On Thursday, 16 May 2024 10:42:16 BST Nuno Silva wrote: > On 2024-05-16, Walter Dnes wrote: > > On Wed, May 15, 2024 at 03:06:50PM -0700, Mark Knecht wrote > > > >> Have you checked that the directory where you are attempting to > >> do this is one that your account owns? I generally have to su - to > >> root, create a directory at the top level, change it so that I own it and > >> have rwx permissions, and then exit root. After that I can do what I > >> want. > >> > > I have a short script ~/bin/tabon > > > > [x8940][waltdnes][~] cat bin/tabon > > #!/bin/bash > > sudo /usr/bin/jmtpfs /home/waltdnes/tablet -o allow_other,auto_unmount,rw > > # > > # Only needed once > > #sudo /bin/chown -R waltdnes:users /home/waltdnes/tablet > > > > The last (commented out) line *USED TO WORK*. Now it spits out a > > > > whole slew of... > > > > /bin/chown: changing ownership of > > '/home/waltdnes/tablet/sdcard1/blah_blah_blah': Function not implemented > > > > ...one for each direcory and file. I believe the phone formats the card > > as either FAT32 or XFAT. > > Did anything change? Any tablet software upgrade? Did the MTP tool on > the computer side change? Or perhaps the kernel, if it can influence > this FUSE interaction somehow? > > At this point I'd consider testing with known good versions if possible > (those that can run chown without that error). Is mkdir something that > used to work too? > > The "Function not implemented" looks off for something that used to work > before. (Or was it failing silently before? If this is FAT* or exFAT, > wouldn't ownership be a thing for the FUSE tool to set itself? Or does > exFAT have the concept of ownership?)
FAT/exFAT do not support filesystem level user permissions and consequently you would get a "Function not implemented" error with chown. When a USB device with a FAT/exFAT fs, is mounted with udisksctl they show up as: $ lsblk -o PATH,TYPE,FSTYPE,OWNER,GROUP,MODE,MOUNTPOINT /dev/sdb1 PATH TYPE FSTYPE OWNER GROUP MODE MOUNTPOINT /dev/sdb1 part vfat root disk brw-rw---- /run/media/michael/CRUCIAL-8G and the fs is mounted with the sticky bit so it writeable by the user: $ ls -la /run/media/michael/CRUCIAL-8G/ total 2500976 drwxr-xr-x 2 michael michael 16384 Jan 1 1970 . drwxr-x---+ 3 root root 60 May 16 15:52 .. exFAT looks the same if you have enabled the exFAT kernel driver, as opposed to using FUSE. I don't have a device using MTP here to check how it is mounted over FUSE, but FUSE is meant to mount a device with the permissions of the user who mounts it AND the user can only mount on a mountpoint for which they have write permission. However, there is a kernel bug if the default_permissions mount option has not been used, whereby results of the first permission check performed by the file system for a directory entry are cached and reused - even if the permissions have since changed - see here: https://github.com/libfuse/libfuse I do remember having some trouble creating directories on an SD card in a GARMIN GPS device. I had to remove it and mount it on Linux to be able to work on it, but can't recall the details.
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