All I can say is that I feel honored that some useful code was produced with my problem statement as an inspiration. I am doing research on the topic trying to learn all that feels like a huge gap of how disks and data relate.
Have a nice day Thomas kAt Thomas Schmitt: > Hi, > > i wrote a small program which shall make a USB stick with isohybrid ISO > more digestible for partition editors by removing all partition tables > except MBR partitions. > It then creates a new partition in the first MBR partition slot which > is found with block count 0. > > usage: ./make_isombr_part file_path partition_end partition_type > > Creates a partition in a free slot of an isohybrid MBR in an ISO. > Removes GPT and APM signatures if present. > file_path must lead to a file or device with isohybrid ISO. > partition_end tells the number of 512-byte blocks of device. > partiton_end value "auto" means full number of device blocks. > partition_type is a hex number in the range of 00 to ff. > Type examples: 83 = Linux , 0c = FAT32 , 17 = Hidden NTFS > > Binary compiled on Debian 8 (you may need to give it x-permission after > download): > > http://scdbackup.webframe.org/make_isombr_part > > MD5: 4856af2c1b50a775325a3e6c09d7d9bc > > Source code: > http://scdbackup.webframe.org/make_isombr_part.c > > The argument "auto" currently works only on Linux kernels. > On other systems one has to give the block number explicitely. > > ------------------------------------------------------------------------ > > See a test run with rescatux ISO on /dev/sdc (any current Debian i386 > or amd64 ISO would be suitable, too). > > Still less dangerous than manipulating /dev files as superuser is > to give the world temporary permission to the one stick in question: > > $ sudo chmod o+rw /dev/sdc > > (The program is supposed to refuse if it does not find an isohybrid ISO. > But better do not bet on those safety measures.) > > Let the program remove APM and GPT and add a MBR partition: > > $ chmod u+x ./make_isombr_part > > $ ./make_isombr_part /dev/sdc auto 83 > Note: Storage capacity of '/dev/sdc' : 3915776 blocks > Note: Wrote MBR partition slot 3, type 0x83, start 1374208, blocks 2541568 > Note: Removed APM signature > Note: Removed GPT signature at block 1 > Note: Removed GPT signature at block 1374207 > > Afterwards, fdisk reports the new partiton table: > > $ /sbin/fdisk -l /dev/sdc > Disk /dev/sdc: 1.9 GiB, 2004877312 bytes, 3915776 sectors > ... > Device Boot Start End Sectors Size Id Type > /dev/sdc1 * 64 1374207 1374144 671M 0 Empty > /dev/sdc2 1297212 1298619 1408 704K ef EFI (FAT-12/16/32) > /dev/sdc3 1374208 3915775 2541568 1.2G 83 Linux > > When done, exclude the world from directly reading and altering the stick > content: > > $ sudo chmod o-rw /dev/sdc > > Best unplug the stick and put it in again, so that the operating system > takes notice of the new partition table situation. > > ------------------------------------------------------------------------ > > It would be interesting to see how various partition editors react on > this state of the USB stick. Can they reduce the size of partition 3 ? > Can they remove partition 3 and add on new one ? > > ------------------------------------------------------------------------ > > Have a nice day :) > > Thomas > >
