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Re: Program-assigned thread names on Windows
On 23/07/2016 18:01, LRN wrote:
On 23.07.2016 19:39, John Baldwin wrote:
> On Saturday, July 23, 2016 12:25:15 PM LRN wrote:
>> The attached patch adds thread naming support on Windows.
Nice. A few comments below.
>>
>> This works as documented[1] on MSDN - by catching a specific
>> exception that the program throws.
>>
>> Setting thread name this way is supported by glib[2] and winpthreads[3]
>> at least, as well as any program developed with MS toolchain (because
>> WinDbg supported this for a long time).
>>
>> [1] https://msdn.microsoft.com/en-us/library/xcb2z8hs.aspx
>> [2] https://git.gnome.org/browse/glib/commit/glib
>> /gthread-win32.c?id=e118856430a798bbc529691ad235fd0b0684439d
>> [3] https://sourceforge.net/p/mingw-w64/mingw-w64/ci
>> /0d95c795b44b76e1b60dfc119fd93cfd0cb35816/
>
This is done by catching an exception number 0x406D1388
(it has no documented name), which is thrown by the program.
The name used in the MSDN article [1] is 'MS_VC_EXCEPTION', so why not
use that?
+ case WINDOWS_THREADNAME_EXCEPTION:
+ DEBUG_EXCEPTION_SIMPLE (WINDOWS_THREADNAME_EXCEPTION_S);
+ ourstatus->value.sig = GDB_SIGNAL_TRAP;
+ if (current_event.u.Exception.ExceptionRecord.NumberParameters == 4)
+ {
+ DWORD named_thread_id;
+ ptid_t named_thread_ptid;
+ struct thread_info *named_thread;
+ uintptr_t thread_name_target;
+ char *thread_name;
+
Shouldn't this check for ExceptionInformation[0] = 0x1000, and treat
this as an unknown exception otherwise?
+ named_thread_id = (DWORD) current_event.u.Exception.ExceptionRecord.ExceptionInformation[2];
+ thread_name_target = (uintptr_t) current_event.u.Exception.ExceptionRecord.ExceptionInformation[1];
Is this going to be correct for 64-bit builds?
+
+ if (named_thread_id == (DWORD) -1)
+ named_thread_id = current_event.dwThreadId;
+
+ named_thread_ptid = ptid_build (current_event.dwProcessId, 0, named_thread_id),
+ named_thread = find_thread_ptid (named_thread_ptid);
+
+ thread_name = NULL;
+ if (target_read_string ((CORE_ADDR) thread_name_target, &thread_name, 1024, 0))
Does thread_name end up not being null terminated if the thread name
length really exceeds 1024? (or is improperly not null terminated in the
target process...)
+ {
+ if (thread_name != NULL && thread_name[0] != '\0')
+ {
+ xfree (named_thread->name);
+ named_thread->name = thread_name;
+ }
+ else if (thread_name != NULL)
+ {
+ /* nothing to do */;
+ xfree (thread_name);
+ }
+ }
+ result = 2;
+ }
+ break;
default:
/* Treat unhandled first chance exceptions specially. */
if (current_event.u.Exception.dwFirstChance)
@@ -1153,7 +1194,7 @@ handle_exception (struct target_waitstatus *ourstatus)
}
exception_count++;
last_sig = ourstatus->value.sig;
- return 1;
+ return result;
}
/* Resume thread specified by ID, or all artificially suspended
@@ -1510,10 +1551,19 @@ get_windows_debug_event (struct target_ops *ops,
"EXCEPTION_DEBUG_EVENT"));
if (saw_create != 1)
break;
- if (handle_exception (ourstatus))
- thread_id = current_event.dwThreadId;
- else
- continue_status = DBG_EXCEPTION_NOT_HANDLED;
+ switch (handle_exception (ourstatus))
+ {
+ case 0:
+ default:
+ continue_status = DBG_EXCEPTION_NOT_HANDLED;
+ break;
+ case 1:
+ thread_id = current_event.dwThreadId;
+ break;
+ case 2:
+ continue_status = DBG_CONTINUE;
+ break;
+ }
break;
case OUTPUT_DEBUG_STRING_EVENT: /* Message from the kernel. */
-- 2.4.0