Annotation of libaitsess/src/aitsess.c, revision 1.3.2.2

1.2       misho       1: /*************************************************************************
                      2: * (C) 2008 AITNET ltd - Sofia/Bulgaria - <misho@aitbg.com>
                      3: *  by Michael Pounov <misho@openbsd-bg.org>
                      4: *
                      5: * $Author: misho $
1.3.2.2 ! misho       6: * $Id: aitsess.c,v 1.3.2.1 2011/09/08 07:22:00 misho Exp $
1.2       misho       7: *
1.3       misho       8: **************************************************************************
                      9: The ELWIX and AITNET software is distributed under the following
                     10: terms:
                     11: 
                     12: All of the documentation and software included in the ELWIX and AITNET
                     13: Releases is copyrighted by ELWIX - Sofia/Bulgaria <info@elwix.org>
                     14: 
                     15: Copyright 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
                     16:        by Michael Pounov <misho@elwix.org>.  All rights reserved.
                     17: 
                     18: Redistribution and use in source and binary forms, with or without
                     19: modification, are permitted provided that the following conditions
                     20: are met:
                     21: 1. Redistributions of source code must retain the above copyright
                     22:    notice, this list of conditions and the following disclaimer.
                     23: 2. Redistributions in binary form must reproduce the above copyright
                     24:    notice, this list of conditions and the following disclaimer in the
                     25:    documentation and/or other materials provided with the distribution.
                     26: 3. All advertising materials mentioning features or use of this software
                     27:    must display the following acknowledgement:
                     28: This product includes software developed by Michael Pounov <misho@elwix.org>
                     29: ELWIX - Embedded LightWeight unIX and its contributors.
                     30: 4. Neither the name of AITNET nor the names of its contributors
                     31:    may be used to endorse or promote products derived from this software
                     32:    without specific prior written permission.
                     33: 
                     34: THIS SOFTWARE IS PROVIDED BY AITNET AND CONTRIBUTORS ``AS IS'' AND
                     35: ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     36: IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     37: ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
                     38: FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     39: DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     40: OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     41: HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     42: LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     43: OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     44: SUCH DAMAGE.
                     45: */
1.1       misho      46: #include "global.h"
                     47: #include "aitsess.h"
                     48: 
                     49: 
                     50: #pragma GCC visibility push(hidden)
                     51: 
1.3       misho      52: int sess_Errno;
                     53: char sess_Error[STRSIZ];
1.1       misho      54: 
                     55: #pragma GCC visibility pop
                     56: 
                     57: // -----------------------------------------------------------
                     58: 
                     59: // Error maintenance functions ...
                     60: 
                     61: // sess_GetErrno() Get error code of last operation
1.3       misho      62: inline int
                     63: sess_GetErrno()
1.1       misho      64: {
1.3       misho      65:        return sess_Errno;
1.1       misho      66: }
                     67: // sess_GetError() Get error text of last operation
1.3       misho      68: inline const char *
                     69: sess_GetError()
1.1       misho      70: {
1.3       misho      71:        return sess_Error;
1.1       misho      72: }
1.3       misho      73: // sess_SetErr() Set error to variables for internal use!!!
                     74: inline void
                     75: sess_SetErr(int eno, char *estr, ...)
1.1       misho      76: {
                     77:        va_list lst;
                     78: 
1.3       misho      79:        sess_Errno = eno;
                     80:        memset(sess_Error, 0, sizeof sess_Error);
                     81:        va_start(lst, estr);
                     82:        vsnprintf(sess_Error, sizeof sess_Error, estr, lst);
1.1       misho      83:        va_end(lst);
                     84: }
                     85: 
                     86: // -----------------------------------------------------------
                     87: 
                     88: /*
                     89:  * initSession() Initializing session structure, if session file not exists creating with specified tech
1.3       misho      90:  * @pnID = Technology using in session. 
                     91:        SHARED_IPC IPC tech; SHARED_MAP BSD MemoryMap tech or if =NULL SHARED_IPC
1.1       misho      92:  * @csFName = Session filename for build key and identified
1.3       misho      93:  * @Sess = Session item, if =NULL allocate memory for session after use must be free!
