[Tarantool-patches] [PATCH v3 1/5] popen: Introduce a backend engine

[Cyrill Gorcunov]

In the patch we introduce popen backend engine which provides
a way to execute external programs and communicate with their
stdin/stdout/stderr streams.

It is possible to run a child process with:

 a) completely closed stdX descriptors
 b) provide /dev/null descriptors to appropritate stdX
 c) pass new transport into a child (currently we use
    pipes for this sake, but may extend to tty/sockets)
 d) inherit stdX from a parent, iow do nothing

On tarantool start we create @popen_pids_map hash which maps
created processes PIDs to popen_handle structure, this structure
keeps everything needed to control and communicate with the children.
The hash will allow us to find a hild process quickly from inside
of a signal handler.

Each handle links into @popen_head list, which is need to be able
to destory children processes on exit procedure (ie when we exit
tarantool and need to cleanup the resources used).

Every new process is born by vfork() call - we can't use fork()
because of at_fork() handlers in libeio which cause deadlocking
in internal mutex usage. Thus the caller waits until vfork()
finishes its work and runs exec (or exit with error).

Because children processes are running without any limitations
they can exit by self or can be killed by some other third side
(say user of a hw node), we need to watch their state which is
done by setting a hook with ev_child_start() helper. This helper
allows us to catch SIGCHLD when a child get exited/signaled
and unregister it from a pool or currently running children.
Note the libev wait() reaps child zomby by self. Another
interesting detail is that libev catches signal in async way
but our SIGCHLD hook is called in sync way before child reap.

This engine provides the following API:
 - popen_init
	to initialize engine
 - popen_free
	to finalize engine and free all reasources
	allocated so far
 - popen_new
	to create a new child process and start it
 - popen_delete
	to release resources occupied and
	terminate a child process
 - popen_stat
	to fetch statistics about a child process
 - popen_command
	to fetch command line string formerly used
	on popen creation
 - popen_write
	to write data into child's stdin
 - popen_read_timeout
	to read data from child's stdout/stderr
	with timeout
 - popen_state
	to fetch state (alive, exited or killed) and
	exit code of a child process
 - popen_state_str
	to get state of a child process in string
	form, for Lua usage mostly
 - popen_send_signal
	to send signal to a child process (for
	example to kill it)

Known issues to fix in next series:

 - environment variables for non-linux systems do not support
   inheritance for now due to lack of testing on my side;

 - for linux base systems we use popen2 system call passing
   O_CLOEXEC flag so that two concurrent popen_create calls
   would not affect each other with pipes inheritance (while
   currently we don't have a case where concurrent calls could
   be done as far as I know, still better to be on a safe side
   from the beginning);

 - there are some files (such as xlog) which tarantool opens
   for own needs without setting O_CLOEXEC flag and it get
   propagated to a children process; for linux based systems
   we use close_inherited_fds helper which walks over opened
   files of a process and close them. But for other targets
   like MachO or FreeBSD this helper just zapped simply because
   I don't have such machines to experimant with; we should
   investigate this moment in more details later once base
   code is merged in;

 - need to consider a case where we will be using piping for
   descriptors (for example we might be writting into stdin
   of a child from another pipe, for this sake we could use
   splice() syscall which gonna be a way faster than copying
   data inside kernel between process). Still the question
   is -- do we really need it? Since we use interanal flags
   in popen handle this should not be a big problem to extend
   this interfaces;

   this particular feature is considered to have a very low
   priority but I left it here just to not forget.

Part of #4031

Signed-off-by: Cyrill Gorcunov <gorcunov at gmail.com>
---
 src/lib/core/CMakeLists.txt |    1 +
 src/lib/core/popen.c        | 1217 +++++++++++++++++++++++++++++++++++
 src/lib/core/popen.h        |  218 +++++++
 src/main.cc                 |    4 +
 4 files changed, 1440 insertions(+)
 create mode 100644 src/lib/core/popen.c
 create mode 100644 src/lib/core/popen.h

