godzie44 authored 1 year ago and Dmitry Ivanov committed 3 months ago

Add `current_cord_name` function to get a name of the current cord,
add `cord_is_main_dont_create` function.
Add exports for `cord_is_main`, `cord_is_main_dont_create` and
`current_cord_name` functions.

NO_DOC=internal
NO_TEST=internal
NO_CHANGELOG=internal

godzie44 authored 1 year ago and Dmitry Ivanov committed 3 months ago

Add `log_default_logger` to get a default logger.
Add exports for `log_set_format`, `log_set_level` and `log_default_logger` functions.

NO_DOC=internal
NO_TEST=internal
NO_CHANGELOG=internal

Dmitry Rodionov authored 1 year ago and Dmitry Ivanov committed 3 months ago

NO_DOC=picodata internal patch
NO_CHANGELOG=picodata internal patch
NO_TEST=picodata internal patch

Dmitry Ivanov authored 1 year ago and Dmitry Ivanov committed 3 months ago

This patch helps us create and write to non-default
loggers provided by `say.h`. We'll use this mainly
for audit log in picodata.

NO_DOC=internal
NO_TEST=internal
NO_CHANGELOG=internal

Georgy Moshkin authored 1 year ago and Dmitry Ivanov committed 3 months ago

Closes #9237

Add exports for fiber_set_name_n, fiber_name, fiber_id, fiber_csw &
fiber_find.

Also make fiber_set_joinable, fiber_set_ctx & fiber_get_ctx interpret
NULL as the current fiber.

@TarantoolBot document
Title: add basic fiber api to ffi exports.

5 basic functions can now be used via ffi api, which were previously
only accessible via lua api: fiber_set_name_n, fiber_name, fiber_id,
fiber_csw & fiber_find.

fiber_set_joinable now interprets NULL as current fiber.

Dmitry Rodionov authored 1 year ago and Dmitry Ivanov committed 3 months ago

NO_DOC=picodata internal patch
NO_CHANGELOG=picodata internal patch
NO_TEST=picodata internal patch

Co-authored-by: Yaroslav Dynnikov <yaroslav.dynnikov@gmail.com>

Georgy Moshkin authored 1 year ago and Dmitry Ivanov committed 3 months ago

Introduce API for opening a read view over the specified spaces and
indexes and creating iterators over the index read views.

NO_DOC=picodata patch

Denis Smirnov authored 1 year ago and Dmitry Ivanov committed 3 months ago

1. Current commit introduces 'box_auth_data_prepare()' to prepare
   a data string for any supported authentication methods.
2. The user name argument is refactored in the auth methods: the
   null-terminated string is replaced with an address range approach.
   Now Rust users don't need to re-allocate username with CString.
3. Password length type was set to uint32_t (previously it was size_t,
   int, uint32_t for different functions). Tarantool uses murmur3a,
   so all the hashed strings should be up to 32 bit long.

NO_DOC=picodata internal patch
NO_CHANGELOG=picodata internal patch
NO_TEST=picodata internal patch

Denis Smirnov authored 1 year ago and Dmitry Ivanov committed 3 months ago

Introduce new methods:

1. box_user_id_by_name - get the user identifier by name;
2. box_effective_user_id - get current effective user
   identifier;
3. box_session_user_id - get current session user identifier;
4. box_session_su - change current session user;

NO_DOC=picodata internal patch
NO_CHANGELOG=picodata internal patch
NO_TEST=picodata internal patch

Maksim Kaitmazian authored 1 year ago and Dmitry Ivanov committed 3 months ago

PG protocol run queries by calling dispatch_query, which stores the
response in port_c contained in box_function_ctx structure.

