py/misc: Change sizeof to offsetof for variable-length alloc.

This fixes the case where e.g.

    struct foo_t {
      mp_obj_t x;
      uint16_t y;
      char buf[];
    };

will have `sizeof(struct foo_t)==8`, but `offsetof(struct foo_t, buf)==6`.

When computing the size to allocate for `m_new_obj_var` we need to use
offsetof to avoid over-allocating. This is important especially when it
might cause it to spill over into another GC block.

This work was funded through GitHub Sponsors.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
This commit is contained in:
Jim Mussared
2023-11-03 14:19:55 +11:00
committed by Damien George
parent c85db05244
commit b6a9778484
11 changed files with 24 additions and 24 deletions

View File

@@ -545,7 +545,7 @@ STATIC mp_obj_t extra_coverage(void) {
fun_bc.context = &context;
fun_bc.child_table = NULL;
fun_bc.bytecode = (const byte *)"\x01"; // just needed for n_state
mp_code_state_t *code_state = m_new_obj_var(mp_code_state_t, mp_obj_t, 1);
mp_code_state_t *code_state = m_new_obj_var(mp_code_state_t, state, mp_obj_t, 1);
code_state->fun_bc = &fun_bc;
code_state->ip = (const byte *)"\x00"; // just needed for an invalid opcode
code_state->sp = &code_state->state[0];