ipc/msg.c

   1 /*
   2  * linux/ipc/msg.c
   3  * Copyright (C) 1992 Krishna Balasubramanian
   4  *
   5  * Removed all the remaining kerneld mess
   6  * Catch the -EFAULT stuff properly
   7  * Use GFP_KERNEL for messages as in 1.2
   8  * Fixed up the unchecked user space derefs
   9  * Copyright (C) 1998 Alan Cox & Andi Kleen
  10  *
  11  * /proc/sysvipc/msg support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
  12  *
  13  * mostly rewritten, threaded and wake-one semantics added
  14  * MSGMAX limit removed, sysctl's added
  15  * (c) 1999 Manfred Spraul <manfreds@colorfullife.com>
  16  */
  17
  18 #include <linux/config.h>
  19 #include <linux/slab.h>
  20 #include <linux/msg.h>
  21 #include <linux/spinlock.h>
  22 #include <linux/init.h>
  23 #include <linux/proc_fs.h>
  24 #include <linux/list.h>
  25 #include <linux/security.h>
  26 #include <asm/uaccess.h>
  27 #include "util.h"
  28
  29 /* sysctl: */
  30 int msg_ctlmax = MSGMAX;
  31 int msg_ctlmnb = MSGMNB;
  32 int msg_ctlmni = MSGMNI;
  33
  34 /* one msg_receiver structure for each sleeping receiver */
  35 struct msg_receiver {
  36         struct list_head r_list;
  37         struct task_struct* r_tsk;
  38
  39         int r_mode;
  40         long r_msgtype;
  41         long r_maxsize;
  42
  43         struct msg_msg* volatile r_msg;
  44 };
  45
  46 /* one msg_sender for each sleeping sender */
  47 struct msg_sender {
  48         struct list_head list;
  49         struct task_struct* tsk;
  50 };
  51
  52 struct msg_msgseg {
  53         struct msg_msgseg* next;
  54         /* the next part of the message follows immediately */
  55 };
  56
  57 #define SEARCH_ANY              1
  58 #define SEARCH_EQUAL            2
  59 #define SEARCH_NOTEQUAL         3
  60 #define SEARCH_LESSEQUAL        4
  61
  62 static atomic_t msg_bytes = ATOMIC_INIT(0);
  63 static atomic_t msg_hdrs = ATOMIC_INIT(0);
  64
  65 static struct ipc_ids msg_ids;
  66
  67 #define msg_lock(id)    ((struct msg_queue*)ipc_lock(&msg_ids,id))
  68 #define msg_unlock(id)  ipc_unlock(&msg_ids,id)
  69 #define msg_rmid(id)    ((struct msg_queue*)ipc_rmid(&msg_ids,id))
  70 #define msg_checkid(msq, msgid) \
  71         ipc_checkid(&msg_ids,&msq->q_perm,msgid)
  72 #define msg_buildid(id, seq) \
  73         ipc_buildid(&msg_ids, id, seq)
  74
  75 static void freeque (int id);
  76 static int newque (key_t key, int msgflg);
  77 #ifdef CONFIG_PROC_FS
  78 static int sysvipc_msg_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data);
  79 #endif
  80
  81 void __init msg_init (void)
  82 {
  83         ipc_init_ids(&msg_ids,msg_ctlmni);
  84
  85 #ifdef CONFIG_PROC_FS
  86         create_proc_read_entry("sysvipc/msg", 0, 0, sysvipc_msg_read_proc, NULL);
  87 #endif
  88 }
  89
  90 static int newque (key_t key, int msgflg)
  91 {
  92         int id;
  93         int retval;
  94         struct msg_queue *msq;
  95
  96         msq  = (struct msg_queue *) kmalloc (sizeof (*msq), GFP_KERNEL);
  97         if (!msq)
  98                 return -ENOMEM;
  99
 100         msq->q_perm.mode = (msgflg & S_IRWXUGO);
 101         msq->q_perm.key = key;
 102
 103         msq->q_perm.security = NULL;
 104         retval = security_ops->msg_queue_alloc_security(msq);
 105         if (retval) {
 106                 kfree(msq);
 107                 return retval;
 108         }
 109
 110         id = ipc_addid(&msg_ids, &msq->q_perm, msg_ctlmni);
 111         if(id == -1) {
 112                 security_ops->msg_queue_free_security(msq);
