[07/19] 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.
---
 nptl/Makefile                |  1 +
 nptl/Versions                |  1 +
 nptl/pthreadP.h              |  6 ++++
 nptl/pthread_attr_copy.c     | 57 ++++++++++++++++++++++++++++++++++++
 sysdeps/nptl/internaltypes.h |  7 +++++
 5 files changed, 72 insertions(+)
 create mode 100644 nptl/pthread_attr_copy.c
  

On 5/19/20 6:44 AM, Florian Weimer via Libc-alpha wrote:
> Also add the private type union pthread_attr_transparent, to reduce
> the amount of casting that is required.

OK for master.

Tested clean on x86_64 and i686.

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

> ---
>  nptl/Makefile                |  1 +
>  nptl/Versions                |  1 +
>  nptl/pthreadP.h              |  6 ++++
>  nptl/pthread_attr_copy.c     | 57 ++++++++++++++++++++++++++++++++++++
>  sysdeps/nptl/internaltypes.h |  7 +++++
>  5 files changed, 72 insertions(+)
>  create mode 100644 nptl/pthread_attr_copy.c
> 
> 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 \

OK

>    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;

OK.

>    }
>  }
>  
> 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)

OK.

> +
>  /* 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.  */

OK. At this point we copy pointers and we no longer own the memory
that was allocated at the extension pointer.

> +  *target = temp.external;
> +  return 0;
> +}
> +libc_hidden_def (__pthread_attr_copy)
> diff --git a/sysdeps/nptl/internaltypes.h b/sysdeps/nptl/internaltypes.h
> index 71f09b4624..6d06a76baf 100644
> --- a/sysdeps/nptl/internaltypes.h
> +++ b/sysdeps/nptl/internaltypes.h
> @@ -49,6 +49,13 @@ struct pthread_attr
>  #define ATTR_FLAG_SCHED_SET		0x0020
>  #define ATTR_FLAG_POLICY_SET		0x0040
>  
> +/* Used to allocate a pthread_attr_t object which is also accessed
> +   internally.  */
> +union pthread_attr_transparent
> +{
> +  pthread_attr_t external;
> +  struct pthread_attr internal;
> +};

OK.

>  
>  /* Mutex attribute data structure.  */
>  struct pthread_mutexattr
>