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October 31, 2021 19:37
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Makes all alsa devices available to jack using alsa_in and alsa_out programs. Polls alsa hw devices every 5 seconds to spawn / kill alsa_out programs as needed.
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| #define _DEFAULT_SOURCE | |
| #include <stdio.h> | |
| #include <spawn.h> | |
| #include <alloca.h> | |
| #include <stdlib.h> | |
| #include <string.h> | |
| #include <unistd.h> | |
| #include <signal.h> | |
| #include <assert.h> | |
| #include <stdbool.h> | |
| #include <alsa/asoundlib.h> | |
| struct device_entry { | |
| struct device_entry* next; | |
| int card, dev, stream; | |
| char* desc; | |
| pid_t pid; | |
| }; | |
| struct device_entry* device_list = 0; | |
| bool running = true; | |
| void on_card_removed(struct device_entry* entry){ | |
| printf("on_card_removed: %c %s\n", entry->stream == SND_PCM_STREAM_PLAYBACK ? '>' : '<', entry->desc); | |
| if(entry->desc) | |
| free(entry->desc); | |
| entry->desc = 0; | |
| if(entry->pid){ | |
| kill(entry->pid, SIGTERM); | |
| if(fork() == 0){ | |
| sleep(2); | |
| kill(entry->pid, SIGKILL); | |
| _Exit(0); | |
| } | |
| } | |
| } | |
| void on_card_added(struct device_entry* entry){ | |
| char name[30]; | |
| snprintf(name, sizeof(name), "hw:%d,%d", entry->card, entry->dev); | |
| printf("on_card_added: %c %s\n", entry->stream == SND_PCM_STREAM_PLAYBACK ? '>' : '<',entry->desc); | |
| int pid = 0; | |
| char* bin = "alsa_out"; | |
| if(entry->stream == SND_PCM_STREAM_CAPTURE) | |
| bin = "alsa_in"; | |
| if(posix_spawnp(&pid, bin, 0, 0, (char*const[]){bin, "-d",name,"-j",entry->desc,0}, 0) == 0){ | |
| entry->pid = pid; | |
| }else{ | |
| perror("posix_spawnp failed"); | |
| } | |
| } | |
| void update_card(struct device_entry*** lit, int card, int dev, int stream, const char* desc){ | |
| struct device_entry** it = *lit; | |
| struct device_entry* entry = *it; | |
| while(entry && entry->card < card && entry->dev < dev && entry->stream < stream){ | |
| struct device_entry* old = entry; | |
| *it = entry = old->next; | |
| on_card_removed(old); | |
| free(old); | |
| } | |
| bool new = false; | |
| bool changed = false; | |
| if(!entry || entry->card != card || entry->dev != dev || entry->stream != stream){ | |
| struct device_entry* enew = calloc(1, sizeof(struct device_entry)); | |
| enew->card = card; | |
| enew->dev = dev; | |
| enew->stream = stream; | |
| enew->next = entry; | |
| entry = enew; | |
| *it = enew; | |
| changed = true; | |
| new = true; | |
| } | |
| *lit = it = &entry->next; | |
| if(entry->desc && desc && strcmp(entry->desc, desc)) | |
| changed = true; | |
| if(!changed) | |
| return; | |
| if(!new) | |
| on_card_removed(entry); | |
| entry->desc = strdup(desc); | |
| on_card_added(entry); | |
| } | |
| void check_cards(void){ | |
| snd_ctl_card_info_t *info = 0; | |
| snd_ctl_card_info_alloca(&info); | |
| snd_pcm_info_t* pcminfo = 0; | |
| snd_pcm_info_alloca(&pcminfo); | |
| struct device_entry** it = &device_list; | |
| for(int card=-1;;){ | |
| { | |
| int ret = snd_card_next(&card); | |
| if(ret){ | |
| fprintf(stderr, "snd_card_next failed: %s\n", snd_strerror(ret)); | |
| break; | |
| } | |
| } | |
| if(card < 0) | |
| break; | |
| char name[32]; | |
| snprintf(name, sizeof(name), "hw:%d", card); | |
| snd_ctl_t* handle=0; | |
| { | |
| int ret = snd_ctl_open(&handle, name, 0); | |
| if(ret){ | |
| fprintf(stderr, "snd_ctl_open(\"%s\") failed: %s\n", name, snd_strerror(ret)); | |
| goto next_card; | |
| } | |
| } | |
| { | |
| int ret = snd_ctl_card_info(handle, info); | |
| if(ret){ | |
| fprintf(stderr, "snd_ctl_card_info(\"%s\") failed: %s\n", name, snd_strerror(ret)); | |
| goto next_card; | |
| } | |
| } | |
| for(int dev=-1;;){ | |
| { | |
| int ret = snd_ctl_pcm_next_device(handle, &dev); | |
| if(ret){ | |
| fprintf(stderr, "snd_ctl_pcm_next_device(\"%s\"): %s\n", name, snd_strerror(ret)); | |
| break; | |
| } | |
| } | |
| if(dev < 0) | |
| break; | |
| for(int i=0; i<2; i++){ | |
| static_assert(SND_PCM_STREAM_PLAYBACK < SND_PCM_STREAM_CAPTURE); | |
| const int stream = ((int[]){SND_PCM_STREAM_PLAYBACK,SND_PCM_STREAM_CAPTURE})[i]; | |
| snd_pcm_info_set_device(pcminfo, dev); | |
| snd_pcm_info_set_subdevice(pcminfo, 0); | |
| snd_pcm_info_set_stream(pcminfo, stream); | |
| { | |
| int ret = snd_ctl_pcm_info(handle, pcminfo); | |
| if(ret){ | |
| if(ret == -ENOENT) | |
| continue; | |
| fprintf(stderr, "snd_ctl_pcm_info(\"%s,%d\"): %s\n", name, dev, snd_strerror(ret)); | |
| continue; | |
| } | |
| } | |
| char desc[30]; // Jack doesn't seam to be able to handle more... | |
| *desc = 0; | |
| snprintf(desc, sizeof(desc), "hw:%d.%d\t%s\t%s", | |
| card, dev, snd_ctl_card_info_get_name(info), snd_pcm_info_get_id(pcminfo)); | |
| update_card(&it, card, dev, stream, desc); | |
| } | |
| } | |
| next_card: | |
| snd_ctl_close(handle); | |
| } | |
| while(*it){ | |
| struct device_entry* entry = *it; | |
| *it = entry->next; | |
| on_card_removed(entry); | |
| free(entry); | |
| } | |
| } | |
| void cleanup(void){ | |
| struct device_entry* entry = device_list; | |
| while(entry){ | |
| struct device_entry* next = entry->next; | |
| on_card_removed(entry); | |
| free(entry); | |
| entry = next; | |
| } | |
| device_list = 0; | |
| } | |
| void set_quit(int signo){ | |
| (void)signo; | |
| running = false; | |
| } | |
| int main(){ | |
| atexit(cleanup); | |
| signal(SIGCHLD, SIG_IGN); | |
| signal(SIGTERM, set_quit); | |
| signal(SIGINT, set_quit); | |
| signal(SIGHUP, SIG_IGN); | |
| while(running){ | |
| check_cards(); | |
| snd_config_update_free_global(); | |
| sleep(5); | |
| } | |
| } |
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