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man pages section 2: System Calls     Oracle Solaris 11.1 Information Library
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Document Information

Preface

Introduction

System Calls

access(2)

acct(2)

acl(2)

adjtime(2)

alarm(2)

brk(2)

chdir(2)

chmod(2)

chown(2)

chroot(2)

close(2)

creat(2)

dup(2)

exec(2)

execl(2)

execle(2)

execlp(2)

execv(2)

execve(2)

execvex(2)

execvp(2)

_Exit(2)

_exit(2)

exit(2)

faccessat(2)

facl(2)

fchdir(2)

fchmod(2)

fchmodat(2)

fchown(2)

fchownat(2)

fchroot(2)

fcntl(2)

fexecve(2)

fgetlabel(2)

fork1(2)

fork(2)

forkall(2)

forkallx(2)

forkx(2)

fpathconf(2)

fstat(2)

fstatat(2)

fstatvfs(2)

futimens(2)

futimesat(2)

getacct(2)

getcontext(2)

getdents(2)

getegid(2)

geteuid(2)

getgid(2)

getgroups(2)

getisax(2)

getitimer(2)

getlabel(2)

getmsg(2)

getpflags(2)

getpgid(2)

getpgrp(2)

getpid(2)

getpmsg(2)

getppid(2)

getppriv(2)

getprojid(2)

getrctl(2)

getrlimit(2)

getsid(2)

gettaskid(2)

getuid(2)

getustack(2)

ioctl(2)

issetugid(2)

kill(2)

lchown(2)

link(2)

linkat(2)

llseek(2)

lseek(2)

lstat(2)

_lwp_cond_broadcast(2)

_lwp_cond_reltimedwait(2)

_lwp_cond_signal(2)

_lwp_cond_timedwait(2)

_lwp_cond_wait(2)

_lwp_continue(2)

_lwp_info(2)

_lwp_kill(2)

_lwp_mutex_lock(2)

_lwp_mutex_trylock(2)

_lwp_mutex_unlock(2)

_lwp_self(2)

_lwp_sema_init(2)

_lwp_sema_post(2)

_lwp_sema_trywait(2)

_lwp_sema_wait(2)

_lwp_suspend(2)

memcntl(2)

meminfo(2)

mincore(2)

mkdir(2)

mkdirat(2)

mknod(2)

mknodat(2)

mmap(2)

mmapobj(2)

mount(2)

mprotect(2)

msgctl(2)

msgget(2)

msgids(2)

msgrcv(2)

msgsnap(2)

msgsnd(2)

munmap(2)

nice(2)

ntp_adjtime(2)

ntp_gettime(2)

open(2)

openat(2)

pathconf(2)

pause(2)

pcsample(2)

pipe(2)

poll(2)

p_online(2)

ppoll(2)

pread(2)

priocntl(2)

priocntlset(2)

processor_bind(2)

processor_info(2)

profil(2)

pset_assign(2)

pset_bind(2)

pset_create(2)

pset_destroy(2)

pset_getattr(2)

pset_info(2)

pset_list(2)

pset_setattr(2)

putacct(2)

putmsg(2)

putpmsg(2)

pwrite(2)

read(2)

readlink(2)

readlinkat(2)

readv(2)

rename(2)

renameat(2)

resolvepath(2)

rmdir(2)

sbrk(2)

semctl(2)

semget(2)

semids(2)

semop(2)

semtimedop(2)

setcontext(2)

setegid(2)

seteuid(2)

setgid(2)

setgroups(2)

setitimer(2)

setpflags(2)

setpgid(2)

setpgrp(2)

setppriv(2)

setrctl(2)

setregid(2)

setreuid(2)

setrlimit(2)

setsid(2)

settaskid(2)

setuid(2)

setustack(2)

shmadv(2)

shmat(2)

shmctl(2)

shmdt(2)

shmget(2)

shmids(2)

shmop(2)

sigaction(2)

sigaltstack(2)

sigpending(2)

sigprocmask(2)

sigsend(2)

sigsendset(2)

sigsuspend(2)

sigwait(2)

__sparc_utrap_install(2)

stat(2)

statvfs(2)

stime(2)

swapctl(2)

symlink(2)

symlinkat(2)

sync(2)

sysfs(2)

sysinfo(2)

time(2)

times(2)

uadmin(2)

ulimit(2)

umask(2)

umount(2)

umount2(2)

uname(2)

unlink(2)

unlinkat(2)

ustat(2)

utime(2)

utimensat(2)

utimes(2)

uucopy(2)

vfork(2)

vforkx(2)

vhangup(2)

waitid(2)

wracct(2)

write(2)

writev(2)

yield(2)

swapctl

- manage swap space

Synopsis

#include <sys/stat.h>
#include <sys/swap.h>

int swapctl(int cmd, void *arg);

Description

The swapctl() function adds, deletes, or returns information about swap resources. cmd specifies one of the following options contained in <sys/swap.h>:

SC_ADD        /* add a resource for swapping */
SC_LIST       /* list the resources for swapping */
SC_REMOVE     /* remove a resource for swapping */
SC_GETNSWP    /* return number of swap resources */

When SC_ADD or SC_REMOVE is specified, arg is a pointer to a swapres structure containing the following members:

char    *sr_name;    /* pathname of resource */
off_t   sr_start;    /* offset to start of swap area */
off_t   sr_length;   /* length of swap area */

The sr_start and sr_length members are specified in 512-byte blocks. A swap resource can only be removed by specifying the same values for the sr_start and sr_length members as were specified when it was added. Swap resources need not be removed in the order in which they were added.