 113                 kfree(msq);
 114                 return -ENOSPC;
 115         }
 116
 117         msq->q_stime = msq->q_rtime = 0;
 118         msq->q_ctime = CURRENT_TIME;
 119         msq->q_cbytes = msq->q_qnum = 0;
 120         msq->q_qbytes = msg_ctlmnb;
 121         msq->q_lspid = msq->q_lrpid = 0;
 122         INIT_LIST_HEAD(&msq->q_messages);
 123         INIT_LIST_HEAD(&msq->q_receivers);
 124         INIT_LIST_HEAD(&msq->q_senders);
 125         msg_unlock(id);
 126
 127         return msg_buildid(id,msq->q_perm.seq);
 128 }
 129
 130 static void free_msg(struct msg_msg* msg)
 131 {
 132         struct msg_msgseg* seg;
 133         seg = msg->next;
 134         kfree(msg);
 135         while(seg != NULL) {
 136                 struct msg_msgseg* tmp = seg->next;
 137                 kfree(seg);
 138                 seg = tmp;
 139         }
 140 }
 141
 142 static struct msg_msg* load_msg(void* src, int len)
 143 {
 144         struct msg_msg* msg;
 145         struct msg_msgseg** pseg;
 146         int err;
 147         int alen;
 148
 149         alen = len;
 150         if(alen > DATALEN_MSG)
 151                 alen = DATALEN_MSG;
 152
 153         msg = (struct msg_msg *) kmalloc (sizeof(*msg) + alen, GFP_KERNEL);
 154         if(msg==NULL)
 155                 return ERR_PTR(-ENOMEM);
 156
 157         msg->next = NULL;
 158
 159         if (copy_from_user(msg+1, src, alen)) {
 160                 err = -EFAULT;
 161                 goto out_err;
 162         }
 163
 164         len -= alen;
 165         src = ((char*)src)+alen;
 166         pseg = &msg->next;
 167         while(len > 0) {
 168                 struct msg_msgseg* seg;
 169                 alen = len;
 170                 if(alen > DATALEN_SEG)
 171                         alen = DATALEN_SEG;
 172                 seg = (struct msg_msgseg *) kmalloc (sizeof(*seg) + alen, GFP_KERNEL);
 173                 if(seg==NULL) {
 174                         err=-ENOMEM;
 175                         goto out_err;
 176                 }
 177                 *pseg = seg;
 178                 seg->next = NULL;
 179                 if(copy_from_user (seg+1, src, alen)) {
 180                         err = -EFAULT;
 181                         goto out_err;
 182                 }
 183                 pseg = &seg->next;
 184                 len -= alen;
 185                 src = ((char*)src)+alen;
 186         }
 187         return msg;
 188
 189 out_err:
 190         free_msg(msg);
 191         return ERR_PTR(err);
 192 }
 193
 194 static int store_msg(void* dest, struct msg_msg* msg, int len)
 195 {
 196         int alen;
 197         struct msg_msgseg *seg;
 198
 199         alen = len;
 200         if(alen > DATALEN_MSG)
 201                 alen = DATALEN_MSG;
 202         if(copy_to_user (dest, msg+1, alen))
 203                 return -1;
 204
 205         len -= alen;
 206         dest = ((char*)dest)+alen;
 207         seg = msg->next;
 208         while(len > 0) {
 209                 alen = len;
 210                 if(alen > DATALEN_SEG)
 211                         alen = DATALEN_SEG;
 212                 if(copy_to_user (dest, seg+1, alen))
 213                         return -1;
 214                 len -= alen;
 215                 dest = ((char*)dest)+alen;
 216                 seg=seg->next;
 217         }
 218         return 0;
 219 }
 220
 221 static inline void ss_add(struct msg_queue* msq, struct msg_sender* mss)
 222 {
 223         mss->tsk=current;
 224         current->state=TASK_INTERRUPTIBLE;
