bug#60291: chmod a-r does not fail for vfat

[Paul Eggert]

On 12/23/22 17:09, Krzysztof Żelechowski wrote:
> chmod a-r a.txt && stat a.txt
>
> Expected: chmod: unsupported permissions
> Got: -r--r--r--
> This is wrong because the command chmod had failed to set the permissions

The chmod command is doing the right thing; the problem lies elsewhere. 
Run "strace chmod a-r a.txt". You should see something like 
"fchmodat(AT_FDCWD, "a.txt", 0200) = 0" which means chmod told the 
kernel to change a.txt's permissions to -w------- and the kernel 
responded that it did so successfully.

The problem here is a squirrelly filesystem. Run "man ntfs-3g" and look 
for "Access Handling and Security".