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/malloc.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 <asm/uaccess.h>
  26 #include "util.h"
  27
  28 /* sysctl: */
  29 int msg_ctlmax = MSGMAX;
  30 int msg_ctlmnb = MSGMNB;
  31 int msg_ctlmni = MSGMNI;
  32
  33 /* one msg_receiver structure for each sleeping receiver */
  34 struct msg_receiver {
  35         struct list_head r_list;
  36         struct task_struct* r_tsk;
  37
  38         int r_mode;
  39         long r_msgtype;
  40         long r_maxsize;
  41
  42         struct msg_msg* volatile r_msg;
  43 };
  44
  45 /* one msg_sender for each sleeping sender */
  46 struct msg_sender {
  47         struct list_head list;
  48         struct task_struct* tsk;
  49 };
  50
  51 struct msg_msgseg {
  52         struct msg_msgseg* next;
  53         /* the next part of the message follows immediately */
  54 };
  55 /* one msg_msg structure for each message */
  56 struct msg_msg {
  57         struct list_head m_list;
  58         long  m_type;
  59         int m_ts;           /* message text size */
  60         struct msg_msgseg* next;
  61         /* the actual message follows immediately */
  62 };
  63
  64 #define DATALEN_MSG     (PAGE_SIZE-sizeof(struct msg_msg))
  65 #define DATALEN_SEG     (PAGE_SIZE-sizeof(struct msg_msgseg))
  66
  67 /* one msq_queue structure for each present queue on the system */
  68 struct msg_queue {
  69         struct kern_ipc_perm q_perm;
  70         time_t q_stime;                 /* last msgsnd time */
  71         time_t q_rtime;                 /* last msgrcv time */
  72         time_t q_ctime;                 /* last change time */
  73         unsigned long q_cbytes;         /* current number of bytes on queue */
  74         unsigned long q_qnum;           /* number of messages in queue */
  75         unsigned long q_qbytes;         /* max number of bytes on queue */
  76         pid_t q_lspid;                  /* pid of last msgsnd */
  77         pid_t q_lrpid;                  /* last receive pid */
  78
  79         struct list_head q_messages;
  80         struct list_head q_receivers;
  81         struct list_head q_senders;
  82 };
  83
  84 #define SEARCH_ANY              1
  85 #define SEARCH_EQUAL            2
  86 #define SEARCH_NOTEQUAL         3
  87 #define SEARCH_LESSEQUAL        4
  88
  89 static atomic_t msg_bytes = ATOMIC_INIT(0);
  90 static atomic_t msg_hdrs = ATOMIC_INIT(0);
  91
  92 static struct ipc_ids msg_ids;
  93
  94 #define msg_lock(id)    ((struct msg_queue*)ipc_lock(&msg_ids,id))
  95 #define msg_unlock(id)  ipc_unlock(&msg_ids,id)
  96 #define msg_rmid(id)    ((struct msg_queue*)ipc_rmid(&msg_ids,id))
  97 #define msg_checkid(msq, msgid) \
  98         ipc_checkid(&msg_ids,&msq->q_perm,msgid)
  99 #define msg_buildid(id, seq) \
 100         ipc_buildid(&msg_ids, id, seq)
 101
 102 static void freeque (int id);
 103 static int newque (key_t key, int msgflg);
 104 #ifdef CONFIG_PROC_FS
 105 static int sysvipc_msg_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data);
 106 #endif
 107
 108 void __init msg_init (void)
 109 {
 110         ipc_init_ids(&msg_ids,msg_ctlmni);
 111
 112 #ifdef CONFIG_PROC_FS
 113         create_proc_read_entry("sysvipc/msg", 0, 0, sysvipc_msg_read_proc, NULL);
 114 #endif
 115 }
 116
 117 static int newque (key_t key, int msgflg)
 118 {
 119         int id;
 120         struct msg_queue *msq;
 121
 122         msq  = (struct msg_queue *) kmalloc (sizeof (*msq), GFP_KERNEL);
 123         if (!msq)
 124                 return -ENOMEM;
