semids(2) - osol9

1semids(2)                        System Calls                        semids(2)
2
3
4

NAME

6       semids - discover all semaphore identifiers
7

SYNOPSIS

9       #include <sys/sem.h>
10
11       int semids(int *buf, uint_t nids, uint_t *pnids);
12
13

DESCRIPTION

15       The  semids() function copies all active semaphore identifiers from the
16       system into the user-defined buffer specified by buf, provided that the
17       number  of  such identifiers is not greater than the number of integers
18       the buffer can contain, as specified by nids.  If the size of the  buf‐
19       fer  is insufficient to contain all of the active semaphore identifiers
20       in the system, none are copied.
21
22
23       Whether or not the size of the buffer is sufficient to contain  all  of
24       them,  the  number  of  active  semaphore  identifiers in the system is
25       copied into the unsigned integer pointed to by pnids.
26
27
28       If nids is 0 or less than the number of active semaphore identifiers in
29       the system, buf is ignored.
30

RETURN VALUES

32       Upon  successful  completion,  semids()  returns  0.   Otherwise, −1 is
33       returned and errno is set to indicate the error.
34

ERRORS

36       The semids() function will fail if:
37
38       EFAULT    The buf or pnids argument points to an illegal address.
39
40

USAGE

42       The semids() function returns a snapshot of all  the  active  semaphore
43       identifiers  in  the system.  More may be added and some may be removed
44       before they can be used by the caller.
45

EXAMPLES

47       Example 1 semids() example
48
49
50       This is sample C code indicating how to use the semids() function.
51
52
53         void
54         examine_semids()
55         {
56              int *ids = NULL;
57              uint_t nids = 0;
58              uint_t n;
59              int i;
60
61              for (;;) {
62                   if (semids(ids, nids, &n) != 0) {
63                        perror("semids");
64                        exit(1);
65                   }
66                   if (n <= nids)     /* we got them all */
67                        break;
68                   /* we need a bigger buffer */
69                   ids = realloc(ids, (nids = n) * sizeof (int));
70              }
71
72              for (i = 0; i < n; i++)
73                   process_semid(ids[i]);
74
75              free(ids);
76         }
77
78

ATTRIBUTES

80       See attributes(5) for descriptions of the following attributes:
81
82
83
84
85       ┌─────────────────────────────┬─────────────────────────────┐
86       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
87       ├─────────────────────────────┼─────────────────────────────┤
88       │MT-Level                     │Async-Signal-Safe            │
89       └─────────────────────────────┴─────────────────────────────┘
90