Add thread_set_name RPC.

Like task_set_name, we use the same size as the task name and will
inherit the task name, whenever it exists. This will be used to
implement pthread_setname_np.
Message-ID: <20240212062634.1082207-2-flaviocruz@gmail.com>

4 files changed, 41 insertions, 4 deletions

diff --git a/ddb/db_print.c b/ddb/db_print.c
index c8d85d26..f08dd6ce 100644
--- a/ddb/db_print.c
+++ b/ddb/db_print.c
@@ -222,10 +222,11 @@ db_print_thread(
 	    }
 	} else {
 	    if (flag & OPTION_INDENT)
-		db_printf("            %3d (%0*X) ", thread_id,
-			  2*sizeof(vm_offset_t), thread);
-	    else
-		db_printf("(%0*X) ", 2*sizeof(vm_offset_t), thread);
+		db_printf("            %3d ", thread_id);
+	    if (thread->name[0] &&
+		strncmp (thread->name, thread->task->name, THREAD_NAME_SIZE))
+		db_printf("%s ", thread->name);
+	    db_printf("(%0*X) ", 2*sizeof(vm_offset_t), thread);
 	    char status[8];
 	    db_printf("%s", db_thread_stat(thread, status));
 	    if (thread->state & TH_SWAPPED) {
diff --git a/include/mach/gnumach.defs b/include/mach/gnumach.defs
index 6252de96..7ecf74d3 100644
--- a/include/mach/gnumach.defs
+++ b/include/mach/gnumach.defs
@@ -207,3 +207,11 @@ routine vm_pages_phys(
 		vaddr		: vm_address_t;
 		size		: vm_size_t;
 	out	pages		: rpc_phys_addr_array_t);
+
+/*
+ *	Set the name of thread THREAD to NAME.  This is a debugging aid.
+ *	NAME will be used in error messages printed by the kernel.
+ */
+simpleroutine thread_set_name(
+		thread	: thread_t;
+		name	: kernel_debug_name_t);
diff --git a/kern/thread.c b/kern/thread.c
index 23ee8b09..2eab1ca4 100644
--- a/kern/thread.c
+++ b/kern/thread.c
@@ -46,6 +46,7 @@
 #include <kern/counters.h>
 #include <kern/debug.h>
 #include <kern/eventcount.h>
+#include <kern/gnumach.server.h>
 #include <kern/ipc_mig.h>
 #include <kern/ipc_tt.h>
 #include <kern/mach_debug.server.h>
@@ -551,6 +552,10 @@ kern_return_t thread_create(
 #endif	/* MACH_PCSAMPLE */
 
 	new_thread->pc_sample.buffer = 0;
+
+	/* Inherit the task name as the thread name. */
+	memcpy (new_thread->name, parent_task->name, THREAD_NAME_SIZE);
+
 	/*
 	 *	Add the thread to the task`s list of threads.
 	 *	The new thread holds another reference to the task.
@@ -2624,3 +2629,18 @@ thread_stats(void)
 	printf("%d using rpc_reply.\n", rpcreply);
 }
 #endif	/* MACH_DEBUG */
+
+/*
+ *	thread_set_name
+ *
+ *	Set the name of thread THREAD to NAME.
+ */
+kern_return_t
+thread_set_name(
+	thread_t	thread,
+	const_kernel_debug_name_t	name)
+{
+	strncpy(thread->name, name, sizeof thread->name - 1);
+	thread->name[sizeof thread->name - 1] = '\0';
+	return KERN_SUCCESS;
+}
diff --git a/kern/thread.h b/kern/thread.h
index 7bfe2e89..21b25030 100644
--- a/kern/thread.h
+++ b/kern/thread.h
@@ -54,6 +54,12 @@
 #include <machine/thread.h>
 #include <ipc/ipc_kmsg_queue.h>
 
+/*
+ * Thread name buffer size. Use the same size as the task so
+ * the thread can inherit the task's name.
+ */
+#define THREAD_NAME_SIZE TASK_NAME_SIZE
+
 struct thread {
 	/* Run queues */
 	queue_chain_t	links;		/* current run queue links */
@@ -232,6 +238,8 @@ struct thread {
 #if	MACH_LOCK_MON
 	unsigned lock_stack;
 #endif
+
+	char	name[THREAD_NAME_SIZE];
 };
 
 #include <kern/cpu_number.h>