NO_DOC=exports
NO_CHANGELOG=exports
NO_TEST=exports

Maksim Kaitmazian authored 1 year ago and Dmitry Ivanov committed 3 months ago

This function is used to determine the authentication method when
authenticating a postgres client.

part of picodata/picodata/sbroad!292

NO_DOC=exports
NO_CHANGELOG=exports
NO_TEST=exports

Maksim Kaitmazian authored 1 year ago and Dmitry Ivanov committed 3 months ago

These exports allow us to perform user authentication and
network communication.

part of picodata/picodata/sbroad!292

NO_DOC=exports
NO_CHANGELOG=exports
NO_TEST=exports

Denis Smirnov authored 1 year ago and Dmitry Ivanov committed 3 months ago

Picodata supports cluster-wide SQL and needs some predictable
method to calculate tuple hashes for the bucket ids. Method
should be available for Lua, C and Rust users. It was decided
to expose a murmur3 hash calculation method of the key_def module.

NO_DOC=picodata internal patch
NO_CHANGELOG=picodata internal patch

godzie44 authored 1 year ago and Dmitry Ivanov committed 3 months ago

Introduced a new type of cbus pipe - lcpipe. The current pipe in the
cbus - cpipe, has a number of limitations, first of all - the cpipe
cannot be used from the 3rd party threads, cpipe only works as a channel
between two cords. That why lcpipe is needed. Its main responsibility -
create channel between any thread and tarantool cord.

Internally lcpipe is a cpipe, but:
- on flush triggers removed, cause triggers use thread-local mem-pool,
this is not possible on a third party thread
- producer event loop removed, cause there is no libev event loop in
third party thread

Also, lcpipe interface is exported to the outside world.

NO_DOC=core feature

godzie44 authored 2 years ago and Dmitry Ivanov committed 3 months ago

sql: add sql_execute_prepared_ext function, same as sql_execute_prepared but without `region` parameter
closes #2

NO_DOC=minor
NO_TEST=minor

godzie44 authored 2 years ago and Dmitry Ivanov committed 3 months ago

- add box_tuple_data_offset function (return offset of the messagePack encoded data from the beginning of the tuple)
- add more export functions

closes #1

NO_DOC=build
NO_TEST=build

box_info_lsn
box_is_ro
box_ro_reason
box_wait_ro

Closes #10378

NO_CHANGELOG=minor change

@TarantoolBot document
Title: document 4 more symbols in public C API

box_info_lsn
box_is_ro
box_ro_reason
box_wait_ro

Their meaning is identical to lua methods:

box.info.lsn
box.info.ro
box.info.ro_reason
box.wait_ro

(cherry picked from commit f1c76b976077e8078c42990546d9dbbdea315425)

Some downgrade operations are performed with disabled system space
triggers because they were prohibited recently (creation of SQL built-in
functions) or never allowed (dropping a system space). This works fine
on the instance running downgrade but apparently fails on replicas.

To fix this issue, let's disable the checks the operations that prevent
downgrade in the following scenarios:
 - in the fiber that is currently running a schema upgrade or downgrade;
 - in the applier fiber so that it can replicate changes done by upgrade
   or downgrade on the master;
 - during recovery so that DDL records written to the WAL can be
   replayed.

We already have all the necessary infrastructure in-place - we use it
for allowing DDL operations with an old schema for upgrade.

Closes #9049

NO_DOC=bug fix

(cherry picked from commit 71de4b2c)

NOTE: We don't have the commit that disables DDL operations with an old
schema in 2.11 so we have to backport bits of it from 3.0, see commit
97c2c9a4 ("box: disable DDL with old schema").

In some cases unsafe extension decoding was done without bound and type
checks: add necessary checks.

Closes tarantool/security#73

NO_DOC=bugfix

(cherry picked from commit 1de6a071)

The `tarantool_version` symbol identifies the binary as Tarantool (see also
https://github.com/tarantool/tarantool/blob/f991f7c0be73558f0710f0af871d07e8bd506efe/tools/tarabrt.sh#L179-L180

).
It is not exported and thus can be optimized away by LTO — add it to the
exports list.

Closes #8129

Acked-by: Aleksandr Lyapunov <alyapunov@tarantool.org>

NO_CHANGELOG=<internal change>
NO_DOC=<internal change>
NO_TEST=<no convenient way to test devtools>

Recently, ffi select was broken on M1 in commit ec1a71ff
("box: introduce pagination to memtx_tree and tuple position methods").
It turned out that ffi on M1 poorly supports a big quantity of arguments.
Fortunately, there is a workaround - we can pass only 64-bit integer
arguments beyond the 8th argument. Let's do it.

