gdbstub: Introduce gdb_handle_detach_user()

The upcoming follow-fork-mode child support needs to perform certain
actions when GDB detaches from the stopped parent or the stopped child.
Introduce a user-specific hook for this.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20240219141628.246823-11-iii@linux.ibm.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240305121005.3528075-12-alex.bennee@linaro.org>

gdbstub/gdbstub.c

@@ -1024,6 +1024,12 @@ static void handle_detach(GArray *params, void *user_ctx)
         pid = get_param(params, 0)->val_ul;
     }
 
+#ifdef CONFIG_USER_ONLY
+    if (gdb_handle_detach_user(pid)) {
+        return;
+    }
+#endif
+
     process = gdb_get_process(pid);
     gdb_process_breakpoint_remove_all(process);
     process->attached = false;

gdbstub/internals.h

@@ -198,6 +198,7 @@ void gdb_handle_query_xfer_exec_file(GArray *params, void *user_ctx); /* user */
 void gdb_handle_set_catch_syscalls(GArray *params, void *user_ctx); /* user */
 void gdb_handle_query_supported_user(const char *gdb_supported); /* user */
 bool gdb_handle_set_thread_user(uint32_t pid, uint32_t tid); /* user */
+bool gdb_handle_detach_user(uint32_t pid); /* user */
 
 void gdb_handle_query_attached(GArray *params, void *user_ctx); /* both */
 

gdbstub/user.c

@@ -391,6 +391,11 @@ bool gdb_handle_set_thread_user(uint32_t pid, uint32_t tid)
     return false;
 }
 
+bool gdb_handle_detach_user(uint32_t pid)
+{
+    return false;
+}
+
 /*
  * Execution state helpers
  */