OSError class of bugs

[Colin Watson]

[Moving to ubuntu-installer@ list]

On Tue, Dec 12, 2006 at 10:54:29PM +0100, Henrik Nilsen Omma wrote:
> A question about bug grouping:
> 
> I'm coming across a range of bugs with OS errors of various kinds that 
> don't seem to quite match bug #47046

The ones you mention certainly don't.

> Should I make these dupes of each other?

Most of these bugs are either hardware problems or due to the squashfs
problems we had in Edgy before release, and should be rejected with a
helpful explanation.

As of Edgy, Ubiquity will spot certain well-known errors (ENOENT, EIO,
ENOTDIR, EROFS; Feisty spots EFAULT IOError exceptions as well) and
display a more helpful error message. The error message used depends on
whether the error was encountered on a file on the CD, on a file on the
hard disk, or indeterminate (the function we use to copy a file at the
moment doesn't distinguish between an error reading from the source file
and an error writing to the target file). These messages are found in
debian/ubiquity.templates in the ubiquity source package, and are as
follows:

  This particular error is often due to a faulty CD/DVD disk or drive. It may
  help to clean the CD/DVD, to burn the CD/DVD at a lower speed, or to clean
  the CD/DVD drive lens (cleaning kits are often available from electronics
  suppliers).

  This particular error is often due to a faulty hard disk. It may help to
  check whether the hard disk is old and in need of replacement, or to move
  the system to a cooler environment.

  This particular error is often due to a faulty CD/DVD disk or drive, or a
  faulty hard disk. It may help to clean the CD/DVD, to burn the CD/DVD at a
  lower speed, to clean the CD/DVD drive lens (cleaning kits are often
  available from electronics suppliers), to check whether the hard disk is
  old and in need of replacement, or to move the system to a cooler
  environment.

As I say, in the case of errors in Edgy pre-releases that could be due
to CD problems, rejections should also mention that they may be due to a
squashfs bug that we fixed in the final release of Ubuntu 6.10 (after
the release candidate).

Generally it's worth having a quick look in /var/log/syslog if it's
attached, since there are usually (though not always) complaints from
the kernel in these situations. For example,
https://bugs.launchpad.net/distros/ubuntu/+source/ubiquity/+bug/74290
has an enormous sequence of this sort of thing:

  Dec  3 20:10:04 ubuntu kernel: [17180492.216000] SQUASHFS error: zlib_fs returned unexpected result 0xfffffffd
  Dec  3 20:10:04 ubuntu kernel: [17180492.216000] SQUASHFS error: Unable to read page, block cc55b6, size 273f

That's either a CD problem or (in some Edgy pre-releases, although that
bug is on Dapper) the squashfs bug fixed in the final release.

> Is there anywhere I can read up on what the different Errno numbers
> mean?

Install glibc-doc on Feisty (the info documentation was missing from
some earlier releases) and:

  info libc 'Error Codes'

More specifically:

> OSError: [Errno 2] No such file or directory:

Usually "the CD suddenly claims that this file isn't here, even though
it thought it was there earlier".

> OSError: [Errno 30] Read-only file system: 

Usually "the hard disk returned too many errors, so the kernel remounted
the filesystem onto which you were trying to install read-only in order
to avoid causing further damage".

Cheers,

-- 
Colin Watson                                       [cjwatson at ubuntu.com]