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freebsd-skq/sys/kern/sysv_msg.c
maxim 523771c06a o Clear a high bit of ipc_perm.seq so msgget(3) never returns a 
negative message queue id.

PR:		kern/46122
Submitted by:	Vladimir B.Grebenschikov <vova@sw.ru>
MFC after:	2 weeks
2002-12-15 09:41:46 +00:00

1150 lines
27 KiB
C
Raw Blame History

/* $FreeBSD$ */
/*
* 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 "opt_sysvipc.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/msg.h>
#include <sys/syscall.h>
#include <sys/sysent.h>
#include <sys/sysctl.h>
#include <sys/malloc.h>
#include <sys/jail.h>
static MALLOC_DEFINE(M_MSG, "msg", "SVID compatible message queues");
static void msginit(void);
static int msgunload(void);
static int sysvmsg_modload(struct module *, int, void *);
#ifdef MSG_DEBUG
#define DPRINTF(a) printf a
#else
#define DPRINTF(a)
#endif
static void msg_freehdr(struct msg *msghdr);
/* XXX casting to (sy_call_t *) is bogus, as usual. */
static sy_call_t *msgcalls[] = {
(sy_call_t *)msgctl, (sy_call_t *)msgget,
(sy_call_t *)msgsnd, (sy_call_t *)msgrcv
};
struct msg {
struct msg *msg_next; /* next msg in the chain */
long msg_type; /* type of this message */
/* >0 -> type of this message */
/* 0 -> free header */
u_short msg_ts; /* size of this message */
short msg_spot; /* location of start of msg in buffer */
};
#ifndef MSGSSZ
#define MSGSSZ 8 /* Each segment must be 2^N long */
#endif
#ifndef MSGSEG
#define MSGSEG 2048 /* must be less than 32767 */
#endif
#define MSGMAX (MSGSSZ*MSGSEG)
#ifndef MSGMNB
#define MSGMNB 2048 /* max # of bytes in a queue */
#endif
#ifndef MSGMNI
#define MSGMNI 40
#endif
#ifndef MSGTQL
#define MSGTQL 40
#endif
/*
* Based on the configuration parameters described in an SVR2 (yes, two)
* config(1m) man page.
*
* Each message is broken up and stored in segments that are msgssz bytes
* long. For efficiency reasons, this should be a power of two. Also,
* it doesn't make sense if it is less than 8 or greater than about 256.
* Consequently, msginit in kern/sysv_msg.c checks that msgssz is a power of
* two between 8 and 1024 inclusive (and panic's if it isn't).
*/
struct msginfo msginfo = {
MSGMAX, /* max chars in a message */
MSGMNI, /* # of message queue identifiers */
MSGMNB, /* max chars in a queue */
MSGTQL, /* max messages in system */
MSGSSZ, /* size of a message segment */
/* (must be small power of 2 greater than 4) */
MSGSEG /* number of message segments */
};
/*
* macros to convert between msqid_ds's and msqid's.
* (specific to this implementation)
*/
#define MSQID(ix,ds) ((ix) & 0xffff | (((ds).msg_perm.seq << 16) & 0xffff0000))
#define MSQID_IX(id) ((id) & 0xffff)
#define MSQID_SEQ(id) (((id) >> 16) & 0xffff)
/*
* The rest of this file is specific to this particular implementation.
