[Tarantool-patches] [PATCH v11 0/3] popen: Introduce backend engine

[Tarantool-patches] [PATCH v11 0/3] popen: Introduce backend engine

[Cyrill Gorcunov]

In v11 I cleaned up some nits and updated the tests.

issue https://github.com/tarantool/tarantool/issues/4031
branch https://github.com/tarantool/tarantool/tree/gorcunov/gh-4031-popen-11

Cyrill Gorcunov (3):
  coio: export helpers
  popen: introduce a backend engine
  test: unit/popen

 src/box/applier.cc          |    2 +-
 src/lib/core/CMakeLists.txt |    1 +
 src/lib/core/coio.h         |   18 +-
 src/lib/core/popen.c        | 1061 +++++++++++++++++++++++++++++++++++
 src/lib/core/popen.h        |  191 +++++++
 src/main.cc                 |    4 +
 test/unit/CMakeLists.txt    |    3 +
 test/unit/popen.c           |  253 +++++++++
 test/unit/popen.result      |   28 +
 9 files changed, 1555 insertions(+), 6 deletions(-)
 create mode 100644 src/lib/core/popen.c
 create mode 100644 src/lib/core/popen.h
 create mode 100644 test/unit/popen.c
 create mode 100644 test/unit/popen.result


base-commit: f54f4dc03afcc9b34261e6275881f0120faef67e
-- 
2.20.1

[Tarantool-patches] [PATCH v11 1/3] coio: export helpers

[Cyrill Gorcunov]

There is no reason to hide functions. In particular
we will use these helpers in popen code.

Part-of #4031

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
---
 src/box/applier.cc  |  2 +-
 src/lib/core/coio.h | 18 +++++++++++++-----
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/src/box/applier.cc b/src/box/applier.cc
index ae3d281a5..ecfe0771b 100644
--- a/src/box/applier.cc
+++ b/src/box/applier.cc
@@ -1009,7 +1009,7 @@ applier_disconnect(struct applier *applier, enum applier_state state)
 		applier->writer = NULL;
 	}
 
-	coio_close(loop(), &applier->io);
+	coio_close_io(loop(), &applier->io);
 	/* Clear all unparsed input. */
 	ibuf_reinit(&applier->ibuf);
 	fiber_gc();
diff --git a/src/lib/core/coio.h b/src/lib/core/coio.h
index 6a2337689..c323955d7 100644
--- a/src/lib/core/coio.h
+++ b/src/lib/core/coio.h
@@ -32,9 +32,16 @@
  */
 #include "fiber.h"
 #include "trivia/util.h"
-#if defined(__cplusplus)
+
 #include "evio.h"
 
+#if defined(__cplusplus)
+extern "C" {
+#endif /* defined(__cplusplus) */
+
+struct sockaddr;
+struct uri;
+
 /**
  * Co-operative I/O
  * Yield the current fiber until IO is ready.
@@ -70,8 +77,12 @@ coio_accept(struct ev_io *coio, struct sockaddr *addr, socklen_t addrlen,
 void
 coio_create(struct ev_io *coio, int fd);
 
+/*
+ * Due to name conflict with coio_close in API_EXPORT
+ * we have to use coio_close_io() instead of plain coio_close().
+ */
 static inline void
-coio_close(ev_loop *loop, struct ev_io *coio)
+coio_close_io(ev_loop *loop, struct ev_io *coio)
 {
 	return evio_close(loop, coio);
 }
@@ -185,9 +196,6 @@ coio_stat_stat_timeout(ev_stat *stat, ev_tstamp delay);
 int
 coio_waitpid(pid_t pid);
 