Closes #7946

NO_TEST=reflected in existing tests
NO_CHANGELOG=bugfix for unreleased feature
NO_DOC=bugfix

If the first argument of box.atomic is a non-callable table then
consider it as options table for box.begin{}.

For test and debug purposes introduce internal getter of current
transaction isolation level as box.internal.txn_isolation().

Closes #7202

@TarantoolBot document
Title: Options in box.atomic

Now it's allowed to pass transaction options in the first argument
of box.atomic(..) call. The options must be a table, exactly as
in box.begin(..). If options are passed as the first arguments,
the second and the rest arguments are expected to be a functions
and its arguments, like in usual box.atomic.

Add `IPROTO_UNKNOWN` command code for overriding the unknown request
handler.

Change request type variable types related to IPROTO to `uint32_t`.

Add request handler hash table to transaction thread and request handler
set to IPROTO threads for storing overridden request handlers: TX thread
notifies IPROTO threads about overridden request handlers using IPROTO
configuration message.

If a given request handler is overridden, the IPROTO thread does not
preprocess it and sends the package immediately over a dedicated route. If
later it is necessary to fallback to the system handler, the message
decoding and dispatching is done in the TX thread.

Add new `box.iproto.override` method to Lua and `box_iproto_override` to C
API, which allow setting IPROTO request handler callbacks.

Closes #7901

@TarantoolBot document
Title: Document overriding IPROTO request handlers feature
For the API description and usage examples, see:
* [design document](https://www.notion.so/tarantool/box-iproto-override-44935a6ac7e04fb5a2c81ca713ed1bce#0f84694523214c0e9bf2f3d75cccace4);
* tarantool/tarantool#7901.

Patch replaces encoding and decoding functions written in Lua with
functions implemented in C.

Performance of Lua implementation (before the patch):

```
uri.escape   152.37  runs/sec
uri.unescape 263.44  runs/sec
```

Performance of C implementation (after the patch):

```
uri.escape   4983.03  runs/sec
uri.unescape 4197.19  runs/sec
```

Follows up #3682

NO_CHANGELOG=see previous commit
NO_DOC=see previous commit

Co-authored-by: Alexander Turenko <alexander.turenko@tarantool.org>

Add translation table for `box.iproto.key` constants encoding to simplify
packet assembly.

Add new `box.iproto.send` method to Lua and `box_iproto_send` function to C
API, which allow sending arbitrary IPROTO packets, using active IPROTO
sessions. Packets are sent asynchronously using Kharon.

Add `xregion_join` to the `xalloc` API.

Change gh-7894 test: instead of simply comparing `box.iproto` table to the
reference table, iterate over `box.iproto` and check that corresponding
non-{function, thread, userdata} type values exist in the reference table.

Closes #7897

@TarantoolBot document
Title: Document sending arbitrary IPROTO packets feature
For the API description and usage examples, see:
* [design document](https://www.notion.so/tarantool/box-iproto-override-44935a6ac7e04fb5a2c81ca713ed1bce#a2cc04da89d34fad8f8564c150cd9977);
* tarantool/tarantool#7897.

Before commit 24323448 ("log: add log.new() function that creates a
new logger"), log_write_flightrec() was called from log_vsay() regardless
of the log level. After, the log level is checked in Lua, so log_vsay()
may not be called. This patch restores the original behaviour by moving
log_write_flightrec() calls to say_default() and say().

Part of https://github.com/tarantool/tarantool-ee/issues/320

NO_DOC=bugfix
NO_CHANGELOG=unreleased
NO_TEST=will be enabled in EE, because there are no flightrec in CE

Since commit f6ea7180 ("Try to load several variants of libssl.")
the digest module uses an internal version of SHA1. Back then, we didn't
link the OpenSSL library. Instead, we tried to load it dynamically.
Since on some distributions the library could be missing, it was decided
to implement an internal version of SHA1, see #405.

