libbb: introduce and use safe_waitpid (loops in EINTR)

*: use more approproate (shorter) versions of wait()

function                                             old     new   delta
safe_waitpid                                           -      48     +48
wait_any_nohang                                        -      17     +17
send_tree                                            365     369      +4
processorstop                                        432     435      +3
text_yank                                            110     108      -2
make_human_readable_str                              202     200      -2
crond_main                                          1368    1366      -2
handle_sigchld                                        49      43      -6
reapchild                                            166     159      -7
custom                                               260     250     -10
checkscript                                          191     177     -14
wait_nohang                                           17       -     -17
wait_pid                                              43       -     -43
------------------------------------------------------------------------------
(add/remove: 2/2 grow/shrink: 2/7 up/down: 72/-103)           Total: -31 bytes

3 files changed, 3 insertions, 2 deletions

diff --git a/shell/ash.c b/shell/ash.c
index a5b19c863..96563bf06 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -3768,7 +3768,7 @@ waitproc(int block, int *status)
 #endif
         if (block == 0)
                 flags |= WNOHANG;
-        return wait3(status, flags, (struct rusage *)NULL);
+        return waitpid(-1, status, flags); // safe_waitpid?
 }
 
 /*
diff --git a/shell/hush.c b/shell/hush.c
index cb2c3e98e..b08fe10b6 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -1649,6 +1649,7 @@ static int checkjobs(struct pipe* fg_pipe)
 // + killall -STOP cat
 
  wait_more:
+// TODO: safe_waitpid?
         while ((childpid = waitpid(-1, &status, attributes)) > 0) {
                 const int dead = WIFEXITED(status) || WIFSIGNALED(status);
 
diff --git a/shell/msh.c b/shell/msh.c
index 9edf793ab..9e9b798a1 100644
--- a/shell/msh.c
+++ b/shell/msh.c
@@ -4162,7 +4162,7 @@ static int grave(int quoted)
                 return 0;
         }
         if (i != 0) {
-                waitpid(i, NULL, 0);
+                waitpid(i, NULL, 0); // safe_waitpid?
                 global_env.iop->argp->aword = ++cp;
                 close(pf[1]);
                 PUSHIO(afile, remap(pf[0]),