First commit

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 302 insertions, 0 deletions

diff --git a/alsause.c b/alsause.c
new file mode 100644
index 0000000..e157e71
--- /dev/null
+++ b/alsause.c
@@ -0,0 +1,302 @@
+/* See LICENSE file for copyright and license details. */
+#include <sys/mount.h>
+#include <sched.h>
+#include <alsa/asoundlib.h>
+#include <libsimple.h>
+#include <libsimple-arg.h>
+
+NUSAGE(125, "[(-r | name | card:device) [command [argument] ...]]");
+
+
+static char *
+get_config_path(void)
+{
+	const char *home = getenv("HOME");
+	char *ret;
+	if (!home) {
+		struct passwd *pw;
+		errno = 0;
+		pw = getpwuid(getuid());
+		if (!pw || !pw->pw_dir)
+			eprintf("pwgetuid <real user>: %s", (!errno || errno == EIO) ? "User does not exist" : strerror(errno));
+		home = pw->pw_dir;
+	}
+	if (strlen(home) > SIZE_MAX - sizeof("/.asoundrc") ||
+	    !(ret = malloc(strlen(home) + sizeof("/.asoundrc")))) {
+		errno = ENOMEM;
+		eprintf("malloc:");
+	}
+	stpcpy(stpcpy(ret, home), "/.asoundrc");
+	return ret;
+}
+
+
+#if defined(__GNUC__)
+__attribute__((__pure__))
+#endif
+static int
+is_name(const char *s)
+{
+	if (!isdigit(*s))
+		return 1;
+	if (*s == '0' && s[1] != ':')
+		return 1;
+	while (isdigit(*s))
+		s++;
+	if (*s != ':')
+		return 1;
+	s++;
+
+	if (!isdigit(*s))
+		return 1;
+	if (*s == '0' && s[1])
+		return 1;
+	while (isdigit(*s))
+		s++;
+	if (*s)
+		return 1;
+	return 0;
+}
+
+
+static int
+list_outputs(const char *find, int *card_out, int *device_out)
+{
+	snd_ctl_t *ctl;
+	snd_ctl_card_info_t *info;
+	snd_pcm_info_t *pcminfo;
+	char dev[sizeof("hw:") + 3 * sizeof(int)];
+	int r, card, device, failed = 0;
+
+	snd_ctl_card_info_alloca(&info);
+	snd_pcm_info_alloca(&pcminfo);
+
+	for (card = -1;;) {
+		r = snd_card_next(&card);
+		if (r < 0) {
+			weprintf("snd_card_next: %s", snd_strerror(r));
+			return -1;
+		}
+		if (card < 0)
+			break;
+
+		sprintf(dev, "hw:%i", card);
+		r = snd_ctl_open(&ctl, dev, 0);
+		if (r < 0) {
+			weprintf("snd_ctl_open %s 0: %s", dev, snd_strerror(r));
+			failed = 1;
+			continue;
+		}
+
+		r = snd_ctl_card_info(ctl, info);
+		if (r < 0) {
+			weprintf("snd_ctl_card_info <%s>: %s", dev, snd_strerror(r));
+			failed = 1;
+			goto close_card;
+		}
+
+		for (device = -1;;) {
+			r = snd_ctl_pcm_next_device(ctl, &device);
+			if (r < 0) {
+				weprintf("snd_ctl_pcm_next_device <%s>: %s", dev, snd_strerror(r));
+				failed = 1;
+				goto close_card;
+			}
+			if (device < 0)
+				break;
+
+			snd_pcm_info_set_device(pcminfo, (unsigned int)device);
+			snd_pcm_info_set_subdevice(pcminfo, 0);
+			snd_pcm_info_set_stream(pcminfo, SND_PCM_STREAM_PLAYBACK);
+			r = snd_ctl_pcm_info(ctl, pcminfo);
+			if (r < 0) {
+				if (r == -ENOENT)
+					continue;
+				weprintf("snd_ctl_pcm_info <%s>: %s (%i)", dev, snd_strerror(r), r);
+				failed = 1;
+				goto close_card;
+			}
+
+			if (find) {
+				const char *s, *n = find;
+				s = snd_ctl_card_info_get_name(info);
+				if (strncmp(n, s, strlen(s)))
+					continue;
+				n = &n[strlen(s)];
+				if (strncmp(n, " - ", 3))
+					continue;
+				n = &n[3];
+				s = snd_pcm_info_get_name(pcminfo);
+				if (strcmp(n, s))
+					continue;
+				*card_out = snd_ctl_card_info_get_card(info);
+				*device_out = device;
+				snd_ctl_close(ctl);
+				return 0;
+			} else {
+				printf("%i:%i\t%s - %s\n",
+				       snd_ctl_card_info_get_card(info), device,
+				       snd_ctl_card_info_get_name(info),
+				       snd_pcm_info_get_name(pcminfo));
+			}
+		}
+
+	close_card:
+		snd_ctl_close(ctl);
+	}
+
+	if (find) {
+		*card_out = -1;
+		*device_out = -1;
+	}
+	return -failed;
+}
+
+
+static int
+writeall(int fd, void *data, size_t len)
+{
+	char *text = data;
+	ssize_t r;
+	while (len) {
+		r = write(fd, text, len);
+		if (r < 0) {
+			if (errno == EINTR)
