Properly initialize variable to make valgrind happy in checkChildrenDone(). Removed usage for the obsolete wait3() and wait4() in favor of waitpid(), and properly check for the exit status code. (#8666)

src/aof.c

@@ -218,7 +218,7 @@ void killAppendOnlyChild(void) {
     serverLog(LL_NOTICE,"Killing running AOF rewrite child: %ld",
         (long) server.child_pid);
     if (kill(server.child_pid,SIGUSR1) != -1) {
-        while(wait3(&statloc,0,NULL) != server.child_pid);
+        while(waitpid(-1, &statloc, 0) != server.child_pid);
     }
     /* Reset the buffer accumulating changes while the child saves. */
     aofRewriteBufferReset();

src/module.c

@@ -7821,7 +7821,7 @@ int TerminateModuleForkChild(int child_pid, int wait) {
     serverLog(LL_VERBOSE,"Killing running module fork child: %ld",
         (long) server.child_pid);
     if (kill(server.child_pid,SIGUSR1) != -1 && wait) {
-        while(wait4(server.child_pid,&statloc,0,NULL) !=
+        while(waitpid(server.child_pid, &statloc, 0) !=
               server.child_pid);
     }
     /* Reset the buffer accumulating changes while the child saves. */

src/rdb.c

@@ -2732,7 +2732,7 @@ void backgroundSaveDoneHandler(int exitcode, int bysignal) {
  * the cleanup needed. */
 void killRDBChild(void) {
     kill(server.child_pid, SIGUSR1);
-    /* Because we are not using here wait4 (like we have in killAppendOnlyChild
+    /* Because we are not using here waitpid (like we have in killAppendOnlyChild
      * and TerminateModuleForkChild), all the cleanup operations is done by
      * checkChildrenDone, that later will find that the process killed.
      * This includes:

src/sentinel.c

@@ -904,7 +904,7 @@ void sentinelCollectTerminatedScripts(void) {
     int statloc;
     pid_t pid;
 
-    while ((pid = wait3(&statloc,WNOHANG,NULL)) > 0) {
+    while ((pid = waitpid(-1, &statloc, WNOHANG)) > 0) {
         int exitcode = WEXITSTATUS(statloc);
         int bysignal = 0;
         listNode *ln;
@@ -916,7 +916,7 @@ void sentinelCollectTerminatedScripts(void) {
 
         ln = sentinelGetScriptListNodeByPid(pid);
         if (ln == NULL) {
-            serverLog(LL_WARNING,"wait3() returned a pid (%ld) we can't find in our scripts execution queue!", (long)pid);
+            serverLog(LL_WARNING,"waitpid() returned a pid (%ld) we can't find in our scripts execution queue!", (long)pid);
             continue;
         }
         sj = ln->value;

src/server.c

@@ -1928,11 +1928,11 @@ void updateCachedTime(int update_daylight_info) {
 }
 
 void checkChildrenDone(void) {
-    int statloc;
+    int statloc = 0;
     pid_t pid;
 
-    if ((pid = wait3(&statloc,WNOHANG,NULL)) != 0) {
-        int exitcode = WEXITSTATUS(statloc);
+    if ((pid = waitpid(-1, &statloc, WNOHANG)) != 0) {
+        int exitcode = WIFEXITED(statloc) ? WEXITSTATUS(statloc) : -1;
         int bysignal = 0;
 
         if (WIFSIGNALED(statloc)) bysignal = WTERMSIG(statloc);
@@ -1940,15 +1940,14 @@ void checkChildrenDone(void) {
         /* sigKillChildHandler catches the signal and calls exit(), but we
          * must make sure not to flag lastbgsave_status, etc incorrectly.
          * We could directly terminate the child process via SIGUSR1
-         * without handling it, but in this case Valgrind will log an
-         * annoying error. */
+         * without handling it */
         if (exitcode == SERVER_CHILD_NOERROR_RETVAL) {
             bysignal = SIGUSR1;
             exitcode = 1;
         }
 
         if (pid == -1) {
-            serverLog(LL_WARNING,"wait3() returned an error: %s. "
+            serverLog(LL_WARNING,"waitpid() returned an error: %s. "
                 "child_type: %s, child_pid = %d",
                 strerror(errno),
                 strChildType(server.child_type),

tests/integration/replication.tcl

@@ -722,7 +722,7 @@ start_server {tags {"repl"}} {
 test "diskless replication child being killed is collected" {
     # when diskless master is waiting for the replica to become writable
     # it removes the read event from the rdb pipe so if the child gets killed
-    # the replica will hung. and the master may not collect the pid with wait3
+    # the replica will hung. and the master may not collect the pid with waitpid
     start_server {tags {"repl"}} {
         set master [srv 0 client]
         set master_host [srv 0 host]