/* $NetBSD: sysv_msg.c,v 1.39 2005/04/01 11:59:37 yamt Exp $ */ /*- * Copyright (c) 1999 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, * NASA Ames Research Center. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the NetBSD * Foundation, Inc. and its contributors. * 4. Neither the name of The NetBSD Foundation nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* * 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 __KERNEL_RCSID(0, "$NetBSD: sysv_msg.c,v 1.39 2005/04/01 11:59:37 yamt Exp $"); #define SYSVMSG #include #include #include #include #include /* XXX for */ #include #include #define MSG_DEBUG #undef MSG_DEBUG_OK #ifdef MSG_DEBUG_OK #define MSG_PRINTF(a) printf a #else #define MSG_PRINTF(a) #endif static int nfree_msgmaps; /* # of free map entries */ static short free_msgmaps; /* head of linked list of free map entries */ static struct __msg *free_msghdrs; /* list of free msg headers */ static char *msgpool; /* MSGMAX byte long msg buffer pool */ static struct msgmap *msgmaps; /* MSGSEG msgmap structures */ static struct __msg *msghdrs; /* MSGTQL msg headers */ struct msqid_ds *msqids; /* MSGMNI msqid_ds struct's */ static void msg_freehdr(struct __msg *); void msginit() { int i, sz; vaddr_t v; /* * 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) { MSG_PRINTF(("msginfo.msgssz=%d (0x%x)\n", msginfo.msgssz, msginfo.msgssz)); panic("msginfo.msgssz not a small power of 2"); } if (msginfo.msgseg > 32767) { MSG_PRINTF(("msginfo.msgseg=%d\n", msginfo.msgseg)); panic("msginfo.msgseg > 32767"); } /* Allocate pageable memory for our structures */ sz = msginfo.msgmax + msginfo.msgseg * sizeof(struct msgmap) + msginfo.msgtql * sizeof(struct __msg) + msginfo.msgmni * sizeof(struct msqid_ds); v = uvm_km_alloc(kernel_map, round_page(sz), 0, UVM_KMF_WIRED|UVM_KMF_ZERO); if (v == 0) panic("sysv_msg: cannot allocate memory"); msgpool = (void *)v; msgmaps = (void *) (msgpool + msginfo.msgmax); msghdrs = (void *) (msgmaps + msginfo.msgseg); msqids = (void *) (msghdrs + msginfo.msgtql); 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; if (msghdr->msg_spot < 0 || msghdr->msg_spot >= msginfo.msgseg) panic("msghdr->msg_spot out of range"); 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; } if (msghdr->msg_spot != -1) panic("msghdr->msg_spot != -1"); msghdr->msg_next = free_msghdrs; free_msghdrs = msghdr; } int sys___msgctl13(l, v, retval) struct lwp *l; void *v; register_t *retval; { struct sys___msgctl13_args /* { syscallarg(int) msqid; syscallarg(int) cmd; syscallarg(struct msqid_ds *) buf; } */ *uap = v; struct proc *p = l->l_proc; struct msqid_ds msqbuf; int cmd, error; cmd = SCARG(uap, cmd); if (cmd == IPC_SET) { error = copyin(SCARG(uap, buf), &msqbuf, sizeof(msqbuf)); if (error) return (error); } error = msgctl1(p, SCARG(uap, msqid), cmd, (cmd == IPC_SET || cmd == IPC_STAT) ? &msqbuf : NULL); if (error == 0 && cmd == IPC_STAT) error = copyout(&msqbuf, SCARG(uap, buf), sizeof(msqbuf)); return (error); } int msgctl1(p, msqid, cmd, msqbuf) struct proc *p; int msqid; int cmd; struct msqid_ds *msqbuf; { struct ucred *cred = p->p_ucred; struct msqid_ds *msqptr; int error = 0, ix; MSG_PRINTF(("call to msgctl1(%d, %d)\n", msqid, cmd)); ix = IPCID_TO_IX(msqid); if (ix < 0 || ix >= msginfo.msgmni) { MSG_PRINTF(("msqid (%d) out of range (0<=msqid<%d)\n", ix, msginfo.msgmni)); return (EINVAL); } msqptr = &msqids[ix]; if (msqptr->msg_qbytes == 0) { MSG_PRINTF(("no such msqid\n")); return (EINVAL); } if (msqptr->msg_perm._seq != IPCID_TO_SEQ(msqid)) { MSG_PRINTF(("wrong sequence number\n")); return (EINVAL); } switch (cmd) { case IPC_RMID: { struct __msg *msghdr; if ((error = ipcperm(cred, &msqptr->msg_perm, IPC_M)) != 0) return (error); /* 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); } if (msqptr->_msg_cbytes != 0) panic("msg_cbytes is screwed up"); if (msqptr->msg_qnum != 0) panic("msg_qnum is screwed up"); msqptr->msg_qbytes = 0; /* Mark it as free */ wakeup(msqptr); } break; case IPC_SET: if ((error = ipcperm(cred, &msqptr->msg_perm, IPC_M))) return (error); if (msqbuf->msg_qbytes > msqptr->msg_qbytes && cred->cr_uid != 0) return (EPERM); if (msqbuf->msg_qbytes > msginfo.msgmnb) { MSG_PRINTF(("can't increase msg_qbytes beyond %d " "(truncating)\n", msginfo.msgmnb)); /* silently restrict qbytes to system limit */ msqbuf->msg_qbytes = msginfo.msgmnb; } if (msqbuf->msg_qbytes == 0) { MSG_PRINTF(("can't reduce msg_qbytes to 0\n")); return (EINVAL); /* XXX non-standard errno! */ } msqptr->msg_perm.uid = msqbuf->msg_perm.uid; msqptr->msg_perm.gid = msqbuf->msg_perm.gid; 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 ((error = ipcperm(cred, &msqptr->msg_perm, IPC_R))) { MSG_PRINTF(("requester doesn't have read access\n")); return (error); } memcpy(msqbuf, msqptr, sizeof(struct msqid_ds)); break; default: MSG_PRINTF(("invalid command %d\n", cmd)); return (EINVAL); } return (error); } int sys_msgget(l, v, retval) struct lwp *l; void *v; register_t *retval; { struct sys_msgget_args /* { syscallarg(key_t) key; syscallarg(int) msgflg; } */ *uap = v; struct proc *p = l->l_proc; int msqid, error; int key = SCARG(uap, key); int msgflg = SCARG(uap, msgflg); struct ucred *cred = p->p_ucred; struct msqid_ds *msqptr = NULL; MSG_PRINTF(("msgget(0x%x, 0%o)\n", key, msgflg)); 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) { MSG_PRINTF(("found public key\n")); if ((msgflg & IPC_CREAT) && (msgflg & IPC_EXCL)) { MSG_PRINTF(("not exclusive\n")); return(EEXIST); } if ((error = ipcperm(cred, &msqptr->msg_perm, msgflg & 0700 ))) { MSG_PRINTF(("requester doesn't have 0%o access\n", msgflg & 0700)); return (error); } goto found; } } MSG_PRINTF(("need to allocate the msqid_ds\n")); 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) { MSG_PRINTF(("no more msqid_ds's available\n")); return (ENOSPC); } MSG_PRINTF(("msqid %d is available\n", msqid)); 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 { MSG_PRINTF(("didn't find it and wasn't asked to create it\n")); return (ENOENT); } found: /* Construct the unique msqid */ *retval = IXSEQ_TO_IPCID(msqid, msqptr->msg_perm); return (0); } int sys_msgsnd(l, v, retval) struct lwp *l; void *v; register_t *retval; { struct sys_msgsnd_args /* { syscallarg(int) msqid; syscallarg(const void *) msgp; syscallarg(size_t) msgsz; syscallarg(int) msgflg; } */ *uap = v; struct proc *p = l->l_proc; 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, error; struct ucred *cred = p->p_ucred; struct msqid_ds *msqptr; struct __msg *msghdr; short next; MSG_PRINTF(("call to msgsnd(%d, %p, %lld, %d)\n", msqid, user_msgp, (long long)msgsz, msgflg)); msqid = IPCID_TO_IX(msqid); if (msqid < 0 || msqid >= msginfo.msgmni) { MSG_PRINTF(("msqid (%d) out of range (0<=msqid<%d)\n", msqid, msginfo.msgmni)); return (EINVAL); } msqptr = &msqids[msqid]; if (msqptr->msg_qbytes == 0) { MSG_PRINTF(("no such message queue id\n")); return (EINVAL); } if (msqptr->msg_perm._seq != IPCID_TO_SEQ(SCARG(uap, msqid))) { MSG_PRINTF(("wrong sequence number\n")); return (EINVAL); } if ((error = ipcperm(cred, &msqptr->msg_perm, IPC_W))) { MSG_PRINTF(("requester doesn't have write