 225         list_add_tail(&mss->list,&msq->q_senders);
 226 }
 227
 228 static inline void ss_del(struct msg_sender* mss)
 229 {
 230         if(mss->list.next != NULL)
 231                 list_del(&mss->list);
 232 }
 233
 234 static void ss_wakeup(struct list_head* h, int kill)
 235 {
 236         struct list_head *tmp;
 237
 238         tmp = h->next;
 239         while (tmp != h) {
 240                 struct msg_sender* mss;
 241
 242                 mss = list_entry(tmp,struct msg_sender,list);
 243                 tmp = tmp->next;
 244                 if(kill)
 245                         mss->list.next=NULL;
 246                 wake_up_process(mss->tsk);
 247         }
 248 }
 249
 250 static void expunge_all(struct msg_queue* msq, int res)
 251 {
 252         struct list_head *tmp;
 253
 254         tmp = msq->q_receivers.next;
 255         while (tmp != &msq->q_receivers) {
 256                 struct msg_receiver* msr;
 257
 258                 msr = list_entry(tmp,struct msg_receiver,r_list);
 259                 tmp = tmp->next;
 260                 msr->r_msg = ERR_PTR(res);
 261                 wake_up_process(msr->r_tsk);
 262         }
 263 }
 264
 265 static void freeque (int id)
 266 {
 267         struct msg_queue *msq;
 268         struct list_head *tmp;
 269
 270         msq = msg_rmid(id);
 271
 272         expunge_all(msq,-EIDRM);
 273         ss_wakeup(&msq->q_senders,1);
 274         msg_unlock(id);
 275
 276         tmp = msq->q_messages.next;
 277         while(tmp != &msq->q_messages) {
 278                 struct msg_msg* msg = list_entry(tmp,struct msg_msg,m_list);
 279                 tmp = tmp->next;
 280                 atomic_dec(&msg_hdrs);
 281                 free_msg(msg);
 282         }
 283         atomic_sub(msq->q_cbytes, &msg_bytes);
 284         security_ops->msg_queue_free_security(msq);
 285         kfree(msq);
 286 }
 287
 288 asmlinkage long sys_msgget (key_t key, int msgflg)
 289 {
 290         int id, ret = -EPERM;
 291         struct msg_queue *msq;
 292
 293         down(&msg_ids.sem);
 294         if (key == IPC_PRIVATE)
 295                 ret = newque(key, msgflg);
 296         else if ((id = ipc_findkey(&msg_ids, key)) == -1) { /* key not used */
 297                 if (!(msgflg & IPC_CREAT))
 298                         ret = -ENOENT;
 299                 else
 300                         ret = newque(key, msgflg);
 301         } else if (msgflg & IPC_CREAT && msgflg & IPC_EXCL) {
 302                 ret = -EEXIST;
 303         } else {
 304                 msq = msg_lock(id);
 305                 if(msq==NULL)
 306                         BUG();
 307                 if (ipcperms(&msq->q_perm, msgflg))
 308                         ret = -EACCES;
 309                 else
 310                         ret = msg_buildid(id, msq->q_perm.seq);
 311                 msg_unlock(id);
 312         }
 313         up(&msg_ids.sem);
 314         return ret;
 315 }
 316
 317 static inline unsigned long copy_msqid_to_user(void *buf, struct msqid64_ds *in, int version)
 318 {
 319         switch(version) {
 320         case IPC_64:
 321                 return copy_to_user (buf, in, sizeof(*in));
 322         case IPC_OLD:
 323             {
 324                 struct msqid_ds out;
 325
 326                 memset(&out,0,sizeof(out));
 327
 328                 ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
 329
 330                 out.msg_stime           = in->msg_stime;
 331                 out.msg_rtime           = in->msg_rtime;
