1 /***************************************************************************
2  * Copyright (c) 2024 Microsoft Corporation
3  *
4  * This program and the accompanying materials are made available under the
5  * terms of the MIT License which is available at
6  * https://opensource.org/licenses/MIT.
7  *
8  * SPDX-License-Identifier: MIT
9  **************************************************************************/
10 
11 
12 /**************************************************************************/
13 /**************************************************************************/
14 /**                                                                       */
15 /** POSIX wrapper for THREADX                                             */
16 /**                                                                       */
17 /**                                                                       */
18 /**                                                                       */
19 /**************************************************************************/
20 /**************************************************************************/
21 
22 /* Include necessary system files.  */
23 
24 #include "tx_api.h"     /* Threadx API */
25 #include "pthread.h"    /* Posix API */
26 #include "px_int.h"     /* Posix helper functions */
27 
28 
29 /**************************************************************************/
30 /*                                                                        */
31 /*  FUNCTION                                               RELEASE        */
32 /*                                                                        */
33 /*    sem_trywait                                         PORTABLE C      */
34 /*                                                           6.1.7        */
35 /*  AUTHOR                                                                */
36 /*                                                                        */
37 /*    William E. Lamie, Microsoft Corporation                             */
38 /*                                                                        */
39 /*  DESCRIPTION                                                           */
40 /*                                                                        */
41 /*    This routine locks(takes) a semaphore if the semaphore is not       */
42 /*    currently locked.                                                   */
43 /*                                                                        */
44 /*  INPUT                                                                 */
45 /*                                                                        */
46 /*    *sem                      Pointer to Semaphore                      */
47 /*                                                                        */
48 /*  OUTPUT                                                                */
49 /*                                                                        */
50 /*    OK                        If successful                             */
51 /*    ERROR                     If error occurs                           */
52 /*                                                                        */
53 /*  CALLS                                                                 */
54 /*                                                                        */
55 /*    posix_internal_error      Returns generic error                     */
56 /*    tx_semaphore_get          ThreadX Semaphore get                     */
57 /*    tx_thread_identify        Returns currently running thread          */
58 /*                                                                        */
59 /*  CALLED BY                                                             */
60 /*                                                                        */
61 /*    Application Code                                                    */
62 /*                                                                        */
63 /*  RELEASE HISTORY                                                       */
64 /*                                                                        */
65 /*    DATE              NAME                      DESCRIPTION             */
66 /*                                                                        */
67 /*  06-02-2021     William E. Lamie         Initial Version 6.1.7         */
68 /*                                                                        */
69 /**************************************************************************/
sem_trywait(sem_t * sem)70 INT sem_trywait(sem_t * sem)
71 {
72 
73 TX_SEMAPHORE          * TheSem;
74 INT                    retval;
75 INT                    pxerror;
76 
77      /* Make sure we're calling this routine from a thread context.  */
78     if (!tx_thread_identify() )
79     {
80         /* No error in POSIX.  */
81         posix_internal_error(242);
82 
83         /* Return error.  */
84         return (ERROR);
85     }
86 
87      /* Get ThreadX semaphore.  */
88     TheSem = (TX_SEMAPHORE *)sem;
89 
90     /* Check for an invalid semaphore pointer.  */
91     if ((!TheSem) || (TheSem -> tx_semaphore_id != TX_SEMAPHORE_ID))
92     {
93         /* error in POSIX.  */
94         posix_errno = EINVAL;
95 	    posix_set_pthread_errno(EINVAL);
96         return (EINVAL);
97     }
98     else
99         retval = tx_semaphore_get(TheSem,TX_NO_WAIT);
100 
101     switch(retval)
102     {
103 
104         case TX_SUCCESS :
105 
106             sem->refCnt -= 1;
107             pxerror = OK;
108             break;
109 
110         case TX_NO_INSTANCE:
111 
112             posix_errno = EAGAIN;
113 	        posix_set_pthread_errno(EAGAIN);
114             pxerror = ERROR;
115             break;
116 
117         case  TX_DELETED :
118         case  TX_WAIT_ABORTED :
119         case  TX_SEMAPHORE_ERROR :
120         case  TX_WAIT_ERROR :
121 
122             /* No error in POSIX, give default.  */
123             posix_errno = EINVAL;
124 	        posix_set_pthread_errno(EINVAL);
125             pxerror = ERROR;
126             break;
127     }
128     return(pxerror);
129 }
130