com.sun.jna.platform.unix

Interface LibCAPI

All Superinterfaces:

Reboot, Resource

All Known Subinterfaces:

LibC, LibC, SystemB

public interface LibCAPI
extends Reboot, Resource

Note: we are using this "intermediate" API in order to allow Linux-like O/S-es to implement the same API, but maybe using a different library name

Author:

Lyor Goldstein

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	LibCAPI.size_t This is an unsigned integer type used to represent the sizes of objects.
static class	LibCAPI.ssize_t This is a signed integer type used for a count of bytes or an error indication.

Nested classes/interfaces inherited from interface com.sun.jna.platform.unix.Resource

Resource.Rlimit

Field Summary

Fields

Modifier and Type	Field and Description
static int	HOST_NAME_MAX

Fields inherited from interface com.sun.jna.platform.unix.Reboot

RB_AUTOBOOT, RB_DISABLE_CAD, RB_ENABLE_CAD, RB_HALT_SYSTEM, RB_KEXEC, RB_POWER_OFF, RB_SW_SUSPEND

Fields inherited from interface com.sun.jna.platform.unix.Resource

RLIMIT_AS, RLIMIT_CORE, RLIMIT_CPU, RLIMIT_DATA, RLIMIT_FSIZE, RLIMIT_LOCKS, RLIMIT_MEMLOCK, RLIMIT_MSGQUEUE, RLIMIT_NICE, RLIMIT_NLIMITS, RLIMIT_NOFILE, RLIMIT_NPROC, RLIMIT_RSS, RLIMIT_RTPRIO, RLIMIT_RTTIME, RLIMIT_SIGPENDING, RLIMIT_STACK

Method Summary

Modifier and Type	Method and Description
int	close(int fd) Closes a file descriptor, so that it no longer refers to any file and may be reused.
int	getdomainname(byte[] name, int len)
int	getegid()
java.lang.String	getenv(java.lang.String name)
int	geteuid()
int	getgid()
int	gethostname(byte[] name, int len)
int	getloadavg(double[] loadavg, int nelem) The getloadavg() function returns the number of processes in the system run queue averaged over various periods of time.
int	getuid()
int	msync(Pointer addr, LibCAPI.size_t length, int flags) Flushes changes made to the in-core copy of a file that was mapped into memory using LibCUtil.mmap(Pointer, long, int, int, int, long) back to the filesystem.
int	munmap(Pointer addr, LibCAPI.size_t length) Deletes the mappings for the specified address range, and causes further references to addresses within the range to generate invalid memory references.
int	setdomainname(java.lang.String name, int len)
int	setegid(int gid)
int	setenv(java.lang.String name, java.lang.String value, int overwrite) Update or add a variable in the environment of the calling process.
int	seteuid(int uid)
int	setgid(int gid)
int	sethostname(java.lang.String name, int len)
int	setuid(int uid)
int	unsetenv(java.lang.String name)

Methods inherited from interface com.sun.jna.platform.unix.Reboot

reboot

Methods inherited from interface com.sun.jna.platform.unix.Resource

getrlimit, setrlimit

Field Detail

HOST_NAME_MAX

static final int HOST_NAME_MAX

See Also:

Constant Field Values

Method Detail

getuid

int getuid()

geteuid

int geteuid()

getgid

int getgid()

getegid

int getegid()

setuid

int setuid(int uid)

seteuid

int seteuid(int uid)

setgid

int setgid(int gid)

setegid

int setegid(int gid)

gethostname

int gethostname(byte[] name,
                int len)

sethostname

int sethostname(java.lang.String name,
                int len)

getdomainname

int getdomainname(byte[] name,
                  int len)

setdomainname

int setdomainname(java.lang.String name,
                  int len)

getenv

java.lang.String getenv(java.lang.String name)

Parameters:

name - Environment variable name

Returns:

Returns the value in the environment, or null if there is no match for the name

See Also:

getenv(3)

setenv

int setenv(java.lang.String name,
           java.lang.String value,
           int overwrite)

Update or add a variable in the environment of the calling process.

Parameters:

name - Environment variable name

value - Required value

overwrite - If the environment variable already exists and the value of overwrite is non-zero, the function shall return success and the environment shall be updated. If the environment variable already exists and the value of overwrite is zero, the function shall return success and the environment shall remain unchanged.

Returns:

Upon successful completion, zero shall be returned. Otherwise, -1 shall be returned, errno set to indicate the error, and the environment shall be unchanged

See Also:

getenv(3)

unsetenv

int unsetenv(java.lang.String name)

Parameters:

name - Environment variable name - If the named variable does not exist in the current environment, the environment shall be unchanged and the function is considered to have completed successfully.

Returns:

Upon successful completion, zero shall be returned. Otherwise, -1 shall be returned, errno set to indicate the error, and the environment shall be unchanged

See Also:

getenv(3)

getloadavg

int getloadavg(double[] loadavg,
               int nelem)

The getloadavg() function returns the number of processes in the system run queue averaged over various periods of time. Up to nelem samples are retrieved and assigned to successive elements of loadavg[]. The system imposes a maximum of 3 samples, representing averages over the last 1, 5, and 15 minutes, respectively.

Parameters:

loadavg - An array of doubles which will be filled with the results

nelem - Number of samples to return

Returns:

If the load average was unobtainable, -1 is returned; otherwise, the number of samples actually retrieved is returned.

See Also:

getloadavg(3)

close

int close(int fd)

Closes a file descriptor, so that it no longer refers to any file and may be reused. Any record locks held on the file it was associated with, and owned by the process, are removed (regardless of the file descriptor that was used to obtain the lock).

If fd is the last file descriptor referring to the underlying open file description, the resources associated with the open file description are freed; if the file descriptor was the last reference to a file which has been removed using unlink, the file is deleted.

Parameters:

fd - a file descriptor

Returns:

returns zero on success. On error, -1 is returned, and errno is set appropriately.

close() should not be retried after an error.

msync

int msync(Pointer addr,
          LibCAPI.size_t length,
          int flags)

Flushes changes made to the in-core copy of a file that was mapped into memory using LibCUtil.mmap(Pointer, long, int, int, int, long) back to the filesystem. Without use of this call, there is no guarantee that changes are written back before munmap(Pointer, size_t) is called. To be more precise, the part of the file that corresponds to the memory area starting at addr and having length length is updated.

Parameters:

addr - The start of the memory area to sync to the filesystem.

length - The length of the memory area to sync to the filesystem.

flags - The flags argument should specify exactly one of MS_ASYNC and MS_SYNC, and may additionally include the MS_INVALIDATE bit.

Returns:

On success, zero is returned. On error, -1 is returned, and errno is set appropriately.

munmap

int munmap(Pointer addr,
           LibCAPI.size_t length)

Deletes the mappings for the specified address range, and causes further references to addresses within the range to generate invalid memory references. The region is also automatically unmapped when the process is terminated. On the other hand, closing the file descriptor does not unmap the region.

It is not an error if the indicated range does not contain any mapped pages.

Parameters:

addr - The base address from which to delete mappings. The address addr must be a multiple of the page size (but length need not be).

length - The length from the base address to delete mappings. All pages containing a part of the indicated range are unmapped, and subsequent references to these pages will generate SIGSEGV.

Returns:

On success, returns 0. On failure, it returns -1, and errno is set to indicate the cause of the error (probably to EINVAL).