/* $OpenBSD: sysv_msg.c,v 1.6 1999/02/04 18:48:25 deraadt Exp $ */ /* $NetBSD: sysv_msg.c,v 1.19 1996/02/09 19:00:18 christos Exp $ */ /* * Implementation of SVID messages * * Author: Daniel Boulet * * Copyright 1993 Daniel Boulet and RTMX Inc. * * This system call was implemented by Daniel Boulet under contract from RTMX. * * Redistribution and use in source forms, with and without modification, * are permitted provided that this entire comment appears intact. * * Redistribution in binary form may occur without any restrictions. * Obviously, it would be nice if you gave credit where credit is due * but requiring it would be too onerous. * * This software is provided ``AS IS'' without any warranties of any kind. */ #include #include #include #include #include #include #include #include #define MSG_DEBUG #undef MSG_DEBUG_OK int nfree_msgmaps; /* # of free map entries */ short free_msgmaps; /* head of linked list of free map entries */ struct msg *free_msghdrs; /* list of free msg headers */ static void msg_freehdr __P((struct msg *)); void msginit() { register int i; /* * msginfo.msgssz should be a power of two for efficiency reasons. * It is also pretty silly if msginfo.msgssz is less than 8 * or greater than about 256 so ... */ i = 8; while (i < 1024 && i != msginfo.msgssz) i <<= 1; if (i != msginfo.msgssz) panic("msginfo.msgssz %d not a small power of 2", msginfo.msgssz); if (msginfo.msgseg > 32767) panic("msginfo.msgseg %d > 32767", msginfo.msgseg); if (msgmaps == NULL) panic("msgmaps is NULL"); for (i = 0; i < msginfo.msgseg; i++) { if (i > 0) msgmaps[i-1].next = i; msgmaps[i].next = -1; /* implies entry is available */ } free_msgmaps = 0; nfree_msgmaps = msginfo.msgseg; if (msghdrs == NULL) panic("msghdrs is NULL"); for (i = 0; i < msginfo.msgtql; i++) { msghdrs[i].msg_type = 0; if (i > 0) msghdrs[i-1].msg_next = &msghdrs[i]; msghdrs[i].msg_next = NULL; } free_msghdrs = &msghdrs[0]; if (msqids == NULL) panic("msqids is NULL"); for (i = 0; i < msginfo.msgmni; i++) { msqids[i].msg_qbytes = 0; /* implies entry is available */ msqids[i].msg_perm.seq = 0; /* reset to a known value */ } } static void msg_freehdr(msghdr) struct msg *msghdr; { while (msghdr->msg_ts > 0) { short next; #ifdef DIAGNOSTIC if (msghdr->msg_spot < 0 || msghdr->msg_spot >= msginfo.msgseg) panic("msghdr->msg_spot out of range"); #endif next = msgmaps[msghdr->msg_spot].next; msgmaps[msghdr->msg_spot].next = free_msgmaps; free_msgmaps = msghdr->msg_spot; nfree_msgmaps++; msghdr->msg_spot = next; if (msghdr->msg_ts >= msginfo.msgssz) msghdr->msg_ts -= msginfo.msgssz; else msghdr->msg_ts = 0; } #ifdef DIAGNOSTIC if (msghdr->msg_spot != -1) panic("msghdr->msg_spot != -1"); #endif msghdr->msg_next = free_msghdrs; free_msghdrs = msghdr; } void msqid_n2o(n, o) struct msqid_ds *n; struct omsqid_ds *o; { o->msg_first = n->msg_first; o->msg_last = n->msg_last; o->msg_cbytes = n->msg_cbytes; o->msg_qnum = n->msg_qnum; o->msg_qbytes = n->msg_qbytes; o->msg_lspid = n->msg_lspid; o->msg_lrpid = n->msg_lrpid; o->msg_stime = n->msg_stime; o->msg_pad1 = n->msg_pad1; o->msg_rtime = n->msg_rtime; o->msg_pad2 = n->msg_pad2; o->msg_ctime = n->msg_ctime; o->msg_pad3 = n->msg_pad3; bcopy(n->msg_pad4, o->msg_pad4, sizeof o->msg_pad4); ipc_n2o(&n->msg_perm, &o->msg_perm); } int sys_omsgctl(p, v, retval) struct proc *p; void *v; register_t *retval; { register struct sys_msgctl_args /* { syscallarg(int) msqid; syscallarg(int) cmd; syscallarg(struct msqid_ds *) buf; } */ *uap = v; int msqid = SCARG(uap, msqid); int cmd = SCARG(uap, cmd); struct msqid_ds *user_msqptr = SCARG(uap, buf); struct ucred *cred = p->p_ucred; int rval, eval; struct omsqid_ds omsqbuf; register struct msqid_ds *msqptr; #ifdef MSG_DEBUG_OK printf("call to msgctl(%d, %d, %p)\n", msqid, cmd, user_msqptr); #endif msqid = IPCID_TO_IX(msqid); if (msqid < 0 || msqid >= msginfo.msgmni) { #ifdef MSG_DEBUG_OK printf("msqid (%d) out of range (0<=msqid<%d)\n", msqid, msginfo.msgmni); #endif return(EINVAL); } msqptr = &msqids[msqid]; if (msqptr->msg_qbytes == 0) { #ifdef MSG_DEBUG_OK printf("no such msqid\n"); #endif return(EINVAL); } if (msqptr->msg_perm.seq != IPCID_TO_SEQ(SCARG(uap, msqid))) { #ifdef MSG_DEBUG_OK printf("wrong sequence number\n"); #endif return(EINVAL); } eval = 0; rval = 0; switch (cmd) { case IPC_RMID: { struct msg *msghdr; if ((eval = ipcperm(cred, &msqptr->msg_perm, IPC_M)) != 0) return(eval); /* Free the message headers */ msghdr = msqptr->msg_first; while (msghdr != NULL) { struct msg *msghdr_tmp; /* Free the segments of each message */ msqptr->msg_cbytes -= msghdr->msg_ts; msqptr->msg_qnum--; msghdr_tmp = msghdr; msghdr = msghdr->msg_next; msg_freehdr(msghdr_tmp); } #ifdef DIAGNOSTIC if (msqptr->msg_cbytes != 0) panic("msg_cbytes is screwed up"); if (msqptr->msg_qnum != 0) panic("msg_qnum is screwed up"); #endif msqptr->msg_qbytes = 0; /* Mark it as free */ wakeup((caddr_t)msqptr); } break; case IPC_SET: if ((eval = ipcperm(cred, &msqptr->msg_perm, IPC_M))) return(eval); if ((eval = copyin(user_msqptr, &omsqbuf, sizeof(omsqbuf))) != 0) return(eval); if (omsqbuf.msg_qbytes > msqptr->msg_qbytes && cred->cr_uid != 0) return(EPERM); if (omsqbuf.msg_qbytes > msginfo.msgmnb) { #ifdef MSG_DEBUG_OK printf("can't increase msg_qbytes beyond %d (truncating)\n", msginfo.msgmnb); #endif omsqbuf.msg_qbytes = msginfo.msgmnb; /* silently restrict qbytes to system limit */ } if (omsqbuf.msg_qbytes == 0) { #ifdef MSG_DEBUG_OK printf("can't reduce msg_qbytes to 0\n"); #endif return(EINVAL); /* non-standard errno! */ } msqptr->msg_perm.uid = omsqbuf.msg_perm.uid; /* change the owner */ msqptr->msg_perm.gid = omsqbuf.msg_perm.gid; /* change the owner */ msqptr->msg_perm.mode = (msqptr->msg_perm.mode & ~0777) | (omsqbuf.msg_perm.mode & 0777); msqptr->msg_qbytes = omsqbuf.msg_qbytes; msqptr->msg_ctime = time.tv_sec; break; case IPC_STAT: if ((eval = ipcperm(cred, &msqptr->msg_perm, IPC_R))) { #ifdef MSG_DEBUG_OK printf("requester doesn't have read access\n"); #endif return(eval); } msqid_n2o(msqptr, &omsqbuf); eval = copyout((caddr_t)&omsqbuf, user_msqptr, sizeof