[bug #60207] -prune returns false for files for which fstatat() fails with EACCESS

[Stephane Chazelas]

URL:
  <https://savannah.gnu.org/bugs/?60207>

                 Summary: -prune returns false for files for which fstatat()
fails with EACCESS
                 Project: findutils
            Submitted by: stephanechazelas
            Submitted on: Wed 10 Mar 2021 12:17:47 PM UTC
                Category: find
                Severity: 3 - Normal
              Item Group: Wrong result
                  Status: None
                 Privacy: Public
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
                 Release: 4.7.0
         Discussion Lock: Any
           Fixed Release: None

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Details:

(initially from
https://unix.stackexchange.com/questions/638372/why-does-find-still-try-to-access-gvfs-and-even-includes-it-in-the-output-de
by DJCrashdummy user there).

Reproduced with GNU find 4.8.0 and current git head (v4.8.0-5-gcaa03867) built
with default options on Debian GNU/Linux testing amd64.

Reproducer:


$ mkdir testdir; cd testdir
$ touch a1 a2 b1 b2
$ sudo bindfs --no-allow-other . a1
$ ls -l
ls: cannot access 'a1': Permission denied
total 0
-????????? ? ?        ?        ?            ? a1
-rw-r--r-- 1 stephane stephane 0 Mar 10 11:53 a2
-rw-r--r-- 1 stephane stephane 0 Mar 10 11:53 b1
-rw-r--r-- 1 stephane stephane 0 Mar 10 11:53 b2
$ find . -name 'a*' -prune -o -print
.
./b1
find: ‘./a1’: Permission denied
./a1
./b2


See how "./a1" was output even though it matches "a*".

Here using bindfs as a different user as a way to have a file (a1) that is not
lstat()able. The OP had the problem initially with a .gvfs directory (also a
fuse FS mount point).

It can also be reproduced with -L/-follow and symlinks to inaccessible areas:


$ mkdir testdir; cd testdir
$ touch a2 b1 b2
$ ln -s /var/spool/cron/crontabs/foo a1
$ ln -s /no/such/file a3
$ ln -s a4 a4
$ ln -s a2/foo a5
$ find -L . -name 'a*' -prune -o -print
.
./b1
find: ‘./a1’: Permission denied
./a1
./b2
find: ‘./a5’: Not a directory
find: ‘./a4’: Too many levels of symbolic links


See how a1 was reported (for which stat() fails with EACCESS), but not  a3
(ENOENT), a4 (ELOOP), a5 (ENOTDIR).





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