From 28990d36fea96f729231dfb6c978b7606b0f74cc Mon Sep 17 00:00:00 2001
From: Umang Jain <umang.jain@ideasonboard.com>
Date: Mon, 26 Jul 2021 14:35:51 +0530
Subject: utils: ipc: Assign a new gid to proxy worker

Isolated IPAs are forked to a new process by the proxy worker, which
shares the same process group. This allows the undesired effect that
the proxy worker will receive signals such as SIGINT and will be closed
by a Ctrl-C event before the pipeline handlers have been able to fully
clean up.

Prevent this signal from being delivered to the proxy worker by moving
the process to a new process group, matching the pid of the isolated
proxy.

Bug: https://bugs.libcamera.org/show_bug.cgi?id=60
Tested-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
---
 .../libcamera_templates/module_ipa_proxy_worker.cpp.tmpl     | 12 ++++++++++++
 1 file changed, 12 insertions(+)

(limited to 'utils/ipc')

diff --git a/utils/ipc/generators/libcamera_templates/module_ipa_proxy_worker.cpp.tmpl b/utils/ipc/generators/libcamera_templates/module_ipa_proxy_worker.cpp.tmpl
index d993e39e..164a4dd6 100644
--- a/utils/ipc/generators/libcamera_templates/module_ipa_proxy_worker.cpp.tmpl
+++ b/utils/ipc/generators/libcamera_templates/module_ipa_proxy_worker.cpp.tmpl
@@ -207,6 +207,18 @@ int main(int argc, char **argv)
 		return EXIT_FAILURE;
 	}
 
+	/*
+	 * Shutdown of proxy worker can be pre-empted by events like
+	 * SIGINT/SIGTERM, even before the pipeline handler can request
+	 * shutdown. Hence, assign a new gid to prevent signals on the
+	 * application being delivered to the proxy.
+	 */
+	if (setpgid(0, 0) < 0) {
+		int err = errno;
+		LOG({{proxy_worker_name}}, Warning)
+			<< "Failed to set new gid: " << strerror(err);
+	}
+
 	{{proxy_worker_name}} proxyWorker;
 	int ret = proxyWorker.init(ipam, fd);
 	if (ret < 0) {
-- 
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