[HELP] stat(), file permission, r/w access : i'm LOST :(

Sebastien Barre Sebastien.Barre@utc.fr
Mon Mar 1 13:28:00 GMT 1999

Dear cygwin people

As some of you might have noticed (sorry for the flood), I'm still trying
to arbitrate The Fight between Perl 5.002 and cygwin32-B20.1 (the
battlefield being NT4/SP4). Well, thanks to some of you, I nearly did it
(and also ruined a couple of nights), but a strange problem lead me to some
more confusion :

Problem : although I'm working as single user on a standalone workstation,
and always logged as sysadmin ("administrateur" in french), cygwin seems to
see/create the files on my hard disk as *not* belonging to me, but to
another "being" (which is not obvious to me). 

I'll do my best to describe it (it's really *easy* to observe) : let's have
a look at a simple Perl example, then a short C example with stat(), and my
/etc/passwd and /etc/group. Finally I will create a simple file with
'touch', and you will notice that it will be reported as NOT belonging to
me and not being writable :((

Note : this seems specific to NT, which is not surprising regarding file

Perl example :

Note : I created /etc/passwd and /etc/group with 'mkpasswd -l' and 'mkgroup
-l' respectively, as reported in many FAQS.

administrateur [26] /etc$ perl -e 'print "yes" if -w "group";'

administrateur [27] /etc$ ll
total 7
-rw-r--r--   1 544 Aucun          27 Feb 26 02:45 group
-rw-r--r--   1 544 Aucun         65 Mar  1 21:08 passwd
-rw-r--r--   1 544 Aucun        9828 Dec  1 14:00 termcap

That command (-w) will display 'yes' if the file (here, /etc/group) is
writable. Apparently, it fails. And fails everywhere in my filesystem. The
'-w' command is using C<stat>, let's move on :

C example :
#include <sys/stat.h>
#include <stdlib.h>

int main() {
    struct stat mystat;

    stat("group", &mystat);

    printf("mode : %o, uid : %u, gid : %u\n", 
           mystat.st_mode, mystat.st_uid, mystat.st_gid);


Run :

administrateur [52] /etc$ gcc mystat.c

administrateur [53] /etc$ a.exe
mode : 100644, uid : 544, gid : 513

administrateur [55] /etc$ ll group
-rw-r--r--   1 544 Aucun          27 Feb 26 02:45 group

Which means : 
	- /etc/group belongs to user which UID is 544, and to group which GID is 513
	- it's a regular file (100000), 
	- read/write permission to owner (600), read permission to group (40) and
read to other (4).

BUT (and it drives me crazy). I CREATED that file, and I'm NOT user 544 !
(more about this strange fellow below).

administrateur [56] /etc$ whoami

administrateur [74] /etc$ cat passwd

administrateur [75] /etc$ cat group

Obviously, I'm user 500 (I changed my name to 'seb' so that to check). 
=> Therefore WHY are all files created as 544 (even with tar) ? (the group
is correct : 513).

I thought it was related to /etc/passwd, but I just do NOT UNDERSTAND the
difference between -l and -g option for 'mkpasswd'.

   -l,--local              print local accounts
   -g,--local-groups       print local group information too

administrateur [77] /etc$ mkpasswd -l

administrateur [79] /etc$ mkpasswd -g
OpÚrateurs de sauvegarde::551:0:::
Utilisateurs avec pouvoir::547:0:::

=> who are these users ?!? these should be groups !! I'm belonging to the
"Administrateurs" group for NT (in the "Gestionnaire d'utilisateurs" ~=
"User manager"), and this has been translated to a user, I'm completely
lost :((

=> dumping 'mkpasswd -l -g' to /etc/passwd (instead of 'mkpasswd -l') did
NOT help.

Here is the same joke :

administrateur [84] /etc$ touch test

administrateur [85] /etc$ ll test
-rw-r--r--   1 544      Aucun           0 Mar  1 21:46 test

administrateur [86] /etc$ perl -e 'print "yes" if -w "test";'
administrateur [87] /etc$

WOAH : I created a file, and it's automatically assigned to someone else !
Give me my file back please :( 
And of course, although I created it, it's now NOT writable for cygwin.

I guess I might be just dumb. Any help would be really appreciated (by my
mental health).


Sebastien Barre                  http://www.hds.utc.fr/~barre/

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