shared/runtime/pyexec: Don't allow Ctrl+C to interrupt frozen boot code.

Helps prevent the filesystem from getting formatted by mistake, among other
things.  For example, on a Pico board, entering Ctrl+D and Ctrl+C fast many
times will eventually wipe the filesystem (without warning or notice).

Further rationale: Ctrl+C is used a lot by automation scripts (eg mpremote)
and UI's (eg Mu, Thonny) to get the board into a known state.  If the board
is not responding for a short time then it's not possible to know if it's
just a slow start up (eg in _boot.py), or an infinite loop in the main
application.  The former should not be interrupted, but the latter should.
The only way to distinguish these two cases would be to wait "long enough",
and if there's nothing on the serial after "long enough" then assume it's
running the application and Ctrl+C should break out of it.  But defining
"long enough" is impossible for all the different boards and their possible
behaviour.  The solution in this commit is to make it so that frozen
start-up code cannot be interrupted by Ctrl+C.  That code then effectively
acts like normal C start-up code, which also cannot be interrupted.

Note: on the stm32 port this was never seen as an issue because all
start-up code is in C.  But now other ports start to put more things in
_boot.py and so this problem crops up.

Signed-off-by: David Grayson <davidegrayson@gmail.com>

13 files changed, 24 insertions, 19 deletions

diff --git a/ports/esp32/main.c b/ports/esp32/main.c
index e2a803fcb6..e7d7626a6e 100644
--- a/ports/esp32/main.c
+++ b/ports/esp32/main.c
@@ -161,7 +161,7 @@ soft_reset:
     #endif
 
     // run boot-up scripts
-    pyexec_frozen_module("_boot.py");
+    pyexec_frozen_module("_boot.py", false);
     pyexec_file_if_exists("boot.py");
     if (pyexec_mode_kind == PYEXEC_MODE_FRIENDLY_REPL) {
         int ret = pyexec_file_if_exists("main.py");
diff --git a/ports/esp8266/main.c b/ports/esp8266/main.c
index 583540a81c..238490ebef 100644
--- a/ports/esp8266/main.c
+++ b/ports/esp8266/main.c
@@ -74,7 +74,7 @@ STATIC void mp_reset(void) {
     }
 
     #if MICROPY_MODULE_FROZEN
-    pyexec_frozen_module("_boot.py");
+    pyexec_frozen_module("_boot.py", false);
     pyexec_file_if_exists("boot.py");
     if (pyexec_mode_kind == PYEXEC_MODE_FRIENDLY_REPL) {
         pyexec_file_if_exists("main.py");
diff --git a/ports/mimxrt/main.c b/ports/mimxrt/main.c
index 907de373de..1a85f21c6d 100644
--- a/ports/mimxrt/main.c
+++ b/ports/mimxrt/main.c
@@ -85,7 +85,7 @@ int main(void) {
         readline_init0();
 
         // Execute _boot.py to set up the filesystem.
-        pyexec_frozen_module("_boot.py");
+        pyexec_frozen_module("_boot.py", false);
 
         // Execute user scripts.
         int ret = pyexec_file_if_exists("boot.py");
diff --git a/ports/minimal/main.c b/ports/minimal/main.c
index 4eb6ca65af..4990997531 100644
--- a/ports/minimal/main.c
+++ b/ports/minimal/main.c
@@ -55,7 +55,7 @@ int main(int argc, char **argv) {
     // do_str("print('hello world!', list(x+1 for x in range(10)), end='eol\\n')", MP_PARSE_SINGLE_INPUT);
     // do_str("for i in range(10):\r\n  print(i)", MP_PARSE_FILE_INPUT);
     #else
-    pyexec_frozen_module("frozentest.py");
+    pyexec_frozen_module("frozentest.py", false);
     #endif
     mp_deinit();
     return 0;
diff --git a/ports/nrf/main.c b/ports/nrf/main.c
index 197fea9ab6..f64107f890 100644
--- a/ports/nrf/main.c
+++ b/ports/nrf/main.c
@@ -184,7 +184,7 @@ soft_reset:
     int ret = mp_vfs_mount_and_chdir_protected((mp_obj_t)&nrf_flash_obj, mount_point);
 
