+++ /dev/null
-/*-------------------------------------------------------------------------
- *
- * sema.c
- * Microsoft Windows Win32 Semaphores Emulation
- *
- * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
- *
- * IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/port/win32/sema.c,v 1.13 2006/04/09 19:21:34 tgl Exp $
- *
- *-------------------------------------------------------------------------
- */
-
-#include "postgres.h"
-#include "storage/shmem.h"
-
-#include <errno.h>
-
-typedef struct
-{
- int m_numSems;
- off_t m_semaphoreHandles;
- /* offset from beginning of header */
- off_t m_semaphoreCounts;
- /* offset from beginning of header */
-} win32_sem_set_hdr;
-
-/* Control of a semaphore pool. The pool is an area in which we stored all
-** the semIds of the pool. The first long is the number of semaphore
-** allocated in the pool followed by semaphore handles
-*/
-
-int
-semctl(int semId, int semNum, int flag, union semun semun)
-{
- win32_sem_set_hdr *the_set = (win32_sem_set_hdr *) MAKE_PTR(semId);
-
- /* semNum might be 0 */
- /* semun.array contains the sem initial values */
- int *sem_counts = (int *) ((off_t) the_set + the_set->m_semaphoreCounts);
-
- /* Fix the count of all sem of the pool to semun.array */
- if (flag == SETALL)
- {
- int i;
- struct sembuf sops;
-
- sops.sem_flg = IPC_NOWAIT;
-
- for (i = 0; i < the_set->m_numSems; ++i)
- {
- if (semun.array[i] == sem_counts[i])
- continue; /* Nothing to do */
-
- if (semun.array[i] < sem_counts[i])
- sops.sem_op = -1;
- else
- sops.sem_op = 1;
-
- sops.sem_num = i;
-
- /* Quickly lock/unlock the semaphore (if we can) */
- if (semop(semId, &sops, 1) < 0)
- return -1;
- }
- return 1;
- }
-
- /* Fix the count of one semaphore to semun.val */
- else if (flag == SETVAL)
- {
- if (semun.val != sem_counts[semNum])
- {
- struct sembuf sops;
-
- sops.sem_flg = IPC_NOWAIT;
- sops.sem_num = semNum;
-
- if (semun.val < sem_counts[semNum])
- sops.sem_op = -1;
- else
- sops.sem_op = 1;
-
- /* Quickly lock/unlock the semaphore (if we can) */
- if (semop(semId, &sops, 1) < 0)
- return -1;
- }
-
- return 1;
- }
-
- /* Delete the pool */
- else if (flag == IPC_RMID)
- {
- int i;
- HANDLE *sem_handles = (HANDLE *) ((off_t) the_set + the_set->m_semaphoreHandles);
-
- /* Loop over all semaphore to delete them */
- for (i = 0; i < the_set->m_numSems; ++i)
- CloseHandle(sem_handles[i]);
-
- return 1;
- }
-
- /* Get the current semaphore count */
- else if (flag == GETNCNT)
- return the_set->m_numSems;
-
- /* Get the current semaphore count of the first semaphore in the pool */
- else if (flag == GETVAL)
- return sem_counts[semNum];
-
- /* Other commands not yet supported */
- else
- {
- errno = EINVAL;
- return -1;
- }
-}
-
-/* Find a pool id based on IPC key */
-int
-semget(int semKey, int semNum, int flags)
-{
- char semname[32];
- char cur_num[20];
- DWORD last_error;
- char *num_part;
- bool ans = true;
- SECURITY_ATTRIBUTES sec_attrs;
- HANDLE cur_handle;
- bool found = false;
- Size sem_set_size = sizeof(win32_sem_set_hdr) + semNum * (sizeof(HANDLE) + sizeof(int));
- HANDLE *sem_handles = NULL;
- int *sem_counts = NULL;
