看看 这段代码的BUG在哪里，有时候真的不注意就出错，

这是我做ALSA开发的时候编写的一段代码，初始化pcm设备，发现总是打开失败，从头到尾看了好几遍才发现问题！

复制

static int snd_pcm_init(snd_para_t *snd_para,snd_pcm_t *pcm)

{

    snd_pcm_hw_params_t *hwparams = NULL;

    int ret;

    if(snd_para->alsa_pcm_dev_name!=NULL)

        // ret = snd_pcm_open(&(pcm), snd_para->alsa_pcm_dev_name, snd_para->stream, 0);

        ret = snd_pcm_open(&(pcm), ALSA_PCM_PLAYBACK_DEV, snd_para->stream, 0);

    else{

        puts(" pcm dev name is null\n");

        return -1;

    }

    if (0 != ret) {

        fprintf(stderr, "snd_pcm_open error: %s: %s\n",

        snd_para->alsa_pcm_dev_name, snd_strerror(ret));

        return -1;

    }

    snd_pcm_hw_params_malloc(&hwparams);

    ret = snd_pcm_hw_params_any(pcm, hwparams);

    if (0 != ret) {

        fprintf(stderr, "snd_pcm_hw_params_any error: %s\n", snd_strerror(ret));

        goto err2;

    }

    ret = snd_pcm_hw_params_set_access(pcm, hwparams, snd_para->_access);

    if (0 !=  ret) {

        fprintf(stderr, "snd_pcm_hw_params_set_access error: %s\n", snd_strerror(ret));

        goto err2;

    }

    ret = snd_pcm_hw_params_set_format(pcm, hwparams, snd_para->fmt);

    if (0 !=  ret) {

        fprintf(stderr, "snd_pcm_hw_params_set_format error: %s\n", snd_strerror(ret));

        goto err2;

    }

    ret = snd_pcm_hw_params_set_rate(pcm, hwparams, snd_para->sample_rate, 0);

    if (0 !=  ret) {

        fprintf(stderr, "snd_pcm_hw_params_set_rate error: %s\n", snd_strerror(ret));

        goto err2;

    }

    ret = snd_pcm_hw_params_set_channels(pcm, hwparams, snd_para->channels);

    if (0!=  ret) {

        fprintf(stderr, "snd_pcm_hw_params_set_channels error: %s\n", snd_strerror(ret));

        goto err2;

    }



    ret = snd_pcm_hw_params_set_period_size(pcm, hwparams, snd_para->period_size, 0);

    if (0 !=  ret) {

        fprintf(stderr, "snd_pcm_hw_params_set_period_size error: %s\n", snd_strerror(ret));

        goto err2;

    }



    ret = snd_pcm_hw_params_set_periods(pcm, hwparams, snd_para->periods, 0);

    if (0!=  ret) {

        fprintf(stderr, "snd_pcm_hw_params_set_periods error: %s\n", snd_strerror(ret));

        goto err2;

    }



    ret = snd_pcm_hw_params(pcm, hwparams);

    snd_pcm_hw_params_free(hwparams); 

    if (0 !=  ret) {

        fprintf(stderr, "snd_pcm_hw_params error: %s\n", snd_strerror(ret));

        goto err1;

    }



    return 0;

    err2:

    snd_pcm_hw_params_free(hwparams); //释放内存

    err1:

    snd_pcm_close(pcm); //关闭 pcm 设备

    return -1;

}