[fuse-devel] Possible bug

[Luca R. <luc...@st...>]

Hello,

I have installed libfuse 2.9.1 under Linux. The version of the kernel is 
3.2.0.

If the "videodev" kernel module is present in memory, when I run the 
cusexmp example under fuse-2.9.1/example with the following options, the 
specified device node is never created, although from the output 
everything seems okay:

# modprobe cuse (required)
fuse-2.9.1/example$ ./cusexmp -d --maj=81 --min=0 -f --name=video0

FUSE library version: 2.9.1
unique: 1, opcode: CUSE_INIT (4096), nodeid: 0, insize: 56, pid: 8007
CUSE_INIT: 7.17
flags=0x00000001
    CUSE_INIT: 7.19
    flags=0x00000001
    max_read=0x00020000
    max_write=0x00020000
    dev_major=81
    dev_minor=0
    dev_info: DEVNAME=video0
    unique: 1, success, outsize: 103

While the output from the kernel is

CUSE: failed to register chrdev region

Note the "success" word at the end of the output from fuse, although no 
/dev/video0 is really created and the program does not exit with an error.

I would like to know if that is a bug. Should not the program terminate 
with an error from fuse after intercepting the error from the kernel?

No matter what names and minor numbers you specify, the problem will be 
  still the same whenever the major number is 81: no device nodes will 
be created. It's likely that once  the "videodev" kernel module is 
present in memory, it reserves all the possible minor numbers the 
video4linux subsystem can handle.
In facts, to make the example work, first you have to unload the 
videodev module.

Let me know if you need more informations.
Thanks in advance.