If the device passed to the -d option is not found, then interpret it as a bus-info string and try to open all media devices and see which one reports a bus-info string equal to the -d argument.
That makes it possible to open a specific media device without having to know the name of the media device. Similar functionality has been implemented for v4l2-ctl and v4l2-compliance, and for the cec utilities. This allows scripts that no longer need to care about the name of a device node, instead they can find it based on a unique string. Also extend the -d option to support -d0 as a shorthand for /dev/media0 to make it consistent with the other utils. Signed-off-by: Hans Verkuil <hverkuil-ci...@xs4all.nl> --- Changes since v1: - fold into the -d option instead of creating a separate option --- diff --git a/utils/media-ctl/options.c b/utils/media-ctl/options.c index 16367857..fb923775 100644 --- a/utils/media-ctl/options.c +++ b/utils/media-ctl/options.c @@ -19,13 +19,18 @@ * along with this program. If not, see <http://www.gnu.org/licenses/>. */ +#include <ctype.h> +#include <dirent.h> +#include <fcntl.h> #include <getopt.h> #include <stdio.h> #include <stdlib.h> #include <string.h> +#include <sys/ioctl.h> #include <unistd.h> #include <v4l2subdev.h> +#include <linux/media.h> #include <linux/videodev2.h> #include "options.h" @@ -43,6 +48,9 @@ static void usage(const char *argv0) printf("%s [options]\n", argv0); printf("-d, --device dev Media device name (default: %s)\n", MEDIA_DEVNAME_DEFAULT); + printf(" If <dev> starts with a digit, then /dev/media<dev> is used.\n"); + printf(" If <dev> doesn't exist, then find a media device that\n"); + printf(" reports a bus info string equal to <dev>.\n"); printf("-e, --entity name Print the device name associated with the given entity\n"); printf("-V, --set-v4l2 v4l2 Comma-separated list of formats to setup\n"); printf(" --get-v4l2 pad Print the active format on a given pad\n"); @@ -161,6 +169,48 @@ static void list_known_mbus_formats(void) } } +static const char *make_devname(const char *device) +{ + static char newdev[300]; + struct dirent *ep; + DIR *dp; + + if (!access(device, F_OK)) + return device; + + if (device[0] >= '0' && device[0] <= '9' && strlen(device) <= 3) { + snprintf(newdev, sizeof(newdev), "/dev/media%s", device); + return newdev; + } + + dp = opendir("/dev"); + if (dp == NULL) + return device; + + while ((ep = readdir(dp))) { + const char *name = ep->d_name; + + if (!memcmp(name, "media", 5) && isdigit(name[5])) { + struct media_device_info mdi; + int ret; + int fd; + + snprintf(newdev, sizeof(newdev), "/dev/%s", name); + fd = open(newdev, O_RDWR); + if (fd < 0) + continue; + ret = ioctl(fd, MEDIA_IOC_DEVICE_INFO, &mdi); + close(fd); + if (!ret && !strcmp(device, mdi.bus_info)) { + closedir(dp); + return newdev; + } + } + } + closedir(dp); + return device; +} + int parse_cmdline(int argc, char **argv) { int opt; @@ -175,7 +225,7 @@ int parse_cmdline(int argc, char **argv) opts, NULL)) != -1) { switch (opt) { case 'd': - media_opts.devname = optarg; + media_opts.devname = make_devname(optarg); break; case 'e':
