msg.c

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    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 <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 static 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_lrpid = 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         msq->q_lspid = current->pid;
  687         msq->q_stime = CURRENT_TIME;
  688 
  689         if(!pipelined_send(msq,msg)) {
  690                 /* noone is waiting for this message, enqueue it */
  691                 list_add_tail(&msg->m_list,&msq->q_messages);
  692                 msq->q_cbytes += msgsz;
  693                 msq->q_qnum++;
  694                 atomic_add(msgsz,&msg_bytes);
  695                 atomic_inc(&msg_hdrs);
  696         }
  697         
  698         err = 0;
  699         msg = NULL;
  700 
  701 out_unlock_free:
  702         msg_unlock(msqid);
  703 out_free:
  704         if(msg!=NULL)
  705                 free_msg(msg);
  706         return err;
  707 }
  708 
  709 static int inline convert_mode(long* msgtyp, int msgflg)
  710 {
  711         /* 
  712          *  find message of correct type.
  713          *  msgtyp = 0 => get first.
  714          *  msgtyp > 0 => get first message of matching type.
  715          *  msgtyp < 0 => get message with least type must be < abs(msgtype).  
  716          */
  717         if(*msgtyp==0)
  718                 return SEARCH_ANY;
  719         if(*msgtyp<0) {
  720                 *msgtyp=-(*msgtyp);
  721                 return SEARCH_LESSEQUAL;
  722         }
  723         if(msgflg & MSG_EXCEPT)
  724                 return SEARCH_NOTEQUAL;
  725         return SEARCH_EQUAL;
  726 }
  727 
  728 asmlinkage long sys_msgrcv (int msqid, struct msgbuf *msgp, size_t msgsz,
  729                             long msgtyp, int msgflg)
  730 {
  731         struct msg_queue *msq;
  732         struct msg_receiver msr_d;
  733         struct list_head* tmp;
  734         struct msg_msg* msg, *found_msg;
  735         int err;
  736         int mode;
  737 
  738         if (msqid < 0 || (long) msgsz < 0)
  739                 return -EINVAL;
  740         mode = convert_mode(&msgtyp,msgflg);
  741 
  742         msq = msg_lock(msqid);
  743         if(msq==NULL)
  744                 return -EINVAL;
  745 retry:
  746         err = -EIDRM;
  747         if (msg_checkid(msq,msqid))
  748                 goto out_unlock;
  749 
  750         err=-EACCES;
  751         if (ipcperms (&msq->q_perm, S_IRUGO))
  752                 goto out_unlock;
  753 
  754         tmp = msq->q_messages.next;
  755         found_msg=NULL;
  756         while (tmp != &msq->q_messages) {
  757                 msg = list_entry(tmp,struct msg_msg,m_list);
  758                 if(testmsg(msg,msgtyp,mode)) {
  759                         found_msg = msg;
  760                         if(mode == SEARCH_LESSEQUAL && msg->m_type != 1) {
  761                                 found_msg=msg;
  762                                 msgtyp=msg->m_type-1;
  763                         } else {
  764                                 found_msg=msg;
  765                                 break;
  766                         }
  767                 }
  768                 tmp = tmp->next;
  769         }
  770         if(found_msg) {
  771                 msg=found_msg;
  772                 if ((msgsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
  773                         err=-E2BIG;
  774                         goto out_unlock;
  775                 }
  776                 list_del(&msg->m_list);
  777                 msq->q_qnum--;
  778                 msq->q_rtime = CURRENT_TIME;
  779                 msq->q_lrpid = current->pid;
  780                 msq->q_cbytes -= msg->m_ts;
  781                 atomic_sub(msg->m_ts,&msg_bytes);
  782                 atomic_dec(&msg_hdrs);
  783                 ss_wakeup(&msq->q_senders,0);
  784                 msg_unlock(msqid);
  785 out_success:
  786                 msgsz = (msgsz > msg->m_ts) ? msg->m_ts : msgsz;
  787                 if (put_user (msg->m_type, &msgp->mtype) ||
  788                     store_msg(msgp->mtext, msg, msgsz)) {
  789                             msgsz = -EFAULT;
  790                 }
  791                 free_msg(msg);
  792                 return msgsz;
  793         } else
  794         {
  795                 struct msg_queue *t;
  796                 /* no message waiting. Prepare for pipelined
  797                  * receive.