 332                 out.msg_ctime           = in->msg_ctime;
 333
 334                 if(in->msg_cbytes > USHRT_MAX)
 335                         out.msg_cbytes  = USHRT_MAX;
 336                 else
 337                         out.msg_cbytes  = in->msg_cbytes;
 338                 out.msg_lcbytes         = in->msg_cbytes;
 339
 340                 if(in->msg_qnum > USHRT_MAX)
 341                         out.msg_qnum    = USHRT_MAX;
 342                 else
 343                         out.msg_qnum    = in->msg_qnum;
 344
 345                 if(in->msg_qbytes > USHRT_MAX)
 346                         out.msg_qbytes  = USHRT_MAX;
 347                 else
 348                         out.msg_qbytes  = in->msg_qbytes;
 349                 out.msg_lqbytes         = in->msg_qbytes;
 350
 351                 out.msg_lspid           = in->msg_lspid;
 352                 out.msg_lrpid           = in->msg_lrpid;
 353
 354                 return copy_to_user (buf, &out, sizeof(out));
 355             }
 356         default:
 357                 return -EINVAL;
 358         }
 359 }
 360
 361 struct msq_setbuf {
 362         unsigned long   qbytes;
 363         uid_t           uid;
 364         gid_t           gid;
 365         mode_t          mode;
 366 };
 367
 368 static inline unsigned long copy_msqid_from_user(struct msq_setbuf *out, void *buf, int version)
 369 {
 370         switch(version) {
 371         case IPC_64:
 372             {
 373                 struct msqid64_ds tbuf;
 374
 375                 if (copy_from_user (&tbuf, buf, sizeof (tbuf)))
 376                         return -EFAULT;
 377
 378                 out->qbytes             = tbuf.msg_qbytes;
 379                 out->uid                = tbuf.msg_perm.uid;
 380                 out->gid                = tbuf.msg_perm.gid;
 381                 out->mode               = tbuf.msg_perm.mode;
 382
 383                 return 0;
 384             }
 385         case IPC_OLD:
 386             {
 387                 struct msqid_ds tbuf_old;
 388
 389                 if (copy_from_user (&tbuf_old, buf, sizeof (tbuf_old)))
 390                         return -EFAULT;
 391
 392                 out->uid                = tbuf_old.msg_perm.uid;
 393                 out->gid                = tbuf_old.msg_perm.gid;
 394                 out->mode               = tbuf_old.msg_perm.mode;
 395
 396                 if(tbuf_old.msg_qbytes == 0)
 397                         out->qbytes     = tbuf_old.msg_lqbytes;
 398                 else
 399                         out->qbytes     = tbuf_old.msg_qbytes;
 400
 401                 return 0;
 402             }
 403         default:
 404                 return -EINVAL;
 405         }
 406 }
 407
 408 asmlinkage long sys_msgctl (int msqid, int cmd, struct msqid_ds *buf)
 409 {
 410         int err, version;
 411         struct msg_queue *msq;
 412         struct msq_setbuf setbuf;
 413         struct kern_ipc_perm *ipcp;
 414
 415         if (msqid < 0 || cmd < 0)
 416                 return -EINVAL;
 417
 418         version = ipc_parse_version(&cmd);
 419
 420         switch (cmd) {
 421         case IPC_INFO:
 422         case MSG_INFO:
 423         {
 424                 struct msginfo msginfo;
 425                 int max_id;
 426                 if (!buf)
 427                         return -EFAULT;
 428                 /* We must not return kernel stack data.
 429                  * due to padding, it's not enough
 430                  * to set all member fields.