1.1       misho      94:  * return: 0 OK new key created, -1 error: no memory or file not created, 1 OK key finded
                     95: */
1.3       misho      96: inline int
                     97: initSession(int *pnID, const char *csFName, tagSess ** __restrict Sess)
1.1       misho      98: {
1.3       misho      99:        int h, ret = 0, id = SHARED_IPC;
                    100:        char szStr[STRSIZ];
1.1       misho     101: 
                    102:        if (!*Sess) {
                    103:                *Sess = malloc(sizeof(tagSess));
                    104:                if (!*Sess) {
                    105:                        LOGERR;
                    106:                        return -1;
                    107:                }
1.3.2.1   misho     108:        }
                    109:        memset(*Sess, 0, sizeof(tagSess));
1.3       misho     110:        if (pnID && *pnID)
                    111:                id = *pnID;
1.1       misho     112: 
1.3       misho     113:        h = open(csFName, O_WRONLY | O_CREAT | O_EXCL, MEM_MODE);
1.1       misho     114:        if (h == -1) {
1.3       misho     115:                if (errno != EEXIST) {
                    116:                        LOGERR;
                    117:                        free(*Sess);
                    118:                        return -1;
                    119:                }
                    120:                /* If key file exist, session already connected */
                    121:                h = open(csFName, O_RDONLY);
                    122:                if (h == -1) {
                    123:                        LOGERR;
                    124:                        free(*Sess);
                    125:                        return -1;
                    126:                }
                    127:                ret = read(h, szStr, sizeof szStr);
                    128:                if (ret == -1) {
1.1       misho     129:                        LOGERR;
                    130:                        close(h);
                    131:                        free(*Sess);
                    132:                        return -1;
1.3       misho     133:                }
                    134:                if (!strncmp(szStr, "IPC@", 4))
                    135:                        id = SHARED_IPC;
                    136:                else if (!strncmp(szStr, "MAP@", 4))
                    137:                        id = SHARED_MAP;
                    138:                else {
                    139:                        sess_SetErr(EPROTONOSUPPORT, "Error:: Session type not supported");
                    140:                        close(h);
                    141:                        free(*Sess);
                    142:                        return -1;
                    143:                }
                    144: 
                    145:                ret = 1;        /* key found */
                    146:        } else {
                    147:                /* Build new key & new session */
                    148:                switch (id) {
                    149:                        case SHARED_IPC:
                    150:                                strlcpy(szStr, "IPC@", sizeof szStr);
                    151:                                break;
                    152:                        case SHARED_MAP:
                    153:                                strlcpy(szStr, "MAP@", sizeof szStr);
                    154:                                break;
                    155:                        default:
                    156:                                sess_SetErr(EPROTONOSUPPORT, "Error:: Session type not supported");
                    157:                                close(h);
                    158:                                unlink(csFName);
                    159:                                free(*Sess);
                    160:                                return -1;
                    161:                }
                    162:                strlcat(szStr, "ELWIX_Session ("PACKAGE_STRING")\n", sizeof szStr);
                    163:                write(h, szStr, strlen(szStr));
                    164: 
                    165:                ret = 0;        /* new key created */
1.1       misho     166:        }
                    167:        close(h);
                    168: 
1.3       misho     169:        (*Sess)->type = id;
1.1       misho     170:        return ret;
                    171: }
                    172: 
                    173: /*
                    174:  * freeSession() Free allocated memory for session item and delete session file if present name
                    175:  * @csFName = Session filename for delete, if NULL nothing delete
                    176:  * @Sess = Session item
                    177: */
1.3       misho     178: inline void
                    179: freeSession(const char *csFName, tagSess ** __restrict Sess)
1.1       misho     180: {
1.3       misho     181:        assert(Sess);
                    182:        if (!Sess)
