mirror of https://github.com/postgres/postgres
Tom Lane
20 years ago
parent
f0df096785
commit
366682fb66
@ -1,270 +0,0 @@ |
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/*-------------------------------------------------------------------------
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* |
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* sema.c |
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* Microsoft Windows Win32 Semaphores Emulation |
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* |
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* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group |
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* |
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* IDENTIFICATION |
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* $PostgreSQL: pgsql/src/backend/port/win32/sema.c,v 1.13 2006/04/09 19:21:34 tgl Exp $ |
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* |
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*------------------------------------------------------------------------- |
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*/ |
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#include "postgres.h" |
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#include "storage/shmem.h" |
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#include <errno.h> |
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typedef struct |
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{ |
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int m_numSems; |
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off_t m_semaphoreHandles; |
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/* offset from beginning of header */ |
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off_t m_semaphoreCounts; |
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/* offset from beginning of header */ |
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} win32_sem_set_hdr; |
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/* Control of a semaphore pool. The pool is an area in which we stored all
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** the semIds of the pool. The first long is the number of semaphore |
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** allocated in the pool followed by semaphore handles |
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*/ |
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int |
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semctl(int semId, int semNum, int flag, union semun semun) |
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{ |
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win32_sem_set_hdr *the_set = (win32_sem_set_hdr *) MAKE_PTR(semId); |
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/* semNum might be 0 */ |
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/* semun.array contains the sem initial values */ |
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int *sem_counts = (int *) ((off_t) the_set + the_set->m_semaphoreCounts); |
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/* Fix the count of all sem of the pool to semun.array */ |
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if (flag == SETALL) |
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{ |
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int i; |
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struct sembuf sops; |
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sops.sem_flg = IPC_NOWAIT; |
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for (i = 0; i < the_set->m_numSems; ++i) |
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{ |
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if (semun.array[i] == sem_counts[i]) |
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continue; /* Nothing to do */ |
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if (semun.array[i] < sem_counts[i]) |
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sops.sem_op = -1; |
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else |
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sops.sem_op = 1; |
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sops.sem_num = i; |
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/* Quickly lock/unlock the semaphore (if we can) */ |
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if (semop(semId, &sops, 1) < 0) |
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return -1; |
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} |
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return 1; |
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} |
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/* Fix the count of one semaphore to semun.val */ |
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else if (flag == SETVAL) |
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{ |
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if (semun.val != sem_counts[semNum]) |
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{ |
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struct sembuf sops; |
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sops.sem_flg = IPC_NOWAIT; |
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sops.sem_num = semNum; |
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if (semun.val < sem_counts[semNum]) |
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sops.sem_op = -1; |
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else |
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sops.sem_op = 1; |
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/* Quickly lock/unlock the semaphore (if we can) */ |
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if (semop(semId, &sops, 1) < 0) |
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return -1; |
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} |
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return 1; |
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} |
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/* Delete the pool */ |
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else if (flag == IPC_RMID) |
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{ |
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int i; |
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HANDLE *sem_handles = (HANDLE *) ((off_t) the_set + the_set->m_semaphoreHandles); |
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/* Loop over all semaphore to delete them */ |
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for (i = 0; i < the_set->m_numSems; ++i) |
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CloseHandle(sem_handles[i]); |
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return 1; |
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} |
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/* Get the current semaphore count */ |
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else if (flag == GETNCNT) |
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return the_set->m_numSems; |
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/* Get the current semaphore count of the first semaphore in the pool */ |
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else if (flag == GETVAL) |
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return sem_counts[semNum]; |
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/* Other commands not yet supported */ |
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else |
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{ |
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errno = EINVAL; |
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return -1; |
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} |
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} |
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/* Find a pool id based on IPC key */ |
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int |
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semget(int semKey, int semNum, int flags) |
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{ |
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char semname[32]; |
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char cur_num[20]; |
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DWORD last_error; |
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char *num_part; |
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bool ans = true; |
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SECURITY_ATTRIBUTES sec_attrs; |
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HANDLE cur_handle; |
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bool found = false; |
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Size sem_set_size = sizeof(win32_sem_set_hdr) + semNum * (sizeof(HANDLE) + sizeof(int)); |
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HANDLE *sem_handles = NULL; |
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int *sem_counts = NULL; |