 125         id = ipc_addid(&msg_ids, &msq->q_perm, msg_ctlmni);
 126         if(id == -1) {
 127                 kfree(msq);
 128                 return -ENOSPC;
 129         }
 130         msq->q_perm.mode = (msgflg & S_IRWXUGO);
 131         msq->q_perm.key = key;
 132
 133         msq->q_stime = msq->q_rtime = 0;
 134         msq->q_ctime = CURRENT_TIME;
 135         msq->q_cbytes = msq->q_qnum = 0;
 136         msq->q_qbytes = msg_ctlmnb;
 137         msq->q_lspid = msq->q_lrpid = 0;
 138         INIT_LIST_HEAD(&msq->q_messages);
 139         INIT_LIST_HEAD(&msq->q_receivers);
 140         INIT_LIST_HEAD(&msq->q_senders);
 141         msg_unlock(id);
 142
 143         return msg_buildid(id,msq->q_perm.seq);
 144 }
 145
 146 static void free_msg(struct msg_msg* msg)
 147 {
 148         struct msg_msgseg* seg;
 149         seg = msg->next;
 150         kfree(msg);
 151         while(seg != NULL) {
 152                 struct msg_msgseg* tmp = seg->next;
 153                 kfree(seg);
 154                 seg = tmp;
 155         }
 156 }
 157
 158 static struct msg_msg* load_msg(void* src, int len)
 159 {
 160         struct msg_msg* msg;
 161         struct msg_msgseg** pseg;
 162         int err;
 163         int alen;
 164
 165         alen = len;
 166         if(alen > DATALEN_MSG)
 167                 alen = DATALEN_MSG;
 168
 169         msg = (struct msg_msg *) kmalloc (sizeof(*msg) + alen, GFP_KERNEL);
 170         if(msg==NULL)
 171                 return ERR_PTR(-ENOMEM);
 172
 173         msg->next = NULL;
 174
 175         if (copy_from_user(msg+1, src, alen)) {
 176                 err = -EFAULT;
 177                 goto out_err;
 178         }
 179
 180         len -= alen;
 181         src = ((char*)src)+alen;
 182         pseg = &msg->next;
 183         while(len > 0) {
 184                 struct msg_msgseg* seg;
 185                 alen = len;
 186                 if(alen > DATALEN_SEG)
 187                         alen = DATALEN_SEG;
 188                 seg = (struct msg_msgseg *) kmalloc (sizeof(*seg) + alen, GFP_KERNEL);
 189                 if(seg==NULL) {
 190                         err=-ENOMEM;
 191                         goto out_err;
 192                 }
 193                 *pseg = seg;
 194                 seg->next = NULL;
 195                 if(copy_from_user (seg+1, src, alen)) {
 196                         err = -EFAULT;
 197                         goto out_err;
 198                 }
 199                 pseg = &seg->next;
 200                 len -= alen;
 201                 src = ((char*)src)+alen;
 202         }
 203         return msg;
 204
 205 out_err:
 206         free_msg(msg);
 207         return ERR_PTR(err);
 208 }
 209
 210 static int store_msg(void* dest, struct msg_msg* msg, int len)
 211 {
 212         int alen;
 213         struct msg_msgseg *seg;
 214
 215         alen = len;
 216         if(alen > DATALEN_MSG)
 217                 alen = DATALEN_MSG;
 218         if(copy_to_user (dest, msg+1, alen))
 219                 return -1;
 220
 221         len -= alen;
 222         dest = ((char*)dest)+alen;
 223         seg = msg->next;
 224         while(len > 0) {
 225                 alen = len;
 226                 if(alen > DATALEN_SEG)
 227                         alen = DATALEN_SEG;
 228                 if(copy_to_user (dest, seg+1, alen))
 229                         return -1;
 230                 len -= alen;
 231                 dest = ((char*)dest)+alen;
 232                 seg=seg->next;
 233         }
 234         return 0;
 235 }
 236
