by realpath call.
+	 */
+	snprintf(ctx->path, ctx->path_len, "%s", resolved);
+	return 0;
+}
+
+int
+cmod_find_package(const char *package, size_t package_len,
+		  char *path, size_t path_len)
+{
+	struct find_ctx ctx = {
+		.package	= package,
+		.package_len	= package_len,
+		.path		= path,
+		.path_len	= path_len,
+	};
+
+	lua_State *L = tarantool_L;
+	int top = lua_gettop(L);
+	if (luaT_cpcall(L, lpackage_search, &ctx) != 0) {
+		diag_set(ClientError, ER_LOAD_MODULE, ctx.package_len,
+			 ctx.package, lua_tostring(L, -1));
+		lua_settop(L, top);
+		return -1;
+	}
+	assert(top == lua_gettop(L));
+	return 0;
+}
+
+/** Increase reference to cmod. */
+void
+cmod_ref(struct cmod *m)
+{
+	assert(m->refs >= 0);
+	++m->refs;
+}
+
+/** Decrease reference to cmod and free it if last one. */
+void
+cmod_unref(struct cmod *m)
+{
+	assert(m->refs > 0);
+	if (--m->refs == 0) {
+		hash_del_kv(cmod_hash, m->package, m->package_len, m);
+		dlclose(m->handle);
+		TRASH(m);
+		free(m);
+	}
+}
+
+struct cmod *
+cmod_cache_find(const char *package, size_t package_len)
+{
+	return hash_find(cmod_hash, package, package_len);
+}
+
+int
+cmod_cache_put(struct cmod *m)
+{
+	return hash_add(cmod_hash, m->package, m->package_len, m);
+}
+
+/** Fill cmod attributes from stat. */
+static void
+cmod_attr_fill(struct cmod_attr *attr, struct stat *st)
+{
+	attr->st_dev = st->st_dev;
+	attr->st_ino = st->st_ino;
+	attr->st_size = st->st_size;
+#ifdef TARGET_OS_DARWIN
+	attr->st_mtimespec = st->st_mtimespec;
+#else
+	attr->st_mtim = st->st_mtim;
+#endif
+}
+
+struct cmod *
+cmod_new(const char *package, size_t package_len, const char *source_path)
+{
+	size_t size = sizeof(struct cmod) + package_len + 1;
+	struct cmod *m = malloc(size);
+	if (m == NULL) {
+		diag_set(OutOfMemory, size, "malloc", "cmod");
+		return NULL;
+	}
+
+	m->package_len = package_len;
+	m->refs = 0;
+
+	memcpy(m->package, package, package_len);
+	m->package[package_len] = 0;
+
+	const char *tmpdir = getenv("TMPDIR");
+	if (tmpdir == NULL)
+		tmpdir = "/tmp";
+
+	char dir_name[PATH_MAX];
+	int rc = snprintf(dir_name, sizeof(dir_name),
+			  "%s/tntXXXXXX", tmpdir);
+	if (rc < 0 || (size_t)rc >= sizeof(dir_name)) {
+		diag_set(SystemError, "failed to generate path to tmp dir");
+		goto error;
+	}
+
+	if (mkdtemp(dir_name) == NULL) {
+		diag_set(SystemError, "failed to create unique dir name: %s",
+			 dir_name);
+		goto error;
+	}
+
+	char load_name[PATH_MAX];
+	rc = snprintf(load_name, sizeof(load_name),
+		      "%s/%.*s." TARANTOOL_LIBEXT,
+		      dir_name, (int)package_len, package);
+	if (rc < 0 || (size_t)rc >= sizeof(dir_name)) {
+		diag_set(SystemError, "failed to generate path to DSO");
+		goto error;
+	}
+
+	struct stat st;
+	if (stat(source_path, &st) < 0) {
+		diag_set(SystemError, "failed to stat() module: %s",
+			 source_path);
+		goto error;
+	}
+	cmod_attr_fill(&m->attr, &st);
+
+	int source_fd = open(source_path, O_RDONLY);
+	if (source_fd < 0) {
+		diag_set(SystemError, "failed to open module %s "
+			 "file for reading", source_path);
+		goto error;
+	}
+	int dest_fd = open(load_name, O_WRONLY | O_CREAT | O_TRUNC,
+			   st.st_mode & 0777);
+	if (dest_fd < 0) {
+		diag_set(SystemError, "failed to open file %s "