diff --git a/src/lib/core/CMakeLists.txt b/src/lib/core/CMakeLists.txt
index 8623aa0de..3f13ff904 100644
--- a/src/lib/core/CMakeLists.txt
+++ b/src/lib/core/CMakeLists.txt
@@ -15,6 +15,7 @@ set(core_sources
     coio.cc
     coio_task.c
     coio_file.c
+    popen.c
     coio_buf.cc
     fio.c
     exception.cc
diff --git a/src/lib/core/popen.c b/src/lib/core/popen.c
new file mode 100644
index 000000000..d6f3c2ab5
--- /dev/null
+++ b/src/lib/core/popen.c
@@ -0,0 +1,1217 @@
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <paths.h>
+#include <signal.h>
+#include <poll.h>
+
+#include <sys/types.h>
+#include <dirent.h>
+#include <sys/wait.h>
+
+#include "popen.h"
+#include "fiber.h"
+#include "assoc.h"
+#include "say.h"
+
+/* Children pids map popen_handle map */
+static struct mh_i32ptr_t *popen_pids_map = NULL;
+
+/* All popen handles to be able to cleanup them on exit */
+static RLIST_HEAD(popen_head);
+
+/* /dev/null to be used inside children if requested */
+static int dev_null_fd_ro = -1;
+static int dev_null_fd_wr = -1;
+
+/**
+ * popen_register - register popen handle in a pids map
+ * @handle:	handle to register
+ */
+static void
+popen_register(struct popen_handle *handle)
+{
+	struct mh_i32ptr_node_t node = {
+		.key	= handle->pid,
+		.val	= handle,
+	};
+	say_debug("popen: register %d", handle->pid);
+	mh_i32ptr_put(popen_pids_map, &node, NULL, NULL);
+}
+
+/**
+ * popen_find - find popen handler by its pid
+ * @pid:	pid of a handler
+ *
+ * Returns a handle if found or NULL otherwise.
+ */
+static struct popen_handle *
+popen_find(pid_t pid)
+{
+	mh_int_t k = mh_i32ptr_find(popen_pids_map, pid, NULL);
+	if (k == mh_end(popen_pids_map))
+		return NULL;
+	return mh_i32ptr_node(popen_pids_map, k)->val;
+}
+
+/**
+ * popen_unregister - remove popen handler from a pids map
+ * @handle:	handle to remove
+ */
+static void
+popen_unregister(struct popen_handle *handle)
+{
+	struct mh_i32ptr_node_t node = {
+		.key	= handle->pid,
+		.val	= NULL,
+	};
+	say_debug("popen: unregister %d", handle->pid);
+	mh_i32ptr_remove(popen_pids_map, &node, NULL);
+}
+
+/**
+ * command_new - allocates a command string from argv array
+ * @argv:	an array with pointers to argv strings
+ * @nr_argv:	number of elements in the @argv
+ *
+ * Returns a new string or NULL on error.
+ */
+static inline char *
+command_new(char **argv, size_t nr_argv)
+{
+	size_t size = 0, i;
+	char *command;
+	char *pos;
+
+	assert(argv != NULL && nr_argv > 0);
+
+	for (i = 0; i < nr_argv; i++) {
+		if (argv[i] == NULL)
+			continue;
+		size += strlen(argv[i]) + 1;
+	}
+
+	command = malloc(size);
+	if (!command) {
+		say_syserror("popen: Can't allocate command");
+		return NULL;
+	}
+
+	pos = command;
+	for (i = 0; i < nr_argv-1; i++) {
+		if (argv[i] == NULL)
+			continue;
+		strcpy(pos, argv[i]);
+		pos += strlen(argv[i]);
+		*pos++ = ' ';
+	}
+	pos[-1] = '\0';
+
+	return command;
+}
+
+/**
+ * command_free - free memory allocated for command
+ * @command:	pointer to free
+ *
+ * To pair with command_new().
+ */
+static inline void
+command_free(char *command)
+{
+	free(command);
+}
+
+/**
+ * handle_new - allocate new popen hanldle with flags specified
+ * @opts:	pointer to options to be used
+ * @command:	command line string
+ *
+ * Returns pointer to a new initialized popen object
+ * or NULL on error.
+ */
+static struct popen_handle *
+handle_new(struct popen_opts *opts, char *command)
+{
+	struct popen_handle *handle;
+
+	handle = malloc(sizeof(*handle));
+	if (!handle) {
+		say_syserror("popen: Can't allocate handle");
+		return NULL;
+	}
+
+	handle->command	= command;
+	handle->wstatus	= 0;
+	handle->pid	= -1;
+	handle->flags	= opts->flags;
+
+	rlist_create(&handle->list);
+
+	/* all fds to -1 */
+	memset(handle->fds, 0xff, sizeof(handle->fds));
+
+	say_debug("popen: handle %p alloc", handle);
+	return handle;
+}
+
+/**
+ * handle_free - free memory allocated for a handle
+ * @handle:	popen handle to free
+ *
+ * Just to match handle_new().
+ */
+static void
+handle_free(struct popen_handle *handle)
+{
+	say_debug("popen: handle %p free %p", handle);
+	free(handle);
+}
+
+/**
+ * popen_may_io - test if handle can run io operation
+ * @handle:	popen handle
+ * @idx:	index of a file descriptor to operate on
+ * @io_flags:	popen_flag_bits flags
+ *
+ * Returns true if IO is allowed and false otherwise
+ * (setting @errno).
+ */
+static inline bool
+popen_may_io(struct popen_handle *handle, unsigned int idx,
+	     unsigned int io_flags)
+{
+	if (!handle) {
+		errno = ESRCH;
+		return false;
+	}
+
+	if (!(io_flags & handle->flags)) {
+		errno = EINVAL;
+		return false;
+	}
+
+	if (handle->fds[idx] < 0) {
+		errno = EPIPE;
+		return false;
+	}
+
+	return true;
+}
+
+/**
+ * popen_may_pidop - test if handle is valid for pid related operations
+ * @handle:	popen handle
+ *
+ * This is shortcut to test if handle is not nil and still have
+ * a valid child process.
+ *
+ * Returns true if ops are allowed and false otherwise
+ * (setting @errno).
+ */
+static inline bool
+popen_may_pidop(struct popen_handle *handle)
+{
+	if (!handle || handle->pid == -1) {
+		errno = ESRCH;