-extern "C" {
-#endif /* defined(__cplusplus) */
-
 /** \cond public */
 
 enum {
-- 
2.20.1

[Tarantool-patches] [PATCH v11 2/3] 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 the popen object creation
 - popen_write_timeout
	to write data into child's stdin with
	timeout
 - 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@gmail.com>
---
 src/lib/core/CMakeLists.txt |    1 +
 src/lib/core/popen.c        | 1061 +++++++++++++++++++++++++++++++++++
 src/lib/core/popen.h        |  191 +++++++
 src/main.cc                 |    4 +
 4 files changed, 1257 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..18e479511
--- /dev/null
+++ b/src/lib/core/popen.c
@@ -0,0 +1,1061 @@
+#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 "coio.h"
+#include "say.h"
+
+/* A mapping to find popens by their pids in a signal handler */
+static struct mh_i32ptr_t *popen_pids_map = NULL;
+
+/* All popen handles to be able to cleanup them at exit */
+static RLIST_HEAD(popen_head);
+
+/*
+ * A user may request to use /dev/null inside a child process
+ * instead of stdin/out/err, for this sake we will open these
+ * fds once on initialization and pass to children.
+ */
+static int dev_null_fd_ro = -1;
+static int dev_null_fd_wr = -1;
+
+/**
+ * Register popen handle in a pids map.
+ */
+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);
+}
+
+/**
+ * Find popen handler by its pid.
+ */
+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;
+}
+
+/**
+ * Remove popen handler from a pids map.
+ */
+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);
+}
+
+/**
+ * Allocate new popen hanldle with flags specified.
+ */
+static struct popen_handle *
+handle_new(struct popen_opts *opts)
+{
+	struct popen_handle *handle;
+	size_t size = 0, i;
+	char *pos;
+
+	assert(opts->argv != NULL && opts->nr_argv > 0);
+
+	for (i = 0; i < opts->nr_argv; i++) {
+		if (opts->argv[i] == NULL)
+			continue;
+		size += strlen(opts->argv[i]) + 1;
+	}
+
+	handle = malloc(sizeof(*handle) + size);
+	if (!handle) {
+		diag_set(OutOfMemory, sizeof(*handle) + size,
+			 "malloc", "popen_handle");
+		return NULL;
+	}
+
+	pos = handle->command = (void *)handle + sizeof(*handle);
+	for (i = 0; i < opts->nr_argv-1; i++) {
+		if (opts->argv[i] == NULL)
+			continue;
+		strcpy(pos, opts->argv[i]);
+		pos += strlen(opts->argv[i]);
+		*pos++ = ' ';
+	}
+	pos[-1] = '\0';
+
+	handle->wstatus	= 0;
+	handle->pid	= -1;
+	handle->flags	= opts->flags;
+
+	rlist_create(&handle->list);
+
+	/*
+	 * No need to initialize the whole ios structure,
+	 * just set fd value to mark as unused.
+	 */
+	for (i = 0; i < lengthof(handle->ios); i++)
+		handle->ios[i].fd = -1;
+
+	say_debug("popen: alloc handle %p command '%s' flags %#x",
+		  handle, handle->command, opts->flags);
+	return handle;
+}
+
+/**
+ * Free memory allocated for a handle. To pair with handle_new().
+ */
+static inline void
+handle_free(struct popen_handle *handle)
+{
+	say_debug("popen: handle %p free %p", handle);
+	free(handle);
+}
+
+/**
+ * Test if the handle can run io operation.
+ */
+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->ios[idx].fd < 0) {
+		errno = EPIPE;
+		return false;
+	}
+
+	return true;
+}
+
+/**
+ * Test if the handle is not nil and still have
