[ Previous | Next | Table of Contents | Index | Library Home |
Legal |
Search ]
Files Reference
Defines file control
options.
The flock structure in
the /usr/include/sys/flock.h file, which describes a lock,
contains the following fields:
| l_type
| Describes the type of lock. If the value of the Command
parameter to the fcntl subroutine is F_SETLK or
F_SETLKW, the l_type field indicates the type of lock to
be created. Possible values are:
- F_RDLCK
- A read lock is requested.
- F_WRLCK
- A write lock is requested.
- F_UNLCK
- Unlock. An existing lock is to be removed.
If the value of the
Command parameter to the fcntl subroutine is
F_GETLK, the l_type field describes an existing
lock. Possible values are:
- F_RDLCK
- A conflicting read lock exists.
- F_WRLCK
- A conflicting write lock exists.
- F_UNLCK
- No conflicting lock exists.
|
| l_whence
| Defines the starting offset. The value of this field indicates the
point from which the relative offset, the l_start field, is
measured. Possible values are:
- SEEK_SET
- The relative offset is measured from the start of the file.
- SEEK_CUR
- The relative offset is measured from the current position.
- SEEK_END
- The relative offset is measured from the end of the file.
These values are defined in the
unistd.h file.
|
| l_start
| Defines the relative offset in bytes, measured from the starting point in
the l_whence field.
|
| l_len
| Specifies the number of consecutive bytes to be locked.
|
| l_sysid
| Contains the ID of the node that already has a lock placed on the area
defined by the fcntl subroutine. This field is returned only
when the value of the Command parameter is
F_GETLK.
|
| l_pid
| Contains the ID of a process that already has a lock placed on the area
defined by the fcntl subroutine. This field is returned only
when the value of the Command parameter is
F_GETLK.
|
| l_vfs
| Specifies the file system type of the node identified in the
l_sysid field.
|
Although the flock
structure is used by application programs to make file lock requests, the
extended flock structure, struct eflock, is
used internally by the kernel. The eflock structure is
identical to the flock structure in that it has the same
fields. The differences are that the l_len and l_start fields are 64
bit integers.
The flock64 structure
(Version 4.2 and later) in the
/usr/include/sys/flock.h file, which describes a lock,
contains the following fields:
| l_type
| Describes the type of lock. If the value of the Command
parameter to the fcntl subroutine is F_SETLK or
F_SETLKW, the l_type field indicates the type of lock to
be created. Possible values are:
- F_RDLCK
- A read lock is requested.
- F_WRLCK
- A write lock is requested.
- F_UNLCK
- Unlock. An existing lock is to be removed.
If the value of the
Command parameter to the fcntl subroutine is
F_GETLK, the l_type field describes an existing
lock. Possible values are:
- F_RDLCK
- A conflicting read lock exists.
- F_WRLCK
- A conflicting write lock exists.
- F_UNLCK
- No conflicting lock exists.
|
| l_whence
| Defines the starting offset. The value of this field indicates the
point from which the relative offset, the l_start field, is
measured. Possible values are:
- SEEK_SET
- The relative offset is measured from the start of the file.
- SEEK_CUR
- The relative offset is measured from the current position.
- SEEK_END
- The relative offset is measured from the end of the file.
These values are defined in the
unistd.h file.
|
| l_start
| Defines the relative offset in bytes, measured from the starting point in
the l_whence field. This field is of the type
off64_t.
|
| l_len
| Specifies the number of consecutive bytes to be locked. This field
is of the type off64_t.
|
| l_sysid
| Contains the ID of the node that already has a lock placed on the area
defined by the fcntl subroutine. This field is returned only
when the value of the Command parameter is
F_GETLK.
|
| l_pid
| Contains the ID of a process that already has a lock placed on the area
defined by the fcntl subroutine. This field is returned only
when the value of the Command parameter is
F_GETLK.
|
| l_vfs
| Specifies the file system type of the node identified in the
l_sysid field.
|
This file is part of Base
Operating System (BOS) Runtime.
The unistd.h file.
The fcntl subroutine, lockfx, lock, or flock
subroutine, open,openx, or
creat subroutine.
Header Files Overview defines header files, describes how they are used,
and lists several of the header files for which information is provided in
this documentation.
[ Previous | Next | Table of Contents | Index |
Library Home |
Legal |
Search ]