nptl: Add __pthread_attr_copy for copying pthread_attr_t objects

Also add the private type union pthread_attr_transparent, to reduce
the amount of casting that is required.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>

4 files changed, 65 insertions, 0 deletions

diff --git a/nptl/Makefile b/nptl/Makefile
index 0dd8800f19..b4aaad0f20 100644
--- a/nptl/Makefile
+++ b/nptl/Makefile
@@ -39,6 +39,7 @@ routines = \
   old_pthread_cond_destroy \
   old_pthread_cond_init \
   pthread_atfork \
+  pthread_attr_copy \
   pthread_attr_destroy \
   pthread_attr_getdetachstate \
   pthread_attr_getinheritsched \
diff --git a/nptl/Versions b/nptl/Versions
index 65f0c077da..4c7b43354d 100644
--- a/nptl/Versions
+++ b/nptl/Versions
@@ -60,6 +60,7 @@ libc {
     __pthread_cond_destroy; __pthread_cond_init;
     __pthread_attr_setaffinity_np;
     __pthread_attr_init; __pthread_attr_destroy;
+    __pthread_attr_copy;
   }
 }
 
diff --git a/nptl/pthreadP.h b/nptl/pthreadP.h
index f218b01574..41b693d034 100644
--- a/nptl/pthreadP.h
+++ b/nptl/pthreadP.h
@@ -580,6 +580,12 @@ extern void __wait_lookup_done (void) attribute_hidden;
 # define PTHREAD_STATIC_FN_REQUIRE(name) __asm (".globl " #name);
 #endif
 
+/* Make a deep copy of the attribute *SOURCE in *TARGET.  *TARGET is
+   not assumed to have been initialized.  Returns 0 on success, or a
+   positive error code otherwise.  */
+int __pthread_attr_copy (pthread_attr_t *target, const pthread_attr_t *source);
+libc_hidden_proto (__pthread_attr_copy)
+
 /* Returns 0 if POL is a valid scheduling policy.  */
 static inline int
 check_sched_policy_attr (int pol)
diff --git a/nptl/pthread_attr_copy.c b/nptl/pthread_attr_copy.c
new file mode 100644
index 0000000000..77a1a43eeb
--- /dev/null
+++ b/nptl/pthread_attr_copy.c
@@ -0,0 +1,57 @@
+/* Deep copy of a pthread_attr_t object.
+   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 <errno.h>
+#include <pthreadP.h>
+#include <stdlib.h>
+
+int
+__pthread_attr_copy (pthread_attr_t *target, const pthread_attr_t *source)
+{
+  /* Avoid overwriting *TARGET until all allocations have
+     succeeded.  */
+  union pthread_attr_transparent temp;
+  temp.external = *source;
+
+  /* Force new allocation.  This function has full ownership of temp.  */
+  temp.internal.cpuset = NULL;
+  temp.internal.cpusetsize = 0;
+
+  int ret = 0;
+
+  struct pthread_attr *isource = (struct pthread_attr *) source;
+
+  /* Propagate affinity mask information.  */
+  if (isource->cpusetsize > 0)
+    ret = __pthread_attr_setaffinity_np (&temp.external,
+                                         isource->cpusetsize,
+                                         isource->cpuset);
+
+  if (ret != 0)
+    {
+      /* Deallocate because we have ownership.  */
+      __pthread_attr_destroy (&temp.external);
+      return ret;
+    }
+
+  /* Transfer ownership.  *target is not assumed to have been
+     initialized.  */
+  *target = temp.external;
+  return 0;
+}
+libc_hidden_def (__pthread_attr_copy)