 237 static inline void ss_add(struct msg_queue* msq, struct msg_sender* mss)
 238 {
 239         mss->tsk=current;
 240         current->state=TASK_INTERRUPTIBLE;
 241         list_add_tail(&mss->list,&msq->q_senders);
 242 }
 243
 244 static inline void ss_del(struct msg_sender* mss)
 245 {
 246         if(mss->list.next != NULL)
 247                 list_del(&mss->list);
 248 }
 249
 250 static void ss_wakeup(struct list_head* h, int kill)
 251 {
 252         struct list_head *tmp;
 253
 254         tmp = h->next;
 255         while (tmp != h) {
 256                 struct msg_sender* mss;
 257
 258                 mss = list_entry(tmp,struct msg_sender,list);
 259                 tmp = tmp->next;
 260                 if(kill)
 261                         mss->list.next=NULL;
 262                 wake_up_process(mss->tsk);
 263         }
 264 }
 265
 266 static void expunge_all(struct msg_queue* msq, int res)
 267 {
 268         struct list_head *tmp;
 269
 270         tmp = msq->q_receivers.next;
 271         while (tmp != &msq->q_receivers) {
 272                 struct msg_receiver* msr;
 273
 274                 msr = list_entry(tmp,struct msg_receiver,r_list);
 275                 tmp = tmp->next;
 276                 msr->r_msg = ERR_PTR(res);
 277                 wake_up_process(msr->r_tsk);
 278         }
 279 }
 280
 281 static void freeque (int id)
 282 {
 283         struct msg_queue *msq;
 284         struct list_head *tmp;
 285
 286         msq = msg_rmid(id);
 287
 288         expunge_all(msq,-EIDRM);
 289         ss_wakeup(&msq->q_senders,1);
 290         msg_unlock(id);
 291
 292         tmp = msq->q_messages.next;
 293         while(tmp != &msq->q_messages) {
 294                 struct msg_msg* msg = list_entry(tmp,struct msg_msg,m_list);
 295                 tmp = tmp->next;
 296                 atomic_dec(&msg_hdrs);
 297                 free_msg(msg);
 298         }
 299         atomic_sub(msq->q_cbytes, &msg_bytes);
 300         kfree(msq);
 301 }
 302
 303 asmlinkage long sys_msgget (key_t key, int msgflg)
 304 {
 305         int id, ret = -EPERM;
 306         struct msg_queue *msq;
 307
 308         down(&msg_ids.sem);
 309         if (key == IPC_PRIVATE)
 310                 ret = newque(key, msgflg);
 311         else if ((id = ipc_findkey(&msg_ids, key)) == -1) { /* key not used */
 312                 if (!(msgflg & IPC_CREAT))
 313                         ret = -ENOENT;
 314                 else
 315                         ret = newque(key, msgflg);
 316         } else if (msgflg & IPC_CREAT && msgflg & IPC_EXCL) {
 317                 ret = -EEXIST;
 318         } else {
 319                 msq = msg_lock(id);
 320                 if(msq==NULL)
 321                         BUG();
 322                 if (ipcperms(&msq->q_perm, msgflg))
 323                         ret = -EACCES;
 324                 else
 325                         ret = msg_buildid(id, msq->q_perm.seq);
 326                 msg_unlock(id);
 327         }
 328         up(&msg_ids.sem);
 329         return ret;
 330 }
 331
 332 static inline unsigned long copy_msqid_to_user(void *buf, struct msqid64_ds *in, int version)
 333 {
 334         switch(version) {
 335         case IPC_64:
 336                 return copy_to_user (buf, in, sizeof(*in));
 337         case IPC_OLD:
 338             {
 339                 struct msqid_ds out;
 340
 341                 memset(&out,0,sizeof(out));
 342
 343                 ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
 344
 345                 out.msg_stime           = in->msg_stime;