                    183:                return;
                    184: 
                    185:        (*Sess)->type = SHARED_UNKNOWN;
1.1       misho     186:        if (csFName)
                    187:                unlink(csFName);
                    188:        if (*Sess)
                    189:                free(*Sess);
                    190:        *Sess = NULL;
                    191: }
                    192: 
                    193: 
                    194: /*
                    195:  * map_createSession() MMAP Created session and allocated resources
                    196:  * @csFName = Session name for identified
                    197:  * @cnSeed = Seed for securing key
                    198:  * @cnSize = Allocated shared memory size in bytes
                    199:  * @Sess = Session item
                    200:  * return: 0 Ok successful, -1 error: not allocated resources
                    201: */
1.3       misho     202: int
                    203: map_createSession(const char *csFName, const int cnSeed, const u_int cnSize, tagSess ** __restrict Sess)
1.1       misho     204: {
1.3       misho     205:        int ret = 0, id = SHARED_MAP;
                    206:        char szSName[2][FILENAME_MAX];
1.1       misho     207: 
1.3       misho     208:        ret = initSession(&id, csFName, Sess);
1.1       misho     209:        if (ret == -1 || !*Sess)
                    210:                return -1;
                    211: 
1.3       misho     212:        /* genkey */
1.1       misho     213:        (*Sess)->key = ftok(csFName, cnSeed);
                    214:        if ((*Sess)->key == -1) {
                    215:                LOGERR;
                    216:                freeSession(csFName, Sess);
                    217:                return -1;
                    218:        }
                    219: 
1.3       misho     220:        /* build semaphore & shared memory name */
                    221:        memset(szSName, 0, sizeof szSName);
                    222:        snprintf(szSName[0], MAX_SEMNAME, "/%X.ANS", (u_int) (*Sess)->key);
                    223:        snprintf(szSName[1], FILENAME_MAX, "%s-%x.ANM", csFName, (u_int) (*Sess)->key);
1.1       misho     224: 
1.3       misho     225:        /* create semaphore & add 1 */
1.2       misho     226:        (*Sess)->id.sid = sem_open(szSName[0], O_CREAT, MEM_MODE);
1.1       misho     227:        if ((*Sess)->id.sid == SEM_FAILED) {
                    228:                LOGERR;
                    229:                map_destroySession(csFName, Sess);
                    230:                return -1;
1.3.2.2 ! misho     231:        }
        !           232:        if (!ret)
1.1       misho     233:                sem_post((*Sess)->id.sid);
                    234: 
1.3       misho     235:        /* create file for shared memory storage */
1.2       misho     236:        (*Sess)->mem.fd = open(szSName[1], O_RDWR | O_CREAT, MEM_MODE);
1.1       misho     237:        if ((*Sess)->mem.fd == -1) {
                    238:                LOGERR;
                    239:                map_destroySession(csFName, Sess);
                    240:                return -1;
                    241:        }
1.3       misho     242:        /* if is new shared memory session, fill file with zeros */
1.1       misho     243:        if (!ret) {
1.3       misho     244:                if (lseek((*Sess)->mem.fd, cnSize - 1, SEEK_SET) == -1) {
1.1       misho     245:                        LOGERR;
                    246:                        map_destroySession(csFName, Sess);
                    247:                        return -1;
1.3       misho     248:                } else
                    249:                        write((*Sess)->mem.fd, "", 1);
                    250:                lseek((*Sess)->mem.fd, 0, SEEK_SET);
1.1       misho     251:        }
                    252:        (*Sess)->eom = cnSize;
                    253: 
                    254:        return ret;
                    255: }
                    256: 
                    257: /*
                    258:  * map_destroySession() MMAP free shared resources
                    259:  * @csFName = Session name for delete
                    260:  * @Sess = Session item
                    261: */
1.3       misho     262: void
                    263: map_destroySession(const char *csFName, tagSess ** __restrict Sess)
1.1       misho     264: {
                    265:        int flg = 1;
1.3       misho     266:        char szSName[2][FILENAME_MAX];
1.1       misho     267: 
1.3       misho     268:        assert(Sess);
                    269:        if (!Sess || !*Sess)
1.1       misho     270:                return;
                    271: 
1.3       misho     272:        memset(szSName, 0, sizeof szSName);
                    273:        snprintf(szSName[0], MAX_SEMNAME, "/%X.ANS", (u_int) (*Sess)->key);
                    274:        snprintf(szSName[1], FILENAME_MAX, "%s-%x.ANM", csFName, (u_int) (*Sess)->key);
1.1       misho     275: 
                    276:        if ((*Sess)->id.sid != SEM_FAILED) {
