1 | /** |
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2 | * @file |
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3 | * |
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4 | * @brief Attempt to Obtain a Read Lock on a RWLock Instance |
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5 | * @ingroup POSIXAPI |
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6 | */ |
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7 | |
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8 | /* |
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9 | * COPYRIGHT (c) 1989-2008. |
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10 | * On-Line Applications Research Corporation (OAR). |
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11 | * |
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12 | * The license and distribution terms for this file may be |
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13 | * found in the file LICENSE in this distribution or at |
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14 | * http://www.rtems.com/license/LICENSE. |
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15 | */ |
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16 | |
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17 | #if HAVE_CONFIG_H |
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18 | #include "config.h" |
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19 | #endif |
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20 | |
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21 | #include <pthread.h> |
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22 | #include <errno.h> |
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23 | |
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24 | #include <rtems/system.h> |
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25 | #include <rtems/posix/rwlock.h> |
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26 | #include <rtems/posix/time.h> |
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27 | |
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28 | /* |
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29 | * pthread_rwlock_timedrdlock |
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30 | * |
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31 | * This directive attempts to obtain a read only lock on an rwlock instance. |
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32 | * |
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33 | * Input parameters: |
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34 | * rwlock - pointer to rwlock id |
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35 | * |
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36 | * Output parameters: |
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37 | * 0 - if successful |
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38 | * error code - if unsuccessful |
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39 | */ |
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40 | |
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41 | int pthread_rwlock_timedrdlock( |
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42 | pthread_rwlock_t *rwlock, |
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43 | const struct timespec *abstime |
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44 | ) |
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45 | { |
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46 | POSIX_RWLock_Control *the_rwlock; |
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47 | Objects_Locations location; |
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48 | Watchdog_Interval ticks; |
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49 | bool do_wait = true; |
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50 | POSIX_Absolute_timeout_conversion_results_t status; |
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51 | |
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52 | if ( !rwlock ) |
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53 | return EINVAL; |
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54 | |
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55 | /* |
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56 | * POSIX requires that blocking calls with timeouts that take |
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57 | * an absolute timeout must ignore issues with the absolute |
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58 | * time provided if the operation would otherwise succeed. |
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59 | * So we check the abstime provided, and hold on to whether it |
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60 | * is valid or not. If it isn't correct and in the future, |
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61 | * then we do a polling operation and convert the UNSATISFIED |
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62 | * status into the appropriate error. |
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63 | * |
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64 | * If the status is POSIX_ABSOLUTE_TIMEOUT_INVALID, |
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65 | * POSIX_ABSOLUTE_TIMEOUT_IS_IN_PAST, or POSIX_ABSOLUTE_TIMEOUT_IS_NOW, |
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66 | * then we should not wait. |
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67 | */ |
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68 | status = _POSIX_Absolute_timeout_to_ticks( abstime, &ticks ); |
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69 | if ( status != POSIX_ABSOLUTE_TIMEOUT_IS_IN_FUTURE ) |
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70 | do_wait = false; |
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71 | |
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72 | the_rwlock = _POSIX_RWLock_Get( rwlock, &location ); |
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73 | switch ( location ) { |
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74 | |
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75 | case OBJECTS_LOCAL: |
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76 | |
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77 | _CORE_RWLock_Obtain_for_reading( |
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78 | &the_rwlock->RWLock, |
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79 | *rwlock, |
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80 | do_wait, |
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81 | ticks, |
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82 | NULL |
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83 | ); |
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84 | |
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85 | _Thread_Enable_dispatch(); |
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86 | if ( !do_wait ) { |
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87 | if ( _Thread_Executing->Wait.return_code == CORE_RWLOCK_UNAVAILABLE ) { |
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88 | if ( status == POSIX_ABSOLUTE_TIMEOUT_INVALID ) |
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89 | return EINVAL; |
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90 | if ( status == POSIX_ABSOLUTE_TIMEOUT_IS_IN_PAST || |
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91 | status == POSIX_ABSOLUTE_TIMEOUT_IS_NOW ) |
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92 | return ETIMEDOUT; |
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93 | } |
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94 | } |
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95 | |
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96 | return _POSIX_RWLock_Translate_core_RWLock_return_code( |
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97 | (CORE_RWLock_Status) _Thread_Executing->Wait.return_code |
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98 | ); |
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99 | |
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100 | #if defined(RTEMS_MULTIPROCESSING) |
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101 | case OBJECTS_REMOTE: |
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102 | #endif |
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103 | case OBJECTS_ERROR: |
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104 | break; |
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105 | } |
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106 | |
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107 | return EINVAL; |
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108 | } |
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