+		return false;
+	}
+	return true;
+}
+
+/**
+ * popen_stat - fill popen object statistics
+ * @handle:	popen handle
+ * @st:		destination popen_stat to fill
+ *
+ * Returns 0 on succes, -1 otherwise (setting @errno).
+ */
+int
+popen_stat(struct popen_handle *handle, struct popen_stat *st)
+{
+	if (!handle) {
+		errno = ESRCH;
+		return -1;
+	}
+
+	st->pid		= handle->pid;
+	st->flags	= handle->flags;
+
+	static_assert(lengthof(st->fds) == lengthof(handle->fds),
+		      "Statistics fds are screwed");
+
+	memcpy(st->fds, handle->fds, sizeof(st->fds));
+	return 0;
+}
+
+/**
+ * popen_command - get a pointer to former command line
+ * @handle:	popen handle
+ *
+ * Returns pointer to a former command line for executiion.
+ * Since it might be big enough it is moved out of popen_stat.
+ *
+ * On error NULL returned.
+ */
+const char *
+popen_command(struct popen_handle *handle)
+{
+	if (!handle) {
+		errno = ESRCH;
+		return NULL;
+	}
+
+	return (const char *)handle->command;
+}
+
+/**
+ * stdX_str - get stdX descriptor string representation
+ * @index:	descriptor index
+ */
+static inline const char *
+stdX_str(unsigned int index)
+{
+	static const char * stdX_names[] = {
+		[STDIN_FILENO]	= "stdin",
+		[STDOUT_FILENO]	= "stdout",
+		[STDERR_FILENO]	= "stderr",
+	};
+
+	return index < lengthof(stdX_names) ?
+		stdX_names[index] : "unknown";
+}
+
+/**
+ * popen_write - write data to the child stdin
+ * @handle:	popen handle
+ * @buf:	data to write
+ * @count:	number of bytes to write
+ * @flags:	a flag representing stdin peer
+ *
+ * Returns number of bytes written or -1 on error (setting @errno).
+ */
+ssize_t
+popen_write(struct popen_handle *handle, void *buf,
+	    size_t count, unsigned int flags)
+{
+	if (!popen_may_io(handle, STDIN_FILENO, flags))
+		return -1;
+
+	if (count > (size_t)SSIZE_MAX) {
+		errno = E2BIG;
+		return -1;
+	}
+
+	say_debug("popen: %d: write idx [%s:%d] buf %p count %zu",
+		  handle->pid, stdX_str(STDIN_FILENO),
+		  STDIN_FILENO, buf, count);
+
+	return write(handle->fds[STDIN_FILENO], buf, count);
+}
+
+/**
+ * popen_wait_read - wait for data appear on a child's peer
+ * @handle:		popen handle
+ * @idx:		peer index to wait on
+ * @timeout_msecs:	timeout in microseconds
+ *
+ * Returns 1 if there is data to read, -1 on error (setting @errno).
+ */
+static int
+popen_wait_read(struct popen_handle *handle, int idx, int timeout_msecs)
+{
+	struct pollfd pollfd = {
+		.fd	= handle->fds[idx],
+		.events	= POLLIN,
+	};
+	int ret;
+
+	ret = poll(&pollfd, 1, timeout_msecs);
+	say_debug("popen: %d: poll: ret %d fd [%s:%d] events %#x revents %#x",
+		  handle->pid, ret, stdX_str(idx), handle->fds[idx],
+		  pollfd.events, pollfd.revents);
+
+	if (ret == 1) {
+		if (pollfd.revents == POLLIN) {
+			return 1;
+		} else {
+			say_error("popen: %d: unexpected revents %#x",
+				  handle->pid, pollfd.revents);
+			errno = EINVAL;
+			return -1;
+		}
+	} else if (ret == 0) {
+		errno = EAGAIN;
+		ret = -1;
+	}
+
+	return ret;
+}
+
+/**
+ * popen_read_timeout - read data from a child's peer with timeout
+ * @handle:		popen handle
+ * @buf:		destination buffer
+ * @count:		number of bytes to read
+ * @flags:		POPEN_FLAG_FD_STDOUT or POPEN_FLAG_FD_STDERR
+ * @timeout_msecs:	time to wait in microseconds if no
+ * 			data available; ignored if less or equal to zero
+ *
+ * Returns number of bytes read, otherwise -1 returned and
+ * @errno set accordingly.
+ */
+ssize_t
+popen_read_timeout(struct popen_handle *handle, void *buf,
+		   size_t count, unsigned int flags,
+		   int timeout_msecs)
+{
+	ssize_t ret;
+	int idx;
+
+	idx = flags & POPEN_FLAG_FD_STDOUT ?
+		STDOUT_FILENO : STDERR_FILENO;
+
+	if (!popen_may_io(handle, idx, flags))
+		return -1;
+
+	if (count > (size_t)SSIZE_MAX) {
+		errno = E2BIG;
+		return -1;
+	}
+
+	say_debug("popen: %d: read idx [%s:%d] buf %p count %zu "
+		  "fds %d timeout_msecs %d",
+		  handle->pid, stdX_str(idx), idx, buf, count,
+		  handle->fds[idx], timeout_msecs);
+
+	if (timeout_msecs > 0) {
+		ret = popen_wait_read(handle, idx, timeout_msecs);
+		if (ret < 0) {
+			if (errno != EAGAIN) {
+				say_syserror("popen: %d: data wait failed",
+					     handle->pid);
+			}
+			return -1;
+		}
+	}
+
+	return read(handle->fds[idx], buf, count);
+}
+
+/**
+ * wstatus_str - encode signal status into human readable form
+ * @buf:	destination buffer
+ * @size:	buffer size
+ * @wstatus:	status to encode
+ *
+ * Operates on S_DEBUG level only simply because snprintf
+ * is pretty heavy in performance, otherwise @buf remains
+ * untouched.
+ *
+ * Returns pointer to @buf with encoded string.
+ */
+static char *
+wstatus_str(char *buf, size_t size, int wstatus)
+{
+	static const char fmt[] =
+		"wstatus %#x exited %d status %d "
+		"signaled %d wtermsig %d "
+		"stopped %d stopsig %d "
+		"coredump %d continued %d";
+
+	assert(size > 0);
+
+	if (say_log_level_is_enabled(S_DEBUG)) {
+		snprintf(buf, size, fmt, wstatus,
+			 WIFEXITED(wstatus),
+			 WIFEXITED(wstatus) ?
+			 WEXITSTATUS(wstatus) : -1,
+			 WIFSIGNALED(wstatus),
+			 WIFSIGNALED(wstatus) ?
+			 WTERMSIG(wstatus) : -1,
+			 WIFSTOPPED(wstatus),
