struct dirent *ent->d_type weirdness

struct dirent *ent->d_type weirdness

[Kristian Köhntopp]

I have a machine running under 2.6.13-SMP, using reiserfs 3.6. On 
this machine, directories are flagged strangely and thus code 
which operates properly under ext3 fails with reiserfs.

Why is this, and what am I doing wrong?

My goal is to walk a spool directory recursively and deal with 
all files inside directories that I encounter. For that, I check 
struct dirent *ent->d_type and get unexpected results.


mx15:/tmp # uname -a
Linux mx15 2.6.13web #4 SMP Fri Sep 16 16:03:39 CEST 2005 i686 
unknown

mx15:/tmp # cat rtest.cpp
#include <stdio.h>
#include <dirent.h>

int main(int argc, char** argv)
{
struct dirent *ent = NULL;
DIR *dd = NULL;

dd = opendir(argv[1]);
if (dd != NULL) {
         while ((ent = readdir(dd)) != NULL) {
	 /* disable actual test and print ent->d_type */
	 /* ent->d_type==DT_DIR && ent->d_name[1]==0 && ent->d_name[0]>0 
&& ent->d_name[0]!='.'*/
		if (1) {
			printf("%s (%d) \n", ent->d_name, ent->d_type);
		}
         }
         closedir(dd);
}
}
mx15:/tmp # ./rtest /netsite/var/spool/wmail.reiser
. (0)
.. (0)
head (0)
dbclub02 (0)
mx15:/tmp # df -Th /netsite/var/spool/wmail.reiser
Dateisystem   Typ    Größe Benut  Verf Ben% Eingehängt auf
/reiserfile
           reiserfs    2.0G   33M  2.0G 
2% /netsite/var/spool/wmail.reiser



Kristian

Re: struct dirent *ent->d_type weirdness

[Vladimir V. Saveliev]

Hello

Kristian Köhntopp wrote:
> I have a machine running under 2.6.13-SMP, using reiserfs 3.6. On 
> this machine, directories are flagged strangely and thus code 
> which operates properly under ext3 fails with reiserfs.
> 
> Why is this, and what am I doing wrong?
> 
> My goal is to walk a spool directory recursively and deal with 
> all files inside directories that I encounter. For that, I check 
> struct dirent *ent->d_type and get unexpected results.
> 
Yes, unfortunately, reiserfs does not support entry types.
Probably it should, but there is nothing wrong to not support it:
man readdir:
       According to POSIX, the dirent structure contains a field char d_name[] of unspecified size, with at most NAME_MAX charac╜
       ters  preceding  the  terminating  null character.  Use of other fields will harm the portability of your programs.  POSIX
       1003.1-2001 also documents the field ino_t d_ino as an XSI extension.

> 
> mx15:/tmp # uname -a
> Linux mx15 2.6.13web #4 SMP Fri Sep 16 16:03:39 CEST 2005 i686 
> unknown
> 
> mx15:/tmp # cat rtest.cpp
> #include <stdio.h>
> #include <dirent.h>
> 
> int main(int argc, char** argv)
> {
> struct dirent *ent = NULL;
> DIR *dd = NULL;
> 
> dd = opendir(argv[1]);
> if (dd != NULL) {
>          while ((ent = readdir(dd)) != NULL) {
> 	 /* disable actual test and print ent->d_type */
> 	 /* ent->d_type==DT_DIR && ent->d_name[1]==0 && ent->d_name[0]>0 
> && ent->d_name[0]!='.'*/
> 		if (1) {
> 			printf("%s (%d) \n", ent->d_name, ent->d_type);
> 		}
>          }
>          closedir(dd);
> }
> }
> mx15:/tmp # ./rtest /netsite/var/spool/wmail.reiser
> . (0)
> .. (0)
> head (0)
> dbclub02 (0)
> mx15:/tmp # df -Th /netsite/var/spool/wmail.reiser
> Dateisystem   Typ    Größe Benut  Verf Ben% Eingehängt auf
> /reiserfile
>            reiserfs    2.0G   33M  2.0G 
> 2% /netsite/var/spool/wmail.reiser
> 
> 
> 
> Kristian
> 
> 

Re: struct dirent *ent->d_type weirdness

[Kristian Koehntopp]

On Monday 19 September 2005 16:33, Vladimir V. Saveliev wrote:
> Yes, unfortunately, reiserfs does not support entry types.
> Probably it should, but there is nothing wrong to not support it:

Thank you. I'll have the code in question changed to Posix conformance.

Kristian

-- 
Kristian =?iso-8859-15?q?K=F6hntopp?= <kris@xn--khntopp-90a.de>

Re: struct dirent *ent->d_type weirdness

[Andreas Dilger]

On Sep 19, 2005  18:33 +0400, Vladimir V. Saveliev wrote:
> Kristian Köhntopp wrote:
> > My goal is to walk a spool directory recursively and deal with 
> > all files inside directories that I encounter. For that, I check 
> > struct dirent *ent->d_type and get unexpected results.
> > 
> Yes, unfortunately, reiserfs does not support entry types.
>
> > 	 /* disable actual test and print ent->d_type */
> > 	 /* ent->d_type==DT_DIR && ent->d_name[1]==0 && ent->d_name[0]>0 
> > && ent->d_name[0]!='.'*/

You need to stat() the entry to find the type if d_type is DT_UNKNOWN.
I would continue to use d_type as an optimization, however, as this
reduces the number of syscalls needed when it is supported, and for
network filesystems a stat() may be an expensive operation.

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.

Re: struct dirent *ent->d_type weirdness

[Grzegorz Jaśkiewicz]

On 9/19/05, Vladimir V. Saveliev <vs@namesys.com> wrote:
> Hello
>
> Yes, unfortunately, reiserfs does not support entry types.
> Probably it should, but there is nothing wrong to not support it:
I guess it shouldn't be hard, and this would make some code nicer. I
have run into this problem quite few times, and I wish reiserfs4 has
this implemented.

--
GJ