Fix sigint handling when running in helper mode

cli_helper/kart.c

@@ -209,18 +209,14 @@ void exit_on_sigalrm(int sig)
     exit(exit_code);
 }
 
-char *socket_filename;
-
 /**
- * @brief Exit signal handler for SIGINT
+ * @brief Exit signal handler for SIGINT.
+ * Tries to kill the whole process group.
  */
 void exit_on_sigint(int sig)
 {
     putchar('\n');
-    const char* kill_cmd_template = "lsof -t '%s' | xargs kill";
-    char* kill_cmd = malloc(strlen(kill_cmd_template) + strlen(socket_filename) + 2);
-    sprintf(kill_cmd, kill_cmd_template, socket_filename);
-    system(kill_cmd);
+    killpg(0, sig);
     exit(128 + sig);
 }
 
@@ -236,6 +232,10 @@ int main(int argc, char **argv, char **environ)
     {
         debug("enabled %s, pid=%d\n", cmd_path, getpid());
 
+        // Make this process the leader of a process group:
+        // The procress-group ID (pgid) will be the same as the pid.
+        setpgrp();
+
         // start or use an existing helper process
         char **env_ptr;
 
@@ -282,7 +282,7 @@ int main(int argc, char **argv, char **environ)
         int fp = open(getcwd(NULL, 0), O_RDONLY);
         int fds[4] = {fileno(stdin), fileno(stdout), fileno(stderr), fp};
 
-        socket_filename = malloc(strlen(getenv("HOME")) + strlen(".kart.socket") + 2);
+        char *socket_filename = malloc(strlen(getenv("HOME")) + strlen(".kart.socket") + 2);
         sprintf(socket_filename, "%s/%s", getenv("HOME"), ".kart.socket");
         int socket_fd = socket(AF_UNIX, SOCK_STREAM, 0);
 

kart/__init__.py

@@ -200,7 +200,7 @@ def _cleanup_process_group(signum, stack_frame):
                 return
             _kart_process_group_killed = True
             try:
-                os.killpg(os.getpid(), signum)
+                os.killpg(0, signum)
             except Exception:
                 pass
             sys.exit(128 + signum)

kart/helper.py

@@ -133,6 +133,7 @@ def helper(ctx, socket_filename, timeout, args):
             else:
                 # child
                 _helper_log("post-fork")
+
                 payload, fds = recv_json_and_fds(client, maxfds=4)
                 if not payload or len(fds) != 4:
                     click.echo(
@@ -169,6 +170,16 @@ def helper(ctx, socket_filename, timeout, args):
                         f"Payload:\n{repr(payload)}",
                     )
                 else:
+                    try:
+                        # Join the process group of the calling process - so that if they get killed, we get killed to.
+                        os.setpgid(0, calling_environment["pid"])
+                        os.environ["_KART_PGID_SET"] = "1"
+                    except Exception as e:
+                        # Kart will still work even if this fails: it just means SIGINT Ctrl+C might not work properly.
+                        # We'll just log it and hope for the best.
+                        _helper_log(f"error joining caller's process group: {e}")
+                        pass
+
                     sys.argv[1:] = calling_environment["argv"][1:]
                     _helper_log(f"cmd={' '.join(calling_environment['argv'])}")
                     os.environ.clear()