[src/trunk]: src/lib/libpthread Avoid incompatible function pointer casts in ...

[kamil <kamil%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/b933de35a1e8
branches:  trunk
changeset: 456257:b933de35a1e8
user:      kamil <kamil%NetBSD.org@localhost>
date:      Mon Apr 29 20:11:43 2019 +0000

description:
Avoid incompatible function pointer casts in thrd_create(3)

Use an intermediate function trampoline to workaround different function
pointer prototypes.

While there, correct scenario returning thrd_nomem from thrd_create(3).
In practice ENOMEM is rarely returned from pthread(3).

Older code worked on tested ports, but was depending on unneeded UB.

diffstat:

 lib/libpthread/thrd.c |  49 +++++++++++++++++++++++++++++++++++++++++++------
 1 files changed, 43 insertions(+), 6 deletions(-)

diffs (82 lines):

diff -r ff4e7abcad9d -r b933de35a1e8 lib/libpthread/thrd.c
--- a/lib/libpthread/thrd.c     Mon Apr 29 19:08:11 2019 +0000
+++ b/lib/libpthread/thrd.c     Mon Apr 29 20:11:43 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: thrd.c,v 1.2 2019/04/24 18:47:54 kamil Exp $   */
+/*     $NetBSD: thrd.c,v 1.3 2019/04/29 20:11:43 kamil Exp $   */
 
 /*-
  * Copyright (c) 2016 The NetBSD Foundation, Inc.
@@ -30,30 +30,67 @@
  */
 
 #include <sys/cdefs.h>
-__RCSID("$NetBSD: thrd.c,v 1.2 2019/04/24 18:47:54 kamil Exp $");
+__RCSID("$NetBSD: thrd.c,v 1.3 2019/04/29 20:11:43 kamil Exp $");
 
 #include <assert.h>
 #include <errno.h>
 #include <pthread.h>
 #include <sched.h>
+#include <stdlib.h>
 #include <time.h>
 #include <threads.h>
 
+struct __thrd_tramp_data {
+       thrd_start_t func;
+       void *arg;
+};
+
+static void *
+__thrd_create_tramp(void *arg)
+{
+       struct __thrd_tramp_data *cookie;
+       int ret;
+
+       _DIAGASSERT(arg != NULL);
+
+       cookie = (struct __thrd_tramp_data *)arg;
+
+       ret = (cookie->func)(cookie->arg);
+
+       free(cookie);
+
+       return (void *)(intptr_t)ret;
+}
+
 int
 thrd_create(thrd_t *thr, thrd_start_t func, void *arg)
 {
+       struct __thrd_tramp_data *cookie;
+       int error;
 
        _DIAGASSERT(thr != NULL);
        _DIAGASSERT(func != NULL);
 
-       switch(pthread_create(thr, NULL, (void *(*)(void *))func, arg)) {
+       cookie = malloc(sizeof(*cookie));
+       if (cookie == NULL)
+               return thrd_nomem;
+
+       cookie->func = func;
+       cookie->arg = arg;
+
+       switch(pthread_create(thr, NULL, __thrd_create_tramp, cookie)) {
        case 0:
                return thrd_success;
-       case EAGAIN:
-               return thrd_nomem;
+       case ENOMEM:
+               error = thrd_nomem;
+               break;
        default:
-               return thrd_error;
+               error = thrd_error;
        }
+
+       free(cookie);
+
+       return error;
 }
 
 thrd_t