Re: [PATCH v3 1/7] Add target method for converting thread handle to thread_info struct pointer

Simon Marchi
2017-07-23T20:39:33Z

Hi Kevin,

Just some formatting stuff, otherwise the patch LGTM.

On 2017-07-19 02:54, Kevin Buettner wrote:
> This patch adds a target method named
> `to_thread_handle_to_thread_info'.
> It is intended to map a thread library specific thread handle (such as
> pthread_t for the pthread library) to the corresponding GDB internal
> thread_info struct (pointer).
>
> An implementation is provided for Linux pthreads; see
> linux-thread-db.c.
>
> gdb/ChangeLog:
>
> * target.h (struct target_ops): Add
> to_thread_handle_to_thread_info.
> (target_thread_handle_to_thread_info): Declare.
> * target.c (target_thread_handle_to_thread_info): New function.
> * target-delegates.c: Regenerate.
> * gdbthread.h (find_thread_by_handle): Declare.
> * thread.c (find_thread_by_handle): New function.
> * linux-thread-db.c (thread_db_thread_handle_to_thread_info): New
> function.
> (init_thread_db_ops): Register
> thread_db_thread_handle_to_thread_info.
> ---
> gdb/gdbthread.h | 4 ++++
> gdb/linux-thread-db.c | 31 +++++++++++++++++++++++++++++++
> gdb/target-delegates.c | 37 +++++++++++++++++++++++++++++++++++++
> gdb/target.c | 9 +++++++++
> gdb/target.h | 11 +++++++++++
> gdb/thread.c | 10 ++++++++++
> 6 files changed, 102 insertions(+)
>
> diff --git a/gdb/gdbthread.h b/gdb/gdbthread.h
> index 046bf95..c16a0d2 100644
> --- a/gdb/gdbthread.h
> +++ b/gdb/gdbthread.h
> @@ -448,6 +448,10 @@ extern struct thread_info *find_thread_ptid
> (ptid_t ptid);
> /* Find thread by GDB global thread ID. */
> struct thread_info *find_thread_global_id (int global_id);
>
> +/* Find thread by thread library specific handle in inferior INF. */
> +struct thread_info *find_thread_by_handle (struct value
> *thread_handle,
> + struct inferior *inf);
> +
> /* Finds the first thread of the inferior given by PID. If PID is -1,
> returns the first thread in the list. */
> struct thread_info *first_thread_of_process (int pid);
> diff --git a/gdb/linux-thread-db.c b/gdb/linux-thread-db.c
> index 86254f8..14dc5d2 100644
> --- a/gdb/linux-thread-db.c
> +++ b/gdb/linux-thread-db.c
> @@ -1410,6 +1410,36 @@ thread_db_extra_thread_info (struct target_ops
> *self,
> return NULL;
> }
>
> +/* Return pointer to the thread_info struct which corresponds to
> + THREAD_HANDLE (having length HANDLE_LEN). */

Please insert a newline between the comment and function (I know there
are tons of bad examples).

> +static struct thread_info *
> +thread_db_thread_handle_to_thread_info (struct target_ops *ops,
> + const gdb_byte *thread_handle,
> + int handle_len,
> + struct inferior *inf)
> +{
> + struct thread_info *tp;
> + thread_t handle_tid;
> +
> + /* Thread handle sizes must match in order to proceed. We don't use
> an
> + assert here because the resulting internal error will cause GDB
> to
> + exit. This isn't necessarily an internal error due to the
> possibility
> + of garbage being passed as the thread handle via the python
> interface. */
> + if (handle_len != sizeof (handle_tid))
> + error (_("Thread handle size mismatch: %d vs %d (from
> libthread_db)"),
> + handle_len, (int) sizeof (handle_tid));

You could use %zu for printing the sizeof. I just learned that the z
length modifier is standard in C++11, so we might as well use it.

