# IPC::SysV

📦 std

System V IPC constants and the system calls Perl’s builtins do not cover. Perl’s core already provides `msgget`/`msgctl`/`msgsnd`/`msgrcv`, `semget`/`semctl`/`semop` and `shmget`/`shmctl`/`shmread`/`shmwrite` as builtins (pp_sys.c). What the `IPC::SysV` XS adds on top is the constant table (`IPC_CREAT`, `SEM_UNDO`, `SHM_RDONLY`, …), the `ftok` key generator, shared-memory attach/detach, and the `pack`/`unpack` pair each of `IPC::Msg::stat`, `IPC::Semaphore::stat` and `IPC::SharedMem::stat` uses to move a `struct msqid_ds` / `semid_ds` / `shmid_ds` across the Perl boundary. This is the XS half only. `IPC/SysV.pm` still loads from disk (`xs_only: true`) and supplies `@EXPORT_OK`, `%EXPORT_TAGS` and the `AUTOLOAD` that turns a constant name into a call to `_constant`. `IPC::Msg`, `IPC::Semaphore` and `IPC::SharedMem` are pure Perl on top of it and need no native half at all. ## Functions ### Other Functions #### `ftok` `ftok(path, id = undef)` - SysV.xs line 307. #### `memread` `memread(addr, sv, pos, size)` - SysV.xs line 345. #### `memwrite` `memwrite(addr, sv, pos, size)` - SysV.xs line 370. #### `shmat` `shmat(id, addr, flag)` - SysV.xs line 388. Returns the attach address as a PV holding the raw pointer bytes, matching sv2addr’s expectation. #### `shmdt` `shmdt(addr)` - SysV.xs line 409. #### `constant` `_constant($name)` - const-xs.inc.