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NetBSD/sys/kern/sysv_msg.c

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/* $NetBSD: sysv_msg.c,v 1.32 2000/07/22 16:11:02 simonb 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.
*/
#define SYSVMSG
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/msg.h>
#include <sys/sysctl.h>
#include <sys/mount.h> /* XXX for <sys/syscallargs.h> */
#include <sys/syscallargs.h>
#define MSG_DEBUG
#undef MSG_DEBUG_OK
#ifdef MSG_DEBUG_OK
#define MSG_PRINTF(a) printf a
#else
#define MSG_PRINTF(a)
#endif
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 */
char *msgpool; /* MSGMAX byte long msg buffer pool */
struct msgmap *msgmaps; /* MSGSEG msgmap structures */
struct __msg *msghdrs; /* MSGTQL msg headers */
struct msqid_ds *msqids; /* MSGMNI msqid_ds struct's */
static void msg_freehdr __P((struct __msg *));
void
msginit()
{
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) {
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");
}
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;
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(p, v, retval)
struct proc *p;
void *v;
register_t *retval;
{
struct sys___msgctl13_args /* {
syscallarg(int) msqid;
syscallarg(int) cmd;
syscallarg(struct msqid_ds *) buf;
} */ *uap = v;
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(p, v, retval)
struct proc *p;
void *v;
register_t *retval;
{
struct sys_msgget_args /* {
syscallarg(key_t) key;
syscallarg(int) msgflg;
} */ *uap = v;
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(p, v, retval)
struct proc *p;
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;
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, %d, %d)\n", msqid, user_msgp, 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=%d, msgssz=%d, segs_needed=%d\n", 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 (%d) < 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(p, v, retval)
struct proc *p;
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;
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, %d, %ld, %d)\n", msqid, user_msgp,
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 %d, got %d)\n",
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 %d, "
"requested %d\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 %d, got %d)\n",
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=%d)\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=%d, msg_ts=%d\n", 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);
}
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