diff options
| -rw-r--r-- | src/backend/port/sysv_shmem.c | 143 |
1 files changed, 75 insertions, 68 deletions
diff --git a/src/backend/port/sysv_shmem.c b/src/backend/port/sysv_shmem.c index 9454c3e92cc..ffe5bfa268a 100644 --- a/src/backend/port/sysv_shmem.c +++ b/src/backend/port/sysv_shmem.c @@ -10,7 +10,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/port/sysv_shmem.c,v 1.9 2003/05/08 14:49:03 momjian Exp $ + * $Header: /cvsroot/pgsql/src/backend/port/sysv_shmem.c,v 1.10 2003/05/08 19:17:07 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -47,6 +47,8 @@ static void IpcMemoryDetach(int status, Datum shmaddr); static void IpcMemoryDelete(int status, Datum shmId); static void *PrivateMemoryCreate(uint32 size); static void PrivateMemoryDelete(int status, Datum memaddr); +static PGShmemHeader *PGSharedMemoryAttach(IpcMemoryKey key, + IpcMemoryId *shmid, void *addr); /* @@ -297,72 +299,48 @@ PGSharedMemoryCreate(uint32 size, bool makePrivate, int port) IpcMemoryKey NextShmemSegID; void *memAddress; PGShmemHeader *hdr; + IpcMemoryId shmid; /* Room for a header? */ Assert(size > MAXALIGN(sizeof(PGShmemHeader))); - if (ExecBackend && UsedShmemSegID != 0) - NextShmemSegID = UsedShmemSegID; - else - NextShmemSegID = port * 1000 + 1; - - for (;;NextShmemSegID++) + /* Just attach and return the pointer */ + if (ExecBackend && UsedShmemSegAddr != NULL && !makePrivate) { - IpcMemoryId shmid; - - /* Special case if creating a private segment --- just malloc() it */ - if (makePrivate) - { - memAddress = PrivateMemoryCreate(size); - break; - } - - /* If attach to fixed address, only try once */ - if (ExecBackend && UsedShmemSegAddr != NULL && NextShmemSegID != UsedShmemSegID) + if ((hdr = (PGShmemHeader *) memAddress = PGSharedMemoryAttach( + UsedShmemSegID, &shmid, UsedShmemSegAddr)) == NULL) { - fprintf(stderr, "Unable to attach to memory at fixed address: shmget(key=%d, addr=%p) failed: %s\n", + fprintf(stderr, "Unable to attach to proper memory at fixed address: shmget(key=%d, addr=%p) failed: %s\n", (int) UsedShmemSegID, UsedShmemSegAddr, strerror(errno)); proc_exit(1); } + return hdr; + } - if (!ExecBackend || UsedShmemSegAddr == NULL) - { - /* Try to create new segment */ - memAddress = InternalIpcMemoryCreate(NextShmemSegID, size); - if (memAddress) - break; /* successful create and attach */ - } - - /* See if it looks to be leftover from a dead Postgres process */ - shmid = shmget(NextShmemSegID, sizeof(PGShmemHeader), 0); - if (shmid < 0) - continue; /* failed: must be some other app's */ - - /* use intimate shared memory on SPARC Solaris */ - memAddress = shmat(shmid, UsedShmemSegAddr, -#if defined(solaris) && defined(__sparc__) - SHM_SHARE_MMU -#else - 0 -#endif - ); - - if (memAddress == (void *) -1) - continue; /* failed: must be some other app's */ + /* Create shared memory */ + + NextShmemSegID = port * 1000 + 1; - hdr = (PGShmemHeader *) memAddress; - if (hdr->magic != PGShmemMagic) + for (;;NextShmemSegID++) + { + /* Special case if creating a private segment --- just malloc() it */ + if (makePrivate) { - shmdt(memAddress); - continue; /* segment belongs to a non-Postgres app */ + memAddress = PrivateMemoryCreate(size); + break; } - /* Successfully attached to shared memory, which is all we wanted */ - if (ExecBackend && UsedShmemSegAddr != NULL) - break; + /* Try to create new segment */ + memAddress = InternalIpcMemoryCreate(NextShmemSegID, size); + if (memAddress) + break; /* successful create and attach */ /* Check shared memory and possibly remove and recreate */ + if ((hdr = (PGShmemHeader *) memAddress = PGSharedMemoryAttach( + NextShmemSegID, &shmid, UsedShmemSegAddr)) == NULL) + continue; /* can't attach, not one of mine */ + /* * If I am not the creator and it belongs to an extant process, * continue. @@ -401,31 +379,60 @@ PGSharedMemoryCreate(uint32 size, bool makePrivate, int port) */ } + /* + * OK, we created a new segment. Mark it as created by this process. + * The order of assignments here is critical so that another Postgres + * process can't see the header as valid but belonging to an invalid + * PID! + */ hdr = (PGShmemHeader *) memAddress; + hdr->creatorPID = getpid(); + hdr->magic = PGShmemMagic; - if (!ExecBackend || makePrivate || UsedShmemSegAddr == NULL) - { - /* - * OK, we created a new segment. Mark it as created by this process. - * The order of assignments here is critical so that another Postgres - * process can't see the header as valid but belonging to an invalid - * PID! - */ - hdr->creatorPID = getpid(); - hdr->magic = PGShmemMagic; - - /* - * Initialize space allocation status for segment. - */ - hdr->totalsize = size; - hdr->freeoffset = MAXALIGN(sizeof(PGShmemHeader)); - } + /* + * Initialize space allocation status for segment. + */ + hdr->totalsize = size; + hdr->freeoffset = MAXALIGN(sizeof(PGShmemHeader)); - if (ExecBackend && !makePrivate && UsedShmemSegAddr == NULL) + + if (ExecBackend && UsedShmemSegAddr == NULL && !makePrivate) { UsedShmemSegAddr = memAddress; UsedShmemSegID = NextShmemSegID; } + + return hdr; +} + + +/* + * Attach to shared memory and make sure it has a Postgres header + */ +static PGShmemHeader * +PGSharedMemoryAttach(IpcMemoryKey key, IpcMemoryId *shmid, void *addr) +{ + PGShmemHeader *hdr; + + if ((*shmid = shmget(key, sizeof(PGShmemHeader), 0)) < 0) + return NULL; + hdr = (PGShmemHeader *) shmat(*shmid, UsedShmemSegAddr, +#if defined(solaris) && defined(__sparc__) + /* use intimate shared memory on SPARC Solaris */ + SHM_SHARE_MMU +#else + 0 +#endif + ); + + if (hdr == (PGShmemHeader *) -1) + return NULL; /* failed: must be some other app's */ + + if (hdr->magic != PGShmemMagic) + { + shmdt(hdr); + return NULL; /* segment belongs to a non-Postgres app */ + } return hdr; } |