+			 WIFSTOPPED(wstatus) ?
+			 WSTOPSIG(wstatus) : -1,
+			 WCOREDUMP(wstatus),
+			 WIFCONTINUED(wstatus));
+	}
+
+	return buf;
+}
+
+/**
+ * popen_notify_sigchld - notify popen subsistem about SIGCHLD event
+ * @pid:	PID of a process which changed its state
+ * @wstatus:	signal status of a process
+ *
+ * The function is called from global SIGCHLD watcher in libev so
+ * we need to figure out if it is our process which possibly been
+ * terminated.
+ *
+ * Note the libev calls for wait() by self so we don't need
+ * to reap children.
+ */
+static void
+popen_notify_sigchld(pid_t pid, int wstatus)
+{
+	struct popen_handle *handle;
+	char buf[128];
+
+	say_debug("popen: sigchld notify %d (%s)",
+		  pid, wstatus_str(buf, sizeof(buf), wstatus));
+
+	handle = popen_find(pid);
+	if (!handle)
+		return;
+
+	handle->wstatus = wstatus;
+	if (WIFEXITED(wstatus) || WIFSIGNALED(wstatus)) {
+		assert(handle->pid == pid);
+		/*
+		 * libev calls for waitpid by self so
+		 * we don't have to wait here.
+		 */
+		popen_unregister(handle);
+		/*
+		 * Since SIGCHLD may come to us not
+		 * due to exit/kill reason (consider
+		 * a case when someone stopped a child
+		 * process) we should continue wathcing
+		 * state changes, thus we stop monitoring
+		 * dead children only.
+		 */
+		say_debug("popen: ev_child_stop %d", handle->pid);
+		ev_child_stop(EV_DEFAULT_ &handle->ev_sigchld);
+		handle->pid = -1;
+	}
+}
+
+/**
+ * ev_sigchld_cb - handle SIGCHLD from a child process
+ * @w:		a child exited
+ * @revents:	unused
+ */
+static void
+ev_sigchld_cb(EV_P_ ev_child *w, int revents)
+{
+	(void)revents;
+	/*
+	 * Stop watching this child, libev will
+	 * remove it from own hashtable.
+	 */
+	ev_child_stop(EV_A_ w);
+
+	/*
+	 * The reason for a separate helper is that
+	 * we might need to notify more subsystems
+	 * in future.
+	 */
+	popen_notify_sigchld(w->rpid, w->rstatus);
+}
+
+/**
+ * popen_state - get current child state
+ * @handle:	popen handle
+ * @state:	state of a child process
+ * @exit_code:	exit code of a child process
+ *
+ * On success returns 0 sets @state to  POPEN_STATE_
+ * constant and @exit_code. On error -1 returned with @errno.
+ */
+int
+popen_state(struct popen_handle *handle, int *state, int *exit_code)
+{
+	if (!handle) {
+		errno = ESRCH;
+		return -1;
+	}
+
+	if (handle->pid != -1) {
+		*state = POPEN_STATE_ALIVE;
+		*exit_code = 0;
+	} else {
+		if (WIFEXITED(handle->wstatus)) {
+			*state = POPEN_STATE_EXITED;
+			*exit_code = WEXITSTATUS(handle->wstatus);
+		} else {
+			*state = POPEN_STATE_SIGNALED;
+			*exit_code = WTERMSIG(handle->wstatus);
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * popen_state_str - get process state string representation
+ * @state:	process state
+ */
+const char *
+popen_state_str(unsigned int state)
+{
+	/*
+	 * A process may be in a number of states,
+	 * running/sleeping/disk sleep/stopped and etc
+	 * but we are interested only if it is alive
+	 * or dead (via plain exit or kill signal).
+	 *
+	 * Thus while it present in a system and not
+	 * yet reaped we call it "alive".
+	 *
+	 * Note this is API for lua, so change with
+	 * caution if needed.
+	 */
+	static const char * state_str[POPEN_STATE_MAX] = {
+		[POPEN_STATE_NONE]	= "none",
+		[POPEN_STATE_ALIVE]	= "alive",
+		[POPEN_STATE_EXITED]	= "exited",
+		[POPEN_STATE_SIGNALED]	= "signaled",
+	};
+
+	return state < POPEN_STATE_MAX ? state_str[state] : "unknown";
+}
+
+/**
+ * popen_send_signal - send a signal to a child process
+ * @handle:	popen handle
+ * @signo:	signal number
+ *
+ * Returns 0 on success, -1 otherwise.
+ */
+int
+popen_send_signal(struct popen_handle *handle, int signo)
+{
+	int ret;
+
+	/*
+	 * A child may be killed or exited already.
+	 */
+	if (!popen_may_pidop(handle))
+		return -1;
+
+	if (handle->flags & POPEN_FLAGS_SETSID) {
+		say_debug("popen: killpg %d signo %d", handle->pid, signo);
+		ret = killpg(handle->pid, signo);
+	} else {
+		say_debug("popen: kill %d signo %d", handle->pid, signo);
+		ret = kill(handle->pid, signo);
+	}
+	if (ret < 0) {
+		say_syserror("popen: Unable to killpg %d signo %d",
+			     handle->pid, signo);
+	}
+	return ret;
+}
+
+/**
+ * popen_delete - delete a popen handle
+ * @handle:	a popen handle to delete
+ *
+ * The function kills a child process and
+ * close all fds and remove the handle from
+ * a living list and finally frees the handle.
+ *
+ * Returns 0 on success, -1 otherwise.
+ */
+int
+popen_delete(struct popen_handle *handle)
+{
+	size_t i;
+
+	if (!handle) {
+		errno = ESRCH;
+		return -1;
+	}
+
+	if (popen_send_signal(handle, SIGKILL) && errno != ESRCH)
+		return -1;
+
+	for (i = 0; i < lengthof(handle->fds); i++) {
+		if (handle->fds[i] != -1)
+			close(handle->fds[i]);
+	}
+
+	/*
+	 * We won't be wathcing this child anymore if
+	 * kill signal is not yet delivered.
+	 */
+	if (handle->pid != -1) {
+		say_debug("popen: ev_child_stop %d", handle->pid);
+		ev_child_stop(EV_DEFAULT_ &handle->ev_sigchld);
+	}
+
+	rlist_del(&handle->list);
+	command_free(handle->command);
+	handle_free(handle);
+	return 0;
+}
+
+/**
+ * make_pipe - create O_CLOEXEC pipe
