Enumerate v4l2 devices

device/v4l2/device_list.c

@@ -0,0 +1,97 @@
+#include "v4l2.h"
+#include "device/device_list.h"
+#include "util/opts/log.h"
+
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <dirent.h>
+
+static void device_list_read_formats(int fd, device_info_formats_t *formats, enum v4l2_buf_type buf_type)
+{
+  for (int i = 0; ; ++i) {
+    struct v4l2_fmtdesc format_desc;
+    memset(&format_desc, 0, sizeof(format_desc));
+    format_desc.type = (enum v4l2_buf_type) buf_type;
+    format_desc.index = i;
+
+    if (-1 == ioctl(fd, VIDIOC_ENUM_FMT, &format_desc)) {
+      break;
+    }
+
+    formats->n++;
+    formats->formats = realloc(formats->formats, sizeof(formats->formats[0]) * formats->n);
+    formats->formats[formats->n - 1] = format_desc.pixelformat;
+  }
+}
+
+static bool device_list_read_dev(device_info_t *info, const char *name)
+{
+  asprintf(&info->path, "/dev/%s", name);
+
+  int fd = open(info->path, O_RDWR|O_NONBLOCK);
+  if (fd < 0) {
+    LOG_ERROR(NULL, "Can't open device: %s", info->path);
+  }
+
+  struct v4l2_capability v4l2_cap;
+  ERR_IOCTL(info, fd, VIDIOC_QUERYCAP, &v4l2_cap, "Can't query device capabilities");
+  info->name = strdup((const char *)v4l2_cap.card);
+
+  if (!(v4l2_cap.capabilities & V4L2_CAP_STREAMING)) {
+    LOG_VERBOSE(info, "Device (%s) does not support streaming (skipping)", info->path);
+    goto error;
+  } else if ((v4l2_cap.capabilities & V4L2_CAP_VIDEO_CAPTURE) && !(v4l2_cap.capabilities & V4L2_CAP_VIDEO_OUTPUT)) {
+    info->camera = true;
+  } else if (!(v4l2_cap.capabilities & (V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_VIDEO_CAPTURE_MPLANE | V4L2_CAP_VIDEO_M2M_MPLANE))) {
+    LOG_VERBOSE(info, "Device (%s) does not support capture (skipping)", info->path);
+    goto error;
+  } else if (!(v4l2_cap.capabilities & (V4L2_CAP_VIDEO_OUTPUT | V4L2_CAP_VIDEO_OUTPUT_MPLANE | V4L2_CAP_VIDEO_M2M_MPLANE))) {
+    LOG_VERBOSE(info, "Device (%s) does not support output (skipping)", info->path);
+    goto error;
+  } else if ((v4l2_cap.capabilities & V4L2_CAP_VIDEO_M2M) || (v4l2_cap.capabilities & V4L2_CAP_VIDEO_M2M_MPLANE)) {
+    info->m2m = true;
+  }
+
+  device_list_read_formats(fd, &info->capture_formats, V4L2_BUF_TYPE_VIDEO_CAPTURE);
+  device_list_read_formats(fd, &info->capture_formats, V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE);
+  device_list_read_formats(fd, &info->output_formats, V4L2_BUF_TYPE_VIDEO_OUTPUT);
+  device_list_read_formats(fd, &info->output_formats, V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE);
+  close(fd);
+
+  return true;
+
+error:
+  free(info->name);
+  free(info->path);
+  close(fd);
+  return false;
+}
+
+device_list_t *device_list_v4l2()
+{
+  DIR *dev = opendir("/dev");
+  if (!dev) {
+    return NULL;
+  }
+
+  device_list_t *list = calloc(1, sizeof(device_list_t));
+  struct dirent *ent;
+
+  while ((ent = readdir(dev)) != NULL) {
+    if (strstr(ent->d_name, "video") != ent->d_name) {
+      continue;
+    }
+
+    device_info_t info = {NULL};
+    if (device_list_read_dev(&info, ent->d_name)) {
+      list->ndevices++;
+      list->devices = realloc(list->devices, sizeof(info) * list->ndevices);
+      list->devices[list->ndevices-1] = info;
+    }
+  }
+
+  closedir(dev);
+
+  return list;
+}