plock(S)                       6 January 1993                       plock(S)


 Name

    plock - lock process, text, or data in memory

 Syntax


    cc  . . .  -lc


    #include  <sys/lock.h>

    int plock (op)
    int op;


 Description

    The plock system call allows the calling process to lock its text segment
    (text lock), its data segment (data lock), or both its text and data seg-
    ments (process lock) into memory.  Locked segments are immune to all rou-
    tine swapping.  plock also allows these segments to be unlocked.  The
    effective user ID of the calling process must be super user to use this
    call.  op specifies the following:

    PROCLOCK-   lock text and data segments into memory (process lock)

    TXTLOCK-    lock text segment into memory (text lock)

    DATLOCK-    lock data segment into memory (data lock)

    UNLOCK-     remove locks

    The plock system call fails and does not perform the requested operation
    if one or more of the following is true:

    [EAGAIN]    Not enough memory.

    [EINVAL]


                1.  op is equal to PROCLOCK and a process lock, a text lock,
                    or a data lock already exists on the calling process.

                2.  op is equal to TXTLOCK and a text lock or a process lock
                    already exists on the calling process.

                3.  op is equal to DATLOCK and a data lock or a process lock
                    already exists on the calling process.

                4.  op is equal to UNLOCK and no type of lock exists on the
                    calling process.

    [EPERM]     The effective user ID of the calling process is not super
                user.


 Diagnostics

    Upon successful completion, a value of 0 is returned to the calling pro-
    cess.  Otherwise, a value of -1 is returned, and errno is set to indicate
    the error.

 See also

    exec(S), exit(S), fork(S)

 Standards conformance

    plock is conformant with:
    AT&T SVID Issue 2, but has been withdrawn from XPG3.