 431                  */
 432                 memset(&msginfo,0,sizeof(msginfo));
 433                 msginfo.msgmni = msg_ctlmni;
 434                 msginfo.msgmax = msg_ctlmax;
 435                 msginfo.msgmnb = msg_ctlmnb;
 436                 msginfo.msgssz = MSGSSZ;
 437                 msginfo.msgseg = MSGSEG;
 438                 down(&msg_ids.sem);
 439                 if (cmd == MSG_INFO) {
 440                         msginfo.msgpool = msg_ids.in_use;
 441                         msginfo.msgmap = atomic_read(&msg_hdrs);
 442                         msginfo.msgtql = atomic_read(&msg_bytes);
 443                 } else {
 444                         msginfo.msgmap = MSGMAP;
 445                         msginfo.msgpool = MSGPOOL;
 446                         msginfo.msgtql = MSGTQL;
 447                 }
 448                 max_id = msg_ids.max_id;
 449                 up(&msg_ids.sem);
 450                 if (copy_to_user (buf, &msginfo, sizeof(struct msginfo)))
 451                         return -EFAULT;
 452                 return (max_id < 0) ? 0: max_id;
 453         }
 454         case MSG_STAT:
 455         case IPC_STAT:
 456         {
 457                 struct msqid64_ds tbuf;
 458                 int success_return;
 459                 if (!buf)
 460                         return -EFAULT;
 461                 if(cmd == MSG_STAT && msqid >= msg_ids.size)
 462                         return -EINVAL;
 463
 464                 memset(&tbuf,0,sizeof(tbuf));
 465
 466                 msq = msg_lock(msqid);
 467                 if (msq == NULL)
 468                         return -EINVAL;
 469
 470                 if(cmd == MSG_STAT) {
 471                         success_return = msg_buildid(msqid, msq->q_perm.seq);
 472                 } else {
 473                         err = -EIDRM;
 474                         if (msg_checkid(msq,msqid))
 475                                 goto out_unlock;
 476                         success_return = 0;
 477                 }
 478                 err = -EACCES;
 479                 if (ipcperms (&msq->q_perm, S_IRUGO))
 480                         goto out_unlock;
 481
 482                 kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm);
 483                 tbuf.msg_stime  = msq->q_stime;
 484                 tbuf.msg_rtime  = msq->q_rtime;
 485                 tbuf.msg_ctime  = msq->q_ctime;
 486                 tbuf.msg_cbytes = msq->q_cbytes;
 487                 tbuf.msg_qnum   = msq->q_qnum;
 488                 tbuf.msg_qbytes = msq->q_qbytes;
 489                 tbuf.msg_lspid  = msq->q_lspid;
 490                 tbuf.msg_lrpid  = msq->q_lrpid;
 491                 msg_unlock(msqid);
 492                 if (copy_msqid_to_user(buf, &tbuf, version))
 493                         return -EFAULT;
 494                 return success_return;
 495         }
 496         case IPC_SET:
 497                 if (!buf)
 498                         return -EFAULT;
 499                 if (copy_msqid_from_user (&setbuf, buf, version))
 500                         return -EFAULT;
 501                 break;
 502         case IPC_RMID:
 503                 break;
 504         default:
 505                 return  -EINVAL;
 506         }
 507
 508         down(&msg_ids.sem);
 509         msq = msg_lock(msqid);
 510         err=-EINVAL;
 511         if (msq == NULL)
 512                 goto out_up;
 513
 514         err = -EIDRM;
 515         if (msg_checkid(msq,msqid))
 516                 goto out_unlock_up;
 517         ipcp = &msq->q_perm;
 518         err = -EPERM;
 519         if (current->euid != ipcp->cuid &&
 520             current->euid != ipcp->uid && !capable(CAP_SYS_ADMIN))
 521             /* We _could_ check for CAP_CHOWN above, but we don't */
 522                 goto out_unlock_up;
 523
 524         switch (cmd) {
 525         case IPC_SET:
 526         {
 527                 if (setbuf.qbytes > msg_ctlmnb && !capable(CAP_SYS_RESOURCE))
 528                         goto out_unlock_up;
 529                 msq->q_qbytes = setbuf.qbytes;
 530
 531                 ipcp->uid = setbuf.uid;
 532                 ipcp->gid = setbuf.gid;
 533                 ipcp->mode = (ipcp->mode & ~S_IRWXUGO) |
 534                         (S_IRWXUGO & setbuf.mode);
 535                 msq->q_ctime = CURRENT_TIME;
 536                 /* sleeping receivers might be excluded by
 537                  * stricter permissions.
 538                  */
 539                 expunge_all(msq,-EAGAIN);
 540                 /* sleeping senders might be able to send
 541                  * due to a larger queue size.