- int i;
- win32_sem_set_hdr *new_set;
-
- sec_attrs.nLength = sizeof(sec_attrs);
- sec_attrs.lpSecurityDescriptor = NULL;
- sec_attrs.bInheritHandle = TRUE;
-
- sprintf(semname, "PG_SEMSET.%d.", semKey);
- num_part = semname + strlen(semname);
-
- strcpy(num_part, _itoa(_getpid() * -1, cur_num, 10)); /* For shared memory,
- * include the pid */
- new_set = (win32_sem_set_hdr *) ShmemInitStruct(semname, sem_set_size, &found);
-
- if (found)
- {
- /* This should *never* happen */
- errno = EEXIST;
- return -1;
- }
-
- new_set->m_numSems = semNum;
- new_set->m_semaphoreHandles = sizeof(win32_sem_set_hdr);
- /* array starts after header */
- new_set->m_semaphoreCounts = new_set->m_semaphoreHandles + (sizeof(HANDLE) * semNum);
-
- sem_handles = (HANDLE *) ((off_t) new_set + new_set->m_semaphoreHandles);
- sem_counts = (int *) ((off_t) new_set + new_set->m_semaphoreCounts);
-
- for (i = 0; i < semNum && ans; ++i)
- {
- strcpy(num_part, _itoa(i, cur_num, 10));
-
- if (flags & IPC_CREAT)
- cur_handle = CreateSemaphore(&sec_attrs, 0, 1, semname);
- else
- cur_handle = OpenSemaphore(SEMAPHORE_ALL_ACCESS, TRUE, semname);
-
- sem_handles[i] = cur_handle;
-
- last_error = GetLastError();
- if (!cur_handle)
- {
- errno = EACCES;
- ans = false;
- }
- else if (last_error == ERROR_ALREADY_EXISTS && (flags & (IPC_CREAT | IPC_EXCL)))
- {
- errno = EEXIST;
- ans = false;
- }
- }
-
- if (ans)
- return MAKE_OFFSET(new_set);
- else
- {
- int i;
-
- /* Blow away what we've got right now... */
- for (i = 0; i < semNum; ++i)
- {
- if (sem_handles[i])
- CloseHandle(sem_handles[i]);
- else
- break;
- }
-
- return -1;
- }
-}
-
-/* Acquire or release in the semaphore pool */
-int
-semop(int semId, struct sembuf * sops, int nsops)
-{
- win32_sem_set_hdr *the_set = (win32_sem_set_hdr *) MAKE_PTR(semId);
- HANDLE *sem_handles = (HANDLE *) ((off_t) the_set + the_set->m_semaphoreHandles);
- int *sem_counts = (int *) ((off_t) the_set + the_set->m_semaphoreCounts);
- HANDLE cur_handle;
-
- if (nsops != 1)
- {
- /*
- * Not supported (we return on 1st success, and don't cancel earlier
- * ops)
- */
- errno = E2BIG;
- return -1;
- }
-
- cur_handle = sem_handles[sops[0].sem_num];
-
- if (sops[0].sem_op == -1)
- {
- DWORD ret;
- HANDLE wh[2];
-
- wh[0] = cur_handle;
- wh[1] = pgwin32_signal_event;
-
- ret = WaitForMultipleObjectsEx(2, wh, FALSE, (sops[0].sem_flg & IPC_NOWAIT) ? 0 : INFINITE, TRUE);
-
- if (ret == WAIT_OBJECT_0)
- {
- /* We got it! */
- sem_counts[sops[0].sem_num]--;
- return 0;
- }
- else if (ret == WAIT_OBJECT_0 + 1 || ret == WAIT_IO_COMPLETION)
- {
- /* Signal event is set - we have a signal to deliver */
- pgwin32_dispatch_queued_signals();
- errno = EINTR;
- }
- else if (ret == WAIT_TIMEOUT)
- /* Couldn't get it */
- errno = EAGAIN;
- else
- errno = EIDRM;
- }
- else if (sops[0].sem_op > 0)
- {
- /* Don't want the lock anymore */
- sem_counts[sops[0].sem_num]++;
- ReleaseSemaphore(cur_handle, sops[0].sem_op, NULL);
- return 0;
- }
- else
- /* Not supported */
- errno = ERANGE;
-
- /* If we get down here, then something is wrong */
- return -1;
-}
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