For further reference: https://github.com/lxc/lxc/commit/a70c9e85a6d8ac1b75d6705d2373fd9c7b567240 Em seg, 2 de set de 2019 às 14:00, <jcfaracco@xxxxxxxxx> escreveu: > > From: Julio Faracco <jcfaracco@xxxxxxxxx> > > This is an issue for LXC loop devices when you are trying to get loop > devices info using `ioctl`. Modern apps uses `/sys/dev/block` to grab > information about devices, but if you use the method mention you won't > be able to retrive the associated file with that loop device. See > example below from cryptsetup sources: > > static char *_ioctl_backing_file(const char *loop) > { > struct loop_info64 lo64 = {0}; > int loop_fd; > > loop_fd = open(loop, O_RDONLY); > if (loop_fd < 0) > return NULL; > > if (ioctl(loop_fd, LOOP_GET_STATUS64, &lo64) < 0) { > close(loop_fd); > return NULL; > } > > lo64.lo_file_name[LO_NAME_SIZE-2] = '*'; > lo64.lo_file_name[LO_NAME_SIZE-1] = 0; > > close(loop_fd); > return strdup((char*)lo64.lo_file_name); > } > > It will return an empty string because lo_file_name was not set. > Function `virFileLoopDeviceOpenSearch()` is using `ioctl` to query data, > but it is not checking `lo_file_name` field. > > v1: I accidentally committed two wrong lines. > > Signed-off-by: Julio Faracco <jcfaracco@xxxxxxxxx> > --- > src/util/virfile.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/src/util/virfile.c b/src/util/virfile.c > index 81a3c096eb..dbfe74e24f 100644 > --- a/src/util/virfile.c > +++ b/src/util/virfile.c > @@ -781,6 +781,14 @@ int virFileLoopDeviceAssociate(const char *file, > memset(&lo, 0, sizeof(lo)); > lo.lo_flags = LO_FLAGS_AUTOCLEAR; > > + /* Set backing file name for LOOP_GET_STATUS64 queries */ > + if (virStrncpy((char *) lo.lo_file_name, file, > + strlen(file), LO_NAME_SIZE) < 0) { > + virReportSystemError(errno, > + _("Unable to set backing file %s"), file); > + goto cleanup; > + } > + > if ((fsfd = open(file, O_RDWR)) < 0) { > virReportSystemError(errno, > _("Unable to open %s"), file); > -- > 2.20.1 > -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
