From 9c6b723adb2341c30fc4958ffa204a941e159d8e Mon Sep 17 00:00:00 2001
From: Bart Van Assche <bvanassche@google.com>
Date: Mon, 20 Nov 2023 14:38:55 -0800
Subject: [PATCH] init: Introduce the function ReapAndRemove()

Prepare for adding a second caller of ReapAndRemove().

Change-Id: I0f54af6136f49caa0198c123a4c8de968e5f41ba
Signed-off-by: Bart Van Assche <bvanassche@google.com>
---
 init/sigchld_handler.cpp | 27 ++++++++++++++++++---------
 init/sigchld_handler.h   |  3 ++-
 2 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/init/sigchld_handler.cpp b/init/sigchld_handler.cpp
index 9d4c7c8e3..02795080a 100644
--- a/init/sigchld_handler.cpp
+++ b/init/sigchld_handler.cpp
@@ -118,8 +118,23 @@ static pid_t ReapOneProcess() {
     return pid;
 }
 
-void ReapAnyOutstandingChildren() {
-    while (ReapOneProcess() != 0) {
+std::set<pid_t> ReapAnyOutstandingChildren() {
+    std::set<pid_t> reaped_pids;
+    for (;;) {
+        const pid_t pid = ReapOneProcess();
+        if (pid <= 0) {
+            return reaped_pids;
+        }
+        reaped_pids.emplace(pid);
+    }
+}
+
+static void ReapAndRemove(std::vector<pid_t>& alive_pids) {
+    for (auto pid : ReapAnyOutstandingChildren()) {
+        const auto it = std::find(alive_pids.begin(), alive_pids.end(), pid);
+        if (it != alive_pids.end()) {
+            alive_pids.erase(it);
+        }
     }
 }
 
@@ -142,13 +157,7 @@ void WaitToBeReaped(int sigchld_fd, const std::vector<pid_t>& pids,
     }
     std::vector<pid_t> alive_pids(pids.begin(), pids.end());
     while (!alive_pids.empty() && t.duration() < timeout) {
-        pid_t pid;
-        while ((pid = ReapOneProcess()) != 0) {
-            auto it = std::find(alive_pids.begin(), alive_pids.end(), pid);
-            if (it != alive_pids.end()) {
-                alive_pids.erase(it);
-            }
-        }
+        ReapAndRemove(alive_pids);
         if (alive_pids.empty()) {
             break;
         }
diff --git a/init/sigchld_handler.h b/init/sigchld_handler.h
index e07a7d66a..535130296 100644
--- a/init/sigchld_handler.h
+++ b/init/sigchld_handler.h
@@ -18,12 +18,13 @@
 #define _INIT_SIGCHLD_HANDLER_H_
 
 #include <chrono>
+#include <set>
 #include <vector>
 
 namespace android {
 namespace init {
 
-void ReapAnyOutstandingChildren();
+std::set<pid_t> ReapAnyOutstandingChildren();
 
 void WaitToBeReaped(int sigchld_fd, const std::vector<pid_t>& pids,
                     std::chrono::milliseconds timeout);