[Tarantool-patches] [PATCH 01/12] popen: allow to kill process group

[Alexander Turenko]

From: Cyrill Gorcunov <gorcunov at gmail.com>

As Alexander pointed out this might be useful
for running a pipe of programs inside shell
(i.e. popen.shell('foo | bar | baz', 'r')).

Part of #4031

Reported-by: Alexander Turenko <alexander.turenko at tarantool.org>
Acked-by: Alexander Turenko <alexander.turenko at tarantool.org>
Signed-off-by: Cyrill Gorcunov <gorcunov at gmail.com>
---
 src/lib/core/popen.c | 28 ++++++++++++++++++++++++----
 src/lib/core/popen.h |  6 ++++++
 2 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/src/lib/core/popen.c b/src/lib/core/popen.c
index df7f797b9..a5a305013 100644
--- a/src/lib/core/popen.c
+++ b/src/lib/core/popen.c
@@ -138,6 +138,19 @@ handle_new(struct popen_opts *opts)
 
 	assert(opts->argv != NULL && opts->nr_argv > 0);
 
+	/*
+	 * Killing group of signals allowed for a new
+	 * session only where it makes sense, otherwise
+	 * child gonna inherit group and we will be killing
+	 * ourself.
+	 */
+	if (opts->flags & POPEN_FLAG_GROUP_SIGNAL &&
+	    (opts->flags & POPEN_FLAG_SETSID) == 0) {
+		diag_set(IllegalParams,
+			 "popen: group signal without setting sid");
+		return NULL;
+	}
+
 	for (i = 0; i < opts->nr_argv; i++) {
 		if (opts->argv[i] == NULL)
 			continue;
@@ -526,6 +539,9 @@ popen_state_str(unsigned int state)
 int
 popen_send_signal(struct popen_handle *handle, int signo)
 {
+	static const char *killops[] = { "kill", "killpg" };
+	const char *killop = handle->flags & POPEN_FLAG_GROUP_SIGNAL ?
+		killops[1] : killops[0];
 	int ret;
 
 	assert(handle != NULL);
@@ -535,17 +551,21 @@ popen_send_signal(struct popen_handle *handle, int signo)
 	 */
 	ret = popen_may_pidop(handle);
 	if (ret == 0) {
-		say_debug("popen: kill %d signo %d", handle->pid, signo);
+		say_debug("popen: %s %d signo %d", killop,
+			  handle->pid, signo);
 		assert(handle->pid != -1);
-		ret = kill(handle->pid, signo);
+		if (handle->flags & POPEN_FLAG_GROUP_SIGNAL)
+			ret = killpg(handle->pid, signo);
+		else
+			ret = kill(handle->pid, signo);
 	}
 	if (ret < 0 && errno == ESRCH) {
 		diag_set(SystemError, "Attempt to send a signal %d to a "
 			 "process that does not exist anymore", signo);
 		return -1;
 	} else if (ret < 0) {
-		diag_set(SystemError, "Unable to kill %d signo %d",
-			 handle->pid, signo);
+		diag_set(SystemError, "Unable to %s %d signo %d",
+			 killop, handle->pid, signo);
 		return -1;
 	}
 	return 0;
diff --git a/src/lib/core/popen.h b/src/lib/core/popen.h
index 97c581c13..623d826b9 100644
--- a/src/lib/core/popen.h
+++ b/src/lib/core/popen.h
@@ -96,6 +96,12 @@ enum popen_flag_bits {
 	 */
 	POPEN_FLAG_RESTORE_SIGNALS_BIT	= 15,
 	POPEN_FLAG_RESTORE_SIGNALS	= (1 << POPEN_FLAG_RESTORE_SIGNALS_BIT),
+
+	/*
+	 * Send signal to a process group.
+	 */
+	POPEN_FLAG_GROUP_SIGNAL_BIT	= 16,
+	POPEN_FLAG_GROUP_SIGNAL		= (1 << POPEN_FLAG_GROUP_SIGNAL_BIT),
 };
 
 /**
-- 
2.25.0