 346                 out.msg_rtime           = in->msg_rtime;
 347                 out.msg_ctime           = in->msg_ctime;
 348
 349                 if(in->msg_cbytes > USHRT_MAX)
 350                         out.msg_cbytes  = USHRT_MAX;
 351                 else
 352                         out.msg_cbytes  = in->msg_cbytes;
 353                 out.msg_lcbytes         = in->msg_cbytes;
 354
 355                 if(in->msg_qnum > USHRT_MAX)
 356                         out.msg_qnum    = USHRT_MAX;
 357                 else
 358                         out.msg_qnum    = in->msg_qnum;
 359
 360                 if(in->msg_qbytes > USHRT_MAX)
 361                         out.msg_qbytes  = USHRT_MAX;
 362                 else
 363                         out.msg_qbytes  = in->msg_qbytes;
 364                 out.msg_lqbytes         = in->msg_qbytes;
 365
 366                 out.msg_lspid           = in->msg_lspid;
 367                 out.msg_lrpid           = in->msg_lrpid;
 368
 369                 return copy_to_user (buf, &out, sizeof(out));
 370             }
 371         default:
 372                 return -EINVAL;
 373         }
 374 }
 375
 376 struct msq_setbuf {
 377         unsigned long   qbytes;
 378         uid_t           uid;
 379         gid_t           gid;
 380         mode_t          mode;
 381 };
 382
 383 static inline unsigned long copy_msqid_from_user(struct msq_setbuf *out, void *buf, int version)
 384 {
 385         switch(version) {
 386         case IPC_64:
 387             {
 388                 struct msqid64_ds tbuf;
 389
 390                 if (copy_from_user (&tbuf, buf, sizeof (tbuf)))
 391                         return -EFAULT;
 392
 393                 out->qbytes             = tbuf.msg_qbytes;
 394                 out->uid                = tbuf.msg_perm.uid;
 395                 out->gid                = tbuf.msg_perm.gid;
 396                 out->mode               = tbuf.msg_perm.mode;
 397
 398                 return 0;
 399             }
 400         case IPC_OLD:
 401             {
 402                 struct msqid_ds tbuf_old;
 403
 404                 if (copy_from_user (&tbuf_old, buf, sizeof (tbuf_old)))
 405                         return -EFAULT;
 406
 407                 out->uid                = tbuf_old.msg_perm.uid;
 408                 out->gid                = tbuf_old.msg_perm.gid;
 409                 out->mode               = tbuf_old.msg_perm.mode;
 410
 411                 if(tbuf_old.msg_qbytes == 0)
 412                         out->qbytes     = tbuf_old.msg_lqbytes;
 413                 else
 414                         out->qbytes     = tbuf_old.msg_qbytes;
 415
 416                 return 0;
 417             }
 418         default:
 419                 return -EINVAL;
 420         }
 421 }
 422
 423 asmlinkage long sys_msgctl (int msqid, int cmd, struct msqid_ds *buf)
 424 {
 425         int err, version;
 426         struct msg_queue *msq;
 427         struct msq_setbuf setbuf;
 428         struct kern_ipc_perm *ipcp;
 429
 430         if (msqid < 0 || cmd < 0)
 431                 return -EINVAL;
 432
 433         version = ipc_parse_version(&cmd);
 434
 435         switch (cmd) {
 436         case IPC_INFO:
 437         case MSG_INFO:
 438         {
 439                 struct msginfo msginfo;
 440                 int max_id;
 441                 if (!buf)
 442                         return -EFAULT;
 443                 /* We must not return kernel stack data.
 444                  * due to padding, it's not enough
 445                  * to set all member fields.