+			 "for writing ", load_name);
+		close(source_fd);
+		goto error;
+	}
+
+	off_t ret = eio_sendfile_sync(dest_fd, source_fd, 0, st.st_size);
+	close(source_fd);
+	close(dest_fd);
+	if (ret != st.st_size) {
+		diag_set(SystemError, "failed to copy DSO %s to %s",
+			 source_path, load_name);
+		goto error;
+	}
+
+	m->handle = dlopen(load_name, RTLD_NOW | RTLD_LOCAL);
+	if (unlink(load_name) != 0)
+		say_warn("failed to unlink dso link: %s", load_name);
+	if (rmdir(dir_name) != 0)
+		say_warn("failed to delete temporary dir: %s", dir_name);
+	if (m->handle == NULL) {
+		diag_set(ClientError, ER_LOAD_MODULE, package_len,
+			  package, dlerror());
+		goto error;
+	}
+
+	m->id = cmod_ids++;
+	cmod_ref(m);
+	return m;
+
+error:
+	free(m);
+	return NULL;
+}
+
+/**
+ * Load a module.
+ *
+ * This function takes a module path from the caller
+ * stack @a L and returns cached module instance or
+ * creates a new module object.
+ *
+ * Possible errors:
+ *
+ * - IllegalParams: module path is either not supplied
+ *   or not a string.
+ * - SystemError: unable to open a module due to a system error.
+ * - ClientError: a module does not exist.
+ * - OutOfMemory: unable to allocate a module.
+ *
+ * @returns module object on success or throws an error.
+ */
+static int
+lcmod_load(struct lua_State *L)
+{
+	const char msg_noname[] = "Expects cmod.load(\'name\') "
+		"but no name passed";
+
+	if (lua_gettop(L) != 1 || !lua_isstring(L, 1)) {
+		diag_set(IllegalParams, msg_noname);
+		return luaT_error(L);
+	}
+
+	size_t name_len;
+	const char *name = lua_tolstring(L, 1, &name_len);
+
+	if (name_len < 1) {
+		diag_set(IllegalParams, msg_noname);
+		return luaT_error(L);
+	}
+
+	char path[PATH_MAX];
+	if (cmod_find_package(name, name_len, path, sizeof(path)) != 0)
+		return luaT_error(L);
+
+	struct cmod *m = hash_find(cmod_hash, name, name_len);
+	if (m != NULL) {
+		struct cmod_attr attr;
+		struct stat st;
+		if (stat(path, &st) != 0) {
+			diag_set(SystemError, "failed to stat() %s",
+				 path);
+			return luaT_error(L);
+		}
+
+		/*
+		 * In case of cache hit we may reuse existing
+		 * module which speedup load procedure.
+		 */
+		cmod_attr_fill(&attr, &st);
+		if (memcmp(&attr, &m->attr, sizeof(attr)) == 0) {
+			cmod_ref(m);
+			new_udata(L, uname_cmod, m);
+			return 1;
+		}
+
+		/*
+		 * Module has been updated on a storage device,
+		 * so load a new instance and update the cache,
+		 * old entry get evicted but continue residing
+		 * in memory, fully functional, until last
+		 * function is unloaded.
+		 */
+		m = cmod_new(name, name_len, path);
+		if (m == NULL)
+			return luaT_error(L);
+
+		hash_update(cmod_hash, name, name_len, m->package, m);
+		/*
+		 * This is transparent procedure so notify a user
+		 * that new module is read otherwise it won't be
+		 * possible to figure out what is going on.
+		 */
+		say_info("cmod: attr change, reload: %s", name);
+	} else {
+		m = cmod_new(name, name_len, path);
+		if (m == NULL)
+			return luaT_error(L);
+		if (hash_add(cmod_hash, m->package, name_len, m) != 0) {
+			/* Never been in hash: safe for hash_del_kv */
+			cmod_unref(m);
+			return luaT_error(L);
+		}
+	}
+
+	new_udata(L, uname_cmod, m);
+	return 1;
+}
+
+/**
+ * Unload a module.
