Resolve filepath via struct path on exec (#229)

* Resolve path via struct path on exec
* Update tests to account for full path resolution

Author: nicholasberlin

GPL/Events/Process/Probe.bpf.c

@@ -166,7 +166,7 @@ int BPF_PROG(sched_process_exec,
 
     // filename
     field = ebpf_vl_field__add(&event->vl_fields, EBPF_VL_FIELD_FILENAME);
-    size  = read_kernel_str_or_empty_str(field->data, PATH_MAX, binprm->filename);
+    size  = ebpf_resolve_path_to_string(field->data, &p, task);
     ebpf_vl_field__set_size(&event->vl_fields, field, size);
 
     ebpf_ringbuf_write(&ringbuf, event, EVENT_SIZE(event), 0);

testing/testrunner/ebpf_test.go

@@ -179,7 +179,7 @@ func ForkExec(t *testing.T, et *Runner) {
 
 	require.Equal(t, execEvent.Creds.CapPermitted, uint64(0x000001ffffffffff))
 	require.Equal(t, execEvent.Creds.CapEffective, uint64(0x000001ffffffffff))
-	require.Equal(t, execEvent.FileName, "./do_nothing")
+	require.Equal(t, execEvent.FileName, "/do_nothing")
 	require.Equal(t, execEvent.Argv[0], "./do_nothing")
 	require.Equal(t, execEvent.Env[0], "TEST_ENV_KEY1=TEST_ENV_VAL1")
 	require.Equal(t, execEvent.Env[1], "TEST_ENV_KEY2=TEST_ENV_VAL2")