omsqbuf); break; default: #ifdef MSG_DEBUG_OK printf("invalid command %d\n", cmd); #endif return(EINVAL); } if (eval == 0) *retval = rval; return(eval); } int sys_msgctl(p, v, retval) struct proc *p; void *v; register_t *retval; { register struct sys_msgctl_args /* { syscallarg(int) msqid; syscallarg(int) cmd; syscallarg(struct msqid_ds *) buf; } */ *uap = v; int msqid = SCARG(uap, msqid); int cmd = SCARG(uap, cmd); struct msqid_ds *user_msqptr = SCARG(uap, buf); struct ucred *cred = p->p_ucred; int rval, eval; struct msqid_ds msqbuf; register struct msqid_ds *msqptr; #ifdef MSG_DEBUG_OK printf("call to msgctl(%d, %d, %p)\n", msqid, cmd, user_msqptr); #endif msqid = IPCID_TO_IX(msqid); if (msqid < 0 || msqid >= msginfo.msgmni) { #ifdef MSG_DEBUG_OK printf("msqid (%d) out of range (0<=msqid<%d)\n", msqid, msginfo.msgmni); #endif return(EINVAL); } msqptr = &msqids[msqid]; if (msqptr->msg_qbytes == 0) { #ifdef MSG_DEBUG_OK printf("no such msqid\n"); #endif return(EINVAL); } if (msqptr->msg_perm.seq != IPCID_TO_SEQ(SCARG(uap, msqid))) { #ifdef MSG_DEBUG_OK printf("wrong sequence number\n"); #endif return(EINVAL); } eval = 0; rval = 0; switch (cmd) { case IPC_RMID: { struct msg *msghdr; if ((eval = ipcperm(cred, &msqptr->msg_perm, IPC_M)) != 0) return(eval); /* Free the message headers */ msghdr = msqptr->msg_first; while (msghdr != NULL) { struct msg *msghdr_tmp; /* Free the segments of each message */ msqptr->msg_cbytes -= msghdr->msg_ts; msqptr->msg_qnum--; msghdr_tmp = msghdr; msghdr = msghdr->msg_next; msg_freehdr(msghdr_tmp); } #ifdef DIAGNOSTIC if (msqptr->msg_cbytes != 0) panic("msg_cbytes is screwed up"); if (msqptr->msg_qnum != 0) panic("msg_qnum is screwed up"); #endif msqptr->msg_qbytes = 0; /* Mark it as free */ wakeup((caddr_t)msqptr); } break; case IPC_SET: if ((eval = ipcperm(cred, &msqptr->msg_perm, IPC_M))) return(eval); if ((eval = copyin(user_msqptr, &msqbuf, sizeof(msqbuf))) != 0) return(eval); if (msqbuf.msg_qbytes > msqptr->msg_qbytes && cred->cr_uid != 0) return(EPERM); if (msqbuf.msg_qbytes > msginfo.msgmnb) { #ifdef MSG_DEBUG_OK printf("can't increase msg_qbytes beyond %d (truncating)\n", msginfo.msgmnb); #endif msqbuf.msg_qbytes = msginfo.msgmnb; /* silently restrict qbytes to system limit */ } if (msqbuf.msg_qbytes == 0) { #ifdef MSG_DEBUG_OK printf("can't reduce msg_qbytes to 0\n"); #endif return(EINVAL); /* non-standard errno! */ } msqptr->msg_perm.uid = msqbuf.msg_perm.uid; /* change the owner */ msqptr->msg_perm.gid = msqbuf.msg_perm.gid; /* change the owner */ msqptr->msg_perm.mode = (msqptr->msg_perm.mode & ~0777) | (msqbuf.msg_perm.mode & 0777); msqptr->msg_qbytes = msqbuf.msg_qbytes; msqptr->msg_ctime = time.tv_sec; break; case IPC_STAT: if ((eval = ipcperm(cred, &msqptr->msg_perm, IPC_R))) { #ifdef MSG_DEBUG_OK printf("requester doesn't have read access\n"); #endif return(eval); } eval = copyout((caddr_t)msqptr, user_msqptr, sizeof(struct msqid_ds)); break; default: #ifdef MSG_DEBUG_OK printf("invalid command %d\n", cmd); #endif