SHMIDS(2) System Calls SHMIDS(2)

NAME

shmids - discover all shared memory identifiers

SYNOPSIS

#include <sys/shm.h>

int shmids(int *buf, uint_t nids, uint_t *pnids);

DESCRIPTION

The shmids() function copies all active shared memory identifiers from
the system into the user-defined buffer specified by buf, provided that
the number of such identifiers is not greater than the number of integers
the buffer can contain, as specified by nids. If the size of the buffer
is insufficient to contain all of the active shared memory identifiers in
the system, none are copied.


Whether or not the size of the buffer is sufficient to contain all of
them, the number of active shared memory identifiers in the system is
copied into the unsigned integer pointed to by pnids.


If nids is 0 or less than the number of active shared memory identifiers
in the system, buf is ignored.

RETURN VALUES

Upon successful completion, shmids() returns 0. Otherwise, -1 is
returned and errno is set to indicate the error.

ERRORS

The shmids() function will fail if:

EFAULT
The buf or pnids argument points to an illegal address.

USAGE

The shmids() function returns a snapshot of all the active shared memory
identifiers in the system. More may be added and some may be removed
before they can be used by the caller.

EXAMPLES

Example 1 shmids() example


This is sample C code indicating how to use the shmids() function.


void
examine_shmids()
{
int *ids = NULL;
uint_t nids = 0;
uint_t n;
int i;

for (;;) {
if (shmids(ids, nids, &n) != 0) {
perror("shmids");
exit(1);
}
if (n <= nids) /* we got them all */
break;
/* we need a bigger buffer */
ids = realloc(ids, (nids = n) * sizeof (int));
}

for (i = 0; i < n; i++)
process_shmid(ids[i]);

free(ids);
}

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+---------------+-------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+-------------------+
|MT-Level | Async-Signal-Safe |
+---------------+-------------------+

SEE ALSO

ipcrm(1), ipcs(1), Intro(2), shmctl(2), shmget(2), shmop(2),
attributes(7)

March 8, 2000 SHMIDS(2)