 542                  */
 543                 ss_wakeup(&msq->q_senders,0);
 544                 msg_unlock(msqid);
 545                 break;
 546         }
 547         case IPC_RMID:
 548                 freeque (msqid);
 549                 break;
 550         }
 551         err = 0;
 552 out_up:
 553         up(&msg_ids.sem);
 554         return err;
 555 out_unlock_up:
 556         msg_unlock(msqid);
 557         goto out_up;
 558 out_unlock:
 559         msg_unlock(msqid);
 560         return err;
 561 }
 562
 563 static int testmsg(struct msg_msg* msg,long type,int mode)
 564 {
 565         switch(mode)
 566         {
 567                 case SEARCH_ANY:
 568                         return 1;
 569                 case SEARCH_LESSEQUAL:
 570                         if(msg->m_type <=type)
 571                                 return 1;
 572                         break;
 573                 case SEARCH_EQUAL:
 574                         if(msg->m_type == type)
 575                                 return 1;
 576                         break;
 577                 case SEARCH_NOTEQUAL:
 578                         if(msg->m_type != type)
 579                                 return 1;
 580                         break;
 581         }
 582         return 0;
 583 }
 584
 585 static int inline pipelined_send(struct msg_queue* msq, struct msg_msg* msg)
 586 {
 587         struct list_head* tmp;
 588
 589         tmp = msq->q_receivers.next;
 590         while (tmp != &msq->q_receivers) {
 591                 struct msg_receiver* msr;
 592                 msr = list_entry(tmp,struct msg_receiver,r_list);
 593                 tmp = tmp->next;
 594                 if(testmsg(msg,msr->r_msgtype,msr->r_mode)) {
 595                         list_del(&msr->r_list);
 596                         if(msr->r_maxsize < msg->m_ts) {
 597                                 msr->r_msg = ERR_PTR(-E2BIG);
 598                                 wake_up_process(msr->r_tsk);
 599                         } else {
 600                                 msr->r_msg = msg;
 601                                 msq->q_lrpid = msr->r_tsk->pid;
 602                                 msq->q_rtime = CURRENT_TIME;
 603                                 wake_up_process(msr->r_tsk);
 604                                 return 1;
 605                         }
 606                 }
 607         }
 608         return 0;
 609 }
 610
 611 asmlinkage long sys_msgsnd (int msqid, struct msgbuf *msgp, size_t msgsz, int msgflg)
 612 {
 613         struct msg_queue *msq;
 614         struct msg_msg *msg;
 615         long mtype;
 616         int err;
 617
 618         if (msgsz > msg_ctlmax || (long) msgsz < 0 || msqid < 0)
 619                 return -EINVAL;
 620         if (get_user(mtype, &msgp->mtype))
 621                 return -EFAULT;
 622         if (mtype < 1)
 623                 return -EINVAL;
 624
 625         msg = load_msg(msgp->mtext, msgsz);
 626         if(IS_ERR(msg))
 627                 return PTR_ERR(msg);
 628
 629         msg->m_type = mtype;
 630         msg->m_ts = msgsz;
 631
 632         msq = msg_lock(msqid);
 633         err=-EINVAL;
 634         if(msq==NULL)
 635                 goto out_free;
 636 retry:
 637         err= -EIDRM;
 638         if (msg_checkid(msq,msqid))
 639                 goto out_unlock_free;
 640
 641         err=-EACCES;
 642         if (ipcperms(&msq->q_perm, S_IWUGO))
 643                 goto out_unlock_free;
 644
 645         if(msgsz + msq->q_cbytes > msq->q_qbytes ||
 646                 1 + msq->q_qnum > msq->q_qbytes) {
 647                 struct msg_sender s;
 648
 649                 if(msgflg&IPC_NOWAIT) {
 650                         err=-EAGAIN;
 651                         goto out_unlock_free;
 652                 }
 653                 ss_add(msq, &s);
 654                 msg_unlock(msqid);
 655                 schedule();
 656                 current->state= TASK_RUNNING;
 657
 658                 msq = msg_lock(msqid);
 659                 err = -EIDRM;
 660                 if(msq==NULL)
 661                         goto out_free;
 662                 ss_del(&s);
 663
 664                 if (signal_pending(current)) {
 665                         err=-EINTR;
 666                         goto out_unlock_free;
 667                 }
 668                 goto retry;
 669         }
 670
 671         msq->q_lspid = current->pid;
 672         msq->q_stime = CURRENT_TIME;
 673
 674         if(!pipelined_send(msq,msg)) {
 675                 /* noone is waiting for this message, enqueue it */
 676                 list_add_tail(&msg->m_list,&msq->q_messages);
 677                 msq->q_cbytes += msgsz;
 678                 msq->q_qnum++;
 679                 atomic_add(msgsz,&msg_bytes);
 680                 atomic_inc(&msg_hdrs);
 681         }
 682
 683         err = 0;
 684         msg = NULL;
 685
 686 out_unlock_free:
 687         msg_unlock(msqid);
 688 out_free:
 689         if(msg!=NULL)
 690                 free_msg(msg);
 691         return err;
 692 }
 693
 694 static int inline convert_mode(long* msgtyp, int msgflg)
 695 {
 696         /*
 697          *  find message of correct type.