*/
struct msgmap {
short next; /* next segment in buffer */
/* -1 -> available */
/* 0..(MSGSEG-1) -> index of next segment */
};
#define MSG_LOCKED 01000 /* Is this msqid_ds locked? */
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 */
static struct msqid_ds *msqids; /* MSGMNI msqid_ds struct's */
static struct mtx msq_mtx; /* global mutex for message queues. */
static void
msginit()
{
register int i;
TUNABLE_INT_FETCH("kern.ipc.msgseg", &msginfo.msgseg);
TUNABLE_INT_FETCH("kern.ipc.msgssz", &msginfo.msgssz);
msginfo.msgmax = msginfo.msgseg * msginfo.msgssz;
TUNABLE_INT_FETCH("kern.ipc.msgmni", &msginfo.msgmni);
msgpool = malloc(msginfo.msgmax, M_MSG, M_WAITOK);
if (msgpool == NULL)
panic("msgpool is NULL");
msgmaps = malloc(sizeof(struct msgmap) * msginfo.msgseg, M_MSG, M_WAITOK);
if (msgmaps == NULL)
panic("msgmaps is NULL");
msghdrs = malloc(sizeof(struct msg) * msginfo.msgtql, M_MSG, M_WAITOK);
if (msghdrs == NULL)
panic("msghdrs is NULL");
msqids = malloc(sizeof(struct msqid_ds) * msginfo.msgmni, M_MSG, M_WAITOK);
if (msqids == NULL)
panic("msqids is NULL");
/*
* 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) {
DPRINTF(("msginfo.msgssz=%d (0x%x)\n", msginfo.msgssz,
msginfo.msgssz));
panic("msginfo.msgssz not a small power of 2");
}
if (msginfo.msgseg > 32767) {
DPRINTF(("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 */
msqids[i].msg_perm.mode = 0;
}
mtx_init(&msq_mtx, "msq", NULL, MTX_DEF);
}
static int
msgunload()
{
struct msqid_ds *msqptr;
int msqid;
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)
return (EBUSY);
free(msgpool, M_MSG);
free(msgmaps, M_MSG);
free(msghdrs, M_MSG);
free(msqids, M_MSG);
mtx_destroy(&msq_mtx);
return (0);
}
static int
sysvmsg_modload(struct module *module, int cmd, void *arg)
{
int error = 0;
switch (cmd) {
case MOD_LOAD:
msginit();
break;
case MOD_UNLOAD:
error = msgunload();
break;
case MOD_SHUTDOWN:
break;
default:
error = EINVAL;
break;
}
return (error);
}
static moduledata_t sysvmsg_mod = {
"sysvmsg",
&sysvmsg_modload,
NULL
};
SYSCALL_MODULE_HELPER(msgsys);
SYSCALL_MODULE_HELPER(msgctl);
SYSCALL_MODULE_HELPER(msgget);
SYSCALL_MODULE_HELPER(msgsnd);
SYSCALL_MODULE_HELPER(msgrcv);
DECLARE_MODULE(sysvmsg, sysvmsg_mod,
SI_SUB_SYSV_MSG, SI_ORDER_FIRST);
MODULE_VERSION(sysvmsg, 1);
/*
* Entry point for all MSG calls
*
* MPSAFE
*/
int
msgsys(td, uap)
struct thread *td;
/* XXX actually varargs. */
struct msgsys_args /* {
u_int which;
int a2;
int a3;
int a4;
int a5;
int a6;
} */ *uap;
{
int error;
if (!jail_sysvipc_allowed && jailed(td->td_ucred))
return (ENOSYS);
if (uap->which >= sizeof(msgcalls)/sizeof(msgcalls[0]))
return (EINVAL);
error = (*msgcalls[uap->which])(td, &uap->a2);
return (error);
}
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;
}
#ifndef _SYS_SYSPROTO_H_
struct msgctl_args {
int msqid;
int cmd;
struct msqid_ds *buf;
};
#endif
/*
* MPSAFE
*/
int
msgctl(td, uap)
struct thread *td;
register struct msgctl_args *uap;
{
int msqid = uap->msqid;
