Hi Hans, Thank you for the patch. On Thu, Feb 14, 2019 at 04:43:17PM +0100, Hans Verkuil wrote: > Add a --bus-info option to media-ctl which opens the media device > that has this bus info string. 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-cisco@xxxxxxxxx> > --- > diff --git a/utils/media-ctl/options.c b/utils/media-ctl/options.c > index 16367857..0430b8bc 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" > @@ -42,7 +47,9 @@ static void usage(const char *argv0) > unsigned int i; > > printf("%s [options]\n", argv0); > + printf("-b, --bus-info name Use the media device with bus info equal to name\n"); When seeing --bus-info I initially thought it was meant to print bus information. I wonder if we could find a name a bit more straightforward to guess. Would it be an option to reuse the -d option, first trying to open the specified device node, and considering it as a bus-info string if the file doesn't exist ? > 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("-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"); > @@ -121,6 +128,7 @@ static void usage(const char *argv0) > #define OPT_GET_DV 260 > > static struct option opts[] = { > + {"bus-info", 1, 0, 'b'}, > {"device", 1, 0, 'd'}, > {"entity", 1, 0, 'e'}, > {"set-format", 1, 0, 'f'}, > @@ -161,6 +169,51 @@ static void list_known_mbus_formats(void) > } > } > > +static const char *find_bus_info(const char *bus_info) > +{ > + static char newdev[300]; > + struct dirent *ep; > + DIR *dp; > + > + dp = opendir("/dev"); > + if (dp == NULL) > + return NULL; > + > + 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); You can use openat() instead of open() to avoid the snprintf. > + if (fd < 0) > + continue; > + ret = ioctl(fd, MEDIA_IOC_DEVICE_INFO, &mdi); > + close(fd); > + if (!ret && !strcmp(bus_info, mdi.bus_info)) { > + closedir(dp); > + return newdev; > + } > + } > + } > + closedir(dp); > + return NULL; Should we try to enumerate media devices using libudev, to support systems with custom udev rules ? > +} > + > +static const char *make_devname(const char *device) > +{ > + static char newdev[300]; Seems a bit long for concatenating /dev/media and a 3 characters string. > + > + if (device[0] >= '0' && device[0] <= '9' && strlen(device) <= 3) { if (isdigit(device[0]) && strlen(device) <= 3) Shouldn't you however check that the whole string parses as a number ? > + snprintf(newdev, sizeof(newdev), "/dev/media%s", device); > + return newdev; > + } > + return device; > +} > + > int parse_cmdline(int argc, char **argv) > { > int opt; > @@ -171,11 +224,20 @@ int parse_cmdline(int argc, char **argv) > } > > /* parse options */ > - while ((opt = getopt_long(argc, argv, "d:e:f:hil:prvV:", > + while ((opt = getopt_long(argc, argv, "b:d:e:f:hil:prvV:", > opts, NULL)) != -1) { > switch (opt) { > + case 'b': > + media_opts.devname = find_bus_info(optarg); > + if (!media_opts.devname) { > + fprintf(stderr, "Error: no media device with bus info '%s' found\n", > + optarg); > + return 1; > + } > + break; > + > case 'd': > - media_opts.devname = optarg; > + media_opts.devname = make_devname(optarg); > break; > > case 'e': -- Regards, Laurent Pinchart