+ * @pfd:	pipe ends to setup
+ *
+ * Returns 0 on success, -1 on error.
+ */
+static int
+make_pipe(int pfd[2])
+{
+#ifdef TARGET_OS_LINUX
+	if (pipe2(pfd, O_CLOEXEC)) {
+		say_syserror("popen: Can't create pipe2");
+		return -1;
+	}
+#else
+	if (pipe(pfd)) {
+		say_syserror("popen: Can't create pipe");
+		return -1;
+	}
+	if (fcntl(pfd[0], F_SETFL, O_CLOEXEC) ||
+	    fcntl(pfd[1], F_SETFL, O_CLOEXEC)) {
+		int saved_errno = errno;
+		say_syserror("popen: Can't unblock pipe");
+		close(pfd[0]), pfd[0] = -1;
+		close(pfd[1]), pfd[1] = -1;
+		errno = saved_errno;
+		return -1;
+	}
+#endif
+	return 0;
+}
+
+/**
+ * close_inherited_fds - close inherited file descriptors
+ * @skip_fds:		an array of descriptors which should
+ * 			be kept opened
+ * @nr_skip_fds:	number of elements in @skip_fds
+ *
+ * Returns 0 on success, -1 otherwise.
+ */
+static int
+close_inherited_fds(int *skip_fds, size_t nr_skip_fds)
+{
+#ifdef TARGET_OS_LINUX
+	static const char path[] = "/proc/self/fd";
+	struct dirent *de;
+	int fd_no, fd_dir;
+	DIR *dir;
+	size_t i;
+
+	dir = opendir(path);
+	if (!dir) {
+		say_syserror("popen: fdin: Can't open %s", path);
+		return -1;
+	}
+	fd_dir = dirfd(dir);
+
+	for (de = readdir(dir); de; de = readdir(dir)) {
+		if (!strcmp(de->d_name, ".") ||
+		    !strcmp(de->d_name, ".."))
+			continue;
+
+		fd_no = atoi(de->d_name);
+
+		if (fd_no == fd_dir)
+			continue;
+
+		/* We don't expect many numbers here */
+		for (i = 0; i < nr_skip_fds; i++) {
+			if (fd_no == skip_fds[i]) {
+				fd_no = -1;
+				break;
+			}
+		}
+
+		if (fd_no == -1)
+			continue;
+
+		if (close(fd_no)) {
+			int saved_errno = errno;
+			say_syserror("popen: fdin: Can't close %d", fd_no);
+			closedir(dir);
+			errno = saved_errno;
+			return -1;
+		}
+	}
+
+	if (closedir(dir)) {
+		say_syserror("popen: fdin: Can't close %s", path);
+		return -1;
+	}
+#else
+	/* FIXME: What about FreeBSD/MachO? */
+	(void)skip_fds;
+	(void)nr_skip_fds;
+
+	static bool said = false;
+	if (!said) {
+		say_warn("popen: fdin: Skip closing inherited");
+		said = true;
+	}
+#endif
+	return 0;
+}
+
+#ifdef TARGET_OS_LINUX
+extern char **environ;
+#endif
+
+static inline char **
+get_envp(struct popen_opts *opts)
+{
+	if (!opts->env) {
+#ifdef TARGET_OS_LINUX
+		return environ;
+#else
+		static const char **empty_envp[] = { NULL };
+		static bool said = false;
+		if (!said)
+			say_warn("popen: Environment inheritance "
+				 "unsupported, passing empty");
+		return (char *)empty_envp;
+#endif
+	}
+	return opts->env;
+}
+
+/**
+ * signal_reset - reset signals to default before executing a program
+ *
+ * FIXME: This is a code duplication fomr main.cc. Need to rework
+ * signal handing otherwise it will become utter crap very fast.
+ */
+static void
+signal_reset(void)
+{
+	struct sigaction sa = { };
+	sigset_t sigset;
+
+	/* Reset all signals to their defaults. */
+	sigemptyset(&sa.sa_mask);
+	sa.sa_handler = SIG_DFL;
+
+	if (sigaction(SIGUSR1, &sa, NULL) == -1 ||
+	    sigaction(SIGINT, &sa, NULL) == -1 ||
+	    sigaction(SIGTERM, &sa, NULL) == -1 ||
+	    sigaction(SIGHUP, &sa, NULL) == -1 ||
+	    sigaction(SIGWINCH, &sa, NULL) == -1 ||
+	    sigaction(SIGSEGV, &sa, NULL) == -1 ||
+	    sigaction(SIGFPE, &sa, NULL) == -1)
+		_exit(errno);
+
+	/* Unblock any signals blocked by libev */
+	sigfillset(&sigset);
+	if (sigprocmask(SIG_UNBLOCK, &sigset, NULL) == -1)
+		_exit(errno);
+}
+
+/**
+ * popen_new - Create new popen handle
+ * @opts: options for popen handle
+ *
+ * This function creates a new child process and passes it
+ * pipe ends to communicate with child's stdin/stdout/stderr
+ * depending on @opts:flags. Where @opts:flags could be
+ * the bitwise "OR" for the following values:
+ *
+ *  POPEN_FLAG_FD_STDIN		- to write to stdin
+ *  POPEN_FLAG_FD_STDOUT	- to read from stdout
+ *  POPEN_FLAG_FD_STDERR	- to read from stderr
+ *
+ * When need to pass /dev/null descriptor into a child
+ * the following values can be used:
+ *
+ *  POPEN_FLAG_FD_STDIN_DEVNULL
+ *  POPEN_FLAG_FD_STDOUT_DEVNULL
+ *  POPEN_FLAG_FD_STDERR_DEVNULL
+ *
+ * These flags have no effect if appropriate POPEN_FLAG_FD_STDx
+ * flags are set.
+ *
+ * When need to completely close the descriptors the
+ * following values can be used:
+ *
+ *  POPEN_FLAG_FD_STDIN_CLOSE
+ *  POPEN_FLAG_FD_STDOUT_CLOSE
+ *  POPEN_FLAG_FD_STDERR_CLOSE
+ *
+ * These flags have no effect if appropriate POPEN_FLAG_FD_STDx
+ * flags are set.
+ *
+ * If none of POPEN_FLAG_FD_STDx flags are specified the child
+ * process will run with all files inherited from a parent.
+ *
+ * Returns pointer to a new popen handle on success,
+ * otherwise NULL returned setting @errno.
+ */
+struct popen_handle *
+popen_new(struct popen_opts *opts)
+{
+	struct popen_handle *handle = NULL;
+	char *command = NULL;
+
+	int pfd[POPEN_FLAG_FD_STDEND_BIT][2] = {
+		{-1, -1}, {-1, -1}, {-1, -1},
+	};
+
+	char **envp = get_envp(opts);
+	int saved_errno;
+	size_t i;
+
+	static const struct {
+		unsigned int	mask;
+		unsigned int	mask_devnull;
+		unsigned int	mask_close;
+		int		fileno;
+		int		*dev_null_fd;
+		int		parent_idx;
+		int		child_idx;
+		bool		nonblock;
