Re: Possible bug in readlink, canonicalize fails.

[Andreas Schwab]

mpb [EMAIL PROTECTED] writes:

 # Create 3 symbolic links inside those directories.
 ln -s a1/a2 /tmp/a0/a2
 ln -s /tmp/a0/a2/b3 /tmp/c0/b3
 ln -s /tmp/a0/a2/a3/a4/a5 /tmp/c0/b3/b4/a5

The problem is that we are crossing the /tmp/a0/a2 symlink twice, so
canonicalize_filename_mode thinks this is a loop.  But in fact the
reference comes from different symlink expansions, and the second one
uses a different way through the filesystem.  Due to the way cycle_check
works this testcase only works when the offending symlink is the second,
fourth, eighth, ... one encountered.  The kernel can cope because it
only errors out after a fixed number of symlink expansions, independent
of the actual nodes crossed.

Andreas.

-- 
Andreas Schwab, SuSE Labs, [EMAIL PROTECTED]
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
PGP key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
And now for something completely different.


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Re: Possible bug in readlink, canonicalize fails.

[Jim Meyering]

mpb [EMAIL PROTECTED] wrote:
 I believe the following script demonstrates that readlink cannot
 always canonicalize paths.  It may be possible to create a simpler
 demonstration of the bug, but I could not trivially do so.

Thanks for the report and the nice test case.
I have code that's a work in progress (needed in another part
of coreutils) that does a better job of detecting such (non)cycles.

This will be fixed before 6.10.


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