From 572baa6c85ab8bbe181b3709c0620156633b6393 Mon Sep 17 00:00:00 2001
From: Jon duSaint
Date: Sat, 16 Sep 2023 09:41:28 -0700
Subject: reolink: Simplify child process handling

Since all we care about is whether the video-generating process is
still running, we can remove the SIGCHLD handling that updates the
list of child processes in favor of directly checking them when
decideding whether to generate a video or not.
---
 reolink/reolink | 39 +++++++++------------------------------
 1 file changed, 9 insertions(+), 30 deletions(-)

(limited to 'reolink')

diff --git a/reolink/reolink b/reolink/reolink
index 7b5ec2c..0b18167 100755
--- a/reolink/reolink
+++ b/reolink/reolink
@@ -337,23 +337,6 @@ sub process_command {
 
 
 my %process_children;
-my @sigchld_handlers;
-
-sub process_complete {
-  local ($!, $?);
-
-  while ((my $pid = waitpid (-1, WNOHANG)) > 0) {
-    if (defined $process_children{$pid}) {
-      debug ("child process $pid ($process_children{$pid}) complete");
-      delete $process_children{$pid};
-      if (@sigchld_handlers) {
-        $SIG{CHLD} = pop @sigchld_handlers;
-      }
-    } else {
-      error ("SIGCHLD for pid $pid ($?), but it's not in the list!");
-    }
-  }
-}
 
 sub maybe_generate_video {
   # [camera list] [time]
@@ -372,10 +355,16 @@ sub maybe_generate_video {
 
  CAMERA:
   foreach my $camera (@cameras) {
-    foreach my $child (values %process_children) {
-      if ($child eq $camera) {
-        debug ("child process $child running...");
+
+    foreach my $pid (keys %process_children) {
+      my $res = waitpid ($pid, WNOHANG);
+      debug ("$pid -> $process_children{$pid}: $res");
+      if ($res == 0) {
+        debug ("child process $pid ($process_children{$pid}) running...");
         next CAMERA;
+      } else {
+        debug ("child process $pid ($process_children{$pid}) complete");
+        delete $process_children{$pid};
       }
     }
 
@@ -408,18 +397,9 @@ sub maybe_generate_video {
     }
     push @process_args, ('--process' => $video_prefix, '--range' => $server_params{video}, '--spool', spool ($camera));
 
-    push @sigchld_handlers, $SIG{CHLD};
-    $SIG{CHLD} = \&process_complete;
-
-    my $sigset = POSIX::SigSet->new (SIGCHLD);
-    my $sigset_prev = POSIX::SigSet->new ();
-
-    sigprocmask (SIG_BLOCK, $sigset, $sigset_prev);
-
     my $process_child = fork ();
     unless (defined ($process_child)) {
       error ("failed to fork video process for $camera");
-      pop @sigchld_handlers;
       next;
     }
 
@@ -428,7 +408,6 @@ sub maybe_generate_video {
     }
 
     $process_children{$process_child} = $camera;
-    sigprocmask (SIG_UNBLOCK, $sigset_prev);
 
     debug ("launched video process for $camera as pid $process_child");
   }
-- 
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