From 54d97251fe2dd4939652a186bf703885e654b4d1 Mon Sep 17 00:00:00 2001 From: Jeff Epler Date: Sat, 12 Sep 2020 13:57:31 -0500 Subject: modstruct: Improve compliance with python3 While checking whether we can enable -Wimplicit-fallthrough, I encountered a diagnostic in mp_binary_set_val_array_from_int which led to discovering the following bug: ``` >>> struct.pack("xb", 3) b'\x03\x03' ``` That is, the next value (3) was used as the value of a padding byte, while standard Python always fills "x" bytes with zeros. I initially thought this had to do with the unintentional fallthrough, but it doesn't. Instead, this code would relate to an array.array with a typecode of padding ('x'), which is ALSO not desktop Python compliant: ``` >>> array.array('x', (1, 2, 3)) array('x', [1, 0, 0]) ``` Possibly this is dead code that used to be shared between struct-setting and array-setting, but it no longer is. I also discovered that the argument list length for struct.pack and struct.pack_into were not checked, and that the length of binary data passed to array.array was not checked to be a multiple of the element size. I have corrected all of these to conform more closely to standard Python and revised some tests where necessary. Some tests for micropython-specific behavior that does not conform to standard Python and is not present in CircuitPython was deleted outright. --- py/modstruct.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) (limited to 'py/modstruct.c') diff --git a/py/modstruct.c b/py/modstruct.c index fe766a4de..7675de275 100644 --- a/py/modstruct.c +++ b/py/modstruct.c @@ -183,16 +183,21 @@ MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(struct_unpack_from_obj, 2, 3, struct_unpack_ // This function assumes there is enough room in p to store all the values STATIC void struct_pack_into_internal(mp_obj_t fmt_in, byte *p, size_t n_args, const mp_obj_t *args) { + size_t size; + size_t count = calc_size_items(mp_obj_str_get_str(fmt_in), &size); + if (count != n_args) { +#if MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE + mp_raise_ValueError(NULL); +#else + mp_raise_ValueError_varg(translate("pack expected %d items for packing (got %d)"), count, n_args); +#endif + } const char *fmt = mp_obj_str_get_str(fmt_in); char fmt_type = get_fmt_type(&fmt); size_t i; for (i = 0; i < n_args;) { mp_uint_t cnt = 1; - if (*fmt == '\0') { - // more arguments given than used by format string; CPython raises struct.error here - break; - } if (unichar_isdigit(*fmt)) { cnt = get_fmt_num(&fmt); } @@ -208,8 +213,7 @@ STATIC void struct_pack_into_internal(mp_obj_t fmt_in, byte *p, size_t n_args, c memset(p + to_copy, 0, cnt - to_copy); p += cnt; } else { - // If we run out of args then we just finish; CPython would raise struct.error - while (cnt-- && i < n_args) { + while (cnt--) { mp_binary_set_val(fmt_type, *fmt, args[i], &p); // Pad bytes don't have a corresponding argument. if (*fmt != 'x') { @@ -222,7 +226,6 @@ STATIC void struct_pack_into_internal(mp_obj_t fmt_in, byte *p, size_t n_args, c } STATIC mp_obj_t struct_pack(size_t n_args, const mp_obj_t *args) { - // TODO: "The arguments must match the values required by the format exactly." mp_int_t size = MP_OBJ_SMALL_INT_VALUE(struct_calcsize(args[0])); vstr_t vstr; vstr_init_len(&vstr, size); -- cgit v1.2.3