/*------------------------------------------------------------------------- * * shm.c * System V Shared Memory Emulation * * Copyright (c) 1999, repas AEG Automation GmbH * * * IDENTIFICATION * $Header: /cvsroot/pgsql/src/backend/port/qnx4/Attic/shm.c,v 1.6 2001/08/24 14:07:49 petere Exp $ * *------------------------------------------------------------------------- */ #include "postgres.h" #include <errno.h> #include <fcntl.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/mman.h> #include <sys/shm.h> #include <sys/stat.h> #define MODE 0777 #define SHMMAX 1024 struct shm_info { int shmid; key_t key; size_t size; void *addr; }; static struct shm_info *ShmInfo; static int shm_putinfo(struct shm_info * info); static int shm_updinfo(int i, struct shm_info * info); static int shm_getinfo(int shmid, struct shm_info * info); static int shm_getinfobyaddr(const void *addr, struct shm_info * info); static char * keytoname(key_t key, char *name) { sprintf( name,"PgShm%x", key ); return name; } static int shm_putinfo(struct shm_info * info) { int i; if (ShmInfo == NULL) { ShmInfo = calloc(SHMMAX, sizeof(struct shm_info)); if (ShmInfo == NULL) return -1; /* initialize ShmInfo */ for (i = 0; i < SHMMAX; i++) ShmInfo[i].shmid = -1; } /* search first free element */ i = 0; while (i < SHMMAX && ShmInfo[i].shmid != -1) i++; if (i >= SHMMAX) { errno = ENOSPC; return -1; } memcpy(&ShmInfo[i], info, sizeof(struct shm_info)); return i; } static int shm_updinfo(int i, struct shm_info * info) { if (i >= SHMMAX) return -1; if (ShmInfo == NULL) return -1; memcpy(&ShmInfo[i], info, sizeof(struct shm_info)); return i; } static int shm_getinfo(int shmid, struct shm_info * info) { int i; if (ShmInfo == NULL) return -1; /* search element */ i = 0; while (i < SHMMAX && ShmInfo[i].shmid != shmid) i++; if (i >= SHMMAX) return -1; memcpy(info, &ShmInfo[i], sizeof(struct shm_info)); return i; } static int shm_getinfobyaddr(const void *addr, struct shm_info * info) { int i; if (ShmInfo == (struct shm_info *) - 1) return -1; /* search element */ i = 0; while (i < SHMMAX && ShmInfo[i].addr != addr) i++; if (i >= SHMMAX) return -1; memcpy(info, &ShmInfo[i], sizeof(struct shm_info)); return i; } void * shmat(int shmid, const void *shmaddr, int shmflg) { struct shm_info info; int i; i = shm_getinfo(shmid, &info); if (i == -1) { errno = EACCES; return (void *) -1; } info.addr = mmap((void *) shmaddr, info.size, PROT_READ | PROT_WRITE, MAP_SHARED, shmid, 0); if (info.addr == MAP_FAILED) return info.addr; if (shm_updinfo(i, &info) == -1) { errno = EACCES; return (void *) -1; } return info.addr; } int shmdt(const void *addr) { struct shm_info info; if (shm_getinfobyaddr(addr, &info) == -1) { errno = EACCES; return -1; } return munmap((void *) addr, info.size); } int shmctl(int shmid, int cmd, struct shmid_ds * buf) { struct shm_info info; char name[NAME_MAX + 1]; int result; int fd; struct stat statbuf; switch( cmd ) { case IPC_RMID : if (shm_getinfo(shmid, &info) == -1) { errno = EACCES; return -1; } close( info.shmid ); keytoname(info.key, name); return shm_unlink( name ); case IPC_STAT : /* * we have to open it first. stat() does no prefix tracking * -> the call would go to fsys instead of proc */ keytoname(shmid, name); fd = shm_open( name, 0, MODE ); if ( fd >= 0 ) { result = fstat( fd, &statbuf ); /* * if the file exists, subtract 2 from linkcount : * one for our own open and one for the dir entry */ if ( ! result ) buf->shm_nattch = statbuf.st_nlink-2; close( fd ); return result; } else { /* * if there's no entry for this key it doesn't matter * the next shmget() would get a different shm anyway */ buf->shm_nattch = 0; return 0; } } errno = EINVAL; return -1; } int shmget(key_t key, size_t size, int flags) { char name[NAME_MAX + 1]; int oflag = 0; struct shm_info info; if (flags & IPC_CREAT) oflag |= O_CREAT; if (flags & IPC_EXCL) oflag |= O_EXCL; if (flags & SHM_R) { if (flags & SHM_W) oflag |= O_RDWR; else oflag |= O_RDONLY; } info.shmid = shm_open(keytoname(key, name), oflag, MODE); /* store shared memory information */ if (info.shmid != -1) { info.key = key; info.size = size; info.addr = NULL; if (shm_putinfo(&info) == -1) { close( info.shmid ); if ( (oflag & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL) ) { shm_unlink( name ); } return -1; } } /* The size may only be set once. Ignore errors. */ ltrunc(info.shmid, size, SEEK_SET); return info.shmid; }