shmids(2) [sunos man page]
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(5) 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(5) SunOS 5.10 8 Mar 2000 shmids(2)
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shmget(2) System Calls shmget(2) NAME
shmget - get shared memory segment identifier SYNOPSIS
#include <sys/types.h> #include <sys/ipc.h> #include <sys/shm.h> int shmget(key_t key, size_t size, int shmflg); DESCRIPTION
The shmget() function returns the shared memory identifier associated with key. A shared memory identifier and associated data structure and shared memory segment of at least size bytes (see Intro(2)) are created for key if one of the following are true: o The key argument is equal to IPC_PRIVATE. o The key argument does not already have a shared memory identifier associated with it, and (shmflg&IPC_CREAT) is true. Upon creation, the data structure associated with the new shared memory identifier is initialized as follows: o The values of shm_perm.cuid, shm_perm.uid, shm_perm.cgid, and shm_perm.gid are set equal to the effective user ID and effective group ID, respectively, of the calling process. o The access permission bits of shm_perm.mode are set equal to the access permission bits of shmflg. shm_segsz is set equal to the value of size. o The values of shm_lpid, shm_nattch shm_atime, and shm_dtime are set equal to 0. o The shm_ctime is set equal to the current time. Shared memory segments must be explicitly removed after the last reference to them has been removed. RETURN VALUES
Upon successful completion, a non-negative integer representing a shared memory identifier is returned. Otherwise, -1 is returned and errno is set to indicate the error. ERRORS
The shmget() function will fail if: EACCES A shared memory identifier exists for key but operation permission (see Intro(2)) as specified by the low-order 9 bits of shmflg would not be granted. EEXIST A shared memory identifier exists for key but both (shmflg&IPC_CREAT) and (shmflg&IPC_EXCL) are true. EINVAL The size argument is less than the system-imposed minimum or greater than the system-imposed maximum. See NOTES. A shared memory identifier exists for key but the size of the segment associated with it is less than size and size is not equal to 0. ENOENT A shared memory identifier does not exist for key and (shmflg&IPC_CREAT) is false. ENOMEM A shared memory identifier and associated shared memory segment are to be created but the amount of available memory is not suf- ficient to fill the request. ENOSPC A shared memory identifier is to be created but the system-imposed limit on the maximum number of allowed shared memory identi- fiers system-wide would be exceeded. See NOTES. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ SEE ALSO
rctladm(1M), Intro(2), setrctl(2), shmctl(2), shmop(2), ftok(3C), getpagesize(3C), attributes(5), standards(5) NOTES
The project.max-shm-memory resource control restricts the total amount of shared memory a project can allocate. The zone.max-shm-memory resource control restricts the total amount of shared memory that can be allocated by a zone. The system-imposed maximum on the size of a shared memory segment is therefore a function of the sizes of any other shared memory segments the calling project might have allocated that are still in use, as well as any other shared memory segments allocated and still in use by processes in the zone. For accounting purposes, segment sizes are rounded up to the nearest multiple of the system page size. See getpagesize(3C). The system-imposed limit on the number of shared memory identifiers is maintained on a per-project basis using the project.max-shm-ids resource control. The zone.max-shm-ids resource control restricts the total number of shared memory identifiers that can be allocated by a zone. See rctladm(1M) and setrctl(2) for information about using resource controls. SunOS 5.11 14 Aug 2006 shmget(2)