However, since commit 59a55740 ("Link against libssl and libcrypto.
Issue #1382") we link the OpenSSL library unconditionally so there's no
need in having an internal implementation of SHA1. Let's drop it and
switch the digest module to the version of SHA1 implemented by the
crypto module using OpenSSL.

Part of #7987

NO_DOC=code cleanup
NO_TEST=code cleanup
NO_CHANGELOG=code cleanup

It allows to create a new instance of a log module, with a custom name:
local my_log = require('log').new('my_module')

The name is added to the log message after fiber name:
YYYY-MM-DD hh:mm:ss.ms [PID]: CORD/FID/FIBERNAME/MODULENAME LEVEL> MSG

Part of #3211

NO_DOC=See next commit
NO_CHANGELOG=See next commit

Co-authored-by: AnastasMIPT <beliaev.ab@tarantool.org>

This commit introduces an abstraction for the authentication code so
that one can easily add new methods. To add a new method, one just needs
to define a set of authentication callbacks in a struct auth_method and
register it with auth_method_register.

The IPROTO_AUTH and _user.auth formats were initially designed with
extensibility in mind: both take the authentication method name
(currently, only 'chap-sha1' is supported) so no changes to the schema
are required.

Note that although 'chap-sha1' is now implemented in its own file
src/box/auth_chap_sha1.c, we don't merge src/scramble.c into it.
This will be done later, in the scope of #7987.

Since we call authentication plug-ins "methods" (not "mechanisms"),
let's rename BOX_USER_FIELD_AUTH_MECH_LIST to BOX_USER_FIELD_AUTH while
we are at it. Anyway, the corresponding field of the _user system space
is called 'auth' (not 'auth_mech_list').

Closes #7986

NO_DOC=refactoring
NO_TEST=refactoring
NO_CHANGELOG=refactoring

In order to send IPROTO packets using `box_iproto_send` (#7897) we need to
have some session identifier source in the C API: for now, export an analog
of `box.session.id`.

Closes #7895

@TarantoolBot document
Title: Document export of current session's identifier to C API
For the API description and usage examples, see:
* [design document](https://www.notion.so/tarantool/box-iproto-override-44935a6ac7e04fb5a2c81ca713ed1bce#0900ff9cb6b148378ce0b185d3f628b9);
* tarantool/tarantool#7895.

The patch introduces pagination to pairs: one can create iterator which
will start after specific tuple or position, described by option after.
Tuple (both cdata and array) and position (obtained by index:tuple_pos
or fetch_pos option of select) can be passed as option after.

NO_CHANGELOG=next commit
NO_DOC=next commit

See [1] for some details on why the code for log configuration needs
some care. In short log config validity checks are spread thru many
places, on some code paths we use one checks and on other code paths
other checks. And we make repetitive validity checks many times in
runtime on single configure call.

We can also reuse code for setting default values, checking options
type and resetting values to default.

- As a side effect of refactoring one can now reset values to default thru
  `log.cfg()` so now `log.cfg()` is on par with `box.cfg` in this respect.

- This patch also drops conversion `log_level` from string to number.

  Before (shorten):

    tarantool> box.cfg{log_level='warn'}
    tarantool> box.cfg.log_level
    - info
    tarantool> log.cfg.level
    - 5

  Also:
    tarantool> log.cfg{level='info'}
    tarantool> log.cfg.level
    - 5
    tarantool> box.cfg{}
    tarantool> box.cfg.log_level
    - 5

  After patch if `log_level`/`level` is given as string than it is saved
  and returned as string too. I guess it should not affect users but looks
  more handy.

- Also fixed issue with inconsistent setting `log_nonblock` thru
  `box.cfg()` and `log.cfg()`. In former case `nil` means setting default
  depending on logger type. In the latter case `nil` meant setting
  `nonblock` to `false`.

- Also patch fixes #7447.

Closes #7447.