+ *
+ * Take a module object from the caller stack @a L and unload it.
+ *
+ * Possible errors:
+ *
+ * - IllegalParams: module is not supplied.
+ * - IllegalParams: the module is unloaded.
+ *
+ * @returns true on success or throwns an error.
+ */
+static int
+lcmod_unload(struct lua_State *L)
+{
+	if (lua_gettop(L) != 1) {
+		diag_set(IllegalParams, "Expects module:unload()");
+		return luaT_error(L);
+	}
+
+	struct cmod *m = get_udata(L, uname_cmod);
+	if (m == NULL) {
+		diag_set(IllegalParams, "The module is unloaded");
+		return luaT_error(L);
+	}
+
+	set_udata(L, uname_cmod, NULL);
+	cmod_unref(m);
+	lua_pushboolean(L, true);
+	return 1;
+}
+
+/** Handle __index request for a module object. */
+static int
+lcmod_index(struct lua_State *L)
+{
+	lua_getmetatable(L, 1);
+	lua_pushvalue(L, 2);
+	lua_rawget(L, -2);
+	if (!lua_isnil(L, -1))
+		return 1;
+
+	struct cmod *m = get_udata(L, uname_cmod);
+	if (m == NULL) {
+		lua_pushnil(L);
+		return 1;
+	}
+
+	const char *key = lua_tostring(L, 2);
+	if (key == NULL || lua_type(L, 2) != LUA_TSTRING) {
+		diag_set(IllegalParams,
+			 "Bad params, use __index(obj, <string>)");
+		return luaT_error(L);
+	}
+
+	if (strcmp(key, "path") == 0) {
+		lua_pushstring(L, m->package);
+		return 1;
+	}
+
+	/*
+	 * Internal keys for debug only, not API.
+	 */
+	if (strncmp(key, "tt_dev.", 7) == 0) {
+		const char *subkey = &key[7];
+		if (strcmp(subkey, "refs") == 0) {
+			lua_pushnumber(L, m->refs);
+			return 1;
+		} else if (strcmp(subkey, "id") == 0) {
+			lua_pushnumber(L, m->id);
+			return 1;
+		}
+	}
+	return 0;
+}
+
+/** Module representation for REPL (console). */
+static int
+lcmod_serialize(struct lua_State *L)
+{
+	struct cmod *m = get_udata(L, uname_cmod);
+	if (m == NULL) {
+		lua_pushnil(L);
+		return 1;
+	}
+
+	lua_createtable(L, 0, 1);
+	lua_pushstring(L, m->package);
+	lua_setfield(L, -2, "path");
+	return 1;
+}
+
+/** Collect a module. */
+static int
+lcmod_gc(struct lua_State *L)
+{
+	struct cmod *m = get_udata(L, uname_cmod);
+	if (m != NULL) {
+		set_udata(L, uname_cmod, NULL);
+		cmod_unref(m);
+	}
+	return 0;
+}
+
+/** Increase reference to a function. */
+static void
+cmod_func_ref(struct cmod_func *cf)
+{
+	assert(cf->refs >= 0);
+	++cf->refs;
+}
+
+/** Free function memory. */
+static void
+cmod_func_delete(struct cmod_func *cf)
+{
+	TRASH(cf);
+	free(cf);
+}
+
+/** Unreference a function and free if last one. */
+static void
+cmod_func_unref(struct cmod_func *cf)
+{
+	assert(cf->refs > 0);
+	if (--cf->refs == 0) {
+		cmod_unref(cf->cmod);
+		hash_del(cmod_func_hash, cf->key, cf->len);
+		cmod_func_delete(cf);
+	}
+}
+
+/** Function name from a hash key. */
+static char *
+cmod_func_name(struct cmod_func *cf)
+{
+	return &cf->key[cf->len - cf->sym_len];
+}
+
+/**
+ * Allocate a new function instance and resolve its address.
+ *
+ * @param m a module the function should be loaded from.