+ * a living child process.
+ */
+static inline bool
+popen_may_pidop(struct popen_handle *handle)
+{
+	if (!handle || handle->pid == -1) {
+		errno = ESRCH;
+		return false;
+	}
+	return true;
+}
+
+/**
+ * Fill popen object statistics.
+ */
+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->ios),
+		      "Statistics fds are screwed");
+
+	for (size_t i = 0; i < lengthof(handle->ios); i++)
+		st->fds[i] = handle->ios[i].fd;
+	return 0;
+}
+
+/**
+ * Get a pointer to the former command line.
+ */
+const char *
+popen_command(struct popen_handle *handle)
+{
+	if (!handle) {
+		errno = ESRCH;
+		return NULL;
+	}
+
+	return (const char *)handle->command;
+}
+
+/**
+ * Get stdX descriptor string representation.
+ */
+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";
+}
+
+/**
+ * Write data to the child stdin.
+ */
+int
+popen_write_timeout(struct popen_handle *handle, void *buf,
+		    size_t count, unsigned int flags,
+		    ev_tstamp timeout)
+{
+	int idx = STDIN_FILENO;
+
+	if (!(flags & POPEN_FLAG_FD_STDIN)) {
+	    errno = EINVAL;
+	    return -1;
+	}
+
+	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 "
+		  "fds %d timeout %.9g",
+		  handle->pid, stdX_str(idx), idx, buf, count,
+		  handle->ios[idx].fd, timeout);
+
+	return coio_write_timeout(&handle->ios[idx], buf,
+				  count, timeout);
+}
+
+/**
+ * Read data from a child's peer with timeout.
+ */
+ssize_t
+popen_read_timeout(struct popen_handle *handle, void *buf,
+		   size_t count, unsigned int flags,
+		   ev_tstamp timeout)
+{
+	int idx = flags & POPEN_FLAG_FD_STDOUT ?
+		STDOUT_FILENO : STDERR_FILENO;
+
+	if (!(flags & (POPEN_FLAG_FD_STDOUT | POPEN_FLAG_FD_STDERR))) {
+	    errno = EINVAL;
+	    return -1;
+	}
+
+	if (!popen_may_io(handle, idx, flags))
+		return -1;
+
+	if (count > (size_t)SSIZE_MAX) {
+		errno = E2BIG;
+		return -1;
+	}
+
+	if (timeout < 0.)
+		timeout = TIMEOUT_INFINITY;
+
+	say_debug("popen: %d: read idx [%s:%d] buf %p count %zu "
+		  "fds %d timeout %.9g",
+		  handle->pid, stdX_str(idx), idx, buf, count,
+		  handle->ios[idx].fd, timeout);
+
+	return coio_read_timeout(&handle->ios[idx], buf,
+				 count, timeout);
+}
+
+/**
+ * Encode signal status into a human readable form.
+ *
+ * Operates on S_DEBUG level only simply because snprintf
+ * is pretty heavy in performance, otherwise @buf remains
+ * untouched.
+ */
+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;
+}
+
+/**
+ * Handle SIGCHLD when a child process exit.
+ */
+static void
+popen_sigchld_handler(EV_P_ ev_child *w, int revents)
+{
+	struct popen_handle *handle;
+	(void)revents;
+
+	say_debug("popen_sigchld_handler");
+
+	/*
+	 * Stop watching this child, libev will
+	 * remove it from own hashtable.
+	 */
+	ev_child_stop(EV_A_ w);
+
+	if (say_log_level_is_enabled(S_DEBUG)) {
+		char buf[128], *str;
+
+		str = wstatus_str(buf, sizeof(buf), w->rstatus);
+		say_debug("popen: sigchld notify %d (%s)", w->rpid, str);
+	}
+
+	handle = popen_find(w->rpid);
+	if (handle) {
+		assert(handle->pid == w->rpid);
+		assert(w == &handle->ev_sigchld);
+
+		handle->wstatus = w->rstatus;
+		if (WIFEXITED(w->rstatus) || WIFSIGNALED(w->rstatus)) {
+			say_debug("popen: ev_child_stop %d", handle->pid);