  798                  */
  799                 if (msgflg & IPC_NOWAIT) {
  800                         err=-ENOMSG;
  801                         goto out_unlock;
  802                 }
  803                 list_add_tail(&msr_d.r_list,&msq->q_receivers);
  804                 msr_d.r_tsk = current;
  805                 msr_d.r_msgtype = msgtyp;
  806                 msr_d.r_mode = mode;
  807                 if(msgflg & MSG_NOERROR)
  808                         msr_d.r_maxsize = INT_MAX;
  809                  else
  810                         msr_d.r_maxsize = msgsz;
  811                 msr_d.r_msg = ERR_PTR(-EAGAIN);
  812                 current->state = TASK_INTERRUPTIBLE;
  813                 msg_unlock(msqid);
  814 
  815                 schedule();
  816                 current->state = TASK_RUNNING;
  817 
  818                 /* This introduces a race so we must always take
  819                    the slow path
  820                 msg = (struct msg_msg*) msr_d.r_msg;
  821                 if(!IS_ERR(msg)) 
  822                         goto out_success;
  823                 */
  824                 t = msg_lock(msqid);
  825                 if(t==NULL)
  826                         msqid=-1;
  827                 msg = (struct msg_msg*)msr_d.r_msg;
  828                 if(!IS_ERR(msg)) {
  829                         /* our message arived while we waited for
  830                          * the spinlock. Process it.
  831                          */
  832                         if(msqid!=-1)
  833                                 msg_unlock(msqid);
  834                         goto out_success;
  835                 }
  836                 err = PTR_ERR(msg);
  837                 if(err == -EAGAIN) {
  838                         if(msqid==-1)
  839                                 BUG();
  840                         list_del(&msr_d.r_list);
  841                         if (signal_pending(current))
  842                                 err=-EINTR;
  843                          else
  844                                 goto retry;
  845                 }
  846         }
  847 out_unlock:
  848         if(msqid!=-1)
  849                 msg_unlock(msqid);
  850         return err;
  851 }
  852 
  853 #ifdef CONFIG_PROC_FS
  854 static int sysvipc_msg_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data)
  855 {
  856         off_t pos = 0;
  857         off_t begin = 0;
  858         int i, len = 0;
  859 
  860         down(&msg_ids.sem);
  861         len += sprintf(buffer, "       key      msqid perms      cbytes       qnum lspid lrpid   uid   gid  cuid  cgid      stime      rtime      ctime\n");
  862 
  863         for(i = 0; i <= msg_ids.max_id; i++) {
  864                 struct msg_queue * msq;
  865                 msq = msg_lock(i);
  866                 if(msq != NULL) {
  867                         len += sprintf(buffer + len, "%10d %10d  %4o  %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n",
  868                                 msq->q_perm.key,
  869                                 msg_buildid(i,msq->q_perm.seq),
  870                                 msq->q_perm.mode,
  871                                 msq->q_cbytes,
  872                                 msq->q_qnum,
  873                                 msq->q_lspid,
  874                                 msq->q_lrpid,
  875                                 msq->q_perm.uid,
  876                                 msq->q_perm.gid,
  877                                 msq->q_perm.cuid,
  878                                 msq->q_perm.cgid,
  879                                 msq->q_stime,
  880                                 msq->q_rtime,
  881                                 msq->q_ctime);
  882                         msg_unlock(i);
  883 
  884                         pos += len;
  885                         if(pos < offset) {
  886                                 len = 0;
  887                                 begin = pos;
  888                         }
  889                         if(pos > offset + length)
  890                                 goto done;
  891                 }
  892 
  893         }
  894         *eof = 1;
  895 done:
  896         up(&msg_ids.sem);
  897         *start = buffer + (offset - begin);
  898         len -= (offset - begin);
  899         if(len > length)
  900                 len = length;
  901         if(len < 0)
  902                 len = 0;
  903         return len;
  904 }
  905 #endif
Cache object: 0cd319cb8d958991ea6afdf4b9306c24
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FreeBSD/Linux Kernel Cross Reference sys/ipc/msg.c

FreeBSD/Linux Kernel Cross Reference
sys/ipc/msg.c