+ * @param key function hash key, ie "1.module.foo".
+ * @param len length of @a key.
+ * @param sym_len function symbol name length, ie 3 for "foo".
+ *
+ * @returns function instance on success, NULL otherwise (diag is set).
+ */
+static struct cmod_func *
+cmod_func_new(struct cmod *m, const char *key, size_t len, size_t sym_len)
+{
+	size_t size = sizeof(struct cmod_func) + len + 1;
+	struct cmod_func *cf = malloc(size);
+	if (cf == NULL) {
+		diag_set(OutOfMemory, size, "malloc", "cf");
+		return NULL;
+	}
+
+	cf->cmod = m;
+	cf->len = len;
+	cf->sym_len = sym_len;
+	cf->refs = 0;
+
+	memcpy(cf->key, key, len);
+	cf->key[len] = '\0';
+
+	cf->addr = dlsym(m->handle, cmod_func_name(cf));
+	if (cf->addr == NULL) {
+		diag_set(ClientError, ER_LOAD_FUNCTION,
+			 cmod_func_name(cf), dlerror());
+		cmod_func_delete(cf);
+		return NULL;
+	}
+
+	if (hash_add(cmod_func_hash, cf->key, cf->len, cf) != 0) {
+		cmod_func_delete(cf);
+		return NULL;
+	}
+
+	/*
+	 * Each new function depends on module presence.
+	 * Module will reside even if been unload
+	 * explicitly after the function creation.
+	 */
+	cmod_ref(cf->cmod);
+	cmod_func_ref(cf);
+	return cf;
+}
+
+/**
+ * Load a function.
+ *
+ * This function takes a function name from the caller
+ * stack @a L and either returns a cached function or
+ * creates a new function object.
+ *
+ * Possible errors:
+ *
+ * - IllegalParams: function name is either not supplied
+ *   or not a string.
+ * - SystemError: unable to open a module due to a system error.
+ * - ClientError: a module does not exist.
+ * - OutOfMemory: unable to allocate a module.
+ *
+ * @returns module object on success or throws an error.
+ */
+static int
+lcmod_load_func(struct lua_State *L)
+{
+	const char *method = "function = module:load";
+	const char fmt_noname[] = "Expects %s(\'name\') but no name passed";
+
+	if (lua_gettop(L) != 2 || !lua_isstring(L, 2)) {
+		diag_set(IllegalParams, fmt_noname, method);
+		return luaT_error(L);
+	}
+
+	struct cmod *m = get_udata(L, uname_cmod);
+	if (m == NULL) {
+		const char *fmt =
+			"Expects %s(\'name\') but not module object passed";
+		diag_set(IllegalParams, fmt, method);
+		return luaT_error(L);
+	}
+
+	size_t sym_len;
+	const char *sym = lua_tolstring(L, 2, &sym_len);
+
+	if (sym_len < 1) {
+		diag_set(IllegalParams, fmt_noname, method);
+		return luaT_error(L);
+	}
+
+	/*
+	 * Functions are bound to a module symbols, thus
+	 * since the hash is global it should be unique
+	 * per module. The symbol (function name) is the
+	 * last part of the hash key.
+	 */
+	const char *key = tt_sprintf("%lld.%s.%s", (long long)m->id,
+				     m->package, sym);
+	size_t len = strlen(key);
+
+	struct cmod_func *cf = hash_find(cmod_func_hash, key, len);
+	if (cf == NULL) {
+		cf = cmod_func_new(m, key, len, sym_len);
+		if (cf == NULL)
+			return luaT_error(L);
+	} else {
+		cmod_func_ref(cf);
+	}
+
+	new_udata(L, uname_func, cf);
+	return 1;
+}
+
+/**
+ * Unload a function.
+ *
+ * Take a function object from the caller stack @a L and unload it.
+ *
+ * Possible errors:
+ *
+ * - IllegalParams: the function is not supplied.
+ * - IllegalParams: the function already unloaded.
+ *
+ * @returns true on success or throwns an error.
