int maildlock (const char user, int retrycnt, const char dir);
int mailunlock (void);
Description
The maillock and maildlock
functions attempt to create a lockfile for the
user's mailfile.
If a lockfile already exists, maillock and maildlock
assume the
contents of the file is the process
ID
(as a null-terminated
ASCII
string)
of the process that created the
lockfile (presumably with a call to maillock or maildlock).
If the process that created the lockfile is still alive,
maillock and maildlock
will sleep and try
again retrycnt times before returning with an error indication.
The sleep algorithm is to sleep for 5 seconds times the attempt number.
That is, the first sleep will be for 5 seconds, the next sleep will be for
10 seconds, etc. until the number of attempts reaches retrycnt.
When the lockfile is no longer needed, it should be removed
by calling mailunlock.
user
is the login name of the user for whose mailbox the lockfile will be created.
maillock assumes that users' mailfiles are in the ``standard''
place as defined in maillock.h.
maildlock uses the directory passed as its third argument.
The following return code definitions are contained in maillock.h.
Only L_SUCCESS is returned for mailunlock.
#define
L_SUCCESS
0
/ Lockfile created or removed /
#define
L_NAMELEN
1
/ Recipient name > 13 chars /
#define
L_TMPLOCK
2
/ Can't create tmp file /
#define
L_TMPWRITE
3
/ Can't write pid into lockfile /
#define
L_MAXTRYS
4
/ Failed after retrycnt attempts /
#define
L_ERROR
5
/ Check errno for reason /
Notices
The maillock routines are obsolete and are
provided for compatibility only.
mailunlock will only remove the lockfile created from the most
previous call to maillock.
Calling maillock for different users
without intervening calls to mailunlock will cause the initially
created lockfile(s) to remain, potentially blocking subsequent message
delivery until the current process finally terminates.
user, int retrycnt);