Aren/NetBSD
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
afc065b0f9
NetBSD/sys/kern/sysv_msg.c
jdolecek 2e59e9ae06 allocate virtual memory for SYSV shm, msg and semaphore structures 
separately from the bufpages, so that it would be possible to eventually
make their limits changeable in runtime

make static all local variables which do not need to be exported to other
kernel parts
2003-10-26 10:32:24 +00:00

939 lines
24 KiB
C
Raw Blame History

/* $NetBSD: sysv_msg.c,v 1.36 2003/10/26 10:32:24 jdolecek 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 <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: sysv_msg.c,v 1.36 2003/10/26 10:32:24 jdolecek Exp $");
#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/sa.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
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 __P((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);
if ((v = uvm_km_zalloc(kernel_map, round_page(sz))) == 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);
}
Reference in New Issue View Git Blame Copy Permalink