From 6655b38a47d54063f0026f963202aa277898c094 Mon Sep 17 00:00:00 2001
From: MadMaurice <madmaurice@zom.bi>
Date: Fri, 15 Jan 2021 20:22:22 +0100
Subject: [PATCH] Use sigaction instead of signal

This way we don't have to handle EINTR.
---
 main.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/main.c b/main.c
index 4033c19..fc79ba5 100644
--- a/main.c
+++ b/main.c
@@ -41,6 +41,7 @@ void drop_root(void)
     }
 }
 
+struct sigaction forward_signal_descriptor;
 void forward_signal(int sig)
 {
   if (kill(pid_child, sig) == -1)
@@ -64,6 +65,10 @@ char** argdup(int argc, const char** argv)
 int main(int argc, const char** argv)
 {
   int err;
+
+  forward_signal_descriptor.sa_flags = SA_RESTART;
+  forward_signal_descriptor.sa_handler = &forward_signal;
+
   if (argc == 1)
     {
       printf("Usage: pidjail PROGRAM ARGUMENTS...\n"
@@ -99,16 +104,15 @@ int main(int argc, const char** argv)
 
       // Setup signal handler to forward SIGTERM
       pid_child = pid;
-      if (signal(SIGTERM, forward_signal) == SIG_ERR)
+      if (sigaction(SIGTERM, &forward_signal_descriptor, NULL) == -1)
         {
           printf("Unable to setup signal handler in head\n");
         }
       // parent waits for child then exits
       // Could be interrupt due to a signal. Retry in that case.
       int status;
-      while (waitpid(pid, &status, 0) == -1)
+      if (waitpid(pid, &status, 0) == -1)
         {
-          if(errno == EINTR) continue; // On EINTR retry.
           err = errno;
           printf("Failed to wait (%d)\n", err);
           return err;
@@ -143,7 +147,7 @@ int main(int argc, const char** argv)
 
           // Setup forward for SIGTERM
           pid_child = first_child;
-          if (signal(SIGTERM, forward_signal) == SIG_ERR)
+          if (sigaction(SIGTERM, &forward_signal_descriptor, NULL) == -1)
             {
               printf("Unable to setup signal forward in init. Aborting.\n");
               return 1;
@@ -153,7 +157,7 @@ int main(int argc, const char** argv)
           do {
             exited_child = wait(&child_status);
             err = errno;
-          } while (!(exited_child == first_child || (exited_child == -1 && err != EINTR)));
+          } while (!(exited_child == first_child || (exited_child == -1 && err == ECHILD)));
 
           if (exited_child == -1)
             {