Re: [PATCH] Implement nbsd_nat_target::thread_alive

[John Baldwin <jhb@FreeBSD.org>]

On 3/25/20 12:36 PM, Kamil Rytarowski wrote:
> gdb/ChangeLog:
> 
> 	* nbsd-nat.h (nbsd_nat_target::thread_alive): Add.
> 	* nbsd-nat.c (nbsd_nat_target::thread_alive): Add.
> ---
>  gdb/ChangeLog  |  5 +++++
>  gdb/nbsd-nat.c | 30 ++++++++++++++++++++++++++++++
>  gdb/nbsd-nat.h |  1 +
>  3 files changed, 36 insertions(+)
> 
> diff --git a/gdb/ChangeLog b/gdb/ChangeLog
> index 1ee58a541cb..d6789f4d7ca 100644
> --- a/gdb/ChangeLog
> +++ b/gdb/ChangeLog
> @@ -1,3 +1,8 @@
> +2020-03-25  Kamil Rytarowski  <n54@gmx.com>
> +
> +	* nbsd-nat.h (nbsd_nat_target::thread_alive): Add.
> +	* nbsd-nat.c (nbsd_nat_target::thread_alive): Add.
> +
>  2020-03-25  Tom Tromey  <tom@tromey.com>
> 
>  	* compile/compile-object-load.c (get_out_value_type): Mention
> diff --git a/gdb/nbsd-nat.c b/gdb/nbsd-nat.c
> index 326bbe3aec3..aa0353309df 100644
> --- a/gdb/nbsd-nat.c
> +++ b/gdb/nbsd-nat.c
> @@ -39,3 +39,33 @@ nbsd_nat_target::pid_to_exec_file (int pid)
>      return NULL;
>    return buf;
>  }
> +
> +bool
> +thread_alive (ptid_t ptid)
> +{
> +  pid_t pid = ptid.pid ();
> +  int lwp = ptid.lwp ();
> +  int mib[5] = {CTL_KERN, KERN_LWP, pid, sizeof (struct kinfo_lwp), 0};
> +  size_t size;
> +
> +  if (sysctl (mib, 5, NULL, &size, NULL, 0) == -1 || size == 0)
> +    perror_with_name (("sysctl"));
> +
> +  mib[4] = size / sizeof (size_t);
> +
> +  gdb::unique_xmalloc_ptr<struct kinfo_lwp> kl
> +    ((struct kinfo_lwp *) xcalloc (size, 1));
> +  if (kl == NULL)
> +    perror_with_name (("calloc"));
> +
> +  if (sysctl (mib, 5, kl.get (), &size, NULL, 0) == -1 || size == 0)
> +    perror_with_name (("sysctl"));
> +
> +  for (size_t i = 0; i < size / sizeof (struct kinfo_lwp); i++)
> +    {
> +      if (kl.get ()[i].l_lid == lwp)
> +	 return true;
> +    }
> +
> +  return false;

Given that you have nearly identical code both here and in the thread_name
method in your other patch, perhaps it makes sense to have a single
"gdb::unique_xmalloc_ptr <struct kinfo_lwp> fetch_kinfo_lwp(ptid_t ptid)"
helper function that the other routines could share?  Perhaps instead of
just returning the pointer to the array of structures it could take a lamda
function that is invoked on the matching 'kl' instance with the correct lwp?

-- 
John Baldwin