Add support for findmnt

[Harshit933]

For now the output of findmnt is:

[harshit:~/dev/util-linux (findmnt|✔)] target/debug/util-linux findmnt
 target                                     source          fstype       options                                                                                               
 /                                          /dev/nvme0n1p7  ext4         rw,relatime                                                                                           
 /proc                                      proc            proc         rw,nosuid,nodev,noexec,relatime                                                                       
 /proc/sys/fs/binfmt_misc                   systemd-1       autofs       rw,relatime,fd=41,pgrp=1,timeout=0,minproto=5,maxproto=5,direct,pipe_ino=6207                         
 /proc/sys/fs/binfmt_misc                   binfmt_misc     binfmt_misc  rw,nosuid,nodev,noexec,relatime                                                                       
 /sys                                       sys             sysfs        rw,nosuid,nodev,noexec,relatime                                                                       
 /sys/firmware/efi/efivars                  efivarfs        efivarfs     rw,nosuid,nodev,noexec,relatime                                                                       
 /sys/kernel/security                       securityfs      securityfs   rw,nosuid,nodev,noexec,relatime                                                                       
 /sys/fs/cgroup                             cgroup2         cgroup2      rw,nosuid,nodev,noexec,relatime,nsdelegate,memory_recursiveprot                                       
 /sys/fs/pstore                             pstore          pstore       rw,nosuid,nodev,noexec,relatime                                                                       
 /sys/fs/bpf                                bpf             bpf          rw,nosuid,nodev,noexec,relatime,mode=700                                                              
 /sys/kernel/tracing                        tracefs         tracefs      rw,nosuid,nodev,noexec,relatime                                                                       
 /sys/kernel/debug                          debugfs         debugfs      rw,nosuid,nodev,noexec,relatime                                                                       
 /sys/fs/fuse/connections                   fusectl         fusectl      rw,nosuid,nodev,noexec,relatime                                                                       
 /sys/kernel/config                         configfs        configfs     rw,nosuid,nodev,noexec,relatime                                                                       
 /dev                                       dev             devtmpfs     rw,nosuid,relatime,size=8027368k,nr_inodes=2006842,mode=755,inode64                                   
 /dev/shm                                   tmpfs           tmpfs        rw,nosuid,nodev,inode64                                                                               
 /dev/pts                                   devpts          devpts       rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000                                                 
 /dev/hugepages                             hugetlbfs       hugetlbfs    rw,nosuid,nodev,relatime,pagesize=2M                                                                  
 /dev/mqueue                                mqueue          mqueue       rw,nosuid,nodev,noexec,relatime                                                                       
 /run                                       run             tmpfs        rw,nosuid,nodev,relatime,mode=755,inode64                                                             
 /run/credentials/systemd-journald.service  tmpfs           tmpfs        ro,nosuid,nodev,noexec,relatime,nosymfollow,size=1024k,nr_inodes=1024,mode=700,inode64,noswap         
 /run/user/1000                             tmpfs           tmpfs        rw,nosuid,nodev,relatime,size=1612004k,nr_inodes=403001,mode=700,uid=1000,gid=1000,inode64            
 /run/user/1000/doc                         portal          fuse.portal  rw,nosuid,nodev,relatime,user_id=1000,group_id=1000                                                   
 /tmp                                       tmpfs           tmpfs        rw,nosuid,nodev,nr_inodes=1048576,inode64                                                             
 /boot                                      /dev/nvme0n1p6  vfat         rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=ascii,shortname=mixed,utf8,errors=remount-ro

Potential fix #23

[cakebaker]

Can you please run cargo clippy? The CI shows some clippy errors. Plus the test fails on macOS because there's no /proc on macOS as far as I know.

[Harshit933]

Plus the test fails on macOS because there's no /proc on macOS as far as I know.

Yup. I guess that is the case. I'll feature gate this on linux only

error: test failed, to rerun pass `--test tests`
run: /Users/runner/work/util-linux/util-linux/target/debug/util-linux findmnt
thread 'test_findmnt::test_findmnt' panicked at tests/by-util/test_findmnt.rs:5:17:
Command was expected to succeed. Exit code: 101.
stdout = 
 stderr = thread 'main' panicked at src/uu/findmnt/src/findmnt.rs:43:54:
called `Result::unwrap()` on an `Err` value: Os { code: 2, kind: NotFound, message: "No such file or directory" }
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

[sylvestre]

Yup. I guess that is the case. I'll feature gate this on linux only

there might be crate or equivalent for mac/unix. Maybe have a look before making this linux specific

[Harshit933]

@sylvestre I see there are some alternatives present inside macOS like the mount and diskutil commands. But shouldn't they be implemented differently from the findmnt one? I am a bit confused here on what do I need to do further.

[cakebaker]

We recently removed tabled and so this will no longer work. And as the output currently looks quite different from the output of the original findmnt, I think it is probably easier to do the output manually than trying to figure out how to do it with tabled.

[alxndrv]

@Harshit933 I had started working on a findmnt implementation as well before realizing you had this PR open, feel free to take the output code from here, that version doesn't use tabled.