+			/*
+			 * libev calls for waitpid by self so
+			 * we don't have to wait here.
+			 */
+			popen_unregister(handle);
+			handle->pid = -1;
+		}
+	}
+}
+
+/**
+ * Get current child state.
+ */
+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;
+}
+
+/**
+ * Get process state string representation.
+ */
+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";
+}
+
+/**
+ * Send a signal to a child process.
+ */
+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;
+
+	say_debug("popen: kill %d signo %d", handle->pid, signo);
+	ret = kill(handle->pid, signo);
+	if (ret < 0) {
+		diag_set(SystemError, "Unable to kill %d signo %d",
+			 handle->pid, signo);
+	}
+	return ret;
+}
+
+/**
+ * Delete a popen handle.
+ *
+ * The function kills a child process and
+ * close all fds and remove the handle from
+ * a living list and finally frees the handle.
+ */
+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->ios); i++) {
+		if (handle->ios[i].fd != -1)
+			coio_close_io(loop(), &handle->ios[i]);
+	}
+
+	/*
+	 * Once we send a termination signal we no longer
+	 * interested in this child process. Thus stop
+	 * watching it. Note that we can enter deletion
+	 * during error in popen creation so use list
+	 * as a marker.
+	 */
+	if (handle->pid != -1 && !rlist_empty(&handle->list)) {
+		say_debug("popen: ev_child_stop %d", handle->pid);
+		ev_child_stop(EV_DEFAULT_ &handle->ev_sigchld);
+		popen_unregister(handle);
+	}
+
+	rlist_del(&handle->list);
+	handle_free(handle);
+	return 0;
+}
+
+/**
+ * Create O_CLOEXEC pipes.
+ */
+static int
+make_pipe(int pfd[2])
+{
+#ifdef TARGET_OS_LINUX
+	if (pipe2(pfd, O_CLOEXEC)) {
+		diag_set(SystemError, "Can't create pipe2");
+		return -1;
+	}
+#else
+	if (pipe(pfd)) {
+		diag_set(SystemError, "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;
+		diag_set(SystemError, "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 file descriptors.
+ *
+ * @a skip_fds is an array of @a nr_skip_fds elements
+ * with descriptors which should be kept opened.
+ */
+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) {
+		diag_set(SystemError, "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;
+			diag_set(SystemError, "fdin: Can't close %d", fd_no);
+			closedir(dir);
+			errno = saved_errno;
+			return -1;
+		}
+	}
+
+	if (closedir(dir)) {
+		diag_set(SystemError, "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
+
+/**
+ * Get pointer to environment variables to use in
+ * a child process.
+ */
+static inline char **
+get_envp(struct popen_opts *opts)
+{
+	if (!opts->env) {
+#ifdef TARGET_OS_LINUX
+		/* Inherit existing ones if not specified */
+		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;
+}
+
+/**
+ * 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);
+}
+
+/**
+ * Create new popen handle.
+ *
+ * This function creates a new child process and passes it
+ * pipe ends to communicate with child's stdin/stdout/stderr
+ * depending on @a opts:flags. Where @a 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 @a errno.
+ */
+struct popen_handle *
+popen_new(struct popen_opts *opts)
+{
+	/*
+	 * Without volatile compiler claims that
+	 * handle might be clobbered from vfork.
+	 */