int cmd = uap->cmd;
struct msqid_ds *user_msqptr = uap->buf;
int rval, error;
struct msqid_ds msqbuf;
register struct msqid_ds *msqptr;
DPRINTF(("call to msgctl(%d, %d, 0x%x)\n", msqid, cmd, user_msqptr));
if (!jail_sysvipc_allowed && jailed(td->td_ucred))
return (ENOSYS);
msqid = IPCID_TO_IX(msqid);
if (msqid < 0 || msqid >= msginfo.msgmni) {
DPRINTF(("msqid (%d) out of range (0<=msqid<%d)\n", msqid,
msginfo.msgmni));
return (EINVAL);
}
if (cmd == IPC_SET &&
(error = copyin(user_msqptr, &msqbuf, sizeof(msqbuf))) != 0)
return (error);
msqptr = &msqids[msqid];
mtx_lock(&msq_mtx);
if (msqptr->msg_qbytes == 0) {
DPRINTF(("no such msqid\n"));
error = EINVAL;
goto done2;
}
if (msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) {
DPRINTF(("wrong sequence number\n"));
error = EINVAL;
goto done2;
}
error = 0;
rval = 0;
switch (cmd) {
case IPC_RMID:
{
struct msg *msghdr;
if ((error = ipcperm(td, &msqptr->msg_perm, IPC_M)))
goto done2;
/* 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(td, &msqptr->msg_perm, IPC_M)))
goto done2;
if (msqbuf.msg_qbytes > msqptr->msg_qbytes) {
error = suser(td);
if (error)
goto done2;
}
if (msqbuf.msg_qbytes > msginfo.msgmnb) {
DPRINTF(("can't increase msg_qbytes beyond %d"
"(truncating)\n", msginfo.msgmnb));
msqbuf.msg_qbytes = msginfo.msgmnb; /* silently restrict qbytes to system limit */
}
if (msqbuf.msg_qbytes == 0) {
DPRINTF(("can't reduce msg_qbytes to 0\n"));
error = EINVAL; /* non-standard errno! */
goto done2;
}
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_second;
break;
case IPC_STAT:
if ((error = ipcperm(td, &msqptr->msg_perm, IPC_R))) {
DPRINTF(("requester doesn't have read access\n"));
goto done2;
}
break;
default:
DPRINTF(("invalid command %d\n", cmd));
error = EINVAL;
goto done2;
}
if (error == 0)
td->td_retval[0] = rval;
done2:
mtx_unlock(&msq_mtx);
if (cmd == IPC_STAT && error == 0)
error = copyout(msqptr, user_msqptr, sizeof(struct msqid_ds));
return(error);
}
#ifndef _SYS_SYSPROTO_H_
struct msgget_args {
key_t key;
int msgflg;
};
#endif
/*
* MPSAFE
*/
int
msgget(td, uap)
struct thread *td;
register struct msgget_args *uap;
{
int msqid, error = 0;
int key = uap->key;
int msgflg = uap->msgflg;
struct ucred *cred = td->td_ucred;
register struct msqid_ds *msqptr = NULL;
DPRINTF(("msgget(0x%x, 0%o)\n", key, msgflg));
if (!jail_sysvipc_allowed && jailed(td->td_ucred))
return (ENOSYS);
mtx_lock(&msq_mtx);
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) {
DPRINTF(("found public key\n"));
if ((msgflg & IPC_CREAT) && (msgflg & IPC_EXCL)) {
DPRINTF(("not exclusive\n"));
error = EEXIST;
goto done2;
}
if ((error = ipcperm(td, &msqptr->msg_perm, msgflg & 0700 ))) {
DPRINTF(("requester doesn't have 0%o access\n",
msgflg & 0700));
goto done2;
}
goto found;
}
}
DPRINTF(("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) {
DPRINTF(("no more msqid_ds's available\n"));
error = ENOSPC;
goto done2;
}
DPRINTF(("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_perm.seq + 1) & 0x7fff;