     if ((ret == -MP_ENODEV) || (ret == -MP_EIO)) {
-        pyexec_frozen_module("_mkfs.py"); // Frozen script for formatting flash filesystem.
+        pyexec_frozen_module("_mkfs.py", false); // Frozen script for formatting flash filesystem.
         ret = mp_vfs_mount_and_chdir_protected((mp_obj_t)&nrf_flash_obj, mount_point);
     }
 
diff --git a/ports/powerpc/main.c b/ports/powerpc/main.c
index 11013f1755..f3abc64aa7 100644
--- a/ports/powerpc/main.c
+++ b/ports/powerpc/main.c
@@ -95,7 +95,7 @@ int main(int argc, char **argv) {
     pyexec_friendly_repl();
     #endif
     #else
-    pyexec_frozen_module("frozentest.py");
+    pyexec_frozen_module("frozentest.py", false);
     #endif
     mp_deinit();
     return 0;
diff --git a/ports/renesas-ra/main.c b/ports/renesas-ra/main.c
index d403dbacbe..6ba26cd7ba 100644
--- a/ports/renesas-ra/main.c
+++ b/ports/renesas-ra/main.c
@@ -325,7 +325,7 @@ soft_reset:
 
     // Run optional frozen boot code.
     #ifdef MICROPY_BOARD_FROZEN_BOOT_FILE
-    pyexec_frozen_module(MICROPY_BOARD_FROZEN_BOOT_FILE);
+    pyexec_frozen_module(MICROPY_BOARD_FROZEN_BOOT_FILE, false);
     #endif
 
     // Run boot.py (or whatever else a board configures at this stage).
diff --git a/ports/rp2/main.c b/ports/rp2/main.c
index 9e69d159e1..059449695c 100644
--- a/ports/rp2/main.c
+++ b/ports/rp2/main.c
@@ -168,9 +168,9 @@ int main(int argc, char **argv) {
 
         // Execute _boot.py to set up the filesystem.
         #if MICROPY_VFS_FAT && MICROPY_HW_USB_MSC
-        pyexec_frozen_module("_boot_fat.py");
+        pyexec_frozen_module("_boot_fat.py", false);
         #else
-        pyexec_frozen_module("_boot.py");
+        pyexec_frozen_module("_boot.py", false);
         #endif
 
         // Execute user scripts.
diff --git a/ports/samd/main.c b/ports/samd/main.c
index 725fd651d0..bc0e45ee64 100644
--- a/ports/samd/main.c
+++ b/ports/samd/main.c
@@ -52,7 +52,7 @@ void samd_main(void) {
         readline_init0();
 
         // Execute _boot.py to set up the filesystem.
-        pyexec_frozen_module("_boot.py");
+        pyexec_frozen_module("_boot.py", false);
 
         // Execute user scripts.
         int ret = pyexec_file_if_exists("boot.py");
diff --git a/ports/stm32/main.c b/ports/stm32/main.c
index e5ad14fcf7..cc0367b824 100644
--- a/ports/stm32/main.c
+++ b/ports/stm32/main.c
@@ -559,7 +559,7 @@ soft_reset:
 
     // Run optional frozen boot code.
     #ifdef MICROPY_BOARD_FROZEN_BOOT_FILE
-    pyexec_frozen_module(MICROPY_BOARD_FROZEN_BOOT_FILE);
+    pyexec_frozen_module(MICROPY_BOARD_FROZEN_BOOT_FILE, false);
     #endif
 
     // Run boot.py (or whatever else a board configures at this stage).
diff --git a/ports/teensy/main.c b/ports/teensy/main.c
index 37a04c74f8..fa27326e93 100644
--- a/ports/teensy/main.c
+++ b/ports/teensy/main.c
@@ -298,7 +298,7 @@ soft_reset:
     #endif
 
     #if MICROPY_MODULE_FROZEN
-    pyexec_frozen_module("boot.py");
+    pyexec_frozen_module("boot.py", false);
     #else
     if (!pyexec_file_if_exists("/boot.py")) {
         flash_error(4);
@@ -310,7 +310,7 @@ soft_reset:
 