+	struct popen_handle * volatile handle;
+
+	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";
+	}
+
+	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);
+	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) {
+				errno = EBADF;
+				diag_set(SystemError,
+					 "Low fds number [%s:%d:%d]",
+					  stdX_str(i), pfd[i][0],
+					  pfd[i][1]);
+				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_FLAG_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_FLAG_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;
+			int parent_fd = pfd[i][parent_idx];
+
+			coio_create(&handle->ios[i], parent_fd);
+			if (fcntl(parent_fd, F_SETFL, O_NONBLOCK)) {
+				diag_set(SystemError, "Can't set O_NONBLOCK [%s:%d]",
+					 stdX_str(i), parent_fd);
+				goto out_err;
+			}
+
+			say_debug("popen: keep pipe [%s:%d]",
+				  stdX_str(i), parent_fd);
+
+			if (close(pfd[i][child_idx])) {
+				diag_set(SystemError, "Can't 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. Note we use this
+	 * list as a sign that child is registered
+	 * in popen_delete.
+	 */
+	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, popen_sigchld_handler, 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;
+}
+
+/**
+ * Initialize popen subsystem.
+ */
+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);
+}
+
+/**
+ * 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.
+		 */
+		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..9cbfed60c
--- /dev/null
+++ b/src/lib/core/popen.h
@@ -0,0 +1,191 @@
+#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 "trivia/util.h"
+#include "third_party/tarantool_ev.h"
+
+/**
+ * Describes popen object creation. This is API with Lua.
+ */
+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_FLAG_SETSID_BIT		= 13,
+	POPEN_FLAG_SETSID		= (1 << POPEN_FLAG_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_FLAG_RESTORE_SIGNALS_BIT	= 15,
+	POPEN_FLAG_RESTORE_SIGNALS	= (1 << POPEN_FLAG_RESTORE_SIGNALS_BIT),
+};
+
+/**
+ * Popen object states. This is API with Lua.
+ */
+enum popen_states {
+	POPEN_STATE_NONE		= 0,
+	POPEN_STATE_ALIVE		= 1,
+	POPEN_STATE_EXITED		= 2,
+	POPEN_STATE_SIGNALED		= 3,
+
+	POPEN_STATE_MAX,
+};
+
+/**
+ * An instance of popen object
+ */
+struct popen_handle {
+	pid_t			pid;
+	char			*command;
+	int			wstatus;
+	ev_child		ev_sigchld;
+	struct rlist		list;
+	unsigned int		flags;
+	struct ev_io		ios[POPEN_FLAG_FD_STDEND_BIT];
+};
+
+/**
+ * Options for popen creation
+ */
+struct popen_opts {
+	char			**argv;
+	size_t			nr_argv;
+	char			**env;
+	unsigned int		flags;
+};
+
+/**
+ * Popen object statistics
+ *
+ * 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);
+
+extern int
+popen_write_timeout(struct popen_handle *handle, void *buf,
+		    size_t count, unsigned int flags,
+		    ev_tstamp timeout);
+
+extern ssize_t
+popen_read_timeout(struct popen_handle *handle, void *buf,
+		   size_t count, unsigned int flags,
+		   ev_tstamp timeout);
+
+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 e674d85b1..8df94c9e4 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;
@@ -642,6 +643,8 @@ 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);
@@ -819,6 +822,7 @@ main(int argc, char **argv)
 	exception_init();
 
