Re: [MiNT] symlinks and hostfs

[Alan Hourihane <alanh@fairlite.co.uk>]

On Fri, 2009-08-28 at 15:56 +0100, Alan Hourihane wrote:
> On Fri, 2009-08-28 at 15:06 +0200, Vincent Rivière wrote:
> > Hello.
> > 
> > I have noticed that symlinks are seen as regular files on hostfs :-(
> > This can be verified easily by using "ls -l"
> > 
> > In most situations, symlinks are normally treated as the file pointed 
> > to, except with the lstat() function used by ls.
> > 
> > The lstat() implementation is here:
> > http://sparemint.atariforge.net/cgi-bin/cvsweb/mintlib/unix/lstat.c?rev=1.2&content-type=text/x-cvsweb-markup
> > The implementation using MiNT syscalls is in __sys_stat()
> > http://sparemint.atariforge.net/cgi-bin/cvsweb/mintlib/mintlib/do_stat.c?rev=1.11&content-type=text/x-cvsweb-markup
> > 
> > Since Fstat64() does not seem to be implemented in hostfs, we fall back 
> > in Fxattr().
> > 
> > The implementation of Fxattr() is here inside sys_f_xattr():
> > http://sparemint.atariforge.net/cgi-bin/cvsweb/freemint/sys/dosdir.c?rev=1.27.2.2&content-type=text/x-cvsweb-markup
> > 
> > And unfortunately the parameter "flag" set to 1 indicating that the 
> > attributes of the symlink itself should be read is ignored :-(
> > 
> > Actually, I would be happy to use ARAnyM without any ext2 image, but 
> > these limitations are annoying.
> > 
> > Since the UNIX file API is provided by the MiNTLib and properly 
> > implemented in the hosts Linux/Cygwin/OSX, we should manage to get 
> > something satisfying...
> 
> Actually, this is a bug in aranym.
> 
> It uses it's own host_stat64() implementation in host_getxattr() that
> does a stat() on the file instead of lstat() in this case. And so aranym
> ends up stat'ing the actual file rather than the symlink. Only if stat()
> fails it falls back to an lstat() operation.
> 
> I think aranym should use lstat by default here as the filename cookie
> that it gets from FreeMiNT is the one it should be operating on. 
> 
> As far as FreeMiNT and mintlib are concerned. They are correct.
> 
> Attached is a patch that fixes aranym here, although I'm unsure of why
> all the other tricks are needed that I've removed, so I'll leave the
> final patch up to the aranym folks. But I've tested it here and it
> works.

Better patch, which just re-instates the original if () check.

Alan.

Index: hostfs.cpp
===================================================================
RCS file: /var/repos/aranym/src/natfeat/hostfs.cpp,v
retrieving revision 1.53
diff -u -r1.53 hostfs.cpp
--- hostfs.cpp	24 Aug 2009 12:27:48 -0000	1.53
+++ hostfs.cpp	28 Aug 2009 15:07:08 -0000
@@ -1813,24 +1813,6 @@
 	if ( lstat(fpathName, statBuf) )
 		return errnoHost2Mint(errno,TOS_EFILNF);
 
-	// symlink
-	if ( S_ISLNK(statBuf->st_mode) ) {
-		char target[MAXPATHNAMELEN];
-		if (!host_readlink(fpathName,target,sizeof(target)-1))
-			return errnoHost2Mint(errno,TOS_EFILNF);
-
-		// doesn't point to a mapped drive
-		if (!findDrive(fc, target)) {
-			D(bug( "HOSTFS: host_stat64: follow symlink -> %s", target ));
-
-			// get the information from the link target
-			if ( stat(target, statBuf) ) {
-				// on error just rollback to a symlink (broken one)
-				lstat(fpathName, statBuf);
-			}
-		}
-	}
-
 	return TOS_E_OK;
 }