System Calls swapctl(2)
NAME
swapctl - manage swap space
SYNOPSIS
#include
#include
int swapctl(int cmd, void *arg);
DESCRIPTION
The swapctl() function adds, deletes, or returns informa-
tion about swap resources. cmd specifies one of the follow-
ing options contained in: 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 specifyingthe 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 */
SunOS 5.11 Last change: 25 Sep 1997 1
System Calls swapctl(2)
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 pro-
cess 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 speci-
fied swap area is less than one page(SC_ADD).
SunOS 5.11 Last change: 25 Sep 1997 2
System Calls swapctl(2)
EISDIR The path specified for SC_ADD is a direc-
tory. ELOOP Too many symbolic links were encountered intranslating the pathname provided to SC_ADD
or SC_REMOVE.
ENAMETOOLONG The length of a component of the path speci-
fied 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 swapentstructures were provided to SC_LIST, or
there were insufficient system storageresources 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 aSunOS 5.11 Last change: 25 Sep 1997 3
System Calls swapctl(2)
32-bit quantity.
EXAMPLES
Example 1 The usage of the SC_GETNSWP and SC_LIST commands.
The following example demonstrates the usage of theSC_GETNSWP and SC_LIST commands.
#include
#include
#include
#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);
}SunOS 5.11 Last change: 25 Sep 1997 4
System Calls swapctl(2)
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)SunOS 5.11 Last change: 25 Sep 1997 5