+ */
+static int
+lfunc_unload(struct lua_State *L)
+{
+	if (lua_gettop(L) != 1) {
+		diag_set(IllegalParams, "Expects function:unload()");
+		return luaT_error(L);
+	}
+
+	struct cmod_func *cf = get_udata(L, uname_func);
+	if (cf == NULL) {
+		diag_set(IllegalParams, "The function is unloaded");
+		return luaT_error(L);
+	}
+
+	set_udata(L, uname_func, NULL);
+	cmod_func_unref(cf);
+
+	lua_pushboolean(L, true);
+	return 1;
+}
+
+/** Handle __index request for a function object. */
+static int
+lfunc_index(struct lua_State *L)
+{
+	lua_getmetatable(L, 1);
+	lua_pushvalue(L, 2);
+	lua_rawget(L, -2);
+	if (!lua_isnil(L, -1))
+		return 1;
+
+	struct cmod_func *cf = get_udata(L, uname_func);
+	if (cf == NULL) {
+		lua_pushnil(L);
+		return 1;
+	}
+
+	const char *key = lua_tostring(L, 2);
+	if (key == NULL || lua_type(L, 2) != LUA_TSTRING) {
+		diag_set(IllegalParams,
+			 "Bad params, use __index(obj, <string>)");
+		return luaT_error(L);
+	}
+
+	if (strcmp(key, "name") == 0) {
+		lua_pushstring(L, cmod_func_name(cf));
+		return 1;
+	}
+
+	/*
+	 * Internal keys for debug only, not API.
+	 */
+	if (strncmp(key, "tt_dev.", 7) == 0) {
+		const char *subkey = &key[7];
+		if (strcmp(subkey, "refs") == 0) {
+			lua_pushnumber(L, cf->refs);
+			return 1;
+		} else if (strcmp(subkey, "key") == 0) {
+			lua_pushstring(L, cf->key);
+			return 1;
+		} else if (strcmp(subkey, "cmod.id") == 0) {
+			lua_pushnumber(L, cf->cmod->id);
+			return 1;
+		} else if (strcmp(subkey, "cmod.refs") == 0) {
+			lua_pushnumber(L, cf->cmod->refs);
+			return 1;
+		}
+	}
+	return 0;
+}
+
+/** Function representation for REPL (console). */
+static int
+lfunc_serialize(struct lua_State *L)
+{
+	struct cmod_func *cf = get_udata(L, uname_func);
+	if (cf == NULL) {
+		lua_pushnil(L);
+		return 1;
+	}
+
+	lua_createtable(L, 0, 1);
+	lua_pushstring(L, cmod_func_name(cf));
+	lua_setfield(L, -2, "name");
+	return 1;
+}
+
+/** Collect a function. */
+static int
+lfunc_gc(struct lua_State *L)
+{
+	struct cmod_func *cf = get_udata(L, uname_func);
+	if (cf != NULL) {
+		set_udata(L, uname_func, NULL);
+		cmod_func_unref(cf);
+	}
+	return 0;
+}
+
+/** Execute a function. */
+int
+do_lfunc_call(struct cmod_func *cf, struct port *args, struct port *ret)
+{
+	struct region *region = &fiber()->gc;
+	size_t region_svp = region_used(region);
+
+	uint32_t data_sz;
+	const char *data = port_get_msgpack(args, &data_sz);
+	if (data == NULL)
+		return -1;
+
+	port_c_create(ret);
+	box_function_ctx_t ctx = {
+		.port = ret,
+	};
+
+	/*
+	 * Unlike box.schema.func cmod doesn't support
+	 * module run-time reloading and while a function
+	 * is alive a module can't disappear. Still it is
+	 * unclear if there some existing users are running
+	 * code which already tries to unload a function inside
+	 * this call execution, thus make sure the module won't
+	 * disapper inbetween.
