[stgt] [PATCH] add a helper function to run an external program

[FUJITA Tomonori]

I need to run an external program when some events happen (the node
with the global IP crashes, I want to run a script to take over the
global IP on a new host).

It can be used to send administrators an e-mails or do whatever you
like.

=
From: FUJITA Tomonori <fujita.tomonori at lab.ntt.co.jp>
Subject: [PATCH] add a helper function to run an external program

The new helper function can be used to run an external program when a
specific event happens.

Signed-off-by: FUJITA Tomonori <fujita.tomonori at lab.ntt.co.jp>
---
 usr/tgtd.c |   63 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 usr/tgtd.h |    2 +
 2 files changed, 65 insertions(+), 0 deletions(-)

diff --git a/usr/tgtd.c b/usr/tgtd.c
index 18ad7be..8fbefb1 100644
--- a/usr/tgtd.c
+++ b/usr/tgtd.c
@@ -252,6 +252,69 @@ void tgt_remove_sched_event(struct event_data *evt)
 	}
 }
 
+struct ext_prog_info {
+	void (*callback)(void *data, int result);
+	void *data;
+};
+
+static void run_ext_callback(int fd, int events, void *data)
+{
+	int ret, result;
+	struct ext_prog_info *ex = data;
+
+	ret = read(fd, &result, sizeof(result));
+	if (ret != sizeof(result)) {
+		result = -EINVAL;
+		eprintf("failed to get the result.");
+	}
+
+	if (ex->callback)
+		ex->callback(ex->data, result);
+
+	tgt_event_del(fd);
+	close(fd);
+	free(data);
+}
+
+int run_ext_program(const char *cmd,
+		    void (*callback)(void *data, int result), void *data)
+{
+	pid_t pid;
+	int fds[2], ret;
+	struct ext_prog_info *ex;
+
+	ex = zalloc(sizeof(*ex));
+	if (!ex)
+		return -ENOMEM;
+
+	ret = pipe(fds);
+	if (ret < 0) {
+		free(ex);
+		return ret;
+	}
+
+	eprintf("%d %d\n", fds[0], fds[1]);
+
+	ex->callback = callback;
+	ex->data = data;
+
+	tgt_event_add(fds[0], EPOLLIN, run_ext_callback, ex);
+
+	pid = fork();
+	if (pid < 0)
+		return pid;
+
+	if (!pid) {
+		ret = system(cmd);
+		write(fds[1], &ret, sizeof(ret));
+		return 0;
+	}
+
+	close(fds[1]);
+
+	return 0;
+}
+
 static int tgt_exec_scheduled(void)
 {
 	struct list_head *last_sched;
diff --git a/usr/tgtd.h b/usr/tgtd.h
index b8541c8..9c44994 100644
--- a/usr/tgtd.h
+++ b/usr/tgtd.h
@@ -347,4 +347,6 @@ int do_tgt_event_add(int efd, struct list_head *list, int fd, int events,
 void do_tgt_event_del(int efd, struct list_head *list, int fd);
 int do_tgt_event_modify(int efd, struct list_head *list, int fd, int events);
 
+int run_ext_program(const char *cmd,
+		    void (*callback)(void *data, int result), void *data);
 #endif
-- 
1.6.5

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