Prevent duplicate signals from makeparallel

As part of the soong_ui effort, we noticed that we'd sometimes see
multiple SIGINTs from a single ctrl-c from a user. ctrl-c sends a SIGINT
to the entire process group, so make, makeparallel, soong_ui, and all of
its children would get a signal. Since makeparallel was passing it along
to it's child, soong_ui would get two signals.

So instead, follow what Make does and only pass along SIGTERM. Assume
that all other signals went to the entire process group.

Bug: 35214134
Test: Send SIGINT to process group, check in makeparallel's child for
more than one signal received.
Change-Id: I5b2a77ad0fcebbaa5087439948e71bf3b541061a

1 files changed, 2 insertions, 6 deletions

diff --git a/tools/makeparallel/makeparallel.cpp b/tools/makeparallel/makeparallel.cpp
index 0e1e45c153..a99b2867ae 100644
--- a/tools/makeparallel/makeparallel.cpp
+++ b/tools/makeparallel/makeparallel.cpp
@@ -357,8 +357,8 @@ int main(int argc, char* argv[]) {
 
   static pid_t pid;
 
-  // Set up signal handlers to forward SIGHUP, SIGINT, SIGQUIT, SIGTERM, and
-  // SIGALRM to child
+  // Set up signal handlers to forward SIGTERM to child
+  // Assume that all other signals are sent to the entire process group
   struct sigaction action = {};
   action.sa_flags = SA_SIGINFO | SA_RESTART,
   action.sa_sigaction = [](int signal, siginfo_t*, void*) {
@@ -368,11 +368,7 @@ int main(int argc, char* argv[]) {
   };
 
   int ret = 0;
-  if (!ret) ret = sigaction(SIGHUP, &action, NULL);
-  if (!ret) ret = sigaction(SIGINT, &action, NULL);
-  if (!ret) ret = sigaction(SIGQUIT, &action, NULL);
   if (!ret) ret = sigaction(SIGTERM, &action, NULL);
-  if (!ret) ret = sigaction(SIGALRM, &action, NULL);
   if (ret < 0) {
     error(errno, errno, "sigaction failed");
   }