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PURPOSE of /CoreOS/coreutils/Sanity/bz510809-readlink-cannot-handle-recursive-symlinks
Description: Test for bz510809 (readlink cannot handle recursive symlinks)
Author: Jan Scotka <jscotka@redhat.com>
Bug summary: readlink cannot handle recursive symlinks
Bugzilla link: https://bugzilla.redhat.com/show_bug.cgi?id=510809
Description:
Description of problem:
The readlink command fails with an error "Too many levels of symbolic links", even if there are only 2 levels.
The readlink command from RHEL 3 and RHEL 4 and from Fedora 11 all work fine.
Among other changes between RHEL 4 and RHEL 5, RHEL 5's coreutils added calls to cycle_check() in lib/canonicalize.c, but in upstream canonicalize.c (now in gnulib instead of coreutils), we see the comment:
          /* Detect loops.  We cannot use the cycle-check module here,
             since it's actually possible to encounter the same symlink
             more than once in a given traversal.  However, encountering
             the same symlink,NAME pair twice does indicate a loop.  */
http://git.savannah.gnu.org/gitweb/?p=gnulib.git;a=blob;f=lib/canonicalize.c;h=4f348398fd69ae516396313d18ac294a4ca3dde3;hb=b653eda3ac4864de205419d9f41eec267cb89eeb#l262
The latest canonicalize.c uses seen_triple() instead of cycle_check().
Version-Release number of selected component (if applicable):
coreutils-5.97-19.el5
How reproducible:
every time
Steps to Reproduce:
1. Create a directory with a symlink to itself
       mkdir /tmp/dir
       cd /tmp/dir
       ln -s ../dir dirlink
2. Run readlink using the 'dirlink' symlink recursively
       readlink -v -f dirlink
       readlink -v -f dirlink/dirlink
       readlink -v -f dirlink/dirlink/dirlink
  
Actual results:
The first readlink command on just dirlink succeeds, but the 2nd and 3rd commands fail with 
   readlink: dirlink/dirlink: Too many levels of symbolic links
Expected results:
$ readlink -v -f dirlink
/tmp/dir
$ readlink -v -f dirlink/dirlink
/tmp/dir
$ readlink -v -f dirlink/dirlink/dirlink
/tmp/dir
Additional info: