Add support for audio devices

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

6 files changed, 113 insertions, 2 deletions

diff --git a/Makefile b/Makefile
index 36e7dcc..a35fd79 100644
--- a/Makefile
+++ b/Makefile
@@ -31,6 +31,7 @@ OBJ =\
 	libgamepad_create_attachment_monitor.o\
 	libgamepad_destroy_attachment_monitor.o\
 	libgamepad_disable_force_feedback_autocenter.o\
+	libgamepad_find_sound_devices.o\
 	libgamepad_get_absolute_axis_info.o\
 	libgamepad_get_absolute_axis_name.o\
 	libgamepad_get_attachment_event.o\
diff --git a/TODO b/TODO
index c0f54a0..fd8cdc5 100644
--- a/TODO
+++ b/TODO
@@ -1,6 +1,5 @@
 Add support for quirks
 Add support for leds
-Add support for audio
 Add support for accelerometer
 Add support for creating instance from a file descriptor
 Add man pages
diff --git a/common.h b/common.h
index 88acdf0..3cbe4ac 100644
--- a/common.h
+++ b/common.h
@@ -1,6 +1,7 @@
 /* See LICENSE file for copyright and license details. */
 #include "libgamepad.h"
 
+#include <sys/stat.h>
 #include <ctype.h>
 #include <dirent.h>
 #include <errno.h>
diff --git a/libgamepad.h b/libgamepad.h
index 5b6c46c..46a09e2 100644
--- a/libgamepad.h
+++ b/libgamepad.h
@@ -339,6 +339,15 @@ int libgamepad_open_superdevice(struct libgamepad_superdevice *, const char *);
  */
 void libgamepad_close_superdevice(struct libgamepad_superdevice *);
 
+/**
+ * Search for sound devices built into or attached a device
+ * 
+ * @param   syspath  The superdevice's path in /sys
+ * @param   cardsp   Output parameter for a list of sound card indices
+ * @return           The number of found sound cards, -1 on failure
+ */
+ssize_t libgamepad_find_sound_devices(const char *, size_t **);
+
 
 /**
  * Create a device attachment monitor
diff --git a/libgamepad_find_sound_devices.c b/libgamepad_find_sound_devices.c
new file mode 100644
index 0000000..1688106
--- /dev/null
+++ b/libgamepad_find_sound_devices.c
@@ -0,0 +1,92 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+static int
+search(int dirfd, const char *file, size_t **cardsp, size_t *countp, struct stat *st_buf)
+{
+	int fd;
+	DIR *dir;
+	struct dirent *f;
+	unsigned long num;
+	char *end;
+	void *new;
+
+	fd = openat(dirfd, file, O_DIRECTORY);
+	if (fd < 0)
+		return -1;
+	dir = fdopendir(fd);
+	if (!dir) {
+		close(fd);
+		return -1;
+	}
+
+	if (!strcmp(file, "sound")) {
+		while (errno = 0, (f = readdir(dir))) {
+			if (strncmp(f->d_name, "card", 4) || !isdigit(f->d_name[4]))
+				continue;
+			num = strtoul(&f->d_name[4], &end, 10);
+			if (errno || *end)
+				continue;
+			if (*countp == (size_t)SSIZE_MAX)
+				break;
+			new = realloc(*cardsp, (*countp + 1) * sizeof(**cardsp));
+			if (!new)
+				goto fail;
+			*cardsp = new;
+			(*cardsp)[(*countp)++] = (size_t)num;
+		}
+	} else {
+		while (errno = 0, (f = readdir(dir))) {
+			if (f->d_name[0] == '.')
+				continue;
+			if (fstatat(fd, f->d_name, st_buf, AT_SYMLINK_NOFOLLOW))
+				goto fail;
+			if (S_ISLNK(st_buf->st_mode))
+				continue;
+			search(fd, f->d_name, cardsp, countp, st_buf);
+		}
+	}
+
+	closedir(dir);
+	return errno ? -1 : 0;
+
+fail:
+	closedir(dir);
+	return -1;
+}
+
+
+ssize_t
+libgamepad_find_sound_devices(const char *syspath, size_t **cardsp)
+{
+	int fd, i, saved_errno = errno;
+	size_t count = 0;
+	struct stat st;
+	const char *p = syspath;
+
+	*cardsp = NULL;
+
+	if (*p != '/')
+		return 0;
+	for (i = 0; i < 5; i++) {
+		p = strchr(&p[1], '/');
+		if (!p)
+			return 0;
+	}
+
+	fd = open(syspath, O_DIRECTORY);
+	if (fd < 0)
+		return -1;
+
+	if (search(fd, "../..", cardsp, &count, &st)) {
+		close(fd);
+		free(*cardsp);
+		*cardsp = NULL;
+		return -1;
+	}
+
+	close(fd);
+	errno = saved_errno;
+	return (ssize_t)count;
+}
diff --git a/test-list.c b/test-list.c
index f604dd9..51ef13b 100644
--- a/test-list.c
+++ b/test-list.c
@@ -9,7 +9,8 @@ int
 main(void)
 {
 	char **devices;
-	size_t ndevices, i, j;
+	size_t ndevices, i, j, *sound_cards;
+	ssize_t nsound_cards;
 	struct libgamepad_superdevice device;
 
 	if (libgamepad_list_superdevices(&devices, &ndevices)) {
@@ -32,6 +33,14 @@ main(void)
 			printf("\t%s (LED)\n", device.leds[j]);
 		for (j = 0; j < device.npower_supplies; j++)
 			printf("\t%s (PSU)\n", device.power_supplies[j]);
+		nsound_cards = libgamepad_find_sound_devices(device.syspath, &sound_cards);
+		if (nsound_cards < 0) {
+			perror("libgamepad_find_sound_devices");
+		} else {
+			for (j = 0; j < (size_t)nsound_cards; j++)
+				printf("\t%zu (SND)\n", sound_cards[j]);
+			free(sound_cards);
+		}
 
 		libgamepad_close_superdevice(&device);
 	}