                    277:                if (sem_close((*Sess)->id.sid) == -1)
                    278:                        flg = 0;
                    279:                if (sem_unlink(szSName[0]) == -1)
                    280:                        /*flg = 0*/;
                    281:        }
                    282:        if ((*Sess)->mem.fd != -1) {
                    283:                if (close((*Sess)->mem.fd) == -1)
                    284:                        flg = 0;
                    285:                if (unlink(szSName[1]) == -1)
                    286:                        /*flg = 0*/;
                    287:        }
                    288:        (*Sess)->eom ^= (*Sess)->eom;
                    289: 
                    290:        freeSession(flg ? csFName : NULL, Sess);
                    291: }
                    292: 
                    293: /*
                    294:  * ipc_createSession() IPC Created session and allocated resources
                    295:  * @csFName = Session name for identified
                    296:  * @cnSeed = Seed for securing key
                    297:  * @cnSize = Allocated shared memory size in bytes
                    298:  * @Sess = Session item
                    299:  * return: 0 Ok successful, -1 error: not allocated resources
                    300: */
1.3       misho     301: int
                    302: ipc_createSession(const char *csFName, const int cnSeed, const u_int cnSize, tagSess ** __restrict Sess)
1.1       misho     303: {
1.3       misho     304:        int ret = 0, id = SHARED_IPC;
1.1       misho     305:        union semun sems;
                    306: 
1.3       misho     307:        ret = initSession(&id, csFName, Sess);
1.1       misho     308:        if (ret == -1 || !*Sess)
                    309:                return -1;
                    310: 
1.3       misho     311:        /* genkey */
1.1       misho     312:        (*Sess)->key = ftok(csFName, cnSeed);
                    313:        if ((*Sess)->key == -1) {
                    314:                LOGERR;
                    315:                freeSession(csFName, Sess);
                    316:                return -1;
                    317:        }
                    318: 
1.3       misho     319:        /* create semaphore */
1.2       misho     320:        (*Sess)->id.semid = semget((*Sess)->key, 1, MEM_MODE | IPC_CREAT);
1.1       misho     321:        if ((*Sess)->id.semid == -1) {
                    322:                LOGERR;
                    323:                ipc_destroySession(csFName, Sess);
                    324:                return -1;
                    325:        }
1.3       misho     326:        /* if is new shared memory session, init sempahore with 1 */
1.1       misho     327:        if (!ret) {
                    328:                sems.val = 1;
                    329:                if (semctl((*Sess)->id.semid, 0, SETVAL, sems) == -1) {
                    330:                        LOGERR;
                    331:                        ipc_destroySession(csFName, Sess);
                    332:                        return -1;
                    333:                }
                    334:        }
                    335: 
1.3       misho     336:        /* create shared memory object */
1.2       misho     337:        (*Sess)->mem.shmid = shmget((*Sess)->key, cnSize, MEM_MODE | IPC_CREAT);
1.1       misho     338:        if ((*Sess)->mem.shmid == -1) {
                    339:                LOGERR;
                    340:                ipc_destroySession(csFName, Sess);
                    341:                return -1;
                    342:        }
                    343:        (*Sess)->eom = cnSize;
                    344: 
                    345:        return ret;
                    346: }
                    347: 
                    348: /*
                    349:  * ipc_destroySession() IPC free shared resources
                    350:  * @csFName = Session name for delete
                    351:  * @Sess = Session item
                    352: */
1.3       misho     353: void
                    354: ipc_destroySession(const char *csFName, tagSess ** __restrict Sess)
1.1       misho     355: {
                    356:        int flg = 1;
                    357:        union semun sems;
                    358:        struct shmid_ds ds;
                    359: 
1.3       misho     360:        assert(Sess);
                    361:        if (!Sess || !*Sess)
1.1       misho     362:                return;
                    363: 
                    364:        if ((*Sess)->id.semid != -1)
                    365:                if (semctl((*Sess)->id.semid, 0, IPC_RMID, &sems) == -1)
                    366:                        flg = 0;
                    367:        if ((*Sess)->mem.shmid != -1)
                    368:                if (shmctl((*Sess)->mem.shmid, IPC_RMID, &ds) == -1)
                    369:                        flg = 0;
                    370:        (*Sess)->eom ^= (*Sess)->eom;
                    371: 
