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

Kevin Buettner
2017-07-19T00:54:35Z

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). */
+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));
+
+ 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,
+ 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 *);
+
/* 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. */
+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);
+}
+
/*
* Thread iterator function.
*