+	} pfd_map[POPEN_FLAG_FD_STDEND_BIT] = {
+		{
+			.mask		= POPEN_FLAG_FD_STDIN,
+			.mask_devnull	= POPEN_FLAG_FD_STDIN_DEVNULL,
+			.mask_close	= POPEN_FLAG_FD_STDIN_CLOSE,
+			.fileno		= STDIN_FILENO,
+			.dev_null_fd	= &dev_null_fd_ro,
+			.parent_idx	= 1,
+			.child_idx	= 0,
+		}, {
+			.mask		= POPEN_FLAG_FD_STDOUT,
+			.mask_devnull	= POPEN_FLAG_FD_STDOUT_DEVNULL,
+			.mask_close	= POPEN_FLAG_FD_STDOUT_CLOSE,
+			.fileno		= STDOUT_FILENO,
+			.dev_null_fd	= &dev_null_fd_wr,
+			.parent_idx	= 0,
+			.child_idx	= 1,
+		}, {
+			.mask		= POPEN_FLAG_FD_STDERR,
+			.mask_devnull	= POPEN_FLAG_FD_STDERR_DEVNULL,
+			.mask_close	= POPEN_FLAG_FD_STDERR_CLOSE,
+			.fileno		= STDERR_FILENO,
+			.dev_null_fd	= &dev_null_fd_wr,
+			.parent_idx	= 0,
+			.child_idx	= 1,
+		},
+	};
+	/*
+	 * At max we could be skipping each pipe end
+	 * plus dev/null variants.
+	 */
+	int skip_fds[POPEN_FLAG_FD_STDEND_BIT * 2 + 2];
+	size_t nr_skip_fds = 0;
+
+	/*
+	 * A caller must preserve space for this.
+	 */
+	if (opts->flags & POPEN_FLAG_SHELL) {
+		opts->argv[0] = "sh";
+		opts->argv[1] = "-c";
+	}
+
+	/*
+	 * Carry a copy for information sake.
+	 */
+	command = command_new(opts->argv, opts->nr_argv);
+
+	say_debug("popen: command '%s' flags %#x", command, opts->flags);
+
+	static_assert(STDIN_FILENO == 0 &&
+		      STDOUT_FILENO == 1 &&
+		      STDERR_FILENO == 2,
+		      "stdin/out/err are not posix compatible");
+
+	static_assert(lengthof(pfd) == lengthof(pfd_map),
+		      "Pipes number does not map to fd bits");
+
+	static_assert(POPEN_FLAG_FD_STDIN_BIT == STDIN_FILENO &&
+		      POPEN_FLAG_FD_STDOUT_BIT == STDOUT_FILENO &&
+		      POPEN_FLAG_FD_STDERR_BIT == STDERR_FILENO,
+		      "Popen flags do not match stdX");
+
+	handle = handle_new(opts, command);
+	if (!handle)
+		return NULL;
+
+	skip_fds[nr_skip_fds++] = dev_null_fd_ro;
+	skip_fds[nr_skip_fds++] = dev_null_fd_wr;
+	assert(nr_skip_fds <= lengthof(skip_fds));
+
+	for (i = 0; i < lengthof(pfd_map); i++) {
+		if (opts->flags & pfd_map[i].mask) {
+			if (make_pipe(pfd[i]))
+				goto out_err;
+
+			/*
+			 * FIXME: Rather force make_pipe
+			 * to allocate new fds with higher
+			 * number.
+			 */
+			if (pfd[i][0] <= STDERR_FILENO ||
+			    pfd[i][1] <= STDERR_FILENO) {
+				say_error("popen: low fds [%s:%d:%d]",
+					  stdX_str(i), pfd[i][0],
+					  pfd[i][1]);
+				errno = EBADF;
+				goto out_err;
+			}
+
+			skip_fds[nr_skip_fds++] = pfd[i][0];
+			skip_fds[nr_skip_fds++] = pfd[i][1];
+			assert(nr_skip_fds <= lengthof(skip_fds));
+
+			say_debug("popen: created pipe [%s:%d:%d]",
+				  stdX_str(i), pfd[i][0], pfd[i][1]);
+		} else if (!(opts->flags & pfd_map[i].mask_devnull) &&
+			   !(opts->flags & pfd_map[i].mask_close)) {
+			skip_fds[nr_skip_fds++] = pfd_map[i].fileno;
+
+			say_debug("popen: inherit [%s:%d]",
+				  stdX_str(i), pfd_map[i].fileno);
+		}
+	}
+
+	/*
+	 * We have to use vfork here because libev has own
+	 * at_fork helpers with mutex, so we will have double
+	 * lock here and stuck forever otherwise.
+	 *
+	 * The good news that this affect tx only the
+	 * other tarantoll threads are not waiting for
+	 * vfork to complete. Also we try to do as minimum
+	 * operations before the exec() as possible.
+	 */
+	handle->pid = vfork();
+	if (handle->pid < 0) {
+		goto out_err;
+	} else if (handle->pid == 0) {
+		/*
+		 * The documentation for libev says that
+		 * each new fork should call ev_loop_fork(EV_DEFAULT)
+		 * on every new child process, but we're going
+		 * to execute bew binary anyway thus everything
+		 * related to OS resources will be eliminated except
+		 * file descriptors we use for piping. Thus don't
+		 * do anything special.
+		 */
+
+		/*
+		 * Also don't forget to drop signal handlers
+		 * to default inside a child process since we're
+		 * inheriting them from a caller process.
+		 */
+		if (opts->flags & POPEN_FLAGS_RESTORE_SIGNALS)
+			signal_reset();
+
+		/*
+		 * We have to be a session leader otherwise
+		 * won't be able to kill a group of children.
+		 */
+		if (opts->flags & POPEN_FLAGS_SETSID) {
+			if (setsid() == -1)
+				goto exit_child;
+		}
+
+		if (opts->flags & POPEN_FLAG_CLOSE_FDS) {
+			if (close_inherited_fds(skip_fds, nr_skip_fds))
+				goto exit_child;
+		}
+
+		for (i = 0; i < lengthof(pfd_map); i++) {
+			int fileno = pfd_map[i].fileno;
+			/*
+			 * Pass pipe peer to a child.
+			 */
+			if (opts->flags & pfd_map[i].mask) {
+				int child_idx = pfd_map[i].child_idx;
+
+				/* put child peer end at known place */
+				if (dup2(pfd[i][child_idx], fileno) < 0)
+					goto exit_child;
+
+				/* parent's pipe no longer needed */
+				if (close(pfd[i][0]) ||
+				    close(pfd[i][1]))
+					goto exit_child;
+				continue;
+			}
+
+			/*
+			 * Use /dev/null if requested.
+			 */
+			if (opts->flags & pfd_map[i].mask_devnull) {
+				if (dup2(*pfd_map[i].dev_null_fd,
+					 fileno) < 0) {
+					goto exit_child;
+				}
+				continue;
+			}
+
+			/*
+			 * Or close the destination completely, since
+			 * we don't if the file in question is already
+			 * closed by some other code we don't care if
+			 * EBADF happens.
+			 */
