shared/runtime: Set exit code according to the SystemExit exception.

Add abort setup code `nlr_set_abort` to the standard runtime executor.
This makes the standard runtime respond to abort signal without any further
modifications.

- When aborted, the program exits with 137 exit code (configurable, same as
  posix sig abort), to differentiate from a normal shutdown.

- When exited by exception/crash, the program will exit with exit code 1
  (configurable).

- When exited by exception KeyboardInterrupt, the program will exit with
  exit code 130 (configurable, same as posix sig int).

- When exited with a exit code (from Python environment), this code is
  propagated.  When a different object is passed, exit code is set to 1 and
  the value printed, to be consistent with Python docs:
  https://python.readthedocs.io/en/latest/library/exceptions.html#SystemExit

Signed-off-by: John Smith <jsmith@jsmith.cz>

py/mpconfig.h

@@ -1180,6 +1180,16 @@ typedef time_t mp_timestamp_t;
 #define MICROPY_ENABLE_VM_ABORT (0)
 #endif
 
+// Whether to handle abort behavior in pyexec code
+#ifndef MICROPY_PYEXEC_ENABLE_VM_ABORT
+#define MICROPY_PYEXEC_ENABLE_VM_ABORT (0)
+#endif
+
+// Whether to set exit codes according to the exit reason (keyboard interrupt, crash, normal exit, ...)
+#ifndef MICROPY_PYEXEC_ENABLE_EXIT_CODE_HANDLING
+#define MICROPY_PYEXEC_ENABLE_EXIT_CODE_HANDLING (0)
+#endif
+
 // Support for internal scheduler
 #ifndef MICROPY_ENABLE_SCHEDULER
 #define MICROPY_ENABLE_SCHEDULER (MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_EXTRA_FEATURES)

shared/runtime/pyexec.c

@@ -72,6 +72,10 @@ static int parse_compile_execute(const void *source, mp_parse_input_kind_t input
     nlr_buf_t nlr;
     nlr.ret_val = NULL;
     if (nlr_push(&nlr) == 0) {
+        #if MICROPY_PYEXEC_ENABLE_VM_ABORT
+        nlr_set_abort(&nlr);
+        #endif
+
         mp_obj_t module_fun;
         #if MICROPY_MODULE_FROZEN_MPY
         if (exec_flags & EXEC_FLAG_SOURCE_IS_RAW_CODE) {
@@ -116,7 +120,7 @@ static int parse_compile_execute(const void *source, mp_parse_input_kind_t input
         mp_hal_set_interrupt_char(-1); // disable interrupt
         mp_handle_pending(true); // handle any pending exceptions (and any callbacks)
         nlr_pop();
-        ret = 1;
+        ret = PYEXEC_NORMAL_EXIT;
         if (exec_flags & EXEC_FLAG_PRINT_EOF) {
             mp_hal_stdout_tx_strn("\x04", 1);
         }
@@ -135,15 +139,41 @@ static int parse_compile_execute(const void *source, mp_parse_input_kind_t input
             mp_hal_stdout_tx_strn("\x04", 1);
         }
 
-        // check for SystemExit
-        if (mp_obj_is_subclass_fast(MP_OBJ_FROM_PTR(((mp_obj_base_t *)nlr.ret_val)->type), MP_OBJ_FROM_PTR(&mp_type_SystemExit))) {
-            // at the moment, the value of SystemExit is unused
+        #if MICROPY_PYEXEC_ENABLE_VM_ABORT
+        if (nlr.ret_val == NULL) { // abort
+            ret = PYEXEC_ABORT;
+        } else
+        #endif
+        if (mp_obj_is_subclass_fast(MP_OBJ_FROM_PTR(((mp_obj_base_t *)nlr.ret_val)->type), MP_OBJ_FROM_PTR(&mp_type_SystemExit))) { // system exit
+            #if MICROPY_PYEXEC_ENABLE_EXIT_CODE_HANDLING
+            mp_obj_t val = mp_obj_exception_get_value(MP_OBJ_FROM_PTR(nlr.ret_val));
+            if (val != mp_const_none) {
+                if (mp_obj_is_int(val)) {
+                    ret = (int)mp_obj_int_get_truncated(val);
+                } else {
+                    mp_obj_print_helper(MICROPY_ERROR_PRINTER, val, PRINT_STR);
+                    mp_print_str(MICROPY_ERROR_PRINTER, "\n");
+                    ret = PYEXEC_UNHANDLED_EXCEPTION;
+                }
+            } else {
+                ret = PYEXEC_NORMAL_EXIT;
+            }
+            #else
             ret = PYEXEC_FORCED_EXIT;
-        } else {
+            #endif
+        } else { // other exception
             mp_obj_print_exception(&mp_plat_print, MP_OBJ_FROM_PTR(nlr.ret_val));
-            ret = 0;
+            ret = PYEXEC_UNHANDLED_EXCEPTION;
+            #if MICROPY_PYEXEC_ENABLE_EXIT_CODE_HANDLING
+            if (mp_obj_is_subclass_fast(MP_OBJ_FROM_PTR(((mp_obj_base_t *)nlr.ret_val)->type), MP_OBJ_FROM_PTR(&mp_type_KeyboardInterrupt))) { // keyboard interrupt
+                ret = PYEXEC_KEYBOARD_INTERRUPT;
+            }
+            #endif
         }
     }
+    #if MICROPY_PYEXEC_ENABLE_VM_ABORT
+    nlr_set_abort(NULL);
+    #endif
 
     #if MICROPY_REPL_INFO
     // display debugging info if wanted

shared/runtime/pyexec.h

@@ -37,6 +37,17 @@ extern pyexec_mode_kind_t pyexec_mode_kind;
 
 #define PYEXEC_FORCED_EXIT (0x100)
 
+#if MICROPY_PYEXEC_ENABLE_EXIT_CODE_HANDLING
+#define PYEXEC_NORMAL_EXIT (0)
+#define PYEXEC_UNHANDLED_EXCEPTION (1)
+#define PYEXEC_KEYBOARD_INTERRUPT (128 + 2) // same as SIG INT exit code
+#define PYEXEC_ABORT (128 + 9)              // same as SIG KILL exit code
+#else
+#define PYEXEC_NORMAL_EXIT (1)
+#define PYEXEC_UNHANDLED_EXCEPTION (0)
+#define PYEXEC_ABORT PYEXEC_FORCED_EXIT
+#endif
+
 int pyexec_raw_repl(void);
 int pyexec_friendly_repl(void);
 int pyexec_file(const char *filename);