[1] PR for this refactoring
https://github.com/tarantool/tarantool/pull/7454

NO_DOC=refactoring/tiny API improvemnent

By default a user might not have privileges to access the _schema space,
that will cause an error during schema_needs_upgrade(), which calls
get_version(). Fix this by using C variable dd_version_id, which is
updated in the _schema.version replace trigger.

There's a special case for upgrade() during bootstrap() - triggers are
disabled during bootstrap, that's why dd_version_id is not being updated.
Handle this by passing _initial_version=1.7.5 to the upgrade function.

Part of #7149

NO_DOC=internal
NO_CHANGELOG=internal

The patch introduces C and Lua methods for extracting position
of tuple in index. Multikey and functional indexes are not supported.

Also this patch extends method index_create_iterator_after and adds
implementation of iterator_position for memtx tree. Options
after and fetch_pos are added to Lua select as well (both FFI and LuaC).
All the types of memtx tree indexes are supported (multikey, functional).

NO_CHANGELOG=see later commits
NO_DOC=see later commits

Closes #7633
Closes #7636

Before this change there was no way to create a fiber that accepts
parameters without yielding from the current fiber using the c api. You
could pass the function arguments when calling fiber_start, but that
forces you to yield, which is not acceptable in some scenarios (e.g.
within a transaction).

This commit introduces 2 new functions to the api: fiber_set_ctx for
setting an pointer to a context of the given fiber and fiber_get_ctx for
accessing that context.

Closes https://github.com/tarantool/tarantool/issues/7669

@TarantoolBot document
Title: fiber: add fiber_set_ctx & fiber_get_ctx functions

Add 2 api functions: `fiber_set_ctx` & `fiber_get_ctx` which can be used
for passing data to a fiber. Previously this could be done via the
`fiber_start` function, except that this would force the current fiber
to yield, which is not acceptable in some scenarios (e.g. during a
transaction). Now you can create a fiber with `fiber_new`, set it's
contents with `fiber_set_ctx`, make it ready for execution with
`fiber_wakeup` and keep executing the current fiber.

strerror() is MT-Unsafe, because it uses a static buffer under the hood.
We should use strerror_r() instead, which takes a user-provided buffer.
The problem is there are two implementations of strerror_r(): XSI and
GNU. The first one returns an error code and always writes the message
to the beginning of the buffer while the second one returns a pointer to
a location within the buffer where the message starts. Let's introduce a
macro HAVE_STRERROR_R_GNU set if the GNU version is available and define
tt_strerror() which writes the message to the static buffer, like
tt_cstr() or tt_sprintf().

Note, we have to export tt_strerror(), because it is used by Lua via
FFI. We also need to make it available in the module API header, because
the say_syserror() macro uses strerror() directly. In order to avoid
adding tt_strerror() to the module API, we introduce an internal helper
function _say_strerror(), which calls tt_strerror().

NO_DOC=bug fix
NO_TEST=code is covered by existing tests

The Rust module (see the issue) needs a getter and a setter for decimal
values on the Lua stack. Let's make them part of the module API.

Part of #7228

@TarantoolBot document
Title: Lua/C functions for decimals in the module API

The following functions are added into the module API:

```c
/**
 * Allocate a new decimal on the Lua stack and return
 * a pointer to it.
 */
API_EXPORT box_decimal_t *
luaT_newdecimal(struct lua_State *L);

/**
 * Allocate a new decimal on the Lua stack with copy of given
 * decimal and return a pointer to it.
 */
API_EXPORT box_decimal_t *
luaT_pushdecimal(struct lua_State *L, const box_decimal_t *dec);

/**
 * Check whether a value on the Lua stack is a decimal.
 *
 * Returns a pointer to the decimal on a successful check,
 * NULL otherwise.
 */
API_EXPORT box_decimal_t *
luaT_isdecimal(struct lua_State *L, int index);
```

The main decision made in this patch is how large the public
`box_decimal_t` type should be. Let's look on some calculations.

We're interested in the following values.

* How much decimal digits is stored?
* Size of an internal decimal type (`sizeof(decimal_t)`).
* Size of a buffer to store a string representation of any valid
  `decimat_t` value.
* Largest signed integer type fully represented in decimal_t (number of
  bits).
* Largest unsigned integer type fully represented in decimal_t (number
  of bits).