> +
> + handle_tid = * (const thread_t *) thread_handle;
> +
> + ALL_NON_EXITED_THREADS (tp)
> + {
> + if (tp->inf == inf && tp->priv != NULL && handle_tid ==
> tp->priv->tid)
> + return tp;
> + }
> +
> + return NULL;
> +}
> +
> /* Get the address of the thread local variable in load module LM
> which
> is stored at OFFSET within the thread local storage for thread
> PTID. */
>
> @@ -1687,6 +1717,7 @@ init_thread_db_ops (void)
> = thread_db_get_thread_local_address;
> thread_db_ops.to_extra_thread_info = thread_db_extra_thread_info;
> thread_db_ops.to_get_ada_task_ptid = thread_db_get_ada_task_ptid;
> + thread_db_ops.to_thread_handle_to_thread_info =
> thread_db_thread_handle_to_thread_info;
> thread_db_ops.to_magic = OPS_MAGIC;
>
> complete_target_initialization (&thread_db_ops);
> diff --git a/gdb/target-delegates.c b/gdb/target-delegates.c
> index 88e3e0b..dea1d9f 100644
> --- a/gdb/target-delegates.c
> +++ b/gdb/target-delegates.c
> @@ -1583,6 +1583,39 @@ debug_thread_name (struct target_ops *self,
> struct thread_info *arg1)
> return result;
> }
>
> +static struct thread_info *
> +delegate_thread_handle_to_thread_info (struct target_ops *self, const
> gdb_byte *arg1, int arg2, struct inferior *arg3)
> +{
> + self = self->beneath;
> + return self->to_thread_handle_to_thread_info (self, arg1, arg2,
> arg3);
> +}
> +
> +static struct thread_info *
> +tdefault_thread_handle_to_thread_info (struct target_ops *self, const
> gdb_byte *arg1, int arg2, struct inferior *arg3)
> +{
> + return NULL;
> +}
> +
> +static struct thread_info *
> +debug_thread_handle_to_thread_info (struct target_ops *self, const
> gdb_byte *arg1, int arg2, struct inferior *arg3)
> +{
> + struct thread_info * result;
> + fprintf_unfiltered (gdb_stdlog, "->
> %s->to_thread_handle_to_thread_info (...)\n",
> debug_target.to_shortname);
> + result = debug_target.to_thread_handle_to_thread_info
> (&debug_target, arg1, arg2, arg3);
> + fprintf_unfiltered (gdb_stdlog, "<-
> %s->to_thread_handle_to_thread_info (", debug_target.to_shortname);
> + target_debug_print_struct_target_ops_p (&debug_target);
> + fputs_unfiltered (", ", gdb_stdlog);
> + target_debug_print_const_gdb_byte_p (arg1);
> + fputs_unfiltered (", ", gdb_stdlog);
> + target_debug_print_int (arg2);
> + fputs_unfiltered (", ", gdb_stdlog);
> + target_debug_print_struct_inferior_p (arg3);
> + fputs_unfiltered (") = ", gdb_stdlog);
> + target_debug_print_struct_thread_info_p (result);
> + fputs_unfiltered ("\n", gdb_stdlog);
> + return result;
> +}
> +
> static void
> delegate_stop (struct target_ops *self, ptid_t arg1)
> {
> @@ -4267,6 +4300,8 @@ install_delegators (struct target_ops *ops)
> ops->to_extra_thread_info = delegate_extra_thread_info;
> if (ops->to_thread_name == NULL)
> ops->to_thread_name = delegate_thread_name;
> + if (ops->to_thread_handle_to_thread_info == NULL)
> + ops->to_thread_handle_to_thread_info =
> delegate_thread_handle_to_thread_info;
> if (ops->to_stop == NULL)
> ops->to_stop = delegate_stop;
> if (ops->to_interrupt == NULL)
> @@ -4522,6 +4557,7 @@ install_dummy_methods (struct target_ops *ops)
> ops->to_pid_to_str = default_pid_to_str;
> ops->to_extra_thread_info = tdefault_extra_thread_info;
> ops->to_thread_name = tdefault_thread_name;
> + ops->to_thread_handle_to_thread_info =
> tdefault_thread_handle_to_thread_info;
> ops->to_stop = tdefault_stop;
> ops->to_interrupt = tdefault_interrupt;
> ops->to_pass_ctrlc = default_target_pass_ctrlc;
> @@ -4681,6 +4717,7 @@ init_debug_target (struct target_ops *ops)
> ops->to_pid_to_str = debug_pid_to_str;
> ops->to_extra_thread_info = debug_extra_thread_info;
> ops->to_thread_name = debug_thread_name;
> + ops->to_thread_handle_to_thread_info =
> debug_thread_handle_to_thread_info;
> ops->to_stop = debug_stop;
> ops->to_interrupt = debug_interrupt;
> ops->to_pass_ctrlc = debug_pass_ctrlc;
> diff --git a/gdb/target.c b/gdb/target.c
> index e526bcc..23f4b9f 100644
> --- a/gdb/target.c
> +++ b/gdb/target.c
> @@ -2315,6 +2315,15 @@ target_thread_name (struct thread_info *info)
> return current_target.to_thread_name (&current_target, info);
> }
>
> +struct thread_info *
> +target_thread_handle_to_thread_info (const gdb_byte * thread_handle,