+	 */
+	cmod_ref(cf->cmod);
+	int rc = cf->addr(&ctx, data, data + data_sz);
+	cmod_unref(cf->cmod);
+	region_truncate(region, region_svp);
+
+	if (rc != 0) {
+		if (diag_last_error(&fiber()->diag) == NULL)
+			diag_set(ClientError, ER_PROC_C, "unknown error");
+		port_destroy(ret);
+		return -1;
+	}
+
+	return rc;
+}
+
+/** Call a function by its name from the Lua code. */
+static int
+lfunc_call(struct lua_State *L)
+{
+	struct cmod_func *cf = get_udata(L, uname_func);
+	if (cf == NULL) {
+		diag_set(IllegalParams, "The function is unloaded");
+		return luaT_error(L);
+	}
+
+	lua_State *args_L = luaT_newthread(tarantool_L);
+	if (args_L == NULL)
+		return luaT_error(L);
+
+	int coro_ref = luaL_ref(tarantool_L, LUA_REGISTRYINDEX);
+	lua_xmove(L, args_L, lua_gettop(L) - 1);
+
+	struct port args;
+	port_lua_create(&args, args_L);
+	((struct port_lua *)&args)->ref = coro_ref;
+
+	struct port ret;
+
+	if (do_lfunc_call(cf, &args, &ret) != 0) {
+		port_destroy(&args);
+		return luaT_error(L);
+	}
+
+	int top = lua_gettop(L);
+	port_dump_lua(&ret, L, true);
+	int cnt = lua_gettop(L) - top;
+
+	port_destroy(&ret);
+	port_destroy(&args);
+
+	return cnt;
+}
+
+/** Initialize cmod. */
+void
+box_lua_cmod_init(struct lua_State *L)
+{
+	cmod_func_hash = mh_strnptr_new();
+	if (cmod_func_hash == NULL)
+		panic("cmod: Can't allocate func hash table");
+	cmod_hash = mh_strnptr_new();
+	if (cmod_hash == NULL)
+		panic("cmod: Can't allocate cmod hash table");
+
+	(void)L;
+	static const struct luaL_Reg top_methods[] = {
+		{ "load",		lcmod_load		},
+		{ NULL, NULL },
+	};
+	luaL_register_module(L, "cmod", top_methods);
+	lua_pop(L, 1);
+
+	static const struct luaL_Reg lcmod_methods[] = {
+		{ "unload",		lcmod_unload		},
+		{ "load",		lcmod_load_func		},
+		{ "__index",		lcmod_index		},
+		{ "__serialize",	lcmod_serialize		},
+		{ "__gc",		lcmod_gc		},
+		{ NULL, NULL },
+	};
+	luaL_register_type(L, uname_cmod, lcmod_methods);
+
+	static const struct luaL_Reg lfunc_methods[] = {
+		{ "unload",		lfunc_unload		},
+		{ "__index",		lfunc_index		},
+		{ "__serialize",	lfunc_serialize		},
+		{ "__gc",		lfunc_gc		},
+		{ "__call",		lfunc_call		},
+		{ NULL, NULL },
+	};
+	luaL_register_type(L, uname_func, lfunc_methods);
+}
diff --git a/src/box/lua/cmod.h b/src/box/lua/cmod.h
new file mode 100644
index 000000000..224779a04
--- /dev/null
+++ b/src/box/lua/cmod.h
@@ -0,0 +1,123 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright 2010-2021, Tarantool AUTHORS, please see AUTHORS file.
+ */
+
+#pragma once
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include "trivia/config.h"
+
+#if defined(__cplusplus)
+extern "C" {
+#endif /* defined(__cplusplus) */
+
+struct lua_State;
+
+/**
+ * Attributes for cmod cache invalidation.
+ */
+struct cmod_attr {
+#ifdef TARGET_OS_DARWIN
+	struct timespec st_mtimespec;
+#else
+	struct timespec st_mtim;
+#endif
+	dev_t st_dev;
+	ino_t st_ino;
+	off_t st_size;
+};
+
+/**
+ * Shared library module.
+ */
+struct cmod {
+	/** Module dlhandle. */
+	void *handle;
+	/** Module ID. */
+	int64_t id;
+	/** Number of references. */
+	int64_t refs;
+	/** File attributes. */
+	struct cmod_attr attr;
+	/** Length of @a package. */
+	size_t package_len;
+	/** Path to the module. */
+	char package[0];
+};
+
+/** Increase reference to cmod. */
+void
+cmod_ref(struct cmod *m);
+
+/** Decrease reference to cmod and free it if last one. */
+void
+cmod_unref(struct cmod *m);
+
+/**
+ * Lookup for cmod entry in cache.