 446                  */
 447                 memset(&msginfo,0,sizeof(msginfo));
 448                 msginfo.msgmni = msg_ctlmni;
 449                 msginfo.msgmax = msg_ctlmax;
 450                 msginfo.msgmnb = msg_ctlmnb;
 451                 msginfo.msgssz = MSGSSZ;
 452                 msginfo.msgseg = MSGSEG;
 453                 down(&msg_ids.sem);
 454                 if (cmd == MSG_INFO) {
 455                         msginfo.msgpool = msg_ids.in_use;
 456                         msginfo.msgmap = atomic_read(&msg_hdrs);
 457                         msginfo.msgtql = atomic_read(&msg_bytes);
 458                 } else {
 459                         msginfo.msgmap = MSGMAP;
 460                         msginfo.msgpool = MSGPOOL;
 461                         msginfo.msgtql = MSGTQL;
 462                 }
 463                 max_id = msg_ids.max_id;
 464                 up(&msg_ids.sem);
 465                 if (copy_to_user (buf, &msginfo, sizeof(struct msginfo)))
 466                         return -EFAULT;
 467                 return (max_id < 0) ? 0: max_id;
 468         }
 469         case MSG_STAT:
 470         case IPC_STAT:
 471         {
 472                 struct msqid64_ds tbuf;
 473                 int success_return;
 474                 if (!buf)
 475                         return -EFAULT;
 476                 if(cmd == MSG_STAT && msqid > msg_ids.size)
 477                         return -EINVAL;
 478
 479                 memset(&tbuf,0,sizeof(tbuf));
 480
 481                 msq = msg_lock(msqid);
 482                 if (msq == NULL)
 483                         return -EINVAL;
 484
 485                 if(cmd == MSG_STAT) {
 486                         success_return = msg_buildid(msqid, msq->q_perm.seq);
 487                 } else {
 488                         err = -EIDRM;
 489                         if (msg_checkid(msq,msqid))
 490                                 goto out_unlock;
 491                         success_return = 0;
 492                 }
 493                 err = -EACCES;
 494                 if (ipcperms (&msq->q_perm, S_IRUGO))
 495                         goto out_unlock;
 496
 497                 kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm);
 498                 tbuf.msg_stime  = msq->q_stime;
 499                 tbuf.msg_rtime  = msq->q_rtime;
 500                 tbuf.msg_ctime  = msq->q_ctime;
 501                 tbuf.msg_cbytes = msq->q_cbytes;
 502                 tbuf.msg_qnum   = msq->q_qnum;
 503                 tbuf.msg_qbytes = msq->q_qbytes;
 504                 tbuf.msg_lspid  = msq->q_lspid;
 505                 tbuf.msg_lrpid  = msq->q_lrpid;
 506                 msg_unlock(msqid);
 507                 if (copy_msqid_to_user(buf, &tbuf, version))
 508                         return -EFAULT;
 509                 return success_return;
 510         }
 511         case IPC_SET:
 512                 if (!buf)
 513                         return -EFAULT;
 514                 if (copy_msqid_from_user (&setbuf, buf, version))
 515                         return -EFAULT;
 516                 break;
 517         case IPC_RMID:
 518                 break;
 519         default:
 520                 return  -EINVAL;
 521         }
 522
 523         down(&msg_ids.sem);
 524         msq = msg_lock(msqid);
 525         err=-EINVAL;
 526         if (msq == NULL)
 527                 goto out_up;
 528
 529         err = -EIDRM;
 530         if (msg_checkid(msq,msqid))
 531                 goto out_unlock_up;
 532         ipcp = &msq->q_perm;
 533         err = -EPERM;
 534         if (current->euid != ipcp->cuid &&
 535             current->euid != ipcp->uid && !capable(CAP_SYS_ADMIN))
 536             /* We _could_ check for CAP_CHOWN above, but we don't */
 537                 goto out_unlock_up;
 538
 539         switch (cmd) {
 540         case IPC_SET:
 541         {
 542                 if (setbuf.qbytes > msg_ctlmnb && !capable(CAP_SYS_RESOURCE))
 543                         goto out_unlock_up;
 544                 msq->q_qbytes = setbuf.qbytes;
 545
 546                 ipcp->uid = setbuf.uid;
 547                 ipcp->gid = setbuf.gid;
 548                 ipcp->mode = (ipcp->mode & ~S_IRWXUGO) |
 549                         (S_IRWXUGO & setbuf.mode);
 550                 msq->q_ctime = CURRENT_TIME;
 551                 /* sleeping receivers might be excluded by
 552                  * stricter permissions.
 553                  */
 554                 expunge_all(msq,-EAGAIN);
 555                 /* sleeping senders might be able to send
 556                  * due to a larger queue size.