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_second;
} else {
DPRINTF(("didn't find it and wasn't asked to create it\n"));
error = ENOENT;
goto done2;
}
found:
/* Construct the unique msqid */
td->td_retval[0] = IXSEQ_TO_IPCID(msqid, msqptr->msg_perm);
done2:
mtx_unlock(&msq_mtx);
return (error);
}
#ifndef _SYS_SYSPROTO_H_
struct msgsnd_args {
int msqid;
void *msgp;
size_t msgsz;
int msgflg;
};
#endif
/*
* MPSAFE
*/
int
msgsnd(td, uap)
struct thread *td;
register struct msgsnd_args *uap;
{
int msqid = uap->msqid;
void *user_msgp = uap->msgp;
size_t msgsz = uap->msgsz;
int msgflg = uap->msgflg;
int segs_needed, error = 0;
register struct msqid_ds *msqptr;
register struct msg *msghdr;
short next;
DPRINTF(("call to msgsnd(%d, 0x%x, %d, %d)\n", msqid, user_msgp, msgsz,
msgflg));
if (!jail_sysvipc_allowed && jailed(td->td_ucred))
return (ENOSYS);
mtx_lock(&msq_mtx);
msqid = IPCID_TO_IX(msqid);
if (msqid < 0 || msqid >= msginfo.msgmni) {
DPRINTF(("msqid (%d) out of range (0<=msqid<%d)\n", msqid,
msginfo.msgmni));
error = EINVAL;
goto done2;
}
msqptr = &msqids[msqid];
if (msqptr->msg_qbytes == 0) {
DPRINTF(("no such message queue id\n"));
error = EINVAL;
goto done2;
}
if (msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) {
DPRINTF(("wrong sequence number\n"));
error = EINVAL;
goto done2;
}
if ((error = ipcperm(td, &msqptr->msg_perm, IPC_W))) {
DPRINTF(("requester doesn't have write access\n"));
goto done2;
}
segs_needed = (msgsz + msginfo.msgssz - 1) / msginfo.msgssz;
DPRINTF(("msgsz=%d, msgssz=%d, segs_needed=%d\n", msgsz, msginfo.msgssz,
segs_needed));
for (;;) {
int need_more_resources = 0;
/*
* check msgsz
* (inside this loop in case msg_qbytes changes while we sleep)
*/
if (msgsz > msqptr->msg_qbytes) {
DPRINTF(("msgsz > msqptr->msg_qbytes\n"));
error = EINVAL;
goto done2;
}
if (msqptr->msg_perm.mode & MSG_LOCKED) {
DPRINTF(("msqid is locked\n"));
need_more_resources = 1;
}
if (msgsz + msqptr->msg_cbytes > msqptr->msg_qbytes) {
DPRINTF(("msgsz + msg_cbytes > msg_qbytes\n"));
need_more_resources = 1;
}
if (segs_needed > nfree_msgmaps) {
DPRINTF(("segs_needed > nfree_msgmaps\n"));
need_more_resources = 1;
}
if (free_msghdrs == NULL) {
DPRINTF(("no more msghdrs\n"));
need_more_resources = 1;
}
if (need_more_resources) {
int we_own_it;
if ((msgflg & IPC_NOWAIT) != 0) {
DPRINTF(("need more resources but caller "
"doesn't want to wait\n"));
error = EAGAIN;
goto done2;
}
if ((msqptr->msg_perm.mode & MSG_LOCKED) != 0) {
DPRINTF(("we don't own the msqid_ds\n"));
we_own_it = 0;
} else {
/* Force later arrivals to wait for our
request */
DPRINTF(("we own the msqid_ds\n"));
msqptr->msg_perm.mode |= MSG_LOCKED;
we_own_it = 1;
}
DPRINTF(("goodnight\n"));
error = msleep(msqptr, &msq_mtx, (PZERO - 4) | PCATCH,
"msgwait", 0);
DPRINTF(("good morning, error=%d\n", error));
if (we_own_it)
msqptr->msg_perm.mode &= ~MSG_LOCKED;
if (error != 0) {
DPRINTF(("msgsnd: interrupted system call\n"));
error = EINTR;
goto done2;
