modsys: Add basic sys.exc_info() implementation.

The implementation is very basic and non-compliant and provided solely for
CPython compatibility. The function itself is bad Python2 heritage, its
usage is discouraged.

5 files changed, 42 insertions, 0 deletions

diff --git a/py/modsys.c b/py/modsys.c
index 182ae13ecc..aad0fb8d7f 100644
--- a/py/modsys.c
+++ b/py/modsys.c
@@ -121,6 +121,26 @@ STATIC mp_obj_t mp_sys_print_exception(mp_uint_t n_args, const mp_obj_t *args) {
 }
 MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_sys_print_exception_obj, 1, 2, mp_sys_print_exception);
 
+#if MICROPY_PY_SYS_EXC_INFO
+STATIC mp_obj_t mp_sys_exc_info(void) {
+    mp_obj_t cur_exc = MP_STATE_VM(cur_exception);
+    mp_obj_tuple_t *t = mp_obj_new_tuple(3, NULL);
+
+    if (cur_exc == MP_OBJ_NULL) {
+        t->items[0] = mp_const_none;
+        t->items[1] = mp_const_none;
+        t->items[2] = mp_const_none;
+        return t;
+    }
+
+    t->items[0] = mp_obj_get_type(cur_exc);
+    t->items[1] = cur_exc;
+    t->items[2] = mp_const_none;
+    return t;
+}
+MP_DEFINE_CONST_FUN_OBJ_0(mp_sys_exc_info_obj, mp_sys_exc_info);
+#endif
+
 STATIC const mp_map_elem_t mp_module_sys_globals_table[] = {
     { MP_OBJ_NEW_QSTR(MP_QSTR___name__), MP_OBJ_NEW_QSTR(MP_QSTR_sys) },
 
@@ -163,6 +183,10 @@ STATIC const mp_map_elem_t mp_module_sys_globals_table[] = {
     { MP_OBJ_NEW_QSTR(MP_QSTR_stderr), (mp_obj_t)&mp_sys_stderr_obj },
 #endif
 
+    #if MICROPY_PY_SYS_EXC_INFO
+    { MP_OBJ_NEW_QSTR(MP_QSTR_exc_info), (mp_obj_t)&mp_sys_exc_info_obj },
+    #endif
+
     /*
      * Extensions to CPython
      */
diff --git a/py/mpconfig.h b/py/mpconfig.h
index df18290a20..59d6532d04 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -573,6 +573,12 @@ typedef double mp_float_t;
 #define MICROPY_PY_SYS_MAXSIZE (0)
 #endif
 
+// Whether to provide "sys.exc_info" function
+// Avoid enabling this, this function is Python2 heritage
+#ifndef MICROPY_PY_SYS_EXC_INFO
+#define MICROPY_PY_SYS_EXC_INFO (0)
+#endif
+
 // Whether to provide "sys.exit" function
 #ifndef MICROPY_PY_SYS_EXIT
 #define MICROPY_PY_SYS_EXIT (0)
diff --git a/py/mpstate.h b/py/mpstate.h
index a2366df7f4..42593e4c40 100644
--- a/py/mpstate.h
+++ b/py/mpstate.h
@@ -107,6 +107,11 @@ typedef struct _mp_state_vm_t {
     // pending exception object (MP_OBJ_NULL if not pending)
     mp_obj_t mp_pending_exception;
 
+    // current exception being handled, for sys.exc_info()
+    #if MICROPY_PY_SYS_EXC_INFO
+    mp_obj_t cur_exception;
+    #endif
+
     // dictionary for the __main__ module
     mp_obj_dict_t dict_main;
 
diff --git a/py/qstrdefs.h b/py/qstrdefs.h
index 5623c22084..8b1c9297dd 100644
--- a/py/qstrdefs.h
+++ b/py/qstrdefs.h
@@ -457,6 +457,9 @@ Q(implementation)
 #if MICROPY_PY_SYS_MAXSIZE
 Q(maxsize)
 #endif
+#if MICROPY_PY_SYS_EXC_INFO
+Q(exc_info)
+#endif
 Q(print_exception)
 #endif
 
diff --git a/py/vm.c b/py/vm.c
index 1af3636f6b..3a71913685 100644
--- a/py/vm.c
+++ b/py/vm.c
@@ -1228,6 +1228,10 @@ pending_exception_check:
 exception_handler:
             // exception occurred
 
+            #if MICROPY_PY_SYS_EXC_INFO
+            MP_STATE_VM(cur_exception) = nlr.ret_val;
+            #endif
+
             #if SELECTIVE_EXC_IP
             // with selective ip, we store the ip 1 byte past the opcode, so move ptr back
             code_state->ip -= 1;