/* See LICENSE file for copyright and license details. */
#include "common.h"


int
libgamepad_list_superdevices(char ***devicesp, size_t *ndevicesp)
{
	char *path, *target;
	size_t path_size, target_size = 256;
	const size_t path_size_base = sizeof("/sys/class/input//device/device");
	int dirfd;
	DIR *dir;
	struct dirent *f;
	ssize_t r;
	char **paths = NULL;
	size_t n = 0, i;
	void *new;
	int saved_errno = errno;

	*devicesp = NULL;
	*ndevicesp = 0;

	dirfd = open("/sys/class/input/", O_DIRECTORY);
	if (dirfd < 0)
		return -1;

	dir = fdopendir(dirfd);
	if (!dir) {
		close(dirfd);
		return -1;
	}

	path_size = path_size_base + 255;
	path_size = path_size > sizeof("/dev/fd/") + 3 * sizeof(int) ? path_size : sizeof("/dev/fd/") + 3 * sizeof(int);
	path = malloc(path_size);
	if (!path)
		goto fail;

	target = malloc(target_size);
	if (!target)
		goto fail;

	while (errno = 0, (f = readdir(dir))) {
		if (!strncmp(f->d_name, "event", 5) && isdigit(f->d_name[5])) {
			if (path_size_base + strlen(f->d_name) > path_size) {
				path_size = path_size_base + strlen(f->d_name);
				new = realloc(path, path_size);
				if (!new)
					goto fail;
				path = new;
			}
			stpcpy(stpcpy(stpcpy(path, "/sys/class/input/"), f->d_name), "/device/device");
			dirfd = open(path, O_PATH);
			if (dirfd < 0)
				continue;

			sprintf(path, "/dev/fd/%i", dirfd);
			for (;;) {
				r = readlink(path, target, target_size);
				if (r < 0) {
					close(dirfd);
					goto next;
				}
				if ((size_t)r < target_size) {
					close(dirfd);
					target[r] = '\0';
					break;
				}
				new = realloc(target, target_size += 256);
				if (!new)
					goto fail;
				target = new;
			}

			if (paths)
				for (i = 0; i < n; i++)
					if (!strcmp(paths[i], target))
						goto next;
			stpcpy(stpcpy(path, target), "/input");
			if (access(path, F_OK))
				continue;
			new = realloc(paths, (n + 1) * sizeof(*paths));
			if (!new)
				goto fail;
			paths = new;
			paths[n] = strdup(target);
			if (!paths[n])
				goto fail;
			n += 1;
		}
	next:;
	}

	if (errno)
		goto fail;
	free(path);
	free(target);
	closedir(dir);

	errno = saved_errno;
	*devicesp = paths;
	*ndevicesp = n;
	return 0;

fail:
	for (i = 0; i < n; i++)
		free(paths[i]);
	free(paths);
	free(path);
	free(target);
	closedir(dir);
	return -1;
}