Tested the mksquashfs command in version 4.4 (2019/08/29) on Ubuntu 20.04.
It now says: Not enough or invalid arguments in pseudo file definition "/ f 444 root root echo"
Appending to the archive now reports "File system corrupted: filename too long" and fails gracefully.
Listing the archive also reports the corruption, and fails earlier with "FATAL ERROR:dir_scan: failed to read directory squashfs-root"
Tested the mksquashfs command in version 4.4 (2019/08/29) on Ubuntu 20.04.
It now says: Not enough or invalid arguments in pseudo file definition "/ f 444 root root echo"
Appending to the archive now reports "File system corrupted: filename too long" and fails gracefully.
Listing the archive also reports the corruption, and fails earlier with "FATAL ERROR:dir_scan: failed to read directory squashfs-root"