Now `decimal_t` is defined to store 38 decimal digits. It means the
following values:

| digits | sizeof | string | int???_t | uint???_t |
| ------ | ------ | ------ | -------- | --------- |
| 38     | 36     | 52     | 126      | 127       |

In fact, decNumber (the library we currently use under the hood) allows
to vary the 'decimal digits per unit' parameter, which is 3 by default,
so we can choose density of the representation. For example, for given
38 digits the sizeof is 36 by default, but it may vary from 28 to 47
bytes:

| digits | sizeof     | string | int???_t | uint???_t |
| ------ | ---------- | ------ | -------- | --------- |
| 38     | 36 (28-47) | 52     | 126      | 127       |

If we'll want to store `int128_t` and `uint128_t` ranges, we'll need 39
digits:

| digits | sizeof     | string | int???_t | uint???_t |
| ------ | ---------- | ------ | -------- | --------- |
| 39     | 36 (29-48) | 53     | 130      | 129       |

If we'll want to store `int256_t` and `uint256_t` ranges:

| digits | sizeof     | string | int???_t | uint???_t |
| ------ | ---------- | ------ | -------- | --------- |
| 78     | 62 (48-87) | 92     | 260      | 259       |

If we'll want to store `int512_t` and `uint512_t` ranges:

| digits | sizeof       | string | int???_t | uint???_t |
| ------ | ------------ | ------ | -------- | --------- |
| 155    | 114 (84-164) | 169    | 515      | 514       |

The decision here is what we consdider as possible and what as unlikely.
The patch freeze the maximum amount of bytes in `decimal_t` as 64. So
we'll able to store 256 bit integers and will NOT able to store 512 bit
integers in a future (without the ABI breakage at least).

The script, which helps to calculate those tables, is at end of the
commit message.

Next, how else `box_decimal_*()` library is different from the internal
`decimal_*()`?

* Added a structure that may hold any decimal value from any current or
  future tarantool version.
* Added `box_decimal_copy()`.
* Left `strtodec()` out of scope -- we can add it later.
* Left `decimal_str()` out of scope -- it looks dangerous without at
  least a good explanation when data in the static buffer are
  invalidated. There is `box_decimal_to_string()` that writes to an
  explicitly provided buffer.
* Added `box_decimal_mp_*()` for encoding to/decoding from msgpack.
  Unlike `mp_decimal.h` functions, here we always have `box_decimal_t`
  as the first parameter.
* Left `decimal_pack()` out of scope, because a user unlikely wants to
  serialize a decimal value piece-by-piece.
* Exposed `decimal_unpack()` as `box_decimal_mp_decode_data()` to keep a
  consistent terminogoly around msgpack encoding/decoding.
* More detailed API description, grouping by functionality.

