List ALSA devices

#include <stdio.h>
#include <alsa/asoundlib.h>

void print_card_info(snd_ctl_card_info_t *info)
{
        printf("Card #%d: id=%s, driver=%s, name=%s, longname=%s, mixername=%s, components=%s\n",
                snd_ctl_card_info_get_card(info),
                snd_ctl_card_info_get_id(info),
                snd_ctl_card_info_get_driver(info),
                snd_ctl_card_info_get_name(info),
                snd_ctl_card_info_get_longname(info),
                snd_ctl_card_info_get_mixername(info),
                snd_ctl_card_info_get_components(info));
}

void print_elem_id(snd_ctl_elem_id_t *id)
{
        printf("elem_id: numid=%d, interface=%s, device=%d, subdevice=%d, name=%s, index=%d\n",
                snd_ctl_elem_id_get_numid(id),
                snd_ctl_elem_iface_name(snd_ctl_elem_id_get_interface(id)),
                snd_ctl_elem_id_get_device(id),
                snd_ctl_elem_id_get_subdevice(id),
                snd_ctl_elem_id_get_name(id),
                snd_ctl_elem_id_get_index(id));
}

void print_elem_info(snd_ctl_elem_list_t *list, unsigned int i)
{
        snd_ctl_elem_id_t *id;

        printf("Element #%d: numid=%d, interface=%s, device=%d, subdevice=%d, name=%s, index=%d, elem_id follows:\n\t",
                i,
                snd_ctl_elem_list_get_numid(list, i),
                snd_ctl_elem_iface_name(snd_ctl_elem_list_get_interface(list, i)),
                snd_ctl_elem_list_get_device(list, i),
                snd_ctl_elem_list_get_subdevice(list, i),
                snd_ctl_elem_list_get_name(list, i),
                snd_ctl_elem_list_get_index(list, i));

        if (snd_ctl_elem_id_malloc(&id))
        {
                printf("Error allocating snd_ctl_elem_id_t, aborting\n");
                return;
        }
        snd_ctl_elem_list_get_id(list, i, id);
        print_elem_id(id);
        snd_ctl_elem_id_free(id);
}

void print_power_state(unsigned int state)
{
        char *str;

        switch(state & SND_CTL_POWER_MASK) {
        case SND_CTL_POWER_D0:
                str = "D0";
                break;
        case SND_CTL_POWER_D1:
                str = "D1";
                break;
        case SND_CTL_POWER_D2:
                str = "D2";
                break;
        case SND_CTL_POWER_D3hot:
                str = "D3 hot";
                break;
        case SND_CTL_POWER_D3cold:
                str = "D3 cold";
                break;
        default:
                str = "Unknown";
        }

        printf("Power state = %s\n", str);
}

void print_ctl_type(snd_ctl_type_t type)
{
        char *str;

        switch(type) {
        case SND_CTL_TYPE_HW:
                str = "Kernel level CTL";
                break;
        case SND_CTL_TYPE_SHM:
                str = "Shared memory client CTL";
                break;
        case SND_CTL_TYPE_INET:
                str = "INET client CTL";
                break;
        case SND_CTL_TYPE_EXT:
                str = "External control plugin";
                break;
        default:
                str = "Unknown";
        }

        printf("CTL type = %s\n", str);
}

int main(int argc, char **argv)
{
        int card = -1;
        char cardascii[6];
        snd_ctl_t *handle;
        snd_ctl_card_info_t *card_info;
        snd_ctl_elem_list_t *elem_list;
        unsigned int used, count, power_state;

        while (snd_card_next(&card) >= 0 && card >= 0) {
                snprintf(cardascii, sizeof(cardascii), "hw:%d", card);
                if (snd_ctl_open(&handle, cardascii, 0)) {
                        printf("Error opening card #%d, skipping\n", card);
                        continue;
                }
                if (snd_ctl_card_info_malloc(&card_info)) {
                        printf("Error allocating snd_ctl_card_info_t structure, skipping\n");
                        snd_ctl_close(handle);
                        continue;
                }
                if (snd_ctl_card_info(handle, card_info)) {
                        printf("Error getting info for card #%d, skipping\n", card);
                        snd_ctl_close(handle);
                        continue;
                }
                print_card_info(card_info);
                snd_ctl_card_info_free(card_info);
                if (snd_ctl_elem_list_malloc(&elem_list)) {
                        printf("Error allocating snd_ctl_elem_list_t, skipping\n");
                        snd_ctl_close(handle);
                        continue;
                }
                if (snd_ctl_elem_list(handle, elem_list)) {
                        printf("Error getting element list, skipping\n");
                        snd_ctl_close(handle);
                        snd_ctl_elem_list_free(elem_list);
                        continue;
                }
                used = snd_ctl_elem_list_get_used(elem_list);
                count = snd_ctl_elem_list_get_count(elem_list);
                printf("Element used = %d, count = %d.  Allocating space for %d entries...\n", used, count, count);
                if (snd_ctl_elem_list_alloc_space(elem_list, count)) {
                        printf("Error allocating element list space, skipping\n");
                        snd_ctl_close(handle);
                        snd_ctl_elem_list_free(elem_list);
                        continue;
                }
                if (snd_ctl_elem_list(handle, elem_list)) {
                        printf("Error getting element list, skipping\n");
                        snd_ctl_close(handle);
                        snd_ctl_elem_list_free(elem_list);
                        snd_ctl_elem_list_free_space(elem_list);
                        continue;
                }
                used = snd_ctl_elem_list_get_used(elem_list);
                count = snd_ctl_elem_list_get_count(elem_list);
                printf("Element used = %d, count = %d\n", used, count);
                for (unsigned int i = 0; i < used; i++) {
                        print_elem_info(elem_list, i);
                }
                snd_ctl_elem_list_free_space(elem_list);
                snd_ctl_elem_list_free(elem_list);
                if (snd_ctl_get_power_state(handle, &power_state)) {
                        printf("Error getting power state, skipping\n");
                        snd_ctl_close(handle);
                        continue;
                }
                print_power_state(power_state);
                print_ctl_type(snd_ctl_type(handle));
                snd_ctl_close(handle);
        }

        printf("No more cards!\n");

        return 0;
}