Re: incorrect(?) errno value in msdosfs

pluknet <pluknet_at_gmail.com> wrote:
 > I have discovered an unexpected behavior. If I perform a search
 > operation in the directory for non-existing files, then I get
 > the EINVAL value on msdosfs filesystem instead of
 > the ENOENT value returned.

EINVAL should be returned if you try to lookup an invalid
file name.  ENOENT should be returned if the file name is
valid but does not exist.

Remember that MSDOSFS is a lot stricter than UFS, as far
as valid file names are concerned.  For example, the only
characters forbidden in UFS file names are '/' (slash) and
'\0' (zero byte), because slash is the directory separator
and zero byte is the string terminator.  On the other hand,
quite a lot of characters are not allowed in MSDOSFS file
names, including the wildcards '?' and '*'.

 > For example if I run the next command on msdosfs filesystem,
 > this is what I get:
 > 
 > bash-2.05b$ ls /mnt/msdosfs/*.nonexistent
 > ls: /mnt/msdosfs/*.nonexistent: Invalid argument

That's correct behaviour.  Let me explain:

When your shell encounters unquoted wildcards ('*' in this
case), it retrieves a directory listing and tries to match
the entries with your pattern.  If there is no match, the
default behaviour of most bourne-compatible shells
(including bash) is to use the pattern as-is, i.e. as if
it was quoted.  In other words, it tries to look for a
literal file name of "*.nonexistent".

As I explained above, the '*' character is illegal in
MSDOSFS file names, so the lookup function returns EINVAL
without even trying to locate that file name in the
directory.

 > instead of:
 > 
 > bash-2.05b$ ls /mnt/msdosfs/*.nonexistent
 > ls: /mnt/msdosfs/*.nonexistent: No such file or directory

That would be incorrect behaviour.

Try to look up a file name that's valid (but doesn't exist
either).  You will certainly get ENOENT.  If you still get
EINVAL, it's time to submit a PR.  :-)

Best regards
   Oliver

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Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M.
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