 698          *  msgtyp = 0 => get first.
 699          *  msgtyp > 0 => get first message of matching type.
 700          *  msgtyp < 0 => get message with least type must be < abs(msgtype).
 701          */
 702         if(*msgtyp==0)
 703                 return SEARCH_ANY;
 704         if(*msgtyp<0) {
 705                 *msgtyp=-(*msgtyp);
 706                 return SEARCH_LESSEQUAL;
 707         }
 708         if(msgflg & MSG_EXCEPT)
 709                 return SEARCH_NOTEQUAL;
 710         return SEARCH_EQUAL;
 711 }
 712
 713 asmlinkage long sys_msgrcv (int msqid, struct msgbuf *msgp, size_t msgsz,
 714                             long msgtyp, int msgflg)
 715 {
 716         struct msg_queue *msq;
 717         struct msg_receiver msr_d;
 718         struct list_head* tmp;
 719         struct msg_msg* msg, *found_msg;
 720         int err;
 721         int mode;
 722
 723         if (msqid < 0 || (long) msgsz < 0)
 724                 return -EINVAL;
 725         mode = convert_mode(&msgtyp,msgflg);
 726
 727         msq = msg_lock(msqid);
 728         if(msq==NULL)
 729                 return -EINVAL;
 730 retry:
 731         err = -EIDRM;
 732         if (msg_checkid(msq,msqid))
 733                 goto out_unlock;
 734
 735         err=-EACCES;
 736         if (ipcperms (&msq->q_perm, S_IRUGO))
 737                 goto out_unlock;
 738
 739         tmp = msq->q_messages.next;
 740         found_msg=NULL;
 741         while (tmp != &msq->q_messages) {
 742                 msg = list_entry(tmp,struct msg_msg,m_list);
 743                 if(testmsg(msg,msgtyp,mode)) {
 744                         found_msg = msg;
 745                         if(mode == SEARCH_LESSEQUAL && msg->m_type != 1) {
 746                                 found_msg=msg;
 747                                 msgtyp=msg->m_type-1;
 748                         } else {
 749                                 found_msg=msg;
 750                                 break;
 751                         }
 752                 }
 753                 tmp = tmp->next;
 754         }
 755         if(found_msg) {
 756                 msg=found_msg;
 757                 if ((msgsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
 758                         err=-E2BIG;
 759                         goto out_unlock;
 760                 }
 761                 list_del(&msg->m_list);
 762                 msq->q_qnum--;
 763                 msq->q_rtime = CURRENT_TIME;
 764                 msq->q_lrpid = current->pid;
 765                 msq->q_cbytes -= msg->m_ts;
 766                 atomic_sub(msg->m_ts,&msg_bytes);
 767                 atomic_dec(&msg_hdrs);
 768                 ss_wakeup(&msq->q_senders,0);
 769                 msg_unlock(msqid);
 770 out_success:
 771                 msgsz = (msgsz > msg->m_ts) ? msg->m_ts : msgsz;
 772                 if (put_user (msg->m_type, &msgp->mtype) ||
 773                     store_msg(msgp->mtext, msg, msgsz)) {
 774                             msgsz = -EFAULT;
 775                 }
 776                 free_msg(msg);
 777                 return msgsz;
 778         } else
 779         {
 780                 struct msg_queue *t;
 781                 /* no message waiting. Prepare for pipelined
 782                  * receive.