return(EINVAL); } if (eval == 0) *retval = rval; return(eval); } int sys_msgget(p, v, retval) struct proc *p; void *v; register_t *retval; { register struct sys_msgget_args /* { syscallarg(key_t) key; syscallarg(int) msgflg; } */ *uap = v; int msqid, eval; int key = SCARG(uap, key); int msgflg = SCARG(uap, msgflg); struct ucred *cred = p->p_ucred; register struct msqid_ds *msqptr = NULL; #ifdef MSG_DEBUG_OK printf("msgget(0x%x, 0%o)\n", key, msgflg); #endif if (key != IPC_PRIVATE) { for (msqid = 0; msqid < msginfo.msgmni; msqid++) { msqptr = &msqids[msqid]; if (msqptr->msg_qbytes != 0 && msqptr->msg_perm.key == key) break; } if (msqid < msginfo.msgmni) { #ifdef MSG_DEBUG_OK printf("found public key\n"); #endif if ((msgflg & IPC_CREAT) && (msgflg & IPC_EXCL)) { #ifdef MSG_DEBUG_OK printf("not exclusive\n"); #endif return(EEXIST); } if ((eval = ipcperm(cred, &msqptr->msg_perm, msgflg & 0700 ))) { #ifdef MSG_DEBUG_OK printf("requester doesn't have 0%o access\n", msgflg & 0700); #endif return(eval); } goto found; } } #ifdef MSG_DEBUG_OK printf("need to allocate the msqid_ds\n"); #endif if (key == IPC_PRIVATE || (msgflg & IPC_CREAT)) { for (msqid = 0; msqid < msginfo.msgmni; msqid++) { /* * Look for an unallocated and unlocked msqid_ds. * msqid_ds's can be locked by msgsnd or msgrcv while * they are copying the message in/out. We can't * re-use the entry until they release it. */ msqptr = &msqids[msqid]; if (msqptr->msg_qbytes == 0 && (msqptr->msg_perm.mode & MSG_LOCKED) == 0) break; } if (msqid == msginfo.msgmni) { #ifdef MSG_DEBUG_OK printf("no more msqid_ds's available\n"); #endif return(ENOSPC); } #ifdef MSG_DEBUG_OK printf("msqid %d is available\n", msqid); #endif msqptr->msg_perm.key = key; msqptr->msg_perm.cuid = cred->cr_uid; msqptr->msg_perm.uid = cred->cr_uid; msqptr->msg_perm.cgid = cred->cr_gid; msqptr->msg_perm.gid = cred->cr_gid; msqptr->msg_perm.mode = (msgflg & 0777); /* Make sure that the returned msqid is unique */ msqptr->msg_perm.seq++; msqptr->msg_first = NULL; msqptr->msg_last = NULL; msqptr->msg_cbytes = 0; msqptr->msg_qnum = 0; msqptr->msg_qbytes = msginfo.msgmnb; msqptr->msg_lspid = 0; msqptr->msg_lrpid = 0; msqptr->msg_stime = 0; msqptr->msg_rtime = 0; msqptr->msg_ctime = time.tv_sec; } else { #ifdef MSG_DEBUG_OK printf("didn't find it and wasn't asked to create it\n"); #endif return(ENOENT); } found: /* Construct the unique msqid */ *retval = IXSEQ_TO_IPCID(msqid, msqptr->msg_perm); return(0); } int sys_msgsnd(p, v, retval) struct proc *p; void *v; register_t *retval; { register struct sys_msgsnd_args /* { syscallarg(int) msqid; syscallarg(const void *) msgp; syscallarg(size_t) msgsz; syscallarg(int) msgflg; } */ *uap = v; int msqid = SCARG(uap, msqid); const char *user_msgp = SCARG(uap, msgp); size_t msgsz = SCARG(uap, msgsz); int msgflg = SCARG(uap, msgflg); int segs_needed, eval; struct ucred *cred = p->p_ucred; register struct msqid_ds *msqptr; register struct msg *msghdr; short next; #ifdef MSG_DEBUG_OK printf("call to msgsnd(%d, %p, %d, %d)\n", msqid, user_msgp, msgsz, msgflg); #endif