Change SIGCHLD handler to just set a flag.

We already call reap_kids() in multiple event loops so there is no
need to call waitpid() inside the handler itself.
OK denis@ deraadt@

diff --git a/usr.sbin/pppd/main.c b/usr.sbin/pppd/main.c
index cb54143..5b2ee5e 100644 (file)
--- a/usr.sbin/pppd/main.c
+++ b/usr.sbin/pppd/main.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: main.c,v 1.58 2024/08/10 05:32:28 jsg Exp $   */
+/*     $OpenBSD: main.c,v 1.59 2024/08/23 00:43:34 millert Exp $       */
 
 /*
  * main.c - Point-to-Point Protocol main module
@@ -108,6 +108,7 @@ int detached;                       /* have detached from terminal */
 int phase;                     /* where the link is at */
 volatile sig_atomic_t kill_link;
 volatile sig_atomic_t open_ccp_flag;
+volatile sig_atomic_t got_sigchld;
 
 char **script_env;             /* Env. variable values for scripts */
 int s_env_nalloc;              /* # words avail at script_env */
@@ -115,8 +116,6 @@ int s_env_nalloc;           /* # words avail at script_env */
 u_char outpacket_buf[PPP_MRU+PPP_HDRLEN]; /* buffer for outgoing packet */
 u_char inpacket_buf[PPP_MRU+PPP_HDRLEN]; /* buffer for incoming packet */
 
-static int n_children;         /* # child processes still running */
-
 static int locked;             /* lock() has succeeded */
 
 char *no_ppp_msg = "Sorry - this system lacks PPP kernel support\n";
@@ -964,10 +963,7 @@ term(int sig)
 static void
 chld(int sig)
 {
-    int save_errno = errno;
-
-    reap_kids();               /* XXX somewhat unsafe */
-    errno = save_errno;
+    got_sigchld = 1;
 }
 
 
@@ -1162,7 +1158,6 @@ run_program(char *prog, char **args, int must_exist)
        _exit(1);
     }
     MAINDEBUG((LOG_DEBUG, "Script %s started; pid = %ld", prog, (long)pid));
-    ++n_children;
     return 0;
 }
 
@@ -1177,18 +1172,29 @@ reap_kids(void)
     int status;
     pid_t pid;
 
-    if (n_children == 0)
+    if (!got_sigchld)
        return;
-    if ((pid = waitpid(-1, &status, WNOHANG)) == -1) {
-       if (errno != ECHILD)
-           syslog(LOG_ERR, "Error waiting for child process: %m");
-       return;
-    }
-    if (pid > 0) {
-       --n_children;
-       if (WIFSIGNALED(status)) {
-           syslog(LOG_WARNING, "Child process %ld terminated with signal %d",
-                  (long)pid, WTERMSIG(status));
+    got_sigchld = 0;
+
+    for (;;) {
+       pid = waitpid(-1, &status, WNOHANG);
+       switch (pid) {
+       case -1:
+           if (errno == EINTR)
+               continue;
+           if (errno != ECHILD)
+               syslog(LOG_ERR, "Error waiting for child process: %m");
+           return;
+       case 0:
+           /* No children left */
+           return;
+       default:
+           if (WIFSIGNALED(status)) {
+               syslog(LOG_WARNING,
+                   "Child process %d terminated with signal %d",
+                   (int)pid, WTERMSIG(status));
+           }
+           break;
        }
     }
 }