 783                  */
 784                 if (msgflg & IPC_NOWAIT) {
 785                         err=-ENOMSG;
 786                         goto out_unlock;
 787                 }
 788                 list_add_tail(&msr_d.r_list,&msq->q_receivers);
 789                 msr_d.r_tsk = current;
 790                 msr_d.r_msgtype = msgtyp;
 791                 msr_d.r_mode = mode;
 792                 if(msgflg & MSG_NOERROR)
 793                         msr_d.r_maxsize = INT_MAX;
 794                  else
 795                         msr_d.r_maxsize = msgsz;
 796                 msr_d.r_msg = ERR_PTR(-EAGAIN);
 797                 current->state = TASK_INTERRUPTIBLE;
 798                 msg_unlock(msqid);
 799
 800                 schedule();
 801                 current->state = TASK_RUNNING;
 802
 803                 msg = (struct msg_msg*) msr_d.r_msg;
 804                 if(!IS_ERR(msg))
 805                         goto out_success;
 806
 807                 t = msg_lock(msqid);
 808                 if(t==NULL)
 809                         msqid=-1;
 810                 msg = (struct msg_msg*)msr_d.r_msg;
 811                 if(!IS_ERR(msg)) {
 812                         /* our message arived while we waited for
 813                          * the spinlock. Process it.
 814                          */
 815                         if(msqid!=-1)
 816                                 msg_unlock(msqid);
 817                         goto out_success;
 818                 }
 819                 err = PTR_ERR(msg);
 820                 if(err == -EAGAIN) {
 821                         if(msqid==-1)
 822                                 BUG();
 823                         list_del(&msr_d.r_list);
 824                         if (signal_pending(current))
 825                                 err=-EINTR;
 826                          else
 827                                 goto retry;
 828                 }
 829         }
 830 out_unlock:
 831         if(msqid!=-1)
 832                 msg_unlock(msqid);
 833         return err;
 834 }
 835
 836 #ifdef CONFIG_PROC_FS
 837 static int sysvipc_msg_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data)
 838 {
 839         off_t pos = 0;
 840         off_t begin = 0;
 841         int i, len = 0;
 842
 843         down(&msg_ids.sem);
 844         len += sprintf(buffer, "       key      msqid perms      cbytes       qnum lspid lrpid   uid   gid  cuid  cgid      stime      rtime      ctime\n");
 845
 846         for(i = 0; i <= msg_ids.max_id; i++) {
 847                 struct msg_queue * msq;
 848                 msq = msg_lock(i);
 849                 if(msq != NULL) {
 850                         len += sprintf(buffer + len, "%10d %10d  %4o  %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n",
 851                                 msq->q_perm.key,
 852                                 msg_buildid(i,msq->q_perm.seq),
 853                                 msq->q_perm.mode,
 854                                 msq->q_cbytes,
 855                                 msq->q_qnum,
 856                                 msq->q_lspid,
 857                                 msq->q_lrpid,
 858                                 msq->q_perm.uid,
 859                                 msq->q_perm.gid,
 860                                 msq->q_perm.cuid,
 861                                 msq->q_perm.cgid,
 862                                 msq->q_stime,
 863                                 msq->q_rtime,
 864                                 msq->q_ctime);
 865                         msg_unlock(i);
 866
 867                         pos += len;
 868                         if(pos < offset) {
 869                                 len = 0;
 870                                 begin = pos;
 871                         }
 872                         if(pos > offset + length)
 873                                 goto done;
 874                 }
 875
 876         }
 877         *eof = 1;
 878 done:
 879         up(&msg_ids.sem);
 880         *start = buffer + (offset - begin);
 881         len -= (offset - begin);
 882         if(len > length)
 883                 len = length;
 884         if(len < 0)
 885                 len = 0;
 886         return len;
 887 }
 888 #endif