msqid = IPCID_TO_IX(msqid); if (msqid < 0 || msqid >= msginfo.msgmni) { #ifdef MSG_DEBUG_OK printf("msqid (%d) out of range (0<=msqid<%d)\n", msqid, msginfo.msgmni); #endif return(EINVAL); } msqptr = &msqids[msqid]; if (msqptr->msg_qbytes == 0) { #ifdef MSG_DEBUG_OK printf("no such message queue id\n"); #endif return(EINVAL); } if (msqptr->msg_perm.seq != IPCID_TO_SEQ(SCARG(uap, msqid))) { #ifdef MSG_DEBUG_OK printf("wrong sequence number\n"); #endif return(EINVAL); } if ((eval = ipcperm(cred, &msqptr->msg_perm, IPC_W))) { #ifdef MSG_DEBUG_OK printf("requester doesn't have write access\n"); #endif return(eval); } segs_needed = (msgsz + msginfo.msgssz - 1) / msginfo.msgssz; #ifdef MSG_DEBUG_OK printf("msgsz=%d, msgssz=%d, segs_needed=%d\n", msgsz, msginfo.msgssz, segs_needed); #endif for (;;) { int need_more_resources = 0; /* * check msgsz [cannot be negative since it is unsigned] * (inside this loop in case msg_qbytes changes while we sleep) */ if (msgsz > msqptr->msg_qbytes) { #ifdef MSG_DEBUG_OK printf("msgsz > msqptr->msg_qbytes\n"); #endif return(EINVAL); } if (msqptr->msg_perm.mode & MSG_LOCKED) { #ifdef MSG_DEBUG_OK printf("msqid is locked\n"); #endif need_more_resources = 1; } if (msgsz + msqptr->msg_cbytes > msqptr->msg_qbytes) { #ifdef MSG_DEBUG_OK printf("msgsz + msg_cbytes > msg_qbytes\n"); #endif need_more_resources = 1; } if (segs_needed > nfree_msgmaps) { #ifdef MSG_DEBUG_OK printf("segs_needed > nfree_msgmaps\n"); #endif need_more_resources = 1; } if (free_msghdrs == NULL) { #ifdef MSG_DEBUG_OK printf("no more msghdrs\n"); #endif need_more_resources = 1; } if (need_more_resources) { int we_own_it; if ((msgflg & IPC_NOWAIT) != 0) { #ifdef MSG_DEBUG_OK printf("need more resources but caller doesn't want to wait\n"); #endif return(EAGAIN); } if ((msqptr->msg_perm.mode & MSG_LOCKED) != 0) { #ifdef MSG_DEBUG_OK printf("we don't own the msqid_ds\n"); #endif we_own_it = 0; } else { /* Force later arrivals to wait for our request */ #ifdef MSG_DEBUG_OK printf("we own the msqid_ds\n"); #endif msqptr->msg_perm.mode |= MSG_LOCKED; we_own_it = 1; } #ifdef MSG_DEBUG_OK printf("goodnight\n"); #endif eval = tsleep((caddr_t)msqptr, (PZERO - 4) | PCATCH, "msgwait", 0); #ifdef MSG_DEBUG_OK printf("good morning, eval=%d\n", eval); #endif if (we_own_it) msqptr->msg_perm.mode &= ~MSG_LOCKED; if (eval != 0) { #ifdef MSG_DEBUG_OK printf("msgsnd: interrupted system call\n"); #endif return(EINTR); } /* * Make sure that the msq queue still exists */ if (msqptr->msg_qbytes == 0) { #ifdef MSG_DEBUG_OK printf("msqid deleted\n"); #endif /* The SVID says to return EIDRM. */ #ifdef EIDRM return(EIDRM); #else /* Unfortunately, BSD doesn't define that code yet! */ return(EINVAL); #endif } } else { #ifdef MSG_DEBUG_OK printf("got all the resources that we need\n"); #endif break; } } /* * We have the resources that we need. * Make sure! */ #ifdef DIAGNOSTIC if (msqptr->msg_perm.mode & MSG_LOCKED) panic("msg_perm.mode & MSG_LOCKED"); if (segs_needed > nfree_msgmaps) panic("segs_needed > nfree_msgmaps"); if (msgsz + msqptr->msg_cbytes > msqptr->msg_qbytes) panic("msgsz + msg_cbytes > msg_qbytes"); if (free_msghdrs == NULL) panic("no more msghdrs"); #endif /* * Re-lock the msqid_ds in case we page-fault when copying in the * message */ #ifdef DIAGNOSTIC if ((msqptr->msg_perm.mode & MSG_LOCKED) != 0) panic("msqid_ds is already locked"); #endif msqptr->msg_perm.mode |= MSG_LOCKED; /* * Allocate a message header */ msghdr = free_msghdrs; free_msghdrs = msghdr->msg_next; msghdr->msg_spot = -1; msghdr->msg_ts = msgsz; /* * Allocate space for the message */ while (segs_needed > 0) { #ifdef DIAGNOSTIC if (nfree_msgmaps <= 0) panic("not enough msgmaps"); if (free_msgmaps == -1) panic("nil free_msgmaps"); #endif next = free_msgmaps; #ifdef DIAGNOSTIC if (next <= -1) panic("next too low #1"); if (next >= msginfo.msgseg) panic("next out of range #1"); #endif #ifdef MSG_DEBUG_OK printf("allocating segment %d to message\n", next); #endif free_msgmaps = msgmaps[next].next; nfree_msgmaps--; msgmaps[next].next = msghdr->msg_spot; msghdr->msg_spot = next; segs_needed--; } /* * Copy in the message type */ if ((eval = copyin(user_msgp, &msghdr->msg_type, sizeof(msghdr->msg_type))) != 0) { #ifdef MSG_DEBUG_OK printf("error %d copying the message type\n", eval); #endif msg_freehdr(msghdr); msqptr->msg_perm.mode &= ~MSG_LOCKED; wakeup((caddr_t)msqptr); return(eval); } user_msgp += sizeof(msghdr->msg_type); /* * Validate the message type */ if (msghdr->msg_type < 1) { msg_freehdr(msghdr); msqptr->msg_perm.mode &= ~MSG_LOCKED; wakeup((caddr_t)msqptr); #ifdef MSG_DEBUG_OK printf("mtype (%d) < 1\n", msghdr->msg_type); #endif return(EINVAL); } /* * Copy in the message body */ next = msghdr->msg_spot; while (msgsz > 0) { size_t tlen; if (msgsz > msginfo.msgssz) tlen = msginfo.msgssz; else tlen = msgsz; #ifdef DIAGNOSTIC if (next <= -1) panic("next too low #2"); if (next >= msginfo.msgseg) panic("next out of range #2"); #endif if ((eval = copyin(user_msgp, &msgpool[next * msginfo.msgssz], tlen)) != 0) { #ifdef MSG_DEBUG_OK printf("error %d copying in message segment\n", eval); #endif msg_freehdr(msghdr); msqptr->msg_perm.mode &= ~MSG_LOCKED; wakeup((caddr_t)msqptr); return(eval); } msgsz -= tlen; user_msgp += tlen; next = msgmaps[next].next; } #ifdef DIAGNOSTIC if (next != -1) panic("didn't use all the msg segments"); #endif /* * We've got the message. Unlock the msqid_ds. */ msqptr->msg_perm.mode &= ~MSG_LOCKED; /* * Make sure that the msqid_ds is still allocated. */ if (msqptr->msg_qbytes == 0) { msg_freehdr(msghdr); wakeup((caddr_t)msqptr); /* The SVID says to return EIDRM. */ #ifdef EIDRM return(EIDRM); #else /* Unfortunately, BSD doesn't define that code yet! */ return(EINVAL); #endif } /* * Put the message into the queue */ if (msqptr->msg_first == NULL) { msqptr->msg_first = msghdr; msqptr->msg_last = msghdr; } else { msqptr->msg_last->msg_next = msghdr; msqptr->msg_last = msghdr; } msqptr->msg_last->msg_next = NULL; msqptr->msg_cbytes += msghdr->msg_ts; msqptr->msg_qnum++; msqptr->msg_lspid = p->p_pid; msqptr->msg_stime = time.tv_sec; wakeup((caddr_t)msqptr); *retval = 0; return(0); } int sys_msgrcv(p, v, retval) struct proc *p; void *v; register_t *retval; { register struct sys_msgrcv_args /* { syscallarg(int) msqid; syscallarg(void *) msgp; syscallarg(size_t) msgsz; syscallarg(long) msgtyp; syscallarg(int) msgflg; } */ *uap = v; int msqid = SCARG(uap, msqid); char *user_msgp = SCARG(uap, msgp); size_t msgsz = SCARG(uap, msgsz); long msgtyp = SCARG(uap, msgtyp); int msgflg = SCARG(uap, msgflg); size_t len; struct ucred *cred = p->p_ucred; register struct msqid_ds *msqptr; register struct msg *msghdr; int eval; short next; #ifdef MSG_DEBUG_OK printf("call to msgrcv(%d, %p, %d, %ld, %d)\n", msqid, user_msgp, msgsz, msgtyp, msgflg); #endif msqid = IPCID_TO_IX(msqid); if (msqid < 0 || msqid >= msginfo.msgmni) { #ifdef MSG_DEBUG_OK printf("msqid (%d) out of range (0<=msqid<%d)\n", msqid, msginfo.msgmni); #endif return(EINVAL); } msqptr = &msqids[msqid]; if (msqptr->msg_qbytes == 0) { #ifdef MSG_DEBUG_OK printf("no such message queue id\n"); #endif return(EINVAL); } if (msqptr->msg_perm.seq != IPCID_TO_SEQ(SCARG(uap, msqid))) { #ifdef MSG_DEBUG_OK printf("wrong sequence number\n"); #endif return(EINVAL); } if ((eval = ipcperm(cred, &msqptr->msg_perm, IPC_R))) { #ifdef MSG_DEBUG_OK printf("requester doesn't have read access\n"); #endif return(eval); } #if 0 /* cannot happen, msgsz is unsigned */ if (msgsz < 0) { #ifdef MSG_DEBUG_OK printf("msgsz < 0\n"); #endif return(EINVAL); } #endif msghdr = NULL; while (msghdr == NULL) { if (msgtyp == 0) { msghdr = msqptr->msg_first; if (msghdr != NULL) { if (msgsz < msghdr->msg_ts && (msgflg & MSG_NOERROR) == 0) { #ifdef MSG_DEBUG_OK printf("first message on the queue is too big (want %d, got %d)\n", msgsz, msghdr->msg_ts); #endif return(E2BIG); } if (msqptr->msg_first == msqptr->msg_last) { msqptr->msg_first = NULL; msqptr->msg_last = NULL; } else { msqptr->msg_first = msghdr->msg_next; #ifdef DIAGNOSTIC if (msqptr->msg_first == NULL) panic("msg_first/last screwed up #1"); #endif } } } else { struct msg *previous; struct msg **prev; for (previous = NULL, prev = &msqptr->msg_first; (msghdr = *prev) != NULL; previous = msghdr, prev = &msghdr->msg_next) { /* * Is this message's type an exact match or is * this message's type less than or equal to * the absolute value of a negative msgtyp? * Note that the second half of this test can * NEVER be true if msgtyp is positive since * msg_type is always positive! */ if (msgtyp == msghdr->msg_type || msghdr->msg_type <= -msgtyp) { #ifdef MSG_DEBUG_OK printf("found message type %d, requested %d\n", msghdr->msg_type, msgtyp); #endif if (msgsz < msghdr->msg_ts && (msgflg & MSG_NOERROR) == 0) { #ifdef MSG_DEBUG_OK printf("requested message on the queue is too big (want %d, got %d)\n", msgsz, msghdr->msg_ts); #endif return(E2BIG); } *prev = msghdr->msg_next; if (msghdr == msqptr->msg_last) { if (previous == NULL) { #ifdef DIAGNOSTIC if (prev != &msqptr->msg_first) panic("msg_first/last