+			if (opts->flags & pfd_map[i].mask_close) {
+				if (close(fileno) && errno != EBADF)
+					goto exit_child;
+				continue;
+			}
+
+			/*
+			 * Otherwise inherit file descriptor
+			 * from a parent.
+			 */
+		}
+
+		if (close(dev_null_fd_ro) || close(dev_null_fd_wr))
+			goto exit_child;
+
+		if (opts->flags & POPEN_FLAG_SHELL)
+			execve(_PATH_BSHELL, opts->argv, envp);
+		else
+			execve(opts->argv[2], &opts->argv[2], envp);
+exit_child:
+		_exit(errno);
+		unreachable();
+	}
+
+	for (i = 0; i < lengthof(pfd_map); i++) {
+		if (opts->flags & pfd_map[i].mask) {
+			int parent_idx = pfd_map[i].parent_idx;
+			int child_idx = pfd_map[i].child_idx;
+
+			handle->fds[i] = pfd[i][parent_idx];
+			say_debug("popen: keep pipe [%s:%d]",
+				  stdX_str(i), handle->fds[i]);
+
+			if (close(pfd[i][child_idx])) {
+				say_syserror("popen: close child [%s:%d]",
+					     stdX_str(i),
+					     pfd[i][child_idx]);
+				goto out_err;
+			}
+
+			pfd[i][child_idx] = -1;
+		}
+	}
+
+	/*
+	 * Link it into global list for force
+	 * cleanup on exit.
+	 */
+	rlist_add(&popen_head, &handle->list);
+
+	/*
+	 * To watch when a child get exited.
+	 */
+	popen_register(handle);
+
+	say_debug("popen: ev_child_start %d", handle->pid);
+	ev_child_init(&handle->ev_sigchld, ev_sigchld_cb, handle->pid, 0);
+	ev_child_start(EV_DEFAULT_ &handle->ev_sigchld);
+
+	say_debug("popen: created child %d", handle->pid);
+
+	return handle;
+
+out_err:
+	saved_errno = errno;
+	popen_delete(handle);
+	for (i = 0; i < lengthof(pfd); i++) {
+		if (pfd[i][0] != -1)
+			close(pfd[i][0]);
+		if (pfd[i][1] != -1)
+			close(pfd[i][1]);
+	}
+	errno = saved_errno;
+	return NULL;
+}
+
+/**
+ * popen_init - initialize popen subsystem
+ *
+ * Allocates resource needed for popen management.
+ */
+void
+popen_init(void)
+{
+	static const int flags = O_CLOEXEC;
+	static const char dev_null_path[] = "/dev/null";
+
+	say_debug("popen: initialize subsystem");
+	popen_pids_map = mh_i32ptr_new();
+
+	dev_null_fd_ro = open(dev_null_path, O_RDONLY | flags);
+	if (dev_null_fd_ro < 0)
+		goto out_err;
+	dev_null_fd_wr = open(dev_null_path, O_WRONLY | flags);
+	if (dev_null_fd_wr < 0)
+		goto out_err;
+
+	/*
+	 * FIXME: We should allocate them somewhere
+	 * after STDERR_FILENO so the child would be
+	 * able to find these fd numbers not occupied.
+	 * Other option is to use unix scm and send
+	 * them to the child on demand.
+	 *
+	 * For now left as is since we don't close
+	 * our main stdX descriptors and they are
+	 * inherited when we call first vfork.
+	 */
+	if (dev_null_fd_ro <= STDERR_FILENO ||
+	    dev_null_fd_wr <= STDERR_FILENO) {
+		say_error("popen: /dev/null %d %d numbers are too low",
+			  dev_null_fd_ro, dev_null_fd_wr);
+		goto out_err;
+	}
+
+	return;
+
+out_err:
+	say_syserror("popen: Can't open %s", dev_null_path);
+	if (dev_null_fd_ro >= 0)
+		close(dev_null_fd_ro);
+	if (dev_null_fd_wr >= 0)
+		close(dev_null_fd_wr);
+	mh_i32ptr_delete(popen_pids_map);
+	exit(EXIT_FAILURE);
+}
+
+/**
+ * popen_free - free popen subsystem
+ *
+ * Kills all running children and frees resources.
+ */
+void
+popen_free(void)
+{
+	struct popen_handle *handle, *tmp;
+
+	say_debug("popen: free subsystem");
+
+	close(dev_null_fd_ro);
+	close(dev_null_fd_wr);
+	dev_null_fd_ro = -1;
+	dev_null_fd_wr = -1;
+
+	rlist_foreach_entry_safe(handle, &popen_head, list, tmp) {
+		/*
+		 * If children are still running we should move
+		 * them out of the pool and kill them all then.
+		 * Note though that we don't do an explicit wait
+		 * here, OS will reap them anyway, just release
+		 * the memory occupied for popen handles.
+		 */
+		if (popen_may_pidop(handle))
+			popen_unregister(handle);
+		popen_delete(handle);
+	}
+
+	if (popen_pids_map) {
+		mh_i32ptr_delete(popen_pids_map);
+		popen_pids_map = NULL;
+	}
+}
diff --git a/src/lib/core/popen.h b/src/lib/core/popen.h
new file mode 100644
index 000000000..628c4ad46
--- /dev/null
+++ b/src/lib/core/popen.h
@@ -0,0 +1,218 @@
+#ifndef TARANTOOL_LIB_CORE_POPEN_H_INCLUDED
+#define TARANTOOL_LIB_CORE_POPEN_H_INCLUDED
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+#include <signal.h>
+#include <errno.h>
+#include <stdbool.h>
+#include <sys/types.h>
+
+#include <small/rlist.h>
+
+#include "third_party/tarantool_ev.h"
+
+enum popen_flag_bits {
+	POPEN_FLAG_NONE			= (0 << 0),
+
+	/*
+	 * Which fd we should handle as new pipes.
+	 */
+	POPEN_FLAG_FD_STDIN_BIT		= 0,
+	POPEN_FLAG_FD_STDIN		= (1 << POPEN_FLAG_FD_STDIN_BIT),
+
+	POPEN_FLAG_FD_STDOUT_BIT	= 1,
+	POPEN_FLAG_FD_STDOUT		= (1 << POPEN_FLAG_FD_STDOUT_BIT),
+
+	POPEN_FLAG_FD_STDERR_BIT	= 2,
+	POPEN_FLAG_FD_STDERR		= (1 << POPEN_FLAG_FD_STDERR_BIT),
+
+	/*
+	 * Number of bits occupied for stdX descriptors.
+	 */
+	POPEN_FLAG_FD_STDEND_BIT	= POPEN_FLAG_FD_STDERR_BIT + 1,
+
+	/*
+	 * Instead of inheriting fds from a parent
+	 * rather use /dev/null.
+	 */
+	POPEN_FLAG_FD_STDIN_DEVNULL_BIT	= 3,
+	POPEN_FLAG_FD_STDIN_DEVNULL	= (1 << POPEN_FLAG_FD_STDIN_DEVNULL_BIT),
+	POPEN_FLAG_FD_STDOUT_DEVNULL_BIT= 4,
+	POPEN_FLAG_FD_STDOUT_DEVNULL	= (1 << POPEN_FLAG_FD_STDOUT_DEVNULL_BIT),
+	POPEN_FLAG_FD_STDERR_DEVNULL_BIT= 5,