     // run main script
     #if MICROPY_MODULE_FROZEN
-    pyexec_frozen_module("main.py");
+    pyexec_frozen_module("main.py", true);
     #else
     {
         vstr_t *vstr = vstr_new(16);
diff --git a/shared/runtime/pyexec.c b/shared/runtime/pyexec.c
index 40491650e4..ec0ff87f1d 100644
--- a/shared/runtime/pyexec.c
+++ b/shared/runtime/pyexec.c
@@ -57,6 +57,7 @@ STATIC bool repl_display_debugging_info = 0;
 #define EXEC_FLAG_SOURCE_IS_VSTR        (1 << 4)
 #define EXEC_FLAG_SOURCE_IS_FILENAME    (1 << 5)
 #define EXEC_FLAG_SOURCE_IS_READER      (1 << 6)
+#define EXEC_FLAG_NO_INTERRUPT          (1 << 7)
 
 // parses, compiles and executes the code in the lexer
 // frees the lexer before returning
@@ -113,7 +114,9 @@ STATIC int parse_compile_execute(const void *source, mp_parse_input_kind_t input
         }
 
         // execute code
-        mp_hal_set_interrupt_char(CHAR_CTRL_C); // allow ctrl-C to interrupt us
+        if (!(exec_flags & EXEC_FLAG_NO_INTERRUPT)) {
+            mp_hal_set_interrupt_char(CHAR_CTRL_C);
+        }
         #if MICROPY_REPL_INFO
         start = mp_hal_ticks_ms();
         #endif
@@ -686,7 +689,7 @@ int pyexec_file(const char *filename) {
 int pyexec_file_if_exists(const char *filename) {
     #if MICROPY_MODULE_FROZEN
     if (mp_find_frozen_module(filename, NULL, NULL) == MP_IMPORT_STAT_FILE) {
-        return pyexec_frozen_module(filename);
+        return pyexec_frozen_module(filename, true);
     }
     #endif
     if (mp_import_stat(filename) != MP_IMPORT_STAT_FILE) {
@@ -696,20 +699,22 @@ int pyexec_file_if_exists(const char *filename) {
 }
 
 #if MICROPY_MODULE_FROZEN
-int pyexec_frozen_module(const char *name) {
+int pyexec_frozen_module(const char *name, bool allow_keyboard_interrupt) {
     void *frozen_data;
     int frozen_type;
     mp_find_frozen_module(name, &frozen_type, &frozen_data);
+    mp_uint_t exec_flags = allow_keyboard_interrupt ? 0 : EXEC_FLAG_NO_INTERRUPT;
 
     switch (frozen_type) {
         #if MICROPY_MODULE_FROZEN_STR
         case MP_FROZEN_STR:
-            return parse_compile_execute(frozen_data, MP_PARSE_FILE_INPUT, 0);
+            return parse_compile_execute(frozen_data, MP_PARSE_FILE_INPUT, exec_flags);
         #endif
 
         #if MICROPY_MODULE_FROZEN_MPY
         case MP_FROZEN_MPY:
-            return parse_compile_execute(frozen_data, MP_PARSE_FILE_INPUT, EXEC_FLAG_SOURCE_IS_RAW_CODE);
+            return parse_compile_execute(frozen_data, MP_PARSE_FILE_INPUT, exec_flags |
+                EXEC_FLAG_SOURCE_IS_RAW_CODE);
         #endif
 
         default:
diff --git a/shared/runtime/pyexec.h b/shared/runtime/pyexec.h
index 981e7dca9f..64c5ef9434 100644
--- a/shared/runtime/pyexec.h
+++ b/shared/runtime/pyexec.h
@@ -46,7 +46,7 @@ int pyexec_raw_repl(void);
 int pyexec_friendly_repl(void);
 int pyexec_file(const char *filename);
 int pyexec_file_if_exists(const char *filename);
-int pyexec_frozen_module(const char *name);
+int pyexec_frozen_module(const char *name, bool allow_keyboard_interrupt);
 void pyexec_event_repl_init(void);
 int pyexec_event_repl_process_char(int c);
 extern uint8_t pyexec_repl_active;