 	fiber_init(fiber_cxx_invoke);
+	popen_init();
 	coio_init();
 	coio_enable();
 	signal_init();
-- 
2.20.1

[Tarantool-patches] [PATCH v11 3/3] test: unit/popen

[Cyrill Gorcunov]

Basic tests for popen engine

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
---
 test/unit/CMakeLists.txt |   3 +
 test/unit/popen.c        | 253 +++++++++++++++++++++++++++++++++++++++
 test/unit/popen.result   |  28 +++++
 3 files changed, 284 insertions(+)
 create mode 100644 test/unit/popen.c
 create mode 100644 test/unit/popen.result

diff --git a/test/unit/CMakeLists.txt b/test/unit/CMakeLists.txt
index 4a57597e9..14cbb1c9d 100644
--- a/test/unit/CMakeLists.txt
+++ b/test/unit/CMakeLists.txt
@@ -236,3 +236,6 @@ target_link_libraries(swim_errinj.test unit swim)
 
 add_executable(merger.test merger.test.c)
 target_link_libraries(merger.test unit core box)
+
+add_executable(popen.test popen.c)
+target_link_libraries(popen.test misc unit core)
diff --git a/test/unit/popen.c b/test/unit/popen.c
new file mode 100644
index 000000000..f364cee14
--- /dev/null
+++ b/test/unit/popen.c
@@ -0,0 +1,253 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "trivia/util.h"
+#include "unit.h"
+
+#include "coio.h"
+#include "coio_task.h"
+#include "memory.h"
+#include "fiber.h"
+#include "popen.h"
+#include "say.h"
+
+#define TEST_POPEN_COMMON_FLAGS			\
+	(POPEN_FLAG_SETSID		|	\
+	POPEN_FLAG_SHELL		|	\
+	POPEN_FLAG_RESTORE_SIGNALS)
+
+static int
+wait_exit(struct popen_handle *handle, int *state, int *exit_code)
+{
+	for (;;) {
+		if (popen_state(handle, state, exit_code))
+			return -1;
+		if (*state == POPEN_STATE_EXITED ||
+		    *state == POPEN_STATE_SIGNALED)
+			break;
+		fiber_sleep(0.1);
+	}
+	return 0;
+}
+
+static int
+popen_write_exit(void)
+{
+	struct popen_handle *handle;
+	char *child_argv[] = {
+		"/bin/sh", "-c",
+		"prompt=''; read -n 5 prompt; echo -n $prompt",
+		NULL,
+	};
+
+	const char data[] = "12345";
+	int state, exit_code;
+
+	struct popen_opts opts = {
+		.argv		= child_argv,
+		.nr_argv	= lengthof(child_argv),
+		.env		= NULL,
+		.flags		=
+			POPEN_FLAG_FD_STDIN		|
+			POPEN_FLAG_FD_STDOUT		|
+			POPEN_FLAG_FD_STDERR		|
+			TEST_POPEN_COMMON_FLAGS,
+	};
+	int rc;
+
+	plan(7);
+	header();
+
+	handle = popen_new(&opts);
+	ok(handle != NULL, "popen_new");
+	if (handle == NULL)
+		goto out;
+
+	rc = popen_state(handle, &state, &exit_code);
+	ok(rc == 0, "popen_state");
+
+	ok(state == POPEN_STATE_ALIVE, "state %s",
+	   popen_state_str(state));
+
+	rc = popen_write_timeout(handle, (void *)data,
+				 (int)strlen(data),
+				 POPEN_FLAG_FD_STDOUT, 180);
+	ok(rc == -1, "write flag check");
+
+	rc = popen_write_timeout(handle, (void *)data,
+				 (int)strlen(data),
+				 POPEN_FLAG_FD_STDIN, 180);
+	diag("write %d bytes '%s'", (int)strlen(data), data);
+	ok(rc == (int)strlen(data), "write %s (%d bytes)",
+	   data, (int)strlen(data));
+	if (rc != (int)strlen(data))
+		goto out_kill;
+
+	rc = wait_exit(handle, &state, &exit_code);
+	if (rc) {
+		ok(false, "child wait");
+		goto out_kill;
+	}
+
+	ok(state == POPEN_STATE_EXITED, "child exited");
+
+out_kill:
+	rc = popen_delete(handle);
+	ok(rc == 0, "popen_delete");
+
+out:
+	footer();
+	return rc | check_plan();
+}
+
+static int
+popen_read_exit(void)
+{
+	struct popen_handle *handle;
+	char *child_argv[] = {
+		"/bin/sh", "-c",
+		"echo -n 1 2 3 4 5",
+		NULL,
+	};
+
+	int state, exit_code;
+	char data[32] = { };
+
+	struct popen_opts opts = {
+		.argv		= child_argv,
+		.nr_argv	= lengthof(child_argv),
+		.env		= NULL,
+		.flags		=
+			POPEN_FLAG_FD_STDIN		|
+			POPEN_FLAG_FD_STDOUT		|
