path: root/usr/src/man/man2/swapctl.2

'\" te
.\"  Copyright 1989 AT&T  Copyright (c) 1997, Sun Microsystems, Inc.  All Rights Reserved
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.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing.  See the License for the specific language governing permissions and limitations under the License.
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.TH SWAPCTL 2 "Sep 25, 1997"
.SH NAME
swapctl \- manage swap space
.SH SYNOPSIS
.LP
.nf
#include <sys/stat.h>
#include <sys/swap.h>

\fBint\fR \fBswapctl\fR(\fBint\fR \fIcmd\fR, \fBvoid *\fR\fIarg\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBswapctl()\fR function adds,  deletes, or returns information about swap
resources. \fIcmd\fR specifies one of the following options contained in
<\fBsys/swap.h\fR>:
.sp
.in +2
.nf
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 */
.fi
.in -2

.sp
.LP
When \fBSC_ADD\fR or \fBSC_REMOVE\fR is specified, \fIarg\fR is a pointer to a
\fBswapres\fR structure containing the following members:
.sp
.in +2
.nf
char    *sr_name;    /* pathname of resource */
off_t   sr_start;    /* offset to start of swap area */
off_t   sr_length;   /* length of swap area */
.fi
.in -2

.sp
.LP
The \fBsr_start\fR and \fBsr_length\fR members are specified in 512-byte
blocks. A swap resource can only be removed by specifying the same values for
the \fBsr_start\fR and \fBsr_length\fR members as were specified when it was
added. Swap resources need not be removed in the order in which they were
added.
.sp
.LP
When \fBSC_LIST\fR is specified, \fIarg\fR is a pointer to a \fBswaptable\fR
structure containing the following members:
.sp
.in +2
.nf
int             swt_n;       /* number of swapents following */
struct swapent  swt_ent[];   /* array of swt_n swapents */
.fi
.in -2

.sp
.LP
A \fBswapent\fR structure contains the following members:
.sp
.in +2
.nf
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 */
.fi
.in -2

.sp
.LP
The \fBSC_LIST\fR function causes \fBswapctl()\fR to return at most \fBswt_n\fR
entries. The return value of \fBswapctl()\fR is the number actually returned.
The \fBST_INDEL\fR bit is turned on in \fBste_flags\fR if the swap file is in
the process of being deleted.
.sp
.LP
When \fBSC_GETNSWP\fR is specified, \fBswapctl()\fR returns as its value the
number of swap resources in use. \fIarg\fR is ignored for this operation.
.sp
.LP
The \fBSC_ADD\fR and \fBSC_REMOVE\fR functions will fail if calling process
does not have appropriate privileges.
.SH RETURN VALUES
.sp
.LP
Upon successful completion, the function \fBswapctl()\fR returns a value of
\fB0\fR for \fBSC_ADD\fR or \fBSC_REMOVE\fR, the number of \fBstruct\fR
\fBswapent\fR entries actually returned  for \fBSC_LIST\fR, or the number of
swap resources in use for \fBSC_GETNSWP\fR. Upon failure, the function
\fBswapctl()\fR returns a value  of \fB\(mi1\fR and sets \fBerrno\fR to
indicate an error.
.SH ERRORS
.sp
.LP
Under the following conditions, the function \fBswapctl()\fR fails and sets
\fBerrno\fR to:
.sp
.ne 2
.na
\fB\fBEEXIST\fR\fR
.ad
.RS 16n
Part of the range specified by \fBsr_start\fR and \fBsr_length\fR is already
being used for swapping on the specified resource (\fBSC_ADD\fR).
.RE

.sp
.ne 2
.na
\fB\fBEFAULT\fR\fR
.ad
.RS 16n
Either \fIarg\fR, \fBsr_name\fR, or \fBste_path\fR points to an illegal
address.
.RE

.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 16n
The specified function value is not valid, the path specified is not a swap
resource (\fBSC_REMOVE\fR), part of the range specified by \fBsr_start\fR and
\fBsr_length\fR lies outside the resource specified (\fBSC_ADD\fR), or the
specified swap area is less than one page (\fBSC_ADD\fR).
.RE

.sp
.ne 2
.na
\fB\fBEISDIR\fR\fR
.ad
.RS 16n
The path specified for \fBSC_ADD\fR is a directory.
.RE

.sp
.ne 2
.na
\fB\fBELOOP\fR\fR
.ad
.RS 16n
Too many symbolic links were encountered in translating the pathname provided
to \fBSC_ADD\fR or \fBSC_REMOVE\fR.
.RE

.sp
.ne 2
.na
\fB\fBENAMETOOLONG\fR\fR
.ad
.RS 16n
The length of a component of the path specified for \fBSC_ADD\fR or
\fBSC_REMOVE\fR exceeds \fBNAME_MAX\fR characters or the length of the path
exceeds \fBPATH_MAX\fR characters and \fB_POSIX_NO_TRUNC\fR is in effect.
.RE

.sp
.ne 2
.na
\fB\fBENOENT\fR\fR
.ad
.RS 16n
The pathname specified for \fBSC_ADD\fR or \fBSC_REMOVE\fR does not exist.
.RE

.sp
.ne 2
.na
\fB\fBENOMEM\fR\fR
.ad
.RS 16n
An insufficient number of \fBstruct\fR \fBswapent\fR structures were provided
to \fBSC_LIST\fR, or there were insufficient system storage resources available
during an \fBSC_ADD\fR or \fBSC_REMOVE\fR, or the system would not have enough
swap space after an \fBSC_REMOVE\fR.
.RE

.sp
.ne 2
.na
\fB\fBENOSYS\fR\fR
.ad
.RS 16n
The pathname specified for \fBSC_ADD\fR or \fBSC_REMOVE\fR is not a file or
block special device.
.RE

.sp
.ne 2
.na
\fB\fBENOTDIR\fR\fR
.ad
.RS 16n
Pathname provided to \fBSC_ADD\fR or \fBSC_REMOVE\fR contained a component in
the path prefix that was not a directory.
.RE

.sp
.ne 2
.na
\fB\fBEPERM\fR\fR
.ad
.RS 16n
The {\fBPRIV_SYS_MOUNT\fR} was not asserted in the effective set of the calling
process.
.RE

.sp
.ne 2
.na
\fB\fBEROFS\fR\fR
.ad
.RS 16n
The pathname specified for \fBSC_ADD\fR is a read-only file system.
.RE

.sp
.LP
Additionally, the \fBswapctl()\fR function will fail for 32-bit interfaces if:
.sp
.ne 2
.na
\fB\fBEOVERFLOW\fR\fR
.ad
.RS 13n
The amount of swap space configured on the machine is too large to be
represented by a 32-bit quantity.
.RE

.SH EXAMPLES
.LP
\fBExample 1 \fRThe usage of the \fBSC_GETNSWP\fR and \fBSC_LIST\fR commands.
.sp
.LP
The following example demonstrates the usage of the \fBSC_GETNSWP\fR and
\fBSC_LIST\fR commands.

.sp
.in +2
.nf
#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\en");
        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\en");
        exit(3);
    }
    /* allocate num+1 string holders */
    if ((strtab = (char *)
        malloc((num + 1) * MAXSTRSIZE)) == (void *) 0) {
        fprintf(stderr, "Malloc Failed\en");
        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\en",
            s->swt_ent[i].ste_path, s->swt_ent[i].ste_pages);
}
.fi
.in -2

.SH SEE ALSO
.sp
.LP
\fBprivileges\fR(5)