+	POPEN_FLAG_FD_STDERR_DEVNULL	= (1 << POPEN_FLAG_FD_STDERR_DEVNULL_BIT),
+
+	/*
+	 * Instead of inheriting fds from a parent
+	 * close fds completely.
+	 */
+	POPEN_FLAG_FD_STDIN_CLOSE_BIT	= 6,
+	POPEN_FLAG_FD_STDIN_CLOSE	= (1 << POPEN_FLAG_FD_STDIN_CLOSE_BIT),
+	POPEN_FLAG_FD_STDOUT_CLOSE_BIT	= 7,
+	POPEN_FLAG_FD_STDOUT_CLOSE	= (1 << POPEN_FLAG_FD_STDOUT_CLOSE_BIT),
+	POPEN_FLAG_FD_STDERR_CLOSE_BIT	= 8,
+	POPEN_FLAG_FD_STDERR_CLOSE	= (1 << POPEN_FLAG_FD_STDERR_CLOSE_BIT),
+
+	/*
+	 * Reserved for a case where we will handle
+	 * other fds as a source for stdin/out/err.
+	 * Ie piping from child process to our side
+	 * via splices and etc.
+	 */
+	POPEN_FLAG_FD_STDIN_EPIPE_BIT	= 9,
+	POPEN_FLAG_FD_STDIN_EPIPE	= (1 << POPEN_FLAG_FD_STDIN_EPIPE_BIT),
+	POPEN_FLAG_FD_STDOUT_EPIPE_BIT	= 10,
+	POPEN_FLAG_FD_STDOUT_EPIPE	= (1 << POPEN_FLAG_FD_STDOUT_EPIPE_BIT),
+	POPEN_FLAG_FD_STDERR_EPIPE_BIT	= 11,
+	POPEN_FLAG_FD_STDERR_EPIPE	= (1 << POPEN_FLAG_FD_STDERR_EPIPE_BIT),
+
+	/*
+	 * Call exec directly or via shell.
+	 */
+	POPEN_FLAG_SHELL_BIT		= 12,
+	POPEN_FLAG_SHELL		= (1 << POPEN_FLAG_SHELL_BIT),
+
+	/*
+	 * Create a new session.
+	 */
+	POPEN_FLAGS_SETSID_BIT		= 13,
+	POPEN_FLAGS_SETSID		= (1 << POPEN_FLAGS_SETSID_BIT),
+
+	/*
+	 * Close all inherited fds except stdin/out/err.
+	 */
+	POPEN_FLAG_CLOSE_FDS_BIT	= 14,
+	POPEN_FLAG_CLOSE_FDS		= (1 << POPEN_FLAG_CLOSE_FDS_BIT),
+
+	/*
+	 * Restore signal handlers to default.
+	 */
+	POPEN_FLAGS_RESTORE_SIGNALS_BIT	= 15,
+	POPEN_FLAGS_RESTORE_SIGNALS	= (1 << POPEN_FLAGS_RESTORE_SIGNALS_BIT),
+};
+
+enum popen_states {
+	POPEN_STATE_NONE		= 0,
+	POPEN_STATE_ALIVE		= 1,
+	POPEN_STATE_EXITED		= 2,
+	POPEN_STATE_SIGNALED		= 3,
+
+	POPEN_STATE_MAX,
+};
+
+/**
+ * struct popen_handle - an instance of popen object
+ *
+ * @pid:	pid of a child process
+ * @command:	copy of a command line for statistics
+ * @wstatus:	exit status of a child process
+ * @ev_sigchld:	needed by the libev to watch children
+ * @flags:	popen_flag_bits
+ * @fds:	std(in|out|err)
+ */
+struct popen_handle {
+	pid_t			pid;
+	char			*command;
+	int			wstatus;
+	ev_child		ev_sigchld;
+	struct rlist		list;
+	unsigned int		flags;
+	int			fds[POPEN_FLAG_FD_STDEND_BIT];
+};
+
+/**
+ * struct popen_opts - options for popen creation
+ *
+ * @argv:	argv to execute
+ * @nr_argv:	number of elements in @argv
+ * @env:	environment (can be empty)
+ * @flags:	popen_flag_bits
+ */
+struct popen_opts {
+	char			**argv;
+	size_t			nr_argv;
+	char			**env;
+	unsigned int		flags;
+};
+
+/**
+ * struct popen_stat - popen object statistics
+ *
+ * @pid:	pid of a child process
+ * @flags:	popen_flag_bits
+ * @fds:	std(in|out|err)
+ *
+ * This is a short version of struct popen_handle which should
+ * be used by external code and which should be changed/extended
+ * with extreme caution since it is used in Lua code. Consider it
+ * as API for external modules.
+ */
+struct popen_stat {
+	pid_t			pid;
+	unsigned int		flags;
+	int			fds[POPEN_FLAG_FD_STDEND_BIT];
+};
+
+extern int
+popen_stat(struct popen_handle *handle, struct popen_stat *st);
+
+extern const char *
+popen_command(struct popen_handle *handle);
+
+/**
+ * should_retry_io -- test if we should retry IO procedure
+ * @_errno:	error code to test
+ */
+static inline bool
+popen_should_retry_io(int _errno)
+{
+	/*
+	 * Pipes do check for regular signal delivery
+	 * (unlike phys fs like ext4 on which write get
+	 * interrupted by the fatal signal only) so that
+	 * the write could be interrupted and we should
+	 * restart iteration.
+	 */
+	if (_errno == EINTR)
+		return true;
+	return false;
+}
+
+extern ssize_t
+popen_write(struct popen_handle *handle, void *buf,
+	    size_t count, unsigned int flags);
+
+extern ssize_t
+popen_read_timeout(struct popen_handle *handle, void *buf,
+		   size_t count, unsigned int flags,
+		   int timeout_msecs);
+
+extern int
+popen_state(struct popen_handle *handle, int *state, int *exit_code);
+
+extern const char *
+popen_state_str(unsigned int state);
+
+extern int
+popen_send_signal(struct popen_handle *handle, int signo);
+
+extern int
+popen_delete(struct popen_handle *handle);
+
+extern struct popen_handle *
+popen_new(struct popen_opts *opts);
+
+extern void
+popen_init(void);
+
+extern void
+popen_free(void);
+
+#if defined(__cplusplus)
+} /* extern "C" */
+#endif
+
+#endif /* TARANTOOL_LIB_CORE_POPEN_H_INCLUDED */
diff --git a/src/main.cc b/src/main.cc
index 0ff2213b6..87654fb14 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -77,6 +77,7 @@
 #include "box/session.h"
 #include "systemd.h"
 #include "crypto/crypto.h"
+#include "core/popen.h"
 
 static pid_t master_pid = getpid();
 static struct pidfh *pid_file_handle;
@@ -614,6 +615,8 @@ tarantool_free(void)
 
 	title_free(main_argc, main_argv);
 
+	popen_free();
+
 	/* unlink pidfile. */
 	if (pid_file_handle != NULL && pidfile_remove(pid_file_handle) == -1)
 		say_syserror("failed to remove pid file '%s'", pid_file);
@@ -801,6 +804,7 @@ main(int argc, char **argv)
 	exception_init();
 
 	fiber_init(fiber_cxx_invoke);
+	popen_init();
 	coio_init();
 	coio_enable();
 	signal_init();
-- 
2.20.1