+ *
+ * @param package package name.
+ * @param package_len length of @a package.
+ *
+ * @returns module pointer if found, NULL otherwise.
+ */
+struct cmod *
+cmod_cache_find(const char *package, size_t package_len);
+
+/**
+ * Put new cmod entry to cache.
+ *
+ * @param cmod entry to put.
+ *
+ * @returns 0 on success, -1 otherwise (diag is set).
+ */
+int
+cmod_cache_put(struct cmod *m);
+
+/**
+ * Allocate and load a new C module instance.
+ *
+ * Allocates a new C module instance, copies shared library
+ * to a safe place, loads it and remove then leaving DSO purely
+ * in memory. This is done because libc doesn't detect file
+ * updates properly. The module get cached by putting it into
+ * the modules hash.
+ *
+ * @param package package name.
+ * @param package_len length of @a package.
+ * @param source_path path to the shared library.
+ *
+ * @returns module pointer on succes, NULL otherwise, diag is set.
+ */
+struct cmod *
+cmod_new(const char *package, size_t package_len, const char *source_path);
+
+/**
+ * Find package in Lua's "package.cpath".
+ *
+ * @param package package name.
+ * @param package_len length of @package.
+ * @param path resolved path.
+ * @param path_len length of @a path.
+ *
+ * @return 0 on success, -1 otherwise (diag is set).
+ */
+int
+cmod_find_package(const char *package, size_t package_len,
+		  char *path, size_t path_len);
+
+/**
+ * Initialize cmod Lua module.
+ *
+ * @param L Lua state where to register the cmod module.
+ */
+void
+box_lua_cmod_init(struct lua_State *L);
+
+#if defined(__cplusplus)
+}
+#endif /* defined(__plusplus) */
diff --git a/src/box/lua/init.c b/src/box/lua/init.c
index fbcdfb20b..bad2b7ca9 100644
--- a/src/box/lua/init.c
+++ b/src/box/lua/init.c
@@ -60,6 +60,7 @@
 #include "box/lua/cfg.h"
 #include "box/lua/xlog.h"
 #include "box/lua/console.h"
+#include "box/lua/cmod.h"
 #include "box/lua/tuple.h"
 #include "box/lua/execute.h"
 #include "box/lua/key_def.h"
@@ -465,6 +466,7 @@ box_lua_init(struct lua_State *L)
 	box_lua_tuple_init(L);
 	box_lua_call_init(L);
 	box_lua_cfg_init(L);
+	box_lua_cmod_init(L);
 	box_lua_slab_init(L);
 	box_lua_index_init(L);
 	box_lua_space_init(L);
-- 
2.29.2


  reply	other threads:[~2021-02-17 12:40 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-17 12:39 [Tarantool-patches] [PATCH v18 0/2] box: " Cyrill Gorcunov via Tarantool-patches
2021-02-17 12:39 ` Cyrill Gorcunov via Tarantool-patches [this message]
2021-02-17 12:39 ` [Tarantool-patches] [PATCH v18 2/2] test: box/cfunc -- add cmod test Cyrill Gorcunov via Tarantool-patches
2021-02-17 20:15 ` [Tarantool-patches] [PATCH 0/4] cmod: refactor box/func Cyrill Gorcunov via Tarantool-patches
2021-02-17 20:15   ` [Tarantool-patches] [PATCH 1/4] box/func: drop redundant module argument Cyrill Gorcunov via Tarantool-patches
2021-02-17 20:15   ` [Tarantool-patches] [PATCH 2/4] box/func: update module cache in one pass Cyrill Gorcunov via Tarantool-patches
2021-02-17 20:15   ` [Tarantool-patches] [PATCH 3/4] cmod: export cmod_call helper Cyrill Gorcunov via Tarantool-patches
2021-02-17 20:15   ` [Tarantool-patches] [PATCH 4/4] box/func: simplify func_c_call Cyrill Gorcunov via Tarantool-patches

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