htl: Add support for libc cancellation points

htl/Makefile

@@ -132,6 +132,7 @@ libpthread-routines := pt-attr pt-attr-destroy pt-attr-getdetachstate	    \
 									    \
 	shm-directory							    \
 									    \
+	cancellation							    \
 	cthreads-compat							    \
 	herrno								    \
 	$(SYSDEPS)

htl/Versions

@@ -168,6 +168,8 @@ libpthread {
     __pthread_mutex_init;
     __pthread_mutex_destroy;
     __pthread_mutex_timedlock;
+    __pthread_enable_asynccancel;
+    __pthread_disable_asynccancel;
 
     _pthread_mutex_lock; _pthread_mutex_trylock; _pthread_mutex_unlock;
     _pthread_rwlock_destroy; _pthread_rwlock_init;

htl/cancellation.c

@@ -0,0 +1,45 @@
+/* Set the cancel type during blocking calls.
+   Copyright (C) 2020 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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <pthread.h>
+#include <pthreadP.h>
+#include <pt-internal.h>
+
+int __pthread_enable_asynccancel (void)
+{
+  struct __pthread *p = _pthread_self ();
+  int oldtype;
+
+  __pthread_mutex_lock (&p->cancel_lock);
+  oldtype = p->cancel_type;
+  p->cancel_type = PTHREAD_CANCEL_ASYNCHRONOUS;
+  __pthread_mutex_unlock (&p->cancel_lock);
+
+  __pthread_testcancel ();
+
+  return oldtype;
+}
+
+void __pthread_disable_asynccancel (int oldtype)
+{
+  struct __pthread *p = _pthread_self ();
+
+  __pthread_mutex_lock (&p->cancel_lock);
+  p->cancel_type = oldtype;
+  __pthread_mutex_unlock (&p->cancel_lock);
+}

htl/pt-testcancel.c

@@ -22,7 +22,7 @@
 #include <pthreadP.h>
 
 void
-pthread_testcancel (void)
+__pthread_testcancel (void)
 {
   struct __pthread *p = _pthread_self ();
   int cancelled;
@@ -34,3 +34,4 @@ pthread_testcancel (void)
   if (cancelled)
     __pthread_exit (PTHREAD_CANCELED);
 }
+strong_alias (__pthread_testcancel, pthread_testcancel)

sysdeps/htl/pthreadP.h

@@ -84,6 +84,7 @@ int __pthread_attr_setstacksize (pthread_attr_t *__attr, size_t __stacksize);
 int __pthread_attr_setstack (pthread_attr_t *__attr, void *__stackaddr,
 			     size_t __stacksize);
 int __pthread_attr_getstack (const pthread_attr_t *, void **, size_t *);
+void __pthread_testcancel (void);
 
 #if IS_IN (libpthread)
 hidden_proto (__pthread_key_create)

sysdeps/mach/hurd/sysdep-cancel.h

@@ -1,8 +1,24 @@
 #include <sysdep.h>
 
+int __pthread_enable_asynccancel (void);
+void __pthread_disable_asynccancel (int oldtype);
+
+#pragma weak __pthread_enable_asynccancel
+#pragma weak __pthread_disable_asynccancel
+
 /* Always multi-thread (since there's at least the sig handler), but no
    handling enabled.  */
 #define SINGLE_THREAD_P (0)
 #define RTLD_SINGLE_THREAD_P (0)
-#define LIBC_CANCEL_ASYNC()	0 /* Just a dummy value.  */
-#define LIBC_CANCEL_RESET(val)	((void)(val)) /* Nothing, but evaluate it.  */
+
+#define LIBC_CANCEL_ASYNC() ({ \
+	int __cancel_oldtype = 0; \
+	if (__pthread_enable_asynccancel) \
+		__cancel_oldtype = __pthread_enable_asynccancel(); \
+	__cancel_oldtype; \
+})
+
+#define LIBC_CANCEL_RESET(val) do { \
+	if (__pthread_disable_asynccancel) \
+		__pthread_disable_asynccancel (val); \
+} while (0)