action-scripts: Add pre-stream hook

This hook allows to start image streamer process from an action script.

Signed-off-by: Radostin Stoyanov <rstoyanov@fedoraproject.org>

criu/action-scripts.c

@@ -18,6 +18,7 @@
 #include "common/scm.h"
 
 static const char *action_names[ACT_MAX] = {
+	[ACT_PRE_STREAM] = "pre-stream",
 	[ACT_PRE_DUMP] = "pre-dump",
 	[ACT_POST_DUMP] = "post-dump",
 	[ACT_PRE_RESTORE] = "pre-restore",

criu/img-streamer.c

@@ -12,6 +12,7 @@
 #include "rst-malloc.h"
 #include "common/scm.h"
 #include "common/lock.h"
+#include "action-scripts.h"
 
 /*
  * We use different path names for the dump and restore sockets because:
@@ -49,10 +50,17 @@ static const char *socket_name_for_mode(int mode)
 int img_streamer_init(const char *image_dir, int mode)
 {
 	struct sockaddr_un addr;
+	int pre_stream_ret;
 	int sockfd;
 
 	img_streamer_mode = mode;
 
+	pre_stream_ret = run_scripts(ACT_PRE_STREAM);
+	if (pre_stream_ret != 0) {
+		pr_err("Pre-stream script failed with %d!\n", pre_stream_ret);
+		return -1;
+	}
+
 	sockfd = socket(AF_UNIX, SOCK_STREAM, 0);
 	if (sockfd < 0) {
 		pr_perror("Unable to instantiate UNIX socket");

criu/include/action-scripts.h

@@ -4,6 +4,7 @@
 #include "asm/int.h"
 
 enum script_actions {
+	ACT_PRE_STREAM,
 	ACT_PRE_DUMP,
 	ACT_POST_DUMP,
 	ACT_PRE_RESTORE,