+				continue;
+			return -1;
+		}
+		text = &text[r];
+		len -= (size_t)r;
+	}
+	return 0;
+}
+
+
+int
+main(int argc, char *argv[])
+{
+	int reset = 0;
+
+	libsimple_default_failure_exit = 125;
+
+	ARGBEGIN {
+	case 'r':
+		reset = 1;
+		break;
+	default:
+		usage();
+	} ARGEND;
+
+	if (!argc) {
+		if (reset) {
+			char *path = get_config_path();
+			if (unlink(path) && errno != ENOENT)
+				eprintf("unlink %s:", path);
+			free(path);
+		} else {
+			if (list_outputs(NULL, NULL, NULL))
+				return libsimple_default_failure_exit;
+		}
+	} else {
+		char *path = get_config_path();
+		char *text, temppath[sizeof("/tmp/alsause.") + 3 * sizeof(uintmax_t)];
+		int len, fd, treefd;
+		if (reset) {
+			text = NULL;
+			len = 0;
+		} else if (is_name(argv[0])) {
+			int card, device;
+			if (list_outputs(argv[0], &card, &device))
+				return 1;
+			if (card == -1 || device == -1)
+				eprintf("audio output \"%s\" not found", argv[0]);
+			len = snprintf(NULL, 0, "defaults.pcm.card %i\ndefaults.pcm.device %i\n", card, device);
+			if (len < 0)
+				eprintf("snprintf NULL 0:");
+			text = malloc((size_t)len + 1U);
+			if (!text)
+				eprintf("malloc:");
+			if (sprintf(text, "defaults.pcm.card %i\ndefaults.pcm.device %i\n", card, device) != len)
+				abort();
+			argc--;
+			argv++;
+		} else {
+			char *card = argv[0];
+			char *device = strchr(card, ':');
+			if (!device)
+				usage();
+			*device++ = '\0';
+			if (strchr(device, ':'))
+				usage();
+			len = snprintf(NULL, 0, "defaults.pcm.card %s\ndefaults.pcm.device %s\n", card, device);
+			if (len < 0)
+				eprintf("snprintf NULL 0:");
+			text = malloc((size_t)len + 1U);
+			if (!text)
+				eprintf("malloc:");
+			if (sprintf(text, "defaults.pcm.card %s\ndefaults.pcm.device %s\n", card, device) != len)
+				abort();
+			argc--;
+			argv++;
+		}
+
+		if (!argc) {
+			fd = open(path, O_CREAT | O_TRUNC | O_WRONLY, 0666);
+			if (fd < 0)
+				eprintf("open %s O_CREAT|O_TRUNC|O_WRONLY 0666:", path);
+			if (fchown(fd, getuid(), getgid()))
+				weprintf("fchown %s <read user> <real path>:", path);
+			if (writeall(fd, text, (size_t)len) || (close(fd) && (errno != EINTR)))
+				eprintf("write %s:", path);
+			free(text);
+			free(path);
+			return 0;
+		}
+
+		if (unshare(CLONE_NEWNS))
+			eprintf("unshare CLONE_NEWNS:");
+		if (mount("none", "/", NULL, MS_REC | MS_SLAVE, NULL))
+			eprintf("mount none / NULL MS_REC|MS_SLAVE NULL:");
+
+		fd = open(path, O_CREAT | O_EXCL | O_WRONLY, 0666);
+		if (fd >= 0) {
+			fchown(fd, getuid(), getgid());
+			close(fd);
+		}
+
+		sprintf(temppath, "/tmp/alsause.%ju", (uintmax_t)getpid());
+		unlink(temppath);
+		fd = open(temppath, O_CREAT | O_EXCL | O_WRONLY, 0666);
+		if (fd < 0)
+			eprintf("open %s O_CREAT|O_EXCL|O_WRONLY 0666:", temppath);
+		if (fchown(fd, getuid(), getgid()))
+			weprintf("fchown %s <read user> <real path>:", temppath);
+		if (writeall(fd, text, (size_t)len) || (close(fd) && (errno != EINTR)))
+			eprintf("write %s:", temppath);
+		free(text);
+
+		treefd = open_tree(AT_FDCWD, temppath, OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC);
+		if (treefd < 0) {
+			weprintf("open_tree AT_FDCWD %s OPEN_TREE_CLONE:", temppath);
+			unlink(temppath);
+			exit(libsimple_default_failure_exit);
+		}
+		if (move_mount(treefd, "", AT_FDCWD, path, MOVE_MOUNT_F_EMPTY_PATH)) {
+			weprintf("move_mount %s \"\" AT_FDCWD %s MOVE_MOUNT_F_EMPTY_PATH:", temppath, path);
+			unlink(temppath);
+			exit(libsimple_default_failure_exit);
+		}
+
+		if (unlink(temppath))
+			weprintf("unlink %s:", temppath);
+		if (setegid(getgid()))
+			eprintf("setegid <real group>:");
+		if (seteuid(getuid()))
+			eprintf("seteuid <real user>:");
+
+		execvp(argv[0], argv);
+		enprintf(errno == ENOENT ? 127 : 126, "execvp %s:", argv[0]);
+	}
+
+	return 0;
+}