screwed up #2"); #endif msqptr->msg_first = NULL; msqptr->msg_last = NULL; } else { #ifdef DIAGNOSTIC if (prev == &msqptr->msg_first) panic("msg_first/last screwed up #3"); #endif msqptr->msg_last = previous; } } break; } } } /* * We've either extracted the msghdr for the appropriate * message or there isn't one. * If there is one then bail out of this loop. */ if (msghdr != NULL) break; /* * Hmph! No message found. Does the user want to wait? */ if ((msgflg & IPC_NOWAIT) != 0) { #ifdef MSG_DEBUG_OK printf("no appropriate message found (msgtyp=%d)\n", msgtyp); #endif /* The SVID says to return ENOMSG. */ #ifdef ENOMSG return(ENOMSG); #else /* Unfortunately, BSD doesn't define that code yet! */ return(EAGAIN); #endif } /* * Wait for something to happen */ #ifdef MSG_DEBUG_OK printf("msgrcv: goodnight\n"); #endif eval = tsleep((caddr_t)msqptr, (PZERO - 4) | PCATCH, "msgwait", 0); #ifdef MSG_DEBUG_OK printf("msgrcv: good morning (eval=%d)\n", eval); #endif if (eval != 0) { #ifdef MSG_DEBUG_OK printf("msgsnd: interrupted system call\n"); #endif return(EINTR); } /* * Make sure that the msq queue still exists */ if (msqptr->msg_qbytes == 0 || msqptr->msg_perm.seq != IPCID_TO_SEQ(SCARG(uap, msqid))) { #ifdef MSG_DEBUG_OK printf("msqid deleted\n"); #endif /* The SVID says to return EIDRM. */ #ifdef EIDRM return(EIDRM); #else /* Unfortunately, BSD doesn't define that code yet! */ return(EINVAL); #endif } } /* * Return the message to the user. * * First, do the bookkeeping (before we risk being interrupted). */ msqptr->msg_cbytes -= msghdr->msg_ts; msqptr->msg_qnum--; msqptr->msg_lrpid = p->p_pid; msqptr->msg_rtime = time.tv_sec; /* * Make msgsz the actual amount that we'll be returning. * Note that this effectively truncates the message if it is too long * (since msgsz is never increased). */ #ifdef MSG_DEBUG_OK printf("found a message, msgsz=%d, msg_ts=%d\n", msgsz, msghdr->msg_ts); #endif if (msgsz > msghdr->msg_ts) msgsz = msghdr->msg_ts; /* * Return the type to the user. */ eval = copyout((caddr_t)&msghdr->msg_type, user_msgp, sizeof(msghdr->msg_type)); if (eval != 0) { #ifdef MSG_DEBUG_OK printf("error (%d) copying out message type\n", eval); #endif msg_freehdr(msghdr); wakeup((caddr_t)msqptr); return(eval); } user_msgp += sizeof(msghdr->msg_type); /* * Return the segments to the user */ next = msghdr->msg_spot; for (len = 0; len < msgsz; len += msginfo.msgssz) { size_t tlen; if (msgsz > msginfo.msgssz) tlen = msginfo.msgssz; else tlen = msgsz; #ifdef DIAGNOSTIC if (next <= -1) panic("next too low #3"); if (next >= msginfo.msgseg) panic("next out of range #3"); #endif eval = copyout((caddr_t)&msgpool[next * msginfo.msgssz], user_msgp, tlen); if (eval != 0) { #ifdef MSG_DEBUG_OK printf("error (%d) copying out message segment\n", eval); #endif msg_freehdr(msghdr); wakeup((caddr_t)msqptr); return(eval); } user_msgp += tlen; next = msgmaps[next].next; } /* * Done, return the actual number of bytes copied out. */ msg_freehdr(msghdr); wakeup((caddr_t)msqptr); *retval = msgsz; return(0); }