                    372:        freeSession(flg ? csFName : NULL, Sess);
                    373: }
                    374: 
                    375: 
                    376: /*
                    377:  * map_attachSession() MMAP Attach to shared memory & return begin address
                    378:  * @s = Session item
                    379:  * @procMem = Custom start address (optionl) *default must be 0*
                    380:  * return: NULL failed attach, !=NULL begin address of memory
                    381: */
1.3       misho     382: inline void *
                    383: map_attachSession(tagSess * __restrict s, void *procMem)
1.1       misho     384: {
                    385:        struct stat sb;
                    386: 
                    387:        if (!s)
                    388:                return NULL;
                    389: 
1.3       misho     390:        /* Learn size of shared memory block */
1.1       misho     391:        sync();
                    392:        if (fstat(s->mem.fd, &sb) == -1) {
                    393:                LOGERR;
                    394:                return NULL;
                    395:        } else
                    396:                s->eom = sb.st_size;
                    397: 
1.3       misho     398:        /* attach to memory */
1.1       misho     399:        s->addr = mmap(procMem, s->eom, PROT_READ | PROT_WRITE, MAP_SHARED, s->mem.fd, 0);
                    400:        if (s->addr == MAP_FAILED) {
                    401:                LOGERR;
                    402:                s->addr = NULL;
                    403:        }
                    404: 
                    405:        return s->addr;
                    406: }
                    407: 
                    408: /*
                    409:  * map_detachSession() MMAP Detach from shared memory
                    410:  * @s = Session item
                    411: */
1.3       misho     412: inline void
                    413: map_detachSession(tagSess * __restrict s)
1.1       misho     414: {
                    415:        if (!s)
                    416:                return;
                    417: 
                    418:        msync(s->addr, 0, MS_SYNC | MS_INVALIDATE);
                    419: 
                    420:        if (s->addr && s->eom) {
                    421:                munmap(s->addr, s->eom);
                    422:                s->addr = NULL;
                    423:        }
                    424: }
                    425: 
                    426: /*
                    427:  * ipc_attachSession() IPC Attach to shared memory & return begin address
                    428:  * @s = Session item
                    429:  * @procMem = Custom start address (optionl) *default must be 0*
                    430:  * return: NULL failed attach, !=NULL begin address of memory
                    431: */
1.3       misho     432: inline void *
                    433: ipc_attachSession(tagSess * __restrict s, void *procMem)
1.1       misho     434: {
                    435:        if (!s)
                    436:                return NULL;
                    437: 
                    438:        s->addr = shmat(s->mem.shmid, procMem, 0);
                    439:        if (s->addr == (void*) -1) {
                    440:                LOGERR;
                    441:                s->addr = NULL;
                    442:        }
                    443: 
                    444:        return s->addr;
                    445: }
                    446: 
                    447: /*
                    448:  * ipc_detachSession() IPC Detach from shared memory
                    449:  * @s = Session item
                    450: */
1.3       misho     451: inline void
                    452: ipc_detachSession(tagSess * __restrict s)
1.1       misho     453: {
                    454:        if (!s)
                    455:                return;
                    456: 
                    457:        if (s->addr) {
                    458:                shmdt(s->addr);
                    459:                s->addr = NULL;
                    460:        }
                    461: }
                    462: 
1.2       misho     463: /*
                    464:  * isAttached() Check for mapped/(attached) shared memory
                    465:  * @s = Session item
                    466:  * return: -1 null session item, 0 not attached, 1 attached memory
                    467: */
1.3       misho     468: inline int
                    469: isAttached(tagSess * __restrict s)
1.2       misho     470: {
                    471:        if (!s)
                    472:                return -1;
                    473: 
                    474:        return (s->addr ? 1 : 0);
                    475: }
                    476: 
1.1       misho     477: 
                    478: /*
                    479:  * map_notSemaphore() MMAP negative block if semaphore isn`t signaled
                    480:  * @s = Session item
                    481: */
1.3       misho     482: inline void
                    483: map_notSemaphore(tagSess * __restrict s)
