From a17516f5b6bdbcb0a88345961fd3917346fab184 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Mon, 9 Nov 2020 09:23:06 -0700
Subject: [PATCH] rktio: repair for subprocesses on Unix witthout threads

A list of pending process records was not managed correctly when
interest in a subprocess is abandoned before the subprocess completes.
---
 .../tests/racket/subprocess.rktl              | 15 ++++++++++++++
 racket/src/rktio/rktio_process.c              | 20 +++++++++++++++----
 2 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/pkgs/racket-test-core/tests/racket/subprocess.rktl b/pkgs/racket-test-core/tests/racket/subprocess.rktl
index e73347cf8f..0d399c87b7 100644
--- a/pkgs/racket-test-core/tests/racket/subprocess.rktl
+++ b/pkgs/racket-test-core/tests/racket/subprocess.rktl
@@ -662,6 +662,21 @@
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
+;; Check for cleaning up a subprocess without waiting for it to complete:
+(for ([j 10])
+  (for-each
+   (lambda (f) (f))
+   (for/list ([i 10])
+     (define-values (sp o i e) (subprocess #f #f #f cat))
+     (subprocess-kill sp 'kill)
+     (lambda ()
+       (close-output-port i)
+       (close-input-port o)
+       (close-input-port e))))
+  (collect-garbage))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
 (for ([f (list tmpfile tmpfile2)] #:when (file-exists? f)) (delete-file f))
 
 
diff --git a/racket/src/rktio/rktio_process.c b/racket/src/rktio/rktio_process.c
index 5820f6554c..be17d7aa2a 100644
--- a/racket/src/rktio/rktio_process.c
+++ b/racket/src/rktio/rktio_process.c
@@ -602,7 +602,6 @@ static void init_sigchld(rktio_t *rktio)
 #endif
 }
 
-#if !defined(CENTRALIZED_SIGCHILD)
 static void remove_from_sigchld_chain(rktio_t *rktio)
 {
   if (rktio->in_sigchld_chain) {
@@ -620,7 +619,6 @@ static void remove_from_sigchld_chain(rktio_t *rktio)
     }
   }
 }
-#endif
 
 static void check_child_done(rktio_t *rktio, pid_t pid)
 {
@@ -948,14 +946,25 @@ void rktio_process_forget(rktio_t *rktio, rktio_process_t *sp)
     centralized_ended_child();
   }
 # else
-  if (!((System_Child *)sp->handle)->done) {
+  System_Child *sc = (System_Child *)sp->handle, *sc2, *prev;
+  if (!sc->done) {
     void **unused_pid;
     unused_pid = malloc(sizeof(void *) * 2);
     unused_pid[0] = (void *)(intptr_t)sp->pid;
     unused_pid[1] = unused_pids;
     rktio->need_to_check_children = 1;
+
+    prev = NULL;
+    for (sc2 = rktio->system_children; sc2; prev = sc2, sc2 = sc2->next) {
+      if (sc2 == sc) {
+        if (prev)
+          prev->next = sc->next;
+        else
+          rktio->system_children = sc->next;
+      }
+    }
   }
-  free(sp->handle);
+  free(sc);
 # endif
 #endif
 
@@ -1457,6 +1466,9 @@ rktio_process_result_t *rktio_process(rktio_t *rktio,
       if (env)
         free(env);
       free(new_argv);
+#if !defined(CENTRALIZED_SIGCHILD)
+      free(sc);
+#endif
 
       return NULL;