 557                  */
 558                 ss_wakeup(&msq->q_senders,0);
 559                 msg_unlock(msqid);
 560                 break;
 561         }
 562         case IPC_RMID:
 563                 freeque (msqid);
 564                 break;
 565         }
 566         err = 0;
 567 out_up:
 568         up(&msg_ids.sem);
 569         return err;
 570 out_unlock_up:
 571         msg_unlock(msqid);
 572         goto out_up;
 573 out_unlock:
 574         msg_unlock(msqid);
 575         return err;
 576 }
 577
 578 static int testmsg(struct msg_msg* msg,long type,int mode)
 579 {
 580         switch(mode)
 581         {
 582                 case SEARCH_ANY:
 583                         return 1;
 584                 case SEARCH_LESSEQUAL:
 585                         if(msg->m_type <=type)
 586                                 return 1;
 587                         break;
 588                 case SEARCH_EQUAL:
 589                         if(msg->m_type == type)
 590                                 return 1;
 591                         break;
 592                 case SEARCH_NOTEQUAL:
 593                         if(msg->m_type != type)
 594                                 return 1;
 595                         break;
 596         }
 597         return 0;
 598 }
 599
 600 int inline pipelined_send(struct msg_queue* msq, struct msg_msg* msg)
 601 {
 602         struct list_head* tmp;
 603
 604         tmp = msq->q_receivers.next;
 605         while (tmp != &msq->q_receivers) {
 606                 struct msg_receiver* msr;
 607                 msr = list_entry(tmp,struct msg_receiver,r_list);
 608                 tmp = tmp->next;
 609                 if(testmsg(msg,msr->r_msgtype,msr->r_mode)) {
 610                         list_del(&msr->r_list);
 611                         if(msr->r_maxsize < msg->m_ts) {
 612                                 msr->r_msg = ERR_PTR(-E2BIG);
 613                                 wake_up_process(msr->r_tsk);
 614                         } else {
 615                                 msr->r_msg = msg;
 616                                 msq->q_lspid = msr->r_tsk->pid;
 617                                 msq->q_rtime = CURRENT_TIME;
 618                                 wake_up_process(msr->r_tsk);
 619                                 return 1;
 620                         }
 621                 }
 622         }
 623         return 0;
 624 }
 625
 626 asmlinkage long sys_msgsnd (int msqid, struct msgbuf *msgp, size_t msgsz, int msgflg)
 627 {
 628         struct msg_queue *msq;
 629         struct msg_msg *msg;
 630         long mtype;
 631         int err;
 632
 633         if (msgsz > msg_ctlmax || (long) msgsz < 0 || msqid < 0)
 634                 return -EINVAL;
 635         if (get_user(mtype, &msgp->mtype))
 636                 return -EFAULT;
 637         if (mtype < 1)
 638                 return -EINVAL;
 639
 640         msg = load_msg(msgp->mtext, msgsz);
 641         if(IS_ERR(msg))
 642                 return PTR_ERR(msg);
 643
 644         msg->m_type = mtype;
 645         msg->m_ts = msgsz;
 646
 647         msq = msg_lock(msqid);
 648         err=-EINVAL;
 649         if(msq==NULL)
 650                 goto out_free;
 651 retry:
 652         err= -EIDRM;
 653         if (msg_checkid(msq,msqid))
 654                 goto out_unlock_free;
 655
 656         err=-EACCES;
 657         if (ipcperms(&msq->q_perm, S_IWUGO))
 658                 goto out_unlock_free;
 659
 660         if(msgsz + msq->q_cbytes > msq->q_qbytes ||
 661                 1 + msq->q_qnum > msq->q_qbytes) {
 662                 struct msg_sender s;
 663
 664                 if(msgflg&IPC_NOWAIT) {
 665                         err=-EAGAIN;
 666                         goto out_unlock_free;
 667                 }
 668                 ss_add(msq, &s);
 669                 msg_unlock(msqid);
 670                 schedule();
 671                 current->state= TASK_RUNNING;
 672
 673                 msq = msg_lock(msqid);
 674                 err = -EIDRM;
 675                 if(msq==NULL)
 676                         goto out_free;
 677                 ss_del(&s);
 678
 679                 if (signal_pending(current)) {
 680                         err=-EINTR;
 681                         goto out_unlock_free;
 682                 }
 683                 goto retry;
 684         }
 685
 686         if(!pipelined_send(msq,msg)) {
 687                 /* noone is waiting for this message, enqueue it */
 688                 list_add_tail(&msg->m_list,&msq->q_messages);
 689                 msq->q_cbytes += msgsz;
 690                 msq->q_qnum++;
 691                 atomic_add(msgsz,&msg_bytes);
 692                 atomic_inc(&msg_hdrs);
 693         }
 694
 695         err = 0;
 696         msg = NULL;
 697         msq->q_lspid = current->pid;
 698         msq->q_stime = CURRENT_TIME;
 699
 700 out_unlock_free:
 701         msg_unlock(msqid);
 702 out_free:
 703         if(msg!=NULL)
 704                 free_msg(msg);
 705         return err;
 706 }
 707
 708 int inline convert_mode(long* msgtyp, int msgflg)
 709 {
 710         /*
 711          *  find message of correct type.