1.1       misho     484: {
                    485:        int i = -1;
                    486: 
                    487:        if (!s)
                    488:                return;
                    489: 
                    490:        sem_getvalue(s->id.sid, &i);
                    491:        for (;i > 0; i--)
                    492:                sem_wait(s->id.sid);
                    493: }
                    494: 
                    495: /*
                    496:  * map_isSemaphored() MMAP Check semaphore
                    497:  * @s = Session item
                    498:  * return: -1 error: can`t return semaphore, 0 = false, 1 = true
                    499: */
1.3       misho     500: inline int
                    501: map_isSemaphored(tagSess * __restrict s)
1.1       misho     502: {
                    503:        int val = -1;
                    504: 
                    505:        if (!s)
                    506:                return -1;
                    507: 
                    508:        sem_getvalue(s->id.sid, &val);
                    509:        return val ? 0 : 1;
                    510: }
                    511: 
                    512: /*
                    513:  * map_addSemaphore() MMAP unblock semaphore, increment semaphore
                    514:  * @s = Session item
                    515:  * return: 0 Ok, -1 error: can`t increment 
                    516: */
1.3       misho     517: inline int
                    518: map_addSemaphore(tagSess * __restrict s)
1.1       misho     519: {
                    520:        if (!s)
                    521:                return -1;
                    522: 
                    523:        return sem_post(s->id.sid);
                    524: }
                    525: 
                    526: /*
                    527:  * map_decSemaphore() MMAP block semaphore, decrement semaphore
                    528:  * @s = Session item
                    529:  * return: 0 Ok, -1 error: can`t decrement 
                    530: */
1.3       misho     531: inline int
                    532: map_decSemaphore(tagSess * __restrict s)
1.1       misho     533: {
                    534:        if (!s)
                    535:                return -1;
                    536: 
                    537:        return sem_wait(s->id.sid);
                    538: }
                    539: 
                    540: /*
                    541:  * ipc_notSemaphore() IPC negative block if semaphore isn`t signaled
                    542:  * @s = Session item
                    543: */
1.3       misho     544: inline void
                    545: ipc_notSemaphore(tagSess * __restrict s)
1.1       misho     546: {
                    547:        struct sembuf sb = { 0, 0, 0 };
                    548: 
                    549:        if (s)
                    550:                semop(s->id.semid, &sb, 1);
                    551: }
                    552: 
                    553: /*
                    554:  * ipc_isSemaphored() IPC Check semaphore
                    555:  * @s = Session item
                    556:  * return: -1 error: can`t return semaphore, 0 = false, 1 = true
                    557: */
1.3       misho     558: inline int
                    559: ipc_isSemaphored(tagSess * __restrict s)
1.1       misho     560: {
                    561:        struct sembuf sb = { 0, 0, IPC_NOWAIT };
                    562: 
                    563:        if (!s)
                    564:                return -1;
                    565: 
                    566:        return semop(s->id.semid, &sb, 1) + 1;
                    567: }
                    568: 
                    569: /*
                    570:  * ipc_addSemaphore() IPC unblock semaphore, increment semaphore
                    571:  * @s = Session item
                    572:  * return: 0 Ok, -1 error: can`t increment 
                    573: */
1.3       misho     574: inline int
                    575: ipc_addSemaphore(tagSess * __restrict s)
1.1       misho     576: {
                    577:        struct sembuf sb = { 0, 1, 0 };
                    578: 
                    579:        if (!s)
                    580:                return -1;
                    581: 
                    582:        return semop(s->id.semid, &sb, 1);
                    583: }
                    584: 
                    585: /*
                    586:  * ipc_decSemaphore() IPC block semaphore, decrement semaphore
                    587:  * @s = Session item
                    588:  * return: 0 Ok, -1 error: can`t decrement 
                    589: */
1.3       misho     590: inline int
                    591: ipc_decSemaphore(tagSess * __restrict s)
1.1       misho     592: {
                    593:        struct sembuf sb = { 0, -1, 0 };
                    594: 
                    595:        if (!s)
                    596:                return -1;
                    597: 
                    598:        return semop(s->id.semid, &sb, 1);
                    599: }

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