}
/*
* Make sure that the msq queue still exists
*/
if (msqptr->msg_qbytes == 0) {
DPRINTF(("msqid deleted\n"));
error = EIDRM;
goto done2;
}
} else {
DPRINTF(("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");
DPRINTF(("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
*/
mtx_unlock(&msq_mtx);
if ((error = copyin(user_msgp, &msghdr->msg_type,
sizeof(msghdr->msg_type))) != 0) {
mtx_lock(&msq_mtx);
DPRINTF(("error %d copying the message type\n", error));
msg_freehdr(msghdr);
msqptr->msg_perm.mode &= ~MSG_LOCKED;
wakeup(msqptr);
goto done2;
}
mtx_lock(&msq_mtx);
user_msgp = (char *)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);
DPRINTF(("mtype (%d) < 1\n", msghdr->msg_type));
error = EINVAL;
goto done2;
}
/*
* 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");
mtx_unlock(&msq_mtx);
if ((error = copyin(user_msgp, &msgpool[next * msginfo.msgssz],
tlen)) != 0) {
mtx_lock(&msq_mtx);
DPRINTF(("error %d copying in message segment\n",
error));
msg_freehdr(msghdr);
msqptr->msg_perm.mode &= ~MSG_LOCKED;
wakeup(msqptr);
goto done2;
}
mtx_lock(&msq_mtx);
msgsz -= tlen;
user_msgp = (char *)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);
error = EIDRM;
goto done2;
}
/*
* 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 = td->td_proc->p_pid;
msqptr->msg_stime = time_second;
wakeup(msqptr);
td->td_retval[0] = 0;
done2:
mtx_unlock(&msq_mtx);
return (error);
}
#ifndef _SYS_SYSPROTO_H_
struct msgrcv_args {
int msqid;
void *msgp;
size_t msgsz;
long msgtyp;
int msgflg;
};
#endif
/*
* MPSAFE
*/
int
msgrcv(td, uap)
struct thread *td;
register struct msgrcv_args *uap;
{
int msqid = uap->msqid;
void *user_msgp = uap->msgp;
size_t msgsz = uap->msgsz;
long msgtyp = uap->msgtyp;
int msgflg = uap->msgflg;
size_t len;
register struct msqid_ds *msqptr;
register struct msg *msghdr;
int error = 0;
short next;
DPRINTF(("call to msgrcv(%d, 0x%x, %d, %ld, %d)\n", msqid, user_msgp,
msgsz, msgtyp, msgflg));
if (!jail_sysvipc_allowed && jailed(td->td_ucred))
return (ENOSYS);
msqid = IPCID_TO_IX(msqid);
if (msqid < 0 || msqid >= msginfo.msgmni) {
DPRINTF(("msqid (%d) out of range (0<=msqid<%d)\n", msqid,
msginfo.msgmni));
return (EINVAL);
}
msqptr = &msqids[msqid];
mtx_lock(&msq_mtx);
if (msqptr->msg_qbytes == 0) {
DPRINTF(("no such message queue id\n"));
error = EINVAL;
goto done2;
}
if (msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) {
DPRINTF(("wrong sequence number\n"));
error = EINVAL;
goto done2;
}
if ((error = ipcperm(td, &msqptr->msg_perm, IPC_R))) {
DPRINTF(("requester doesn't have read access\n"));
goto done2;
}
msghdr = NULL;
while (msghdr == NULL) {
if (msgtyp == 0) {
msghdr = msqptr->msg_first;
if (msghdr != NULL) {
if (msgsz < msghdr->msg_ts &&
(msgflg & MSG_NOERROR) == 0) {
DPRINTF(("first message on the queue "
"is too big (want %d, got %d)\n",
msgsz, msghdr->msg_ts));
error = E2BIG;
goto done2;
}
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;
previous = NULL;
prev = &(msqptr->msg_first);
