libplatform-254.40.4.tar.gz

[apple/libplatform.git] / src / ucontext / generic / swapcontext.c

diff --git a/src/ucontext/generic/swapcontext.c b/src/ucontext/generic/swapcontext.c
index 21957004095cd6d084901a632964fd96da67dced..6750b5d757559b81578af74d7f3a8afbdc9b1f39 100644 (file)
--- a/src/ucontext/generic/swapcontext.c
+++ b/src/ucontext/generic/swapcontext.c
@@ -2,14 +2,14 @@
  * Copyright (c) 2007, 2009 Apple Inc. All rights reserved.
  *
  * @APPLE_LICENSE_HEADER_START@
- * 
+ *
  * This file contains Original Code and/or Modifications of Original Code
  * as defined in and that are subject to the Apple Public Source License
  * Version 2.0 (the 'License'). You may not use this file except in
  * compliance with the License. Please obtain a copy of the License at
  * http://www.opensource.apple.com/apsl/ and read it before using this
  * file.
- * 
+ *
  * The Original Code and all software distributed under the License are
  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
@@ -17,7 +17,7 @@
  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  * Please see the License for the specific language governing rights and
  * limitations under the License.
- * 
+ *
  * @APPLE_LICENSE_HEADER_END@
  */
 
@@ -50,8 +50,15 @@
 #define _XOPEN_SOURCE 600L
 #include <ucontext.h>
 #include <errno.h>
+#include <TargetConditionals.h>
+
+/* This is a macro to capture all the code added in here that is purely to make
+ * conformance tests pass and seems to have no functional reason nor is it
+ * required by the standard */
+#define CONFORMANCE_SPECIFIC_HACK 1
+
+#if TARGET_OS_OSX || TARGET_OS_DRIVERKIT
 
-#if defined(__x86_64__) || defined(__i386__)
 #pragma clang diagnostic ignored "-Wdeprecated-declarations"
 
 #include <sys/param.h>
@@ -65,22 +72,34 @@ int
 swapcontext(ucontext_t *oucp, const ucontext_t *ucp)
 {
        int ret;
-
        if ((oucp == NULL) || (ucp == NULL)) {
                errno = EINVAL;
-               return (-1);
+               return -1;
        }
+
        oucp->uc_flags &= ~UCF_SWAPPED;
+
+#if CONFORMANCE_SPECIFIC_HACK
+       // getcontext overwrites uc_link so we save it and restore it
+       ucontext_t *next_context = oucp->uc_link;
        ret = getcontext(oucp);
+       oucp->uc_link = next_context;
+#endif
+
        if ((ret == 0) && !(oucp->uc_flags & UCF_SWAPPED)) {
                oucp->uc_flags |= UCF_SWAPPED;
+               /* In the future, when someone calls setcontext(oucp), that will return
+                * us to the getcontext call above with ret = 0. However, because we
+                * just flipped the UCF_SWAPPED bit, we will not call setcontext again
+                * and will return. */
                ret = setcontext(ucp);
        }
+
        asm(""); // Prevent tailcall <rdar://problem/12581792>
        return (ret);
 }
 
-#else
+#else /* TARGET_OS_OSX || TARGET_OS_DRIVERKIT */
 
 int
 swapcontext(ucontext_t *oucp, const ucontext_t *ucp)
@@ -89,4 +108,4 @@ swapcontext(ucontext_t *oucp, const ucontext_t *ucp)
        return -1;
 }
 
-#endif
+#endif /* TARGET_OS_OSX || TARGET_OS_DRIVERKIT */