Re: [RFC] Fixing pthread_* namespace issues for thrd_* symbols

[Juan Manuel Torres Palma <j dot m dot torrespalma at gmail dot com>]

Sorry for late reply.

My solution so far is this one, only for x86, will work on other
architectures as long as this strategy is acceptable. What I have
mainly done is copy pthread_mutex_t and pthread_cond_t renaming them,
so I won't be breaking any ABI and namespaces will be clean. Let me
know if it's acceptable.

Cheers.

--------------------------------------------------------------------------------------------------------------------------------------------

>From 73f2aee3c1fc299c73607d23a49d75fefc72ad75 Mon Sep 17 00:00:00 2001
From: Juan Manuel Torres Palma <jmtorrespalma@gmail.com>
Date: Thu, 18 Jun 2015 09:48:19 +0200
Subject: [PATCH] New threads.h types

---
 nptl/Makefile                   |   3 +-
 sysdeps/x86/bits/threadstypes.h | 116 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 118 insertions(+), 1 deletion(-)
 create mode 100644 sysdeps/x86/bits/threadstypes.h

diff --git a/nptl/Makefile b/nptl/Makefile
index 530d14b..1527134 100644
--- a/nptl/Makefile
+++ b/nptl/Makefile
@@ -22,7 +22,8 @@ subdir := nptl

 include ../Makeconfig

-headers := pthread.h semaphore.h bits/semaphore.h
+headers := pthread.h semaphore.h bits/semaphore.h \
+   bits/threadstypes.h

 extra-libs := libpthread
 extra-libs-others := $(extra-libs)
diff --git a/sysdeps/x86/bits/threadstypes.h b/sysdeps/x86/bits/threadstypes.h
new file mode 100644
index 0000000..6a7a68a
--- /dev/null
+++ b/sysdeps/x86/bits/threadstypes.h
@@ -0,0 +1,116 @@
+/* Copyright (C) 2002-2015 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _BITS_THREADSTYPES_H
+#define _BITS_THREADSTYPES_H 1
+
+#include <bits/wordsize.h>
+
+
+#ifdef __x86_64__
+# if __WORDSIZE == 64
+#  define __SIZEOF_MTX_T 40
+#  define __SIZEOF_CND_T 48
+# else
+#  define __SIZEOF_MTX_T 32
+#  define __SIZEOF_CND_T 48
+# endif
+#else
+# define __SIZEOF_MTX_T 24
+# define __SIZEOF_CND_T 48
+#endif
+
+
+#ifdef __x86_64__
+typedef struct __pthread_internal_list
+{
+  struct __pthread_internal_list *__prev;
+  struct __pthread_internal_list *__next;
+} __pthread_list_t;
+#else
+typedef struct __pthread_internal_slist
+{
+  struct __pthread_internal_slist *__next;
+} __pthread_slist_t;
+#endif
+
+
+/* Data structure for C11 mtx_t. It's a copy of pthread_mutex_t to
+   make both types compatible*/
+
+typedef union
+{
+  struct __pthread_mutex_s
+  {
+    int __lock;
+    unsigned int __count;
+    int __owner;
+#ifdef __x86_64__
+    unsigned int __nusers;
+#endif
+    /* KIND must stay at this position in the structure to maintain
+       binary compatibility.  */
+    int __kind;
+#ifdef __x86_64__
+    short __spins;
+    short __elision;
+    __pthread_list_t __list;
+# define __PTHREAD_MUTEX_HAVE_PREV 1
+/* Mutex __spins initializer used by PTHREAD_MUTEX_INITIALIZER.  */
+# define __PTHREAD_SPINS             0, 0
+#else
+    unsigned int __nusers;
+    __extension__ union
+    {
+      struct
+      {
+ short __espins;
+ short __elision;
+# define __spins __elision_data.__espins
+# define __elision __elision_data.__elision
+# define __PTHREAD_SPINS         { 0, 0 }
+      } __elision_data;
+      __pthread_slist_t __list;
+    };
+#endif
+  } __data;
+  char __size[__SIZEOF_MTX_T];
+  long int __align;
+} pthread_mutex_t;
+
+
+/* Data structure for C11 cnd_t. A copy of pthread_cond_t
+   to make them compatible.  */
+
+typedef union
+{
+  struct
+  {
+    int __lock;
+    unsigned int __futex;
+    __extension__ unsigned long long int __total_seq;
+    __extension__ unsigned long long int __wakeup_seq;
+    __extension__ unsigned long long int __woken_seq;
+    void *__mutex;
+    unsigned int __nwaiters;
+    unsigned int __broadcast_seq;
+  } __data;
+  char __size[__SIZEOF_CND_T];
+  __extension__ long long int __align;
+} cnd_t;
+
+#endif /* bits/threadstypes.h */
-- 
2.1.0

2015-05-01 15:10 GMT+02:00 Szabolcs Nagy <nsz@port70.net>:
> * Juan Manuel Torres Palma <j.m.torrespalma@gmail.com> [2015-05-01 13:49:44 +0200]:
>> > how do you plan to solve the namespace issue for the pthread types?
>>
>> Most pthread types (some of them will be required for C11 types) are
>> architecture dependent, so my plan was to create a new header file
>> (keeping all the architecture dependent defines and types here)
>> including definitions of types like __pthread_t.
>>
>> Then the pthread.h will include it and do:
>> typedef __pthread_mutex_t pthread__mutex_t;
>>
>
> that will break the c++ abi of pthreads
>
> (we had the same problem back when c11 threads were implemented
> in musl libc and ended up duplicating the typedefs i think..
> you may want to look at the discussions on the musl list around
> the alternatives
>
> i think the type duplication within the implementation is ok,
> but not pedantically correct on the abstract c language level:
> wrappers redeclare the __pthread* functions with incompatible
> types to be able to pass c11 type pointers
>
> for future reference: all types in libc api should have type tag
> in the implementation reserved namespace (ie __ prefixed) to
> allow fixes like c11 threads later despite the hideous c++ abi)
>
>> For other types like pthread_t that basically are unsigned long, will
>> just copy the type:
>> typedef unsigned long thrd_t;
>>
>> Cheers.
>>
>> --
>> Juan Manuel Torres Palma.
>> Computer Science Student at Universidad de Granada.



-- 
Juan Manuel Torres Palma.
Computer Science Student at Universidad de Granada.