More recent versions of blkid don't report an ISO9660 file system on the
whole disk device if partitions can be reports for embedded partitions.
However when querying the whole disk device directly then the expected
ISO9660 file system is reported. For example on CentOS 7 with the
previous ISO images:
# wget http://git.kernel.org/cgit/utils/util-linux/util-linux.git/plain/tests/ts/isosize/sample.iso.gz
# dd if=/dev/zero bs=1M of=/dev/sdc
# zcat sample.iso.gz | dd of=/dev/sdc
# blkid -v
blkid from util-linux 2.23.2 (libblkid 2.23.0, 25-Apr-2013)
# blkid | fgrep /dev/sdc
/dev/sdc1: UUID="2013-01-04-22-05-45-00" LABEL="ARCH_201301" TYPE="iso9660" PTTYPE="dos"
# blkid /dev/sdc
/dev/sdc: UUID="2013-01-04-22-05-45-00" LABEL="ARCH_201301" TYPE="iso9660" PTTYPE="dos"
# wget http://cdimage.debian.org/debian-cd/8.6.0/amd64/iso-cd/debian-8.6.0-amd64-netinst.iso
# dd if=/dev/zero bs=1M of=/dev/sdc
# dd if=debian-8.6.0-amd64-netinst.iso bs=1M of=/dev/sdc
# blkid | fgrep /dev/sdc
/dev/sdc1: UUID="2016-09-17-14-23-48-00" LABEL="Debian 8.6.0 amd64 1" TYPE="iso9660" PTTYPE="dos"
/dev/sdc2: SEC_TYPE="msdos" UUID="17F3-1162" TYPE="vfat"
# blkid /dev/sdc
/dev/sdc: UUID="2016-09-17-14-23-48-00" LABEL="Debian 8.6.0 amd64 1" TYPE="iso9660" PTTYPE="dos"
This behavioural difference with blkid is probably as a result of newer
versions of udev informing the kernel of the partitions embedded within
the ISO9660 image, and not directly as a result of a change in blkid
itself. Older distributions don't have partition entries for the above
ISO images, but CentOS 7 (with udev 219) and later distributions do have
partition entries:
# fgrep sdc /proc/partitions
8 16 8388608 sdc
8 17 252928 sdc1
8 18 416 sdc2
Fix by ensuring that the blkid FS_Info cache has entries for whole disk
devices, even if each entry has all empty attributes because there is a
partition table and not a recognised file system.
Calling blkid on whole disk devices containing partition tables produces
output like this, with newer versions of blkid:
# blkid /dev/sda
/dev/sda: PTTYPE="dos"
# blkid /dev/sdb
/dev/sdb: PTTYPE="gpt"
This will be loaded into the FS_Info cache as a blank entry for the
device by run_blkid_load_cache(). There will be a path name but all the
other attributes will be blank because there are no TYPE, SEC_TYPE, UUID
or LABEL name value pairs. With older versions of blkid no output is
produced at all. In that case load_fs_info_cache_extra_for_path() will
create the same blank entry with just the path name defined.
Bug 771244 - gparted does not recognize the iso9660 file system in
cloned Ubuntu USB boot drives
b2190372d0