No space after *.

> + int handle_len,
> + struct inferior *inf)
> +{
> + return current_target.to_thread_handle_to_thread_info
> + (&current_target, thread_handle, handle_len, inf);
> +}
> +
> void
> target_resume (ptid_t ptid, int step, enum gdb_signal signal)
> {
> diff --git a/gdb/target.h b/gdb/target.h
> index c0155c1..1bb8c0f 100644
> --- a/gdb/target.h
> +++ b/gdb/target.h
> @@ -646,6 +646,11 @@ struct target_ops
> TARGET_DEFAULT_RETURN (NULL);
> const char *(*to_thread_name) (struct target_ops *, struct
> thread_info *)
> TARGET_DEFAULT_RETURN (NULL);
> + struct thread_info *(*to_thread_handle_to_thread_info) (struct
> target_ops *,
> + const
> gdb_byte *,
> + int,
> + struct inferior *inf)
> + TARGET_DEFAULT_RETURN (NULL);
> void (*to_stop) (struct target_ops *, ptid_t)
> TARGET_DEFAULT_IGNORE ();
> void (*to_interrupt) (struct target_ops *, ptid_t)
> @@ -1857,6 +1862,12 @@ extern const char *normal_pid_to_str (ptid_t
> ptid);
>
> extern const char *target_thread_name (struct thread_info *);
>
> +/* Given a pointer to a thread library specific thread handle and
> + its length, return a pointer to the corresponding thread_info
> struct. */
> +
> +extern struct thread_info *target_thread_handle_to_thread_info
> + (const gdb_byte * thread_handle, int handle_len, struct inferior *);

No space after *. Could you name the last parameter as well?

> +
> /* Attempts to find the pathname of the executable file
> that was run to create a specified process.
>
> diff --git a/gdb/thread.c b/gdb/thread.c
> index 3cf1b94..456b1ad 100644
> --- a/gdb/thread.c
> +++ b/gdb/thread.c
> @@ -534,6 +534,16 @@ find_thread_ptid (ptid_t ptid)
> return NULL;
> }
>
> +/* Find a thread_info by matching thread libary specific handle. */

That comment should only refer to the header, which already contains a
comment for that function.

/* See gdbthread.h. */

Also, newline after the comment.

> +struct thread_info *
> +find_thread_by_handle (struct value *thread_handle, struct inferior
> *inf)
> +{
> + return target_thread_handle_to_thread_info
> + (value_contents_all (thread_handle),
> + TYPE_LENGTH (value_type (thread_handle)),
> + inf);

Those last two lines should be intended with one more space (aligned
with value_contents_all).

> +}
> +
> /*
> * Thread iterator function.
> *

Thanks!

Simon