access\n")); return (error); } segs_needed = (msgsz + msginfo.msgssz - 1) / msginfo.msgssz; MSG_PRINTF(("msgsz=%lld, msgssz=%d, segs_needed=%d\n", (long long)msgsz, msginfo.msgssz, segs_needed)); 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) { MSG_PRINTF(("msgsz > msqptr->msg_qbytes\n")); return (EINVAL); } if (msqptr->msg_perm.mode & MSG_LOCKED) { MSG_PRINTF(("msqid is locked\n")); need_more_resources = 1; } if (msgsz + msqptr->_msg_cbytes > msqptr->msg_qbytes) { MSG_PRINTF(("msgsz + msg_cbytes > msg_qbytes\n")); need_more_resources = 1; } if (segs_needed > nfree_msgmaps) { MSG_PRINTF(("segs_needed > nfree_msgmaps\n")); need_more_resources = 1; } if (free_msghdrs == NULL) { MSG_PRINTF(("no more msghdrs\n")); need_more_resources = 1; } if (need_more_resources) { int we_own_it; if ((msgflg & IPC_NOWAIT) != 0) { MSG_PRINTF(("need more resources but caller " "doesn't want to wait\n")); return (EAGAIN); } if ((msqptr->msg_perm.mode & MSG_LOCKED) != 0) { MSG_PRINTF(("we don't own the msqid_ds\n")); we_own_it = 0; } else { /* Force later arrivals to wait for our request */ MSG_PRINTF(("we own the msqid_ds\n")); msqptr->msg_perm.mode |= MSG_LOCKED; we_own_it = 1; } MSG_PRINTF(("goodnight\n")); error = tsleep(msqptr, (PZERO - 4) | PCATCH, "msgwait", 0); MSG_PRINTF(("good morning, error=%d\n", error)); if (we_own_it) msqptr->msg_perm.mode &= ~MSG_LOCKED; if (error != 0) { MSG_PRINTF(("msgsnd: interrupted system " "call\n")); return (EINTR); } /* * Make sure that the msq queue still exists */ if (msqptr->msg_qbytes == 0) { MSG_PRINTF(("msqid deleted\n")); return (EIDRM); } } else { MSG_PRINTF(("got all the resources that we need\n")); break; } } /* * We have the resources that we need. * Make sure! */ 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"); /* * Re-lock the msqid_ds in case we page-fault when copying in the * message */ if ((msqptr->msg_perm.mode & MSG_LOCKED) != 0) panic("msqid_ds is already locked"); 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) { if (nfree_msgmaps <= 0) panic("not enough msgmaps"); if (free_msgmaps == -1) panic("nil free_msgmaps"); next = free_msgmaps; if (next <= -1) panic("next too low #1"); if (next >= msginfo.msgseg) panic("next out of range #1"); MSG_PRINTF(("allocating segment %d to message\n", next)); 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 ((error = copyin(user_msgp, &msghdr->msg_type, sizeof(msghdr->msg_type))) != 0) { MSG_PRINTF(("error %d copying the message type\n", error)); msg_freehdr(msghdr); msqptr->msg_perm.mode &= ~MSG_LOCKED; wakeup(msqptr); return (error); } 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(msqptr); MSG_PRINTF(("mtype (%ld) < 1\n", msghdr->msg_type)); 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; if (next <= -1) panic("next too low #2"); if (next >= msginfo.msgseg) panic("next out of range #2"); if ((error = copyin(user_msgp, &msgpool[next * msginfo.msgssz], tlen)) != 0) { MSG_PRINTF(("error %d copying in message segment\n", error)); msg_freehdr(msghdr); msqptr->msg_perm.mode &= ~MSG_LOCKED; wakeup(msqptr); return (error); } msgsz -= tlen; user_msgp += tlen; next = msgmaps[next].next; } if (next != -1) panic("didn't use all the msg segments"); /* * 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(msqptr); return (EIDRM); } /* * 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(msqptr); return (0); } int sys_msgrcv(l, v, retval) struct lwp *l; void *v; register_t *retval; { struct sys_msgrcv_args /* { syscallarg(int) msqid; syscallarg(void *) msgp; syscallarg(size_t) msgsz; syscallarg(long) msgtyp; syscallarg(int) msgflg; } */ *uap = v; struct proc *p = l->l_proc; 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; struct msqid_ds *msqptr; struct __msg *msghdr; int error; short next; MSG_PRINTF(("call to msgrcv(%d, %p, %lld, %ld, %d)\n", msqid, user_msgp, (long long)msgsz, msgtyp, msgflg)); msqid = IPCID_TO_IX(msqid); if (msqid < 0 || msqid >= msginfo.msgmni) { MSG_PRINTF(("msqid (%d) out of range (0<=msqid<%d)\n", msqid, msginfo.msgmni)); return (EINVAL); } msqptr = &msqids[msqid]; if (msqptr->msg_qbytes == 0) { MSG_PRINTF(("no such message queue id\n")); return (EINVAL); } if (msqptr->msg_perm._seq != IPCID_TO_SEQ(SCARG(uap, msqid))) { MSG_PRINTF(("wrong sequence number\n")); return (EINVAL); } if ((error = ipcperm(cred, &msqptr->msg_perm, IPC_R))) { MSG_PRINTF(("requester doesn't have read access\n")); return (error); } #if 0 /* cannot happen, msgsz is unsigned */ if (msgsz < 0) { MSG_PRINTF(("msgsz < 0\n")); 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) { MSG_PRINTF(("first message on the " "queue is too big " "(want %lld, got %d)\n", (long long)msgsz, msghdr->msg_ts)); return (E2BIG); } if (msqptr->_msg_first == msqptr->_msg_last) { msqptr->_msg_first = NULL; msqptr->_msg_last = NULL; } else { msqptr->_msg_first = msghdr->msg_next; if (msqptr->_msg_first == NULL) panic("msg_first/last screwed " "up #1"); } } } 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) { MSG_PRINTF(("found message type %ld, " "requested %ld\n", msghdr->msg_type, msgtyp)); if (msgsz < msghdr->msg_ts && (msgflg & MSG_NOERROR) == 0) { MSG_PRINTF(("requested message " "on the queue is too big " "(want %lld, got %d)\n", (long long)msgsz, msghdr->msg_ts)); return (E2BIG); } *prev = msghdr->msg_next; if (msghdr == msqptr->_msg_last) { if (previous == NULL) { if (prev != &msqptr->_msg_first) panic("msg_first/last screwed up #2"); msqptr->_msg_first = NULL; msqptr->_msg_last = NULL; } else { if (prev == &msqptr->_msg_first) panic("msg_first/last screwed up #3"); 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) { MSG_PRINTF(("no appropriate message found (msgtyp=%ld)\n", msgtyp)); /* 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 */ MSG_PRINTF(("msgrcv: goodnight\n")); error = tsleep(msqptr, (PZERO - 4) | PCATCH, "msgwait", 0); MSG_PRINTF(("msgrcv: good morning (error=%d)\n", error)); if (error != 0) { MSG_PRINTF(("msgsnd: interrupted system call\n")); 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))) { MSG_PRINTF(("msqid deleted\n")); return (EIDRM); } } /* * 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). */ MSG_PRINTF(("found a message, msgsz=%lld, msg_ts=%d\n", (long long)msgsz, msghdr->msg_ts)); if (msgsz > msghdr->msg_ts) msgsz = msghdr->msg_ts; /* * Return the type to the user. */ error = copyout(&msghdr->msg_type, user_msgp, sizeof(msghdr->msg_type)); if (error != 0) { MSG_PRINTF(("error (%d) copying out message type\n", error)); msg_freehdr(msghdr); wakeup(msqptr); return (error); } 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 - len > msginfo.msgssz) tlen = msginfo.msgssz; else tlen = msgsz - len; if (next <= -1) panic("next too low #3"); if (next >= msginfo.msgseg) panic("next out of range #3"); error = copyout(&msgpool[next * msginfo.msgssz], user_msgp, tlen); if (error != 0) { MSG_PRINTF(("error (%d) copying out message segment\n", error)); msg_freehdr(msghdr); wakeup(msqptr); return (error); } user_msgp += tlen; next = msgmaps[next].next; } /* * Done, return the actual number of bytes copied out. */ msg_freehdr(msghdr); wakeup(msqptr); *retval = msgsz; return (0); }