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| | msgids - discover all message queue identifiers |
SYNOPSIS
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#include <sys/msg.h> int msgids(int *buf, uint_t nids, uint_t *pnids); |
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The msgids() function copies all active message
queue 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 message queue 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 message queue 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
message queue identifiers in the system, buf is ignored.
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Upon successful completion, msgids() returns 0. Otherwise, -1 is returned
and errno is set to indicate the error.
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The msgids() function will fail if:
-
EFAULT
- The buf or pnids argument points to an illegal address.
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The msgids() function returns a snapshot of all
the active message queue identifiers in the system. More may be added and
some may be removed before they can be used by the caller.
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| | Example 1. msgids example
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This is sample C code indicating how to use the msgids()
function (see msgsnap(2)):
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void
examine_queues()
{
int *ids = NULL;
uint_t nids = 0;
uint_t n;
int i;
for (;;) {
if (msgids(ids, nids, &n) != 0) {
perror("msgids");
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_msgid(ids[i]);
free(ids);
}
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See attributes(5)
for descriptions of the following attributes:
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| MT-Level | Async-Signal-Safe |
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