 712          *  msgtyp = 0 => get first.
 713          *  msgtyp > 0 => get first message of matching type.
 714          *  msgtyp < 0 => get message with least type must be < abs(msgtype).
 715          */
 716         if(*msgtyp==0)
 717                 return SEARCH_ANY;
 718         if(*msgtyp<0) {
 719                 *msgtyp=-(*msgtyp);
 720                 return SEARCH_LESSEQUAL;
 721         }
 722         if(msgflg & MSG_EXCEPT)
 723                 return SEARCH_NOTEQUAL;
 724         return SEARCH_EQUAL;
 725 }
 726
 727 asmlinkage long sys_msgrcv (int msqid, struct msgbuf *msgp, size_t msgsz,
 728                             long msgtyp, int msgflg)
 729 {
 730         struct msg_queue *msq;
 731         struct msg_receiver msr_d;
 732         struct list_head* tmp;
 733         struct msg_msg* msg, *found_msg;
 734         int err;
 735         int mode;
 736
 737         if (msqid < 0 || (long) msgsz < 0)
 738                 return -EINVAL;
 739         mode = convert_mode(&msgtyp,msgflg);
 740
 741         msq = msg_lock(msqid);
 742         if(msq==NULL)
 743                 return -EINVAL;
 744 retry:
 745         err=-EACCES;
 746         if (ipcperms (&msq->q_perm, S_IRUGO))
 747                 goto out_unlock;
 748
 749         tmp = msq->q_messages.next;
 750         found_msg=NULL;
 751         while (tmp != &msq->q_messages) {
 752                 msg = list_entry(tmp,struct msg_msg,m_list);
 753                 if(testmsg(msg,msgtyp,mode)) {
 754                         found_msg = msg;
 755                         if(mode == SEARCH_LESSEQUAL && msg->m_type != 1) {
 756                                 found_msg=msg;
 757                                 msgtyp=msg->m_type-1;
 758                         } else {
 759                                 found_msg=msg;
 760                                 break;
 761                         }
 762                 }
 763                 tmp = tmp->next;
 764         }
 765         if(found_msg) {
 766                 msg=found_msg;
 767                 if ((msgsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
 768                         err=-E2BIG;
 769                         goto out_unlock;
 770                 }
 771                 list_del(&msg->m_list);
 772                 msq->q_qnum--;
 773                 msq->q_rtime = CURRENT_TIME;
 774                 msq->q_lrpid = current->pid;
 775                 msq->q_cbytes -= msg->m_ts;
 776                 atomic_sub(msg->m_ts,&msg_bytes);
 777                 atomic_dec(&msg_hdrs);
 778                 ss_wakeup(&msq->q_senders,0);
 779                 msg_unlock(msqid);
 780 out_success:
 781                 msgsz = (msgsz > msg->m_ts) ? msg->m_ts : msgsz;
 782                 if (put_user (msg->m_type, &msgp->mtype) ||
 783                     store_msg(msgp->mtext, msg, msgsz)) {
 784                             msgsz = -EFAULT;
 785                 }
 786                 free_msg(msg);
 787                 return msgsz;
 788         } else
 789         {
 790                 struct msg_queue *t;
 791                 /* no message waiting. Prepare for pipelined
 792                  * receive.
