This will do mandetory locking { which can also be done with "chmod +l
filename"}. If someone can rewrite this into perl , that would be great.
/*
write by Mark Goland use and enjoy keep the tag
[EMAIL PROTECTED]
*/
#include <sys/types.h>
#include <sys/stat.h>
int main(int argc,char **argv){
int mode;
struct stat buf;
if( argc !=2 ){
printf("%s [file_to_lock]\n",argv[0]);
exit(1);
}
if (stat(argv[1], &buf) < 0) {
perror("stat");
exit (2);
}
/* get currently set mode */
mode = buf.st_mode;
/* remove group execute permission from mode */
mode &= ~(S_IEXEC>>3);
/* set 'set group id bit' in mode */
mode |= S_ISGID;
if (chmod(argv[1], mode) < 0) {
perror("chmod");
exit(2);
}
exit(0);
}
----- Original Message -----
From: "Ramprasad A Padmanabhan" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>; "Michael Fowler" <[EMAIL PROTECTED]>
Cc: <[EMAIL PROTECTED]>
Sent: Wednesday, September 04, 2002 2:49 AM
Subject: Re: locking a file in linux
> Michael Fowler wrote:
> > On Mon, Sep 02, 2002 at 03:56:22PM +0530, Ramprasad A Padmanabhan wrote:
> >
> >>Hi All,
> >> I am writing an web application where multiple users may write into
> >>the same file concurrently. Also there is a probability that there may
> >>be an admin who has opened up the file in 'vi' and editing the file.
> >>
> >> I want to avoid this concurrent multiple opens.
> >>I tried a range on perl modules like IO::LockedFile, File::Flock;
> >>LockFile::Simple etc but all these do not enforce any lock and worst
> >>they lock a file even if it is already open in vi
> >
> >
> > As has been mentioned elsewhere on this thread, all of these modules
provide
> > only advisory locking. This means that each process that wishes to
modify
> > the file must first lock it with the same method.
> >
> > This will not cause a problem with your application, because you can add
the
> > locked ability to it. It will, however, cause a problem with your admin
> > editing the file directly. One solution is to force the admin to run
their
> > editor in a wrapper. For example, you can provide the admin with a
simple
> > script, say "edit-db-file", that locks the file just as your web
application
> > does, and then invokes his preferred editor (in $ENV{VISUAL} or
> > $ENV{EDITOR}). You'll have to educate your admin (assuming he or she
needs
> > it) that this is the only method with which they are to edit the file,
and
> > that they must make their edits quickly. The quickly part is so that
the
> > web application, and by extension the user of that application, doesn't
have
> > to wait forever to edit the file, or receive an error after the lock
times
> > out.
> >
> > Really, though, why is the admin editing this file directly? Can you
not
> > provide some sort of web interface for the admin as well? That way the
> > admin can't screw up with the lock, and errors in the file itself are
less
> > likely.
> >
> >
> > Michael
> > --
> > Administrator www.shoebox.net
> > Programmer, System Administrator www.gallanttech.com
> > --
>
> Thanx All
> But I will still like to have kernel enforced mandatory locking on
> the file Can you tell me how to do it
>
>
> --
> To unsubscribe, e-mail: [EMAIL PROTECTED]
> For additional commands, e-mail: [EMAIL PROTECTED]
>
--
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
