sshfs mounts cannot be browsed with mc

[basz]

remote directory mounted with sshfs (FUSE) can be normally used from cmd-line, however it cannot be browsed with mc 2.8.26. the same mount point, on the same host, works fine with mc 2.8.22.

example steps to reproduce:

1. /etc/fstab mount looks like this:

   user@host:/mnt/remote/stuff  /mnt/stuff  fuse.sshfs 
    noauto,_netdev,user,transform_symlinks,identityfile=/path/to/key,default_permissions,uid=user,gid=user,allow_other,cache=no   0   0
   

2. docker run -it --rm -v /mnt/stuff:/mnt:ro debian:11

3. apt update && apt install mc

4. mc /mnt

directory will appear to be empty, even though ls on the same dir shows real content.

changing debian image version in step 2 from 11 to 10 allows to browse mountpoint's content as usual.

note that mc 2.8.22 is the default in debian:10 (buster - aka: oldstable) and mc 2.8.26 is the default in debian:11 (bullseye - aka: stable).

[basz]

+ LC_MESSAGES=C
+ mc -V
GNU Midnight Commander 4.8.26
Built with GLib 2.66.8
Built with S-Lang 2.3.2 with terminfo database
With builtin Editor and Aspell support
With subshell support as default
With support for background operations
With mouse support on xterm and Linux console
With support for X11 events
With internationalization support
With multiple codepages support
With ext2fs attributes support
Virtual File Systems:
 cpiofs, tarfs, sfs, extfs, ext2undelfs, ftpfs, sftpfs, fish
Data types:
 char: 8; int: 32; long: 64; void *: 64; size_t: 64; off_t: 64;
+ LC_MESSAGES=C
+ mc -F
Home directory: /home/user
Profile root directory: /home/user

[System data]
    Config directory: /etc/mc/
    Data directory:   /usr/share/mc/
    File extension handlers: /usr/lib/mc/ext.d/
    VFS plugins and scripts: /usr/lib/mc/
	extfs.d:        /usr/lib/mc/extfs.d/
	fish:           /usr/lib/mc/fish/

[User data]
    Config directory: /home/user/.config/mc/
    Data directory:   /home/user/.local/share/mc/
	skins:          /home/user/.local/share/mc/skins/
	extfs.d:        /home/user/.local/share/mc/extfs.d/
	fish:           /home/user/.local/share/mc/fish/
	mcedit macros:  /home/user/.local/share/mc/mc.macros
	mcedit external macros: /home/user/.local/share/mc/mcedit/macros.d/macro.*
    Cache directory:  /home/user/.cache/mc/
+ mc --configure-options
 '--build=x86_64-linux-gnu' '--prefix=/usr' '--includedir=${prefix}/include' '--mandir=${prefix}/share/man' '--infodir=${prefix}/share/info' '--sysconfdir=/etc' '--localstatedir=/var' '--disable-option-checking' '--libdir=${prefix}/lib/x86_64-linux-gnu' '--runstatedir=/run' '--disable-maintainer-mode' '--disable-dependency-tracking' 'AWK=awk' 'X11_WWW=x-www-browser' '--libexecdir=/usr/lib' '--with-x' '--with-screen=slang' '--disable-rpath' '--disable-static' '--disable-silent-rules' '--enable-aspell' '--enable-vfs-sftp' '--enable-vfs-undelfs' '--enable-tests' 'build_alias=x86_64-linux-gnu' 'CFLAGS=-g -O2 -ffile-prefix-map=/build/mc-xlv0ck/mc-4.8.26=. -fstack-protector-strong -Wformat -Werror=format-security' 'LDFLAGS=-Wl,-z,relro -Wl,-z,now -Wl,--as-needed' 'CPPFLAGS=-Wdate-time -D_FORTIFY_SOURCE=2'

[andrew_b]

This is a result of #3987. Now mc calls the rewinddir(3) when reads a directory. I think sshfs has a bug related to rewinddir(3). Disabling of sshfs's cache should help.

Small test program can be find ​here.

[basz]

yes, this appears to be a problem with sshfs. i've checked the linked program and indeed on "regular" directories, i get the same output for both reads, yet for sshfs-mounts first read is good, but the second one yields empty result. unfortunately disabling caching does not seem to help.

anyway - we can close this ticket. i'll followup with sshfs team.

thank you. :)

[basz]

ticket on sshfs:
​https://github.com/libfuse/sshfs/issues/278

[andrew_b]

Thanks!