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

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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
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extmod/nimble/modbluetooth_nimble.c
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@@ -1701,7 +1701,7 @@ STATIC int create_l2cap_channel(uint16_t mtu, mp_bluetooth_nimble_l2cap_channel_
// multiply that by the "MTUs per channel" (set to 3 above).
const size_t buf_blocks = MP_CEIL_DIVIDE(mtu, L2CAP_BUF_BLOCK_SIZE) * L2CAP_BUF_SIZE_MTUS_PER_CHANNEL;
mp_bluetooth_nimble_l2cap_channel_t *chan = m_new_obj_var(mp_bluetooth_nimble_l2cap_channel_t, uint8_t, OS_MEMPOOL_SIZE(buf_blocks, L2CAP_BUF_BLOCK_SIZE) * sizeof(os_membuf_t));
mp_bluetooth_nimble_l2cap_channel_t *chan = m_new_obj_var(mp_bluetooth_nimble_l2cap_channel_t, sdu_mem, uint8_t, OS_MEMPOOL_SIZE(buf_blocks, L2CAP_BUF_BLOCK_SIZE) * sizeof(os_membuf_t));
MP_STATE_PORT(bluetooth_nimble_root_pointers)->l2cap_chan = chan;
// Will be set in BLE_L2CAP_EVENT_COC_CONNECTED or BLE_L2CAP_EVENT_COC_ACCEPT.