binder_parse

通过ServiceManager的启动我们可以知道，循环在binder_loop()过程， 会调用binder_parse()方法。

int binder_parse(struct binder_state *bs, struct binder_io *bio,
                 uint32_t *ptr, uint32_t size, binder_handler func)
{
    int r = 1;
    uint32_t *end = ptr + (size / 4);

    while (ptr < end) {
        uint32_t cmd = *ptr++;
        switch(cmd) {
        case BR_NOOP:
            break;
        case BR_TRANSACTION_COMPLETE:
            break;
        ......
        case BR_TRANSACTION: {
            struct binder_txn *txn = (void *) ptr;
            if ((end - ptr) * sizeof(uint32_t) < sizeof(struct binder_txn)) {
                ALOGE("parse: txn too small!\n");
                return -1;
            }
            binder_dump_txn(txn);
            if (func) {
                unsigned rdata[256/4];
                struct binder_io msg;
                struct binder_io reply;
                int res;

                bio_init(&reply, rdata, sizeof(rdata), 4);
                bio_init_from_txn(&msg, txn);
                res = func(bs, txn, &msg, &reply);
                binder_send_reply(bs, &reply, txn->data, res);
            }
            ptr += sizeof(*txn) / sizeof(uint32_t);
            break;
        }
        case BR_REPLY: {
            struct binder_txn *txn = (void*) ptr;
            if ((end - ptr) * sizeof(uint32_t) < sizeof(struct binder_txn)) {
                ALOGE("parse: reply too small!\n");
                return -1;
            }
            binder_dump_txn(txn);
            if (bio) {
                bio_init_from_txn(bio, txn);
                bio = 0;
            } else {
                    /* todo FREE BUFFER */
            }
            ptr += (sizeof(*txn) / sizeof(uint32_t));
            r = 0;
            break;
        }
        ......
        }
    }
    return r;
}

这个地方重点看一下BR_TRANSACTION、BR_REPLY的分支。

请注意func这个参数在service_manager.c文件的main方法传入，详情。

binder_send_reply方法请查看