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Date: | Fri, 28 Mar 2025 13:02:30 +0100 |
To: | Bruno Haible <bruno AT clisp DOT org> |
Subject: | Re: symbolic link curiousity in 3.6.0 |
Message-ID: | <Z-aP1jhjXTUVvP-E@calimero.vinschen.de> |
Mail-Followup-To: | Bruno Haible <bruno AT clisp DOT org>, cygwin AT cygwin DOT com |
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From: | Corinna Vinschen via Cygwin <cygwin AT cygwin DOT com> |
Reply-To: | cygwin AT cygwin DOT com |
Cc: | Corinna Vinschen <corinna-cygwin AT cygwin DOT com>, cygwin AT cygwin DOT com |
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Hi Bruno, I found the problem, it's in a gnulib header. See below. On Mar 28 12:21, Corinna Vinschen via Cygwin wrote: > On Mar 28 10:59, Corinna Vinschen via Cygwin wrote: > > [Adding Bruno Haible] > > > > Hi Bruno, > > > > can you please take a look? To reiterate, with coreutils 9.6: > > > > $ ln -s foo bar > > $ ls -l bar > > ls: bar: Not supported > > lrwxrwxrwx 1 corinna vinschen 3 Mar 27 10:20 bar -> foo > > > > The introducing commit in coreutils is apparently commit > > b58e321c8d5dd ("ls: suppress "Permission denied" errors on NFS") > > > > The reason this works as expected on Linux but not on Cygwin is that the > > underlying gnulib function file_has_aclinfo() differs between Linux and > > Cygwin. On Cygwin, it's basically just a call to acl_get_file() since > > Cygwin has the POSIX.1e functions but none of the extensions of Linux > > or FreeBSD/NetBSD. > > > > As a result, when calling file_has_aclinfo("bar",...), the symlink > > "bar" is always followed and file_has_aclinfo() returns with errno > > set to ENOENT. > > > > See below for the rest of the story. > > > > Two questions: > > > > - Would you place the problem inside gnulib:file_has_aclinfo() or > > coreutils:gobble_file()? > > > > Personally I think this is a coreutils problem rather than a > > gnulib problem in that it fails to take ENOENT on symlinks into > > account. > > > > - Would it make sense to implement the FreeBSD/NetBSD functions > > acl_get_fd_np() and acl_get_link_np() in Cygwin? Theoretically > > this should fix the problem without having to fix coreutils, > > but I think coreutils really should take systems into account > > which only have the documented POSIX.1e functions. > > > > What do you think? > > Ok, there's something fishy going on. > > Cygwin has acl_extended_file/acl_extended_file_nofollow. > > And after configure, gnulib's config.h contains this: > > #define USE_ACL 1 > #define HAVE_ACL_GET_FILE 1 > #define HAVE_ACL_EXTENDED_FILE 1 > > But for some reason I still have to figure out the coreutils 9.6 build > doesn't use acl_extended_file/acl_extended_file_nofollow, but > acl_get_file. > > Hmm... Gnulib's acl-internal.h contains this: /* Linux-specific */ /* Cygwin >= 2.5 implements this function, but it returns 1 for all directories, thus is unusable. */ # if !defined HAVE_ACL_EXTENDED_FILE || defined __CYGWIN__ # undef HAVE_ACL_EXTENDED_FILE # define HAVE_ACL_EXTENDED_FILE false # define acl_extended_file(name) (-1) # endif This is simply not true. Cygwin's acl_extended_file only returns 1 on dirs, if they actually contain more than the 3 default entries to emulate POSIX access. I just tried it and it works exactly as required. Can this be fixed, please? Thanks, Corinna -- Problem reports: https://cygwin.com/problems.html FAQ: https://cygwin.com/faq/ Documentation: https://cygwin.com/docs.html Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple
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