NAME
lckpwdf(), ulckpwdf() — control access to /etc/passwd file
SYNOPSIS
#include <shadow.h>
int lckpwdf (void)
int ulckpwdf (void)
DESCRIPTION
The
lckpwdf()
and
ulckpwdf()
routines are used to coordinate modification access to the password file
/etc/passwd
and to the secure password entries.
The lock file used by these two routines is
/etc/.pwd.lock.
A process first calls
lckpwdf()
to gain exclusive access rights for password modification.
When modifications are complete,
ulckpwdf()
is called to release the lock on
/etc/.pwd.lock.
This mechanism prevents
simultaneous modification of password files or entries.
APPLICATION USAGE
lckpwdf()
and
ulckpwdf()
are thread-safe. These interfaces are not cancel-safe.
A cancellation point may occur when a thread is executing
these interfaces.
RETURN VALUE
The
lckpwdf()
routine returns zero upon successful completion.
If the lock could not be obtained, it returns -1 and sets
errno
to indicate the error.
The
ulckpwdf()
routine returns zero upon successful completion.
If the lock has already been released,
ulckpwdf()
returns -1 and sets
errno
to indicate the error.
FILES
/etc/passwd
/etc/.pwd.lock
