refactor(libsinsp/threadinfo): export static fields via static method

Signed-off-by: Leonardo Di Giovanna <leonardodigiovanna1@gmail.com>

userspace/libsinsp/threadinfo.cpp

@@ -59,54 +59,63 @@ sinsp_threadinfo::sinsp_threadinfo(
 }
 
 libsinsp::state::static_struct::field_infos sinsp_threadinfo::static_fields() const {
+	return get_static_fields();
+}
+
+libsinsp::state::static_struct::field_infos sinsp_threadinfo::get_static_fields() {
 	libsinsp::state::static_struct::field_infos ret;
+
+	// Use a zero-initialized pointer as define_static_field only use it to evaluate the offset of
+	// the provided field (i.e. pointer is never dereferenced to access a field value).
+	const auto* ptr = static_cast<const sinsp_threadinfo*>(0);
+
 	// todo(jasondellaluce): support missing fields that are vectors, maps, or sub-tables
-	define_static_field(ret, this, &m_tid, "tid");
-	define_static_field(ret, this, &m_pid, "pid");
-	define_static_field(ret, this, &m_ptid, "ptid");
-	define_static_field(ret, this, &m_reaper_tid, "reaper_tid");
-	define_static_field(ret, this, &m_sid, "sid");
-	define_static_field(ret, this, &m_comm, "comm");
-	define_static_field(ret, this, &m_exe, "exe");
-	define_static_field(ret, this, &m_exepath, "exe_path");
-	define_static_field(ret, this, &m_exe_writable, "exe_writable");
-	define_static_field(ret, this, &m_exe_upper_layer, "exe_upper_layer");
-	define_static_field(ret, this, &m_exe_lower_layer, "exe_lower_layer");
-	define_static_field(ret, this, &m_exe_from_memfd, "exe_from_memfd");
-	define_static_field(ret, this, &m_args_table_adapter.table_ptr(), "args", true);
-	define_static_field(ret, this, &m_env_table_adapter.table_ptr(), "env", true);
-	define_static_field(ret, this, &m_cgroups_table_adapter.table_ptr(), "cgroups", true);
-	define_static_field(ret, this, &m_flags, "flags");
-	define_static_field(ret, this, &m_fdlimit, "fd_limit");
-	define_static_field(ret, this, &m_uid, "uid");
-	define_static_field(ret, this, &m_gid, "gid");
-	define_static_field(ret, this, &m_loginuid, "loginuid");
+	define_static_field(ret, ptr, &ptr->m_tid, "tid");
+	define_static_field(ret, ptr, &ptr->m_pid, "pid");
+	define_static_field(ret, ptr, &ptr->m_ptid, "ptid");
+	define_static_field(ret, ptr, &ptr->m_reaper_tid, "reaper_tid");
+	define_static_field(ret, ptr, &ptr->m_sid, "sid");
+	define_static_field(ret, ptr, &ptr->m_comm, "comm");
+	define_static_field(ret, ptr, &ptr->m_exe, "exe");
+	define_static_field(ret, ptr, &ptr->m_exepath, "exe_path");
+	define_static_field(ret, ptr, &ptr->m_exe_writable, "exe_writable");
+	define_static_field(ret, ptr, &ptr->m_exe_upper_layer, "exe_upper_layer");
+	define_static_field(ret, ptr, &ptr->m_exe_lower_layer, "exe_lower_layer");
+	define_static_field(ret, ptr, &ptr->m_exe_from_memfd, "exe_from_memfd");
+	define_static_field(ret, ptr, &ptr->m_args_table_adapter.table_ptr(), "args", true);
+	define_static_field(ret, ptr, &ptr->m_env_table_adapter.table_ptr(), "env", true);
+	define_static_field(ret, ptr, &ptr->m_cgroups_table_adapter.table_ptr(), "cgroups", true);
+	define_static_field(ret, ptr, &ptr->m_flags, "flags");
+	define_static_field(ret, ptr, &ptr->m_fdlimit, "fd_limit");
+	define_static_field(ret, ptr, &ptr->m_uid, "uid");
+	define_static_field(ret, ptr, &ptr->m_gid, "gid");
+	define_static_field(ret, ptr, &ptr->m_loginuid, "loginuid");
 	// m_cap_permitted
 	// m_cap_effective
 	// m_cap_inheritable
-	define_static_field(ret, this, &m_exe_ino, "exe_ino");
-	define_static_field(ret, this, &m_exe_ino_ctime, "exe_ino_ctime");
-	define_static_field(ret, this, &m_exe_ino_mtime, "exe_ino_mtime");
+	define_static_field(ret, ptr, &ptr->m_exe_ino, "exe_ino");
+	define_static_field(ret, ptr, &ptr->m_exe_ino_ctime, "exe_ino_ctime");
+	define_static_field(ret, ptr, &ptr->m_exe_ino_mtime, "exe_ino_mtime");
 	// m_exe_ino_ctime_duration_clone_ts
 	// m_exe_ino_ctime_duration_pidns_start
 	// m_vmsize_kb
 	// m_vmrss_kb
 	// m_vmswap_kb
 	// m_pfmajor
 	// m_pfminor
-	define_static_field(ret, this, &m_vtid, "vtid");
-	define_static_field(ret, this, &m_vpid, "vpid");
-	define_static_field(ret, this, &m_vpgid, "vpgid");
-	define_static_field(ret, this, &m_pgid, "pgid");
-	define_static_field(ret, this, &m_pidns_init_start_ts, "pidns_init_start_ts");
-	define_static_field(ret, this, &m_root, "root");
-	define_static_field(ret, this, &m_tty, "tty");
+	define_static_field(ret, ptr, &ptr->m_vtid, "vtid");
+	define_static_field(ret, ptr, &ptr->m_vpid, "vpid");
+	define_static_field(ret, ptr, &ptr->m_vpgid, "vpgid");
+	define_static_field(ret, ptr, &ptr->m_pgid, "pgid");
+	define_static_field(ret, ptr, &ptr->m_pidns_init_start_ts, "pidns_init_start_ts");
+	define_static_field(ret, ptr, &ptr->m_root, "root");
+	define_static_field(ret, ptr, &ptr->m_tty, "tty");
 	// m_category
 	// m_clone_ts
 	// m_lastexec_ts
 	// m_latency
-	define_static_field(ret, this, &m_main_fdtable, "file_descriptors", true);
-	define_static_field(ret, this, &m_cwd, "cwd", true);
+	define_static_field(ret, ptr, &ptr->m_main_fdtable, "file_descriptors", true);
+	define_static_field(ret, ptr, &ptr->m_cwd, "cwd", true);
 	// m_parent_loop_detected
 	return ret;
 }
@@ -1322,7 +1331,7 @@ static void fd_to_scap(scap_fdinfo* dst, sinsp_fdinfo* src) {
 	}
 }
 
-static const auto s_threadinfo_static_fields = sinsp_threadinfo().static_fields();
+static const auto s_threadinfo_static_fields = sinsp_threadinfo::get_static_fields();
 
 ///////////////////////////////////////////////////////////////////////////////
 // sinsp_thread_manager implementation

userspace/libsinsp/threadinfo.h

@@ -584,6 +584,12 @@ class SINSP_PUBLIC sinsp_threadinfo : public libsinsp::state::table_entry {
 
 	void set_exepath(std::string&& exepath);
 
+	/*!
+	  \brief A static version of static_fields()
+	  \return The group of field infos available.
+	 */
+	static static_struct::field_infos get_static_fields();
+
 private:
 	sinsp_threadinfo* get_cwd_root();
 	bool set_env_from_proc();