The script, which helps to calculate sizes around `decimal_t`:

```lua
-- See notes in decNumber.h.

-- DECOPUN: DECimal Digits Per UNit
local function unit_size(DECOPUN)
    assert(DECOPUN > 0 and DECOPUN < 10)
    if DECOPUN <= 2 then
        return 1
    elseif DECOPUN <= 4 then
        return 2
    end
    return 4
end

function sizeof_decimal_t(digits, DECOPUN)
    -- int32_t digits;
    -- int32_t exponent;
    -- uint8_t bits;
    -- <..padding..>
    -- <..units..>
    local us = unit_size(DECOPUN)
    local padding = us - 1
    local unit_count = math.ceil(digits / DECOPUN)
    return 4 + 4 + 1 + padding + us * unit_count
end

function string_buffer(digits)
    -- -9.{9...}E+999999999# (# is '\0')
    -- ^ ^      ^^^^^^^^^^^^
    return digits + 14
end

function binary_signed(digits)
    local x = 1
    while math.log10(2 ^ (x - 1)) < digits do
        x = x + 1
    end
    return x - 1
end

function binary_unsigned(digits)
    local x = 1
    while math.log10(2 ^ x) < digits do
        x = x + 1
    end
    return x - 1
end

function digits_for_binary_signed(x)
    return math.ceil(math.log10(2 ^ (x - 1)))
end

function digits_for_binary_unsigned(x)
    return math.ceil(math.log10(2 ^ x))
end

function summary(digits)
    print('digits', digits)
    local sizeof_min = math.huge
    local sizeof_max = 0
    local DECOPUN_sizeof_min
    local DECOPUN_sizeof_max
    for DECOPUN = 1, 9 do
        local sizeof = sizeof_decimal_t(digits, DECOPUN)
        print('sizeof', sizeof, 'DECOPUN', DECOPUN)
        if sizeof < sizeof_min then
            sizeof_min = sizeof
            DECOPUN_sizeof_min = DECOPUN
        end
        if sizeof > sizeof_max then
            sizeof_max = sizeof
            DECOPUN_sizeof_max = DECOPUN
        end
    end
    print('sizeof min', sizeof_min, 'DECOPUN', DECOPUN_sizeof_min)
    print('sizeof max', sizeof_max, 'DECOPUN', DECOPUN_sizeof_max)
    print('string', string_buffer(digits))
    print('int???_t', binary_signed(digits))
    print('uint???_t', binary_unsigned(digits))
end
```

Part of #7228

@TarantoolBot document
Title: Module API for decimals

See the declarations in `src/box/decimal.h` in tarantool sources.

The Rust module [1] leans on several internal symbols. They were open in
Tarantool 2.8 (see #2971 and #5932), but never were in the public API.
Tarantool 2.10.0 hides the symbols and we need a way to get them back to
use in the module.

We have the following options:

1. Design and expose a module API for fiber channels.
2. Export the symbols with a prefix like `tnt_internal_` (to don't spoil
   the global namespace).
3. Provide a `dlsym()` alike function to get an address of an internal
   symbol for users who knows what they're doing.

I think that the third way offers the best compromise between amount of
effort, quality of the result and opportunities to extend. In this
commit I hardcoded the list of functions to make the change as safe as
possible. Later I'll return here to autogenerate the list.

Exported the following function from the tarantool executable:

```c
void *
tnt_internal_symbol(const char *name);
```

I don't add it into the module API headers, because the function is to
perform a dark magic and we don't suggest it for users.

While I'm here, added `static` to a couple of fiber channel functions,
which are only used within the compilation unit.

[1]: https://github.com/picodata/tarantool-module

Part of #7228
Related to #6372

NO_DOC=don't advertize the dangerous API
NO_CHANGELOG=don't advertize the dangerous API

Added a function (see the API in the documentation request below), which
reflects the `tuple[json_path]` Lua API (see #1285).

Part of #7228

@TarantoolBot document
Title: tuple: access a field using JSON path via module API

The following function is added into the module API:

```c
/**
 * Return a raw tuple field in the MsgPack format pointed by
 * a JSON path.
 *
 * The JSON path includes the outmost field. For example, "c" in
 * ["a", ["b", "c"], "d"] can be accessed using "[2][2]" path (if
 * index_base is 1, as in Lua). If index_base is set to 0, the
 * same field will be pointed by the "[1][1]" path.
 *
 * The first JSON path token may be a field name if the tuple
 * has associated format with named fields. A field of a nested
 * map can be accessed in the same way: "foo.bar" or ".foo.bar".
 *
 * The return value is valid until the tuple is destroyed, see
 * box_tuple_ref().
 *
 * Return NULL if the field does not exist or if the JSON path is
 * malformed or invalid. Multikey JSON path token [*] is treated
 * as invalid in this context.
 *
 * \param tuple a tuple
 * \param path a JSON path
 * \param path_len a length of @a path
 * \param index_base 0 if array element indexes in @a path are
 *        zero-based (like in C) or 1 if they're one-based (like
 *        in Lua)
 * \retval a pointer to a field data if the field exists or NULL
 */
API_EXPORT const char *
box_tuple_field_by_path(box_tuple_t *tuple, const char *path,
			uint32_t path_len, int index_base);
```