[iso9660] Index out of range panic

[mraerino]

I'm getting this panic as part of running the linuxkit metadata service

panic: runtime error: index out of range [0] with length 0

goroutine 1 [running]:
github.com/linuxkit/linuxkit/pkg/metadata/vendor/github.com/diskfs/go-diskfs/filesystem/iso9660.parseDirEntry(0xa60458, 0x0, 0x0, 0xc0000e4000, 0x17000, 0x0, 0x0)
	/go/src/github.com/linuxkit/linuxkit/pkg/metadata/vendor/github.com/diskfs/go-diskfs/filesystem/iso9660/directoryentry.go:281 +0x789
github.com/linuxkit/linuxkit/pkg/metadata/vendor/github.com/diskfs/go-diskfs/filesystem/iso9660.Read(0x818500, 0xc00000e068, 0x400000, 0x0, 0x1000, 0x1, 0x8122e0, 0xc000010ed0)
	/go/src/github.com/linuxkit/linuxkit/pkg/metadata/vendor/github.com/diskfs/go-diskfs/filesystem/iso9660/iso9660.go:223 +0x965
github.com/linuxkit/linuxkit/pkg/metadata/vendor/github.com/diskfs/go-diskfs/disk.(*Disk).GetFilesystem(0xc000078230, 0x0, 0x0, 0xc000078230, 0x0, 0x0)
	/go/src/github.com/linuxkit/linuxkit/pkg/metadata/vendor/github.com/diskfs/go-diskfs/disk/disk.go:227 +0x241

when i mount the cdrom in linux it works fine and i can list the files on it and view them

here is an image of the cdrom: broken-cdrom.img.gz

[mraerino]

ok, i did some more investigation into this

looks like this is caused by a wrongly detected physical block size on the device.

• iso9660.Read(f, 0, 0, 2048) works fine
• iso9660.Read(f, 0, 0, 4096) panics

I think it should not panic, but produce an error instead

[deitch]

@mraerino could you share a simple program that can replicate this?

[mraerino]

i put a test here which panics: #105

[deitch]

Please try the branch with the PR at #106