/*- * See the file LICENSE for redistribution information. * * Copyright (c) 1996, 1997, 1998, 1999 * Sleepycat Software. All rights reserved. */ #include "db_config.h" #ifndef lint static const char sccsid[] = "@(#)os_map.c 11.10 (Sleepycat) 10/31/99"; #endif /* not lint */ #ifndef NO_SYSTEM_INCLUDES #include #ifdef HAVE_MMAP #include #endif #ifdef HAVE_SHMGET #include #include #endif #include #include #endif #include "db_int.h" #include "os_jump.h" #ifdef HAVE_MMAP static int CDB___os_map __P((DB_ENV *, char *, DB_FH *, size_t, int, int, void **)); #endif /* * CDB___os_r_sysattach -- * Create/join a shared memory region. * * PUBLIC: int CDB___os_r_sysattach __P((DB_ENV *, REGINFO *, REGION *)); */ int CDB___os_r_sysattach(dbenv, infop, rp) DB_ENV *dbenv; REGINFO *infop; REGION *rp; { DB_FH fh; int ret; if (F_ISSET(dbenv, DB_ENV_SYSTEM_MEM)) { /* * If the region is in system memory on UNIX, we use shmget(2). * * !!! * There exist spinlocks that don't work in shmget memory, e.g., * the HP/UX msemaphore interface. If we don't have locks that * will work in shmget memory, we better be private and not be * threaded. If we reach this point, we know we're public, so * it's an error. */ #if defined(MUTEX_NO_SHMGET_LOCKS) CDB___db_err(dbenv, "%s", "architecture does not support locks inside system (shmget(2)) memory"); CDB___db_err(dbenv, "%s", "application must specify DB_PRIVATE or not specify DB_SYSTEM_MEM"); return (EINVAL); #endif #if defined(HAVE_SHMGET) if (F_ISSET(infop, REGION_CREATE) && (rp->segid = shmget(0, rp->size, IPC_PRIVATE | 0600)) == -1) return (CDB___os_get_errno()); if ((infop->addr = shmat(rp->segid, NULL, 0)) == (void *)-1) { infop->addr = NULL; return (CDB___os_get_errno()); } return (0); #else CDB___db_err(dbenv, "architecture lacks shmget(2), environments in system memory not possible"); return (CDB___db_eopnotsup(dbenv)); #endif } #ifdef HAVE_MMAP /* * Try to open/create the file. We DO NOT need to ensure that multiple * threads/processes attempting to simultaneously create the region are * properly ordered, our caller has already taken care of that. */ if ((ret = CDB___os_open(infop->name, F_ISSET(infop, REGION_CREATE_OK) ? DB_OSO_CREATE: 0, infop->mode, &fh)) != 0) CDB___db_err(dbenv, "%s: %s", infop->name, CDB_db_strerror(ret)); /* * If we created the file, grow it to its full size before mapping * it in. We really want to avoid touching the buffer cache after * mmap(2) is called, doing anything else confuses the hell out of * systems without merged VM/buffer cache systems, or, more to the * point, *badly* merged VM/buffer cache systems. */ if (ret == 0 && F_ISSET(infop, REGION_CREATE)) ret = CDB___os_finit(&fh, rp->size, DB_GLOBAL(db_region_init)); /* Map the file in. */ if (ret == 0) ret = CDB___os_map(dbenv, infop->name, &fh, rp->size, 1, 0, &infop->addr); (void)CDB___os_closehandle(&fh); return (ret); #else CDB___db_err(dbenv, "architecture lacks mmap(2), shared environments not possible"); return (CDB___db_eopnotsup(dbenv)); #endif } /* * CDB___os_r_sysdetach -- * Detach from a shared memory region. * * PUBLIC: int CDB___os_r_sysdetach __P((DB_ENV *, REGINFO *, int)); */ int CDB___os_r_sysdetach(dbenv, infop, destroy) DB_ENV *dbenv; REGINFO *infop; int destroy; { REGION *rp; int segid; rp = infop->rp; if (F_ISSET(dbenv, DB_ENV_SYSTEM_MEM)) { #ifdef HAVE_SHMGET /* * We may be about to remove the memory referenced by rp, * save the segment ID, and (optionally) wipe the original. */ segid = rp->segid; if (destroy) rp->segid = INVALID_REGION_SEGID; if (shmdt(infop->addr) != 0) return (CDB___os_get_errno()); if (destroy) if (shmctl(segid, IPC_RMID, NULL) != 0) return (CDB___os_get_errno()); return (0); #else return (EINVAL); #endif } #ifdef HAVE_MMAP #ifdef HAVE_MUNLOCK if (F_ISSET(dbenv, DB_ENV_LOCKDOWN)) (void)munlock(infop->addr, rp->size); #endif if (munmap(infop->addr, rp->size) != 0) return (CDB___os_get_errno()); if (destroy && CDB___os_unlink(infop->name) != 0) return (CDB___os_get_errno()); return (0); #else return (EINVAL); #endif } /* * CDB___os_mapfile -- * Map in a shared memory file. * * PUBLIC: int CDB___os_mapfile __P((DB_ENV *, * PUBLIC: char *, DB_FH *, size_t, int, void **)); */ int CDB___os_mapfile(dbenv, path, fhp, len, is_rdonly, addrp) DB_ENV *dbenv; char *path; DB_FH *fhp; int is_rdonly; size_t len; void **addrp; { #ifdef HAVE_MMAP return (CDB___os_map(dbenv, path, fhp, len, 0, is_rdonly, addrp)); #else COMPQUIET(dbenv, NULL); return (EINVAL); #endif } /* * CDB___os_unmapfile -- * Unmap the shared memory file. * * PUBLIC: int CDB___os_unmapfile __P((DB_ENV *, void *, size_t)); */ int CDB___os_unmapfile(dbenv, addr, len) DB_ENV *dbenv; void *addr; size_t len; { /* If the user replaced the map call, call through their interface. */ if (CDB___db_jump.j_unmap != NULL) return (CDB___db_jump.j_unmap(addr, len)); #ifdef HAVE_MMAP #ifdef HAVE_MUNLOCK if (F_ISSET(dbenv, DB_ENV_LOCKDOWN)) (void)munlock(addr, len); #else COMPQUIET(dbenv, NULL); #endif return (munmap(addr, len) ? CDB___os_get_errno() : 0); #else COMPQUIET(dbenv, NULL); return (EINVAL); #endif } #ifdef HAVE_MMAP /* * CDB___os_map -- * Call the mmap(2) function. */ static int CDB___os_map(dbenv, path, fhp, len, is_region, is_rdonly, addrp) DB_ENV *dbenv; char *path; DB_FH *fhp; int is_region, is_rdonly; size_t len; void **addrp; { void *p; int flags, prot; /* If the user replaced the map call, call through their interface. */ if (CDB___db_jump.j_map != NULL) return (CDB___db_jump.j_map (path, len, is_region, is_rdonly, addrp)); /* * If it's read-only, it's private, and if it's not, it's shared. * Don't bother with an additional parameter. */ flags = is_rdonly ? MAP_PRIVATE : MAP_SHARED; #ifdef MAP_FILE /* * Historically, MAP_FILE was required for mapping regular files, * even though it was the default. Some systems have it, some * don't, some that have it set it to 0. */ flags |= MAP_FILE; #endif /* * I know of no systems that implement the flag to tell the system * that the region contains semaphores, but it's not an unreasonable * thing to do, and has been part of the design since forever. I * don't think anyone will object, but don't set it for read-only * files, it doesn't make sense. */ #ifdef MAP_HASSEMAPHORE if (is_region && !is_rdonly) flags |= MAP_HASSEMAPHORE; #else COMPQUIET(is_region, 0); #endif prot = PROT_READ | (is_rdonly ? 0 : PROT_WRITE); /* * XXX * Work around a bug in the VMS V7.1 mmap() implementation. To map * a file into memory on VMS it needs to be opened in a certain way, * originally. To get the file opened in that certain way, the VMS * mmap() closes the file and re-opens it. When it does this, it * doesn't flush any caches out to disk before closing. The problem * this causes us is that when the memory cache doesn't get written * out, the file isn't big enough to match the memory chunk and the * mmap() call fails. This call to fsync() fixes the problem. DEC * thinks this isn't a bug because of language in XPG5 discussing user * responsibility for on-disk and in-memory synchronization. */ #ifdef VMS if (CDB___os_fsync(fhp) == -1) return(CDB___os_get_errno()); #endif /* MAP_FAILED was not defined in early mmap implementations. */ #ifndef MAP_FAILED #define MAP_FAILED -1 #endif if ((p = mmap(NULL, len, prot, flags, fhp->fd, (off_t)0)) == (void *)MAP_FAILED) return (CDB___os_get_errno()); #ifdef HAVE_MLOCK /* * If it's a region, we want to make sure that the memory isn't paged. * For example, Solaris will page large mpools because it thinks that * I/O buffer memory is more important than we are. The mlock system * call may or may not succeed (mlock is restricted to the super-user * on some systems). Currently, the only other use of mmap in DB is * to map read-only databases -- we don't want them paged, either, so * the call isn't conditional. */ if (F_ISSET(dbenv, DB_ENV_LOCKDOWN) && mlock(p, len) != 0) { (void)munmap(p, len); return (CDB___os_get_errno()); } #else COMPQUIET(dbenv, NULL); #endif *addrp = p; return (0); } #endif