PeterBee97 commented on code in PR #18745:
URL: https://github.com/apache/nuttx/pull/18745#discussion_r3206138456
##########
arch/sim/src/sim/posix/sim_host_v4l2.c:
##########
@@ -84,27 +86,246 @@ static int host_video_ioctl(int fd, int request, void *arg)
return r;
}
+static int host_video_parse_device_index(const char *name, int *index)
+{
+ long value;
+ char *endptr;
+
+ if (strncmp(name, "video", 5) != 0)
+ {
+ return -EINVAL;
+ }
+
+ name += 5;
+ if (*name == '\0')
+ {
+ return -EINVAL;
+ }
+
+ value = strtol(name, &endptr, 10);
+ if (*endptr != '\0' || value < 0 || value > INT_MAX)
+ {
+ return -EINVAL;
+ }
+
+ *index = value;
+ return 0;
+}
+
+static int host_video_get_next_device_path(int current_index,
+ char *devpath,
+ size_t devpathlen,
+ int *next_index)
+{
+ DIR *dir;
+ struct dirent *entry;
+ int candidate;
+ int found = INT_MAX;
+
+ dir = opendir("/dev");
+ if (dir == NULL)
+ {
+ return -errno;
+ }
+
+ while ((entry = readdir(dir)) != NULL)
+ {
+ if (host_video_parse_device_index(entry->d_name, &candidate) < 0 ||
+ candidate <= current_index || candidate >= found)
+ {
+ continue;
+ }
+
+ found = candidate;
+ }
+
+ closedir(dir);
+
+ if (found == INT_MAX)
+ {
+ return -ENODEV;
+ }
+
+ if (snprintf(devpath, devpathlen, "/dev/video%d", found) >=
+ (int)devpathlen)
+ {
+ return -ENAMETOOLONG;
+ }
+
+ *next_index = found;
+ return 0;
+}
+
+static bool host_video_is_capture_device(const char *host_video_dev_path)
+{
+ struct v4l2_capability cap;
+ int fd;
+ bool available = false;
+
+ fd = open(host_video_dev_path, O_RDWR | O_NONBLOCK);
+ if (fd < 0)
+ {
+ fd = open(host_video_dev_path, O_RDONLY | O_NONBLOCK);
+ if (fd < 0)
+ {
+ return false;
+ }
+ }
+
+ memset(&cap, 0, sizeof(cap));
+ if (host_video_ioctl(fd, VIDIOC_QUERYCAP, &cap) == 0)
+ {
+ uint32_t capabilities = cap.device_caps != 0 ? cap.device_caps :
+ cap.capabilities;
+
+ if ((capabilities & V4L2_CAP_VIDEO_CAPTURE) != 0)
+ {
+ available = true;
+ }
+ }
+
+ close(fd);
+ return available;
+}
+
+static int host_video_get_device_path_by_index(int index,
+ char *devpath,
+ size_t devpathlen)
+{
+ int count = 0;
+ int current_index = -1;
+ int ret;
+ char path[PATH_MAX];
+
+ while ((ret = host_video_get_next_device_path(current_index, path,
+ sizeof(path),
+ ¤t_index)) == 0)
+ {
+ if (!host_video_is_capture_device(path))
+ {
+ continue;
+ }
+
+ if (count == index)
+ {
+ if (snprintf(devpath, devpathlen, "%s", path) >=
+ (int)devpathlen)
+ {
+ return -ENAMETOOLONG;
+ }
+
+ return 0;
+ }
+
+ count++;
+ }
+
+ return ret;
Review Comment:
done
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