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int i; |
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win32_sem_set_hdr *new_set; |
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sec_attrs.nLength = sizeof(sec_attrs); |
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sec_attrs.lpSecurityDescriptor = NULL; |
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sec_attrs.bInheritHandle = TRUE; |
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sprintf(semname, "PG_SEMSET.%d.", semKey); |
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num_part = semname + strlen(semname); |
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strcpy(num_part, _itoa(_getpid() * -1, cur_num, 10)); /* For shared memory,
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* include the pid */ |
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new_set = (win32_sem_set_hdr *) ShmemInitStruct(semname, sem_set_size, &found); |
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if (found) |
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{ |
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/* This should *never* happen */ |
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errno = EEXIST; |
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return -1; |
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} |
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new_set->m_numSems = semNum; |
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new_set->m_semaphoreHandles = sizeof(win32_sem_set_hdr); |
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/* array starts after header */ |
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new_set->m_semaphoreCounts = new_set->m_semaphoreHandles + (sizeof(HANDLE) * semNum); |
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sem_handles = (HANDLE *) ((off_t) new_set + new_set->m_semaphoreHandles); |
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sem_counts = (int *) ((off_t) new_set + new_set->m_semaphoreCounts); |
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for (i = 0; i < semNum && ans; ++i) |
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{ |
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strcpy(num_part, _itoa(i, cur_num, 10)); |
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if (flags & IPC_CREAT) |
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cur_handle = CreateSemaphore(&sec_attrs, 0, 1, semname); |
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else |
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cur_handle = OpenSemaphore(SEMAPHORE_ALL_ACCESS, TRUE, semname); |
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sem_handles[i] = cur_handle; |
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last_error = GetLastError(); |
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if (!cur_handle) |
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{ |
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errno = EACCES; |
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ans = false; |
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} |
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else if (last_error == ERROR_ALREADY_EXISTS && (flags & (IPC_CREAT | IPC_EXCL))) |
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{ |
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errno = EEXIST; |
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ans = false; |
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} |
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} |
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if (ans) |
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return MAKE_OFFSET(new_set); |
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else |
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{ |
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int i; |
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/* Blow away what we've got right now... */ |
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for (i = 0; i < semNum; ++i) |
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{ |
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if (sem_handles[i]) |
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CloseHandle(sem_handles[i]); |
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else |
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break; |
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} |
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return -1; |
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} |
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} |
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/* Acquire or release in the semaphore pool */ |
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int |
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semop(int semId, struct sembuf * sops, int nsops) |
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{ |
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win32_sem_set_hdr *the_set = (win32_sem_set_hdr *) MAKE_PTR(semId); |
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HANDLE *sem_handles = (HANDLE *) ((off_t) the_set + the_set->m_semaphoreHandles); |
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int *sem_counts = (int *) ((off_t) the_set + the_set->m_semaphoreCounts); |
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HANDLE cur_handle; |
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if (nsops != 1) |
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{ |
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/*
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* Not supported (we return on 1st success, and don't cancel earlier |
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* ops) |
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*/ |
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errno = E2BIG; |
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return -1; |
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} |
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cur_handle = sem_handles[sops[0].sem_num]; |
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if (sops[0].sem_op == -1) |
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{ |
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DWORD ret; |
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HANDLE wh[2]; |
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wh[0] = cur_handle; |
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wh[1] = pgwin32_signal_event; |
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ret = WaitForMultipleObjectsEx(2, wh, FALSE, (sops[0].sem_flg & IPC_NOWAIT) ? 0 : INFINITE, TRUE); |
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if (ret == WAIT_OBJECT_0) |
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{ |
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/* We got it! */ |
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sem_counts[sops[0].sem_num]--; |
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return 0; |
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} |
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else if (ret == WAIT_OBJECT_0 + 1 || ret == WAIT_IO_COMPLETION) |
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{ |
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/* Signal event is set - we have a signal to deliver */ |
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pgwin32_dispatch_queued_signals(); |
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errno = EINTR; |
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} |
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else if (ret == WAIT_TIMEOUT) |
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/* Couldn't get it */ |
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errno = EAGAIN; |
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else |
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errno = EIDRM; |
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} |
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else if (sops[0].sem_op > 0) |
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{ |
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/* Don't want the lock anymore */ |
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sem_counts[sops[0].sem_num]++; |
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ReleaseSemaphore(cur_handle, sops[0].sem_op, NULL); |
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return 0; |
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} |
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else |
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/* Not supported */ |
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errno = ERANGE; |
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/* If we get down here, then something is wrong */ |
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return -1; |
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} |
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