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[/] [openrisc/] [trunk/] [rtos/] [rtems/] [c/] [src/] [exec/] [posix/] [src/] [semopen.c] - Rev 619
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/* * $Id: semopen.c,v 1.2 2001-09-27 11:59:17 chris Exp $ */ #include <stdarg.h> #include <errno.h> #include <fcntl.h> #include <pthread.h> #include <semaphore.h> #include <limits.h> #include <rtems/system.h> #include <rtems/score/object.h> #include <rtems/posix/semaphore.h> #include <rtems/posix/time.h> #include <rtems/posix/seterr.h> /*PAGE * * sem_open * * Opens a named semaphore. Used in conjunction with the sem_close * and sem_unlink commands. * * 11.2.3 Initialize/Open a Named Semaphore, P1003.1b-1993, p.221 * * NOTE: When oflag is O_CREAT, then optional third and fourth * parameters must be present. */ sem_t *sem_open( const char *name, int oflag, ... /* mode_t mode, */ /* unsigned int value */ ) { va_list arg; mode_t mode; unsigned int value = 0; int status; Objects_Id the_semaphore_id; POSIX_Semaphore_Control *the_semaphore; Objects_Locations location; _Thread_Disable_dispatch(); if ( oflag & O_CREAT ) { va_start(arg, oflag); mode = va_arg( arg, mode_t ); value = va_arg( arg, unsigned int ); va_end(arg); } status = _POSIX_Semaphore_Name_to_id( name, &the_semaphore_id ); /* * If the name to id translation worked, then the semaphore exists * and we can just return a pointer to the id. Otherwise we may * need to check to see if this is a "semaphore does not exist" * or some other miscellaneous error on the name. */ if ( status ) { /* * Unless provided a valid name that did not already exist * and we are willing to create then it is an error. */ if ( !( status == ENOENT && (oflag & O_CREAT) ) ) { _Thread_Enable_dispatch(); set_errno_and_return_minus_one_cast( status, sem_t * ); } } else { /* * Check for existence with creation. */ if ( (oflag & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL) ) { _Thread_Enable_dispatch(); set_errno_and_return_minus_one_cast( EEXIST, sem_t * ); } the_semaphore = _POSIX_Semaphore_Get( &the_semaphore_id, &location ); the_semaphore->open_count += 1; _Thread_Enable_dispatch(); _Thread_Enable_dispatch(); return (sem_t *)&the_semaphore->Object.id; } /* * At this point, the semaphore does not exist and everything has been * checked. We should go ahead and create a semaphore. */ status =_POSIX_Semaphore_Create_support( name, FALSE, /* not shared across processes */ value, &the_semaphore ); /* * errno was set by Create_support, so don't set it again. */ _Thread_Enable_dispatch(); if ( status == -1 ) return SEM_FAILED; return (sem_t *) &the_semaphore->Object.id; }
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