When SC_LIST is specified, arg is a pointer to a swaptable structure containing the following members:

int             swt_n;       /* number of swapents following */
struct swapent  swt_ent[];   /* array of swt_n swapents */

A swapent structure contains the following members:

char   *ste_path;    /* name of the swap file */
off_t  ste_start;    /* starting block for swapping */
off_t  ste_length;   /* length of swap area */
long   ste_pages;    /* number of pages for swapping */
long   ste_free;     /* number of ste_pages free */
long   ste_flags;    /* ST_INDEL bit set if swap file */
                     /* is now being deleted */

The SC_LIST function causes swapctl() to return at most swt_n entries. The return value of swapctl() is the number actually returned. The ST_INDEL bit is turned on in ste_flags if the swap file is in the process of being deleted.

When SC_GETNSWP is specified, swapctl() returns as its value the number of swap resources in use. arg is ignored for this operation.

The SC_ADD and SC_REMOVE functions will fail if calling process does not have appropriate privileges.

Return Values

Upon successful completion, the function swapctl() returns a value of 0 for SC_ADD or SC_REMOVE, the number of struct swapent entries actually returned for SC_LIST, or the number of swap resources in use for SC_GETNSWP. Upon failure, the function swapctl() returns a value of -1 and sets errno to indicate an error.

Errors

Under the following conditions, the function swapctl() fails and sets errno to:

EEXIST

Part of the range specified by sr_start and sr_length is already being used for swapping on the specified resource (SC_ADD).

EFAULT

Either arg, sr_name, or ste_path points to an illegal address.

EINVAL

The specified function value is not valid, the path specified is not a swap resource (SC_REMOVE), part of the range specified by sr_start and sr_length lies outside the resource specified (SC_ADD), or the specified swap area is less than one page (SC_ADD).

EISDIR

The path specified for SC_ADD is a directory.

ELOOP

Too many symbolic links were encountered in translating the pathname provided to SC_ADD or SC_REMOVE.

ENAMETOOLONG

The length of a component of the path specified for SC_ADD or SC_REMOVE exceeds NAME_MAX characters or the length of the path exceeds PATH_MAX characters and _POSIX_NO_TRUNC is in effect.

ENOENT

The pathname specified for SC_ADD or SC_REMOVE does not exist.

ENOMEM

An insufficient number of struct swapent structures were provided to SC_LIST, or there were insufficient system storage resources available during an SC_ADD or SC_REMOVE, or the system would not have enough swap space after an SC_REMOVE.

ENOSYS

The pathname specified for SC_ADD or SC_REMOVE is not a file or block special device.

ENOTDIR

Pathname provided to SC_ADD or SC_REMOVE contained a component in the path prefix that was not a directory.

EPERM

The {PRIV_SYS_MOUNT} was not asserted in the effective set of the calling process.

EROFS

The pathname specified for SC_ADD is a read-only file system.

Additionally, the swapctl() function will fail for 32-bit interfaces if:

EOVERFLOW

The amount of swap space configured on the machine is too large to be represented by a 32-bit quantity.

Examples

Example 1 The usage of the SC_GETNSWP and SC_LIST commands.

The following example demonstrates the usage of the SC_GETNSWP and SC_LIST commands.

#include <sys/stat.h>
#include <sys/swap.h>
#include <stdio.h>

#define MAXSTRSIZE 80

main(argc, argv)
    int            argc;
    char           *argv[];
{
    swaptbl_t      *s;
    int            i, n, num;
    char           *strtab;    /* string table for path names */

again:
    if ((num = swapctl(SC_GETNSWP, 0)) == -1) {
        perror("swapctl: GETNSWP");
        exit(1);
    }
    if (num == 0) {
        fprintf(stderr, "No Swap Devices Configured\n");
        exit(2);
    }
    /* allocate swaptable for num+1 entries */
    if ((s = (swaptbl_t *)
        malloc(num * sizeof(swapent_t) + 
            sizeof(struct swaptable))) ==
        (void *) 0) {
        fprintf(stderr, "Malloc Failed\n");
        exit(3);
    }
    /* allocate num+1 string holders */
    if ((strtab = (char *)
        malloc((num + 1) * MAXSTRSIZE)) == (void *) 0) {
        fprintf(stderr, "Malloc Failed\n");
        exit(3);
    }
    /* initialize string pointers */
    for (i = 0; i < (num + 1); i++) {
        s->swt_ent[i].ste_path = strtab + (i * MAXSTRSIZE);
    }
   
    s->swt_n = num + 1;
    if ((n = swapctl(SC_LIST, s)) < 0) {
        perror("swapctl");
        exit(1);
    }
    if (n > num) {        /* more were added */
        free(s);
        free(strtab);
        goto again;
    }
    for (i = 0; i < n; i++)
        printf("%s %ld\n",
            s->swt_ent[i].ste_path, s->swt_ent[i].ste_pages);
}

See Also

privileges(5)