while ((msghdr = *prev) != NULL) {
/*
* 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) {
DPRINTF(("found message type %d, "
"requested %d\n",
msghdr->msg_type, msgtyp));
if (msgsz < msghdr->msg_ts &&
(msgflg & MSG_NOERROR) == 0) {
DPRINTF(("requested message "
"on the queue is too big "
"(want %d, got %d)\n",
msgsz, msghdr->msg_ts));
error = E2BIG;
goto done2;
}
*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;
}
previous = msghdr;
prev = &(msghdr->msg_next);
}
}
/*
* 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) {
DPRINTF(("no appropriate message found (msgtyp=%d)\n",
msgtyp));
/* The SVID says to return ENOMSG. */
error = ENOMSG;
goto done2;
}
/*
* Wait for something to happen
*/
DPRINTF(("msgrcv: goodnight\n"));
error = msleep(msqptr, &msq_mtx, (PZERO - 4) | PCATCH,
"msgwait", 0);
DPRINTF(("msgrcv: good morning (error=%d)\n", error));
if (error != 0) {
DPRINTF(("msgsnd: interrupted system call\n"));
error = EINTR;
goto done2;
}
/*
* Make sure that the msq queue still exists
*/
if (msqptr->msg_qbytes == 0 ||
msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) {
DPRINTF(("msqid deleted\n"));
error = EIDRM;
goto done2;
}
}
/*
* 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 = td->td_proc->p_pid;
msqptr->msg_rtime = time_second;
/*
* 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).
*/
DPRINTF(("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.
*/
mtx_unlock(&msq_mtx);
error = copyout(&(msghdr->msg_type), user_msgp,
sizeof(msghdr->msg_type));
mtx_lock(&msq_mtx);
if (error != 0) {
DPRINTF(("error (%d) copying out message type\n", error));
msg_freehdr(msghdr);
wakeup(msqptr);
goto done2;
}
user_msgp = (char *)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");
mtx_unlock(&msq_mtx);
error = copyout(&msgpool[next * msginfo.msgssz],
user_msgp, tlen);
mtx_lock(&msq_mtx);
if (error != 0) {
DPRINTF(("error (%d) copying out message segment\n",
error));
msg_freehdr(msghdr);
wakeup(msqptr);
goto done2;
}
user_msgp = (char *)user_msgp + tlen;
next = msgmaps[next].next;
}
/*
* Done, return the actual number of bytes copied out.
*/
msg_freehdr(msghdr);
wakeup(msqptr);
td->td_retval[0] = msgsz;
done2:
mtx_unlock(&msq_mtx);
return (error);
}
static int
sysctl_msqids(SYSCTL_HANDLER_ARGS)
{
return (SYSCTL_OUT(req, msqids,
sizeof(struct msqid_ds) * msginfo.msgmni));
}
SYSCTL_DECL(_kern_ipc);
SYSCTL_INT(_kern_ipc, OID_AUTO, msgmax, CTLFLAG_RD, &msginfo.msgmax, 0, "");
SYSCTL_INT(_kern_ipc, OID_AUTO, msgmni, CTLFLAG_RD, &msginfo.msgmni, 0, "");
SYSCTL_INT(_kern_ipc, OID_AUTO, msgmnb, CTLFLAG_RD, &msginfo.msgmnb, 0, "");
SYSCTL_INT(_kern_ipc, OID_AUTO, msgtql, CTLFLAG_RD, &msginfo.msgtql, 0, "");
SYSCTL_INT(_kern_ipc, OID_AUTO, msgssz, CTLFLAG_RD, &msginfo.msgssz, 0, "");
SYSCTL_INT(_kern_ipc, OID_AUTO, msgseg, CTLFLAG_RD, &msginfo.msgseg, 0, "");
SYSCTL_PROC(_kern_ipc, OID_AUTO, msqids, CTLFLAG_RD,
NULL, 0, sysctl_msqids, "", "Message queue IDs");
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