source: rtems/c/src/exec/posix/src/semopen.c @ 23168f53

4.104.114.84.95
Last change on this file since 23168f53 was 17879f4, checked in by Jennifer Averett <Jennifer.Averett@…>, on Nov 18, 1999 at 7:43:13 PM

+ Debuged to the point that you could open, unlink and close a semaphore.

but all paths have not been checked, yet.

  • Property mode set to 100644
File size: 2.4 KB
Line 
1/*
2 *  $Id$
3 */
4
5#include <stdarg.h>
6
7#include <errno.h>
8#include <fcntl.h>
9#include <pthread.h>
10#include <semaphore.h>
11#include <limits.h>
12
13#include <rtems/system.h>
14#include <rtems/score/object.h>
15#include <rtems/posix/semaphore.h>
16#include <rtems/posix/time.h>
17#include <rtems/posix/seterr.h>
18
19/*PAGE
20 *
21 *  11.2.3 Initialize/Open a Named Semaphore, P1003.1b-1993, p.221
22 *
23 *  NOTE: When oflag is O_CREAT, then optional third and fourth
24 *        parameters must be present.
25 */
26
27sem_t *sem_open(
28  const char *name,
29  int         oflag,
30  ...
31  /* mode_t mode, */
32  /* unsigned int value */
33)
34{
35  va_list                    arg;
36  mode_t                     mode;
37  unsigned int               value = 0;
38  int                        status;
39  Objects_Id                 the_semaphore_id;
40  POSIX_Semaphore_Control   *the_semaphore;
41  Objects_Locations          location;
42 
43
44  if ( oflag & O_CREAT ) {
45    va_start(arg, oflag);
46    mode = va_arg( arg, mode_t );
47    value = va_arg( arg, unsigned int );
48    va_end(arg);
49  }
50
51  status = _POSIX_Semaphore_Name_to_id( name, &the_semaphore_id );
52   
53  /*
54   *  If the name to id translation worked, then the semaphore exists
55   *  and we can just return a pointer to the id.  Otherwise we may
56   *  need to check to see if this is a "semaphore does not exist"
57   *  or some other miscellaneous error on the name.
58   */
59
60  if ( status ) {
61
62    /*
63     * Unless we are willing to create name -> ID translation failure is
64     * an error.
65     */
66
67    if ( status == EINVAL ) { 
68      if ( !(oflag & O_CREAT) ) {
69        set_errno_and_return_minus_one_cast( ENOENT, sem_t * );
70      }
71    }
72
73  } else { 
74
75    /*
76     * Check for existence with creation.
77     */
78
79    if ( (oflag & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL) ) {
80      set_errno_and_return_minus_one_cast( EEXIST, sem_t * );
81    }
82
83    the_semaphore = _POSIX_Semaphore_Get( &the_semaphore_id, &location );
84    the_semaphore->open_count += 1;
85    return (sem_t *)&the_semaphore->Object.id;
86
87  } 
88 
89  /*
90   *  At this point, the semaphore does not exist and everything has been
91   *  checked. We should go ahead and create a semaphore.
92   */
93
94  status = _POSIX_Semaphore_Create_support(
95    name,
96    FALSE,         /* not shared across processes */
97    value,
98    &the_semaphore
99  );
100 
101  /*
102   * errno was set by Create_support, so don't set it again.
103   */
104
105  if ( status == -1 )
106    return SEM_FAILED;
107
108  return (sem_t *) &the_semaphore->Object.id;
109}
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