 793                  */
 794                 if (msgflg & IPC_NOWAIT) {
 795                         err=-ENOMSG;
 796                         goto out_unlock;
 797                 }
 798                 list_add_tail(&msr_d.r_list,&msq->q_receivers);
 799                 msr_d.r_tsk = current;
 800                 msr_d.r_msgtype = msgtyp;
 801                 msr_d.r_mode = mode;
 802                 if(msgflg & MSG_NOERROR)
 803                         msr_d.r_maxsize = INT_MAX;
 804                  else
 805                         msr_d.r_maxsize = msgsz;
 806                 msr_d.r_msg = ERR_PTR(-EAGAIN);
 807                 current->state = TASK_INTERRUPTIBLE;
 808                 msg_unlock(msqid);
 809
 810                 schedule();
 811                 current->state = TASK_RUNNING;
 812
 813                 msg = (struct msg_msg*) msr_d.r_msg;
 814                 if(!IS_ERR(msg))
 815                         goto out_success;
 816
 817                 t = msg_lock(msqid);
 818                 if(t==NULL)
 819                         msqid=-1;
 820                 msg = (struct msg_msg*)msr_d.r_msg;
 821                 if(!IS_ERR(msg)) {
 822                         /* our message arived while we waited for
 823                          * the spinlock. Process it.
 824                          */
 825                         if(msqid!=-1)
 826                                 msg_unlock(msqid);
 827                         goto out_success;
 828                 }
 829                 err = PTR_ERR(msg);
 830                 if(err == -EAGAIN) {
 831                         if(msqid==-1)
 832                                 BUG();
 833                         list_del(&msr_d.r_list);
 834                         if (signal_pending(current))
 835                                 err=-EINTR;
 836                          else
 837                                 goto retry;
 838                 }
 839         }
 840 out_unlock:
 841         if(msqid!=-1)
 842                 msg_unlock(msqid);
 843         return err;
 844 }
 845
 846 #ifdef CONFIG_PROC_FS
 847 static int sysvipc_msg_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data)
 848 {
 849         off_t pos = 0;
 850         off_t begin = 0;
 851         int i, len = 0;
 852
 853         down(&msg_ids.sem);
 854         len += sprintf(buffer, "       key      msqid perms      cbytes       qnum lspid lrpid   uid   gid  cuid  cgid      stime      rtime      ctime\n");
 855
 856         for(i = 0; i <= msg_ids.max_id; i++) {
 857                 struct msg_queue * msq;
 858                 msq = msg_lock(i);
 859                 if(msq != NULL) {
 860                         len += sprintf(buffer + len, "%10d %10d  %4o  %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n",
 861                                 msq->q_perm.key,
 862                                 msg_buildid(i,msq->q_perm.seq),
 863                                 msq->q_perm.mode,
 864                                 msq->q_cbytes,
 865                                 msq->q_qnum,
 866                                 msq->q_lspid,
 867                                 msq->q_lrpid,
 868                                 msq->q_perm.uid,
 869                                 msq->q_perm.gid,
 870                                 msq->q_perm.cuid,
 871                                 msq->q_perm.cgid,
 872                                 msq->q_stime,
 873                                 msq->q_rtime,
 874                                 msq->q_ctime);
 875                         msg_unlock(i);
 876
 877                         pos += len;
 878                         if(pos < offset) {
 879                                 len = 0;
 880                                 begin = pos;
 881                         }
 882                         if(pos > offset + length)
 883                                 goto done;
 884                 }
 885
 886         }
 887         *eof = 1;
 888 done:
 889         up(&msg_ids.sem);
 890         *start = buffer + (offset - begin);
 891         len -= (offset - begin);
 892         if(len > length)
 893                 len = length;
 894         if(len < 0)
 895                 len = 0;
 896         return len;
 897 }
 898 #endif