SquashFS Iteration Fails when FIFO Present

[tri-adam]

What happened:

When iterating through a SquashFS layer within a SIF that contains a FIFO, an error is encountered.

could not read image: failed to walk layer="sha256:14489b4001eb9184a44622395748011affff4f358134049e566e026ab380dc37": could not add path="/foo" link="" during squashfs iteration

What you expected to happen:

I expected SquashFS iteration to succeed, even when a FIFO is present.

How to reproduce it (as minimally and precisely as possible):

Generate a SquashFS partition that contains a fifo:

$ mknod foo p
$ mksquashfs ./foo rootfs.sq
...

Use siftool (available here) to create a SIF containing the SquashFS partition:

$ siftool new fifo.sif
$ siftool add --datatype 4 --partarch 1 --partfs 1 --parttype 2 fifo.sif rootfs.sq

Process with stereoscope:

$ go run examples/basic.go singularity:fifo.sif
DEBU[0000] image: source=Singularity location=fifo.sif  
DEBU[0000] image metadata: digest=sha256:affd044aad62d0250e63e4bf1dcc8f385fe956525c79d6cea8c7dfb3eee96c47 mediaType=application/vnd.sylabs.sif.layer.v1.sif tags=[] 
DEBU[0000] layer metadata: index=0 digest=sha256:14489b4001eb9184a44622395748011affff4f358134049e566e026ab380dc37 mediaType=application/vnd.sylabs.sif.layer.v1.squashfs 
panic: could not read image: failed to walk layer="sha256:14489b4001eb9184a44622395748011affff4f358134049e566e026ab380dc37": could not add path="/foo" link="" during squashfs iteration

goroutine 1 [running]:
main.main()
        /home/adam/src/stereoscope/examples/basic.go:32 +0x73b
exit status 2

Anything else we need to know?:

Environment:

$ cat /etc/os-release 
PRETTY_NAME="Ubuntu 22.04.1 LTS"
NAME="Ubuntu"
VERSION_ID="22.04"
VERSION="22.04.1 LTS (Jammy Jellyfish)"
VERSION_CODENAME=jammy
ID=ubuntu
ID_LIKE=debian
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
UBUNTU_CODENAME=jammy