+			POPEN_FLAG_FD_STDERR		|
+			TEST_POPEN_COMMON_FLAGS,
+	};
+	int rc;
+
+	plan(5);
+	header();
+
+	handle = popen_new(&opts);
+	ok(handle != NULL, "popen_new");
+	if (handle == NULL)
+		goto out;
+
+	rc = wait_exit(handle, &state, &exit_code);
+	if (rc) {
+		ok(false, "child wait");
+		goto out_kill;
+	}
+	ok(state == POPEN_STATE_EXITED, "child exited");
+
+	rc = popen_read_timeout(handle, data, sizeof(data),
+				POPEN_FLAG_FD_STDIN, 180);
+	ok(rc == -1, "read flag check");
+
+	rc = popen_read_timeout(handle, data, sizeof(data),
+				POPEN_FLAG_FD_STDOUT, 180);
+	diag("read %d bytes '%s'\n", rc, data);
+	ok(rc == 9 && !strcmp(data, "1 2 3 4 5"),
+	   "read %s (%d bytes)", data, rc);
+
+out_kill:
+	rc = popen_delete(handle);
+	ok(rc == 0, "popen_delete");
+
+out:
+	footer();
+	return rc | check_plan();
+}
+
+static int
+popen_kill(void)
+{
+	struct popen_handle *handle;
+	char *child_argv[] = {
+		"/bin/sh", "-c",
+		"while [ 1 ]; do sleep 10; done",
+		NULL,
+	};
+
+	int state, exit_code;
+
+	struct popen_opts opts = {
+		.argv		= child_argv,
+		.nr_argv	= lengthof(child_argv),
+		.env		= NULL,
+		.flags		=
+			POPEN_FLAG_FD_STDIN		|
+			POPEN_FLAG_FD_STDOUT		|
+			POPEN_FLAG_FD_STDERR		|
+			TEST_POPEN_COMMON_FLAGS,
+	};
+	int rc;
+
+	plan(4);
+	header();
+
+	handle = popen_new(&opts);
+	ok(handle != NULL, "popen_new");
+	if (handle == NULL)
+		goto out;
+
+	rc = popen_send_signal(handle, SIGTERM);
+	ok(rc == 0, "popen_send_signal");
+	if (rc != 0)
+		goto out_kill;
+
+	rc = wait_exit(handle, &state, &exit_code);
+	if (rc) {
+		ok(false, "child wait");
+		goto out_kill;
+	}
+	ok(state == POPEN_STATE_SIGNALED, "child terminated");
+
+out_kill:
+	rc = popen_delete(handle);
+	ok(rc == 0, "popen_delete");
+
+out:
+	footer();
+	return rc | check_plan();
+}
+
+static int
+main_f(va_list ap)
+{
+	int rc = 0;
+
+	rc |= popen_write_exit();
+	rc |= popen_read_exit();
+	rc |= popen_kill();
+
+	ev_break(loop(), EVBREAK_ALL);
+	return 0;
+}
+
+
+int
+main(int argc, char *argv[])
+{
+	//say_logger_init(NULL, S_DEBUG, 0, "plain", 0);
+	memory_init();
+
+	fiber_init(fiber_c_invoke);
+	popen_init();
+	coio_init();
+	coio_enable();
+
+	if (!loop())
+		panic("%s", "can't init event loop");
+
+	struct fiber *test = fiber_new("coio_stat", main_f);
+	fiber_wakeup(test);
+
+	ev_now_update(loop());
+	ev_run(loop(), 0);
+	popen_free();
+	fiber_free();
+	memory_free();
+
+	return check_plan();
+}
diff --git a/test/unit/popen.result b/test/unit/popen.result
new file mode 100644
index 000000000..f9ffa008f
--- /dev/null
+++ b/test/unit/popen.result
@@ -0,0 +1,28 @@
+# write 5 bytes '12345'
+# read 9 bytes '1 2 3 4 5'
+
+1..7
+	*** popen_write_exit ***
+ok 1 - popen_new
+ok 2 - popen_state
+ok 3 - state alive
+ok 4 - write flag check
+ok 5 - write 12345 (5 bytes)
+ok 6 - child exited
+ok 7 - popen_delete
+	*** popen_write_exit: done ***
+1..5
+	*** popen_read_exit ***
+ok 1 - popen_new
+ok 2 - child exited
+ok 3 - read flag check
+ok 4 - read 1 2 3 4 5 (9 bytes)
+ok 5 - popen_delete
+	*** popen_read_exit: done ***
+1..4
+	*** popen_kill ***
+ok 1 - popen_new
+ok 2 - popen_send_signal
+ok 3 - child terminated
+ok 4 - popen_delete
+	*** popen_kill: done ***
-- 
2.20.1

Re: [Tarantool-patches] [PATCH v11 0/3] popen: Introduce backend engine

[Kirill Yukhin]

Hello,

On 17 фев 15:18, Cyrill Gorcunov wrote:
> In v11 I cleaned up some nits and updated the tests.
> 
> issue https://github.com/tarantool/tarantool/issues/4031
> branch https://github.com/tarantool/tarantool/tree/gorcunov/gh-4031-popen-11

LGTM.
I've checked the patchsrt into master.

--
Regards, Kirill Yukhin