999 lines
22 KiB
C
999 lines
22 KiB
C
/* $Id: sysv_msg.c,v 1.2 1994/09/17 13:24:16 davidg Exp $ */
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/*
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* Implementation of SVID messages
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*
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* Author: Daniel Boulet
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*
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* Copyright 1993 Daniel Boulet and RTMX Inc.
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*
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* This system call was implemented by Daniel Boulet under contract from RTMX.
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*
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* Redistribution and use in source forms, with and without modification,
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* are permitted provided that this entire comment appears intact.
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*
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* Redistribution in binary form may occur without any restrictions.
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* Obviously, it would be nice if you gave credit where credit is due
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* but requiring it would be too onerous.
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*
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* This software is provided ``AS IS'' without any warranties of any kind.
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/proc.h>
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#include <sys/msg.h>
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#include <sys/malloc.h>
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#define MSG_DEBUG
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#undef MSG_DEBUG_OK
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static int msgctl(), msgget(), msgsnd(), msgrcv();
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int (*msgcalls[])() = { msgctl, msgget, msgsnd, msgrcv };
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int nfree_msgmaps; /* # of free map entries */
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short free_msgmaps; /* head of linked list of free map entries */
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struct msg *free_msghdrs; /* list of free msg headers */
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void
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msginit()
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{
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register int i;
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/*
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* msginfo.msgssz should be a power of two for efficiency reasons.
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* It is also pretty silly if msginfo.msgssz is less than 8
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* or greater than about 256 so ...
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*/
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i = 8;
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while (i < 1024 && i != msginfo.msgssz)
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i <<= 1;
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if (i != msginfo.msgssz) {
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printf("msginfo.msgssz=%d (0x%x)\n", msginfo.msgssz,
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msginfo.msgssz);
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panic("msginfo.msgssz not a small power of 2");
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}
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if (msginfo.msgseg > 32767) {
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printf("msginfo.msgseg=%d\n", msginfo.msgseg);
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panic("msginfo.msgseg > 32767");
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}
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if (msgmaps == NULL)
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panic("msgmaps is NULL");
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for (i = 0; i < msginfo.msgseg; i++) {
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if (i > 0)
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msgmaps[i-1].next = i;
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msgmaps[i].next = -1; /* implies entry is available */
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}
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free_msgmaps = 0;
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nfree_msgmaps = msginfo.msgseg;
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if (msghdrs == NULL)
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panic("msghdrs is NULL");
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for (i = 0; i < msginfo.msgtql; i++) {
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msghdrs[i].msg_type = 0;
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if (i > 0)
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msghdrs[i-1].msg_next = &msghdrs[i];
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msghdrs[i].msg_next = NULL;
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}
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free_msghdrs = &msghdrs[0];
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if (msqids == NULL)
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panic("msqids is NULL");
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for (i = 0; i < msginfo.msgmni; i++) {
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msqids[i].msg_qbytes = 0; /* implies entry is available */
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msqids[i].msg_perm.seq = 0; /* reset to a known value */
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}
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}
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/*
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* Entry point for all MSG calls
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*/
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struct msgsys_args {
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u_int which;
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};
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int
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msgsys(p, uap, retval)
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struct caller *p;
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struct msgsys_args *uap;
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int *retval;
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{
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if (uap->which >= sizeof(msgcalls)/sizeof(msgcalls[0]))
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return (EINVAL);
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return ((*msgcalls[uap->which])(p, &uap[1], retval));
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}
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static void
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msg_freehdr(msghdr)
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struct msg *msghdr;
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{
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while (msghdr->msg_ts > 0) {
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short next;
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if (msghdr->msg_spot < 0 || msghdr->msg_spot >= msginfo.msgseg)
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panic("msghdr->msg_spot out of range");
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next = msgmaps[msghdr->msg_spot].next;
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msgmaps[msghdr->msg_spot].next = free_msgmaps;
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free_msgmaps = msghdr->msg_spot;
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nfree_msgmaps++;
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msghdr->msg_spot = next;
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if (msghdr->msg_ts >= msginfo.msgssz)
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msghdr->msg_ts -= msginfo.msgssz;
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else
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msghdr->msg_ts = 0;
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}
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if (msghdr->msg_spot != -1)
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panic("msghdr->msg_spot != -1");
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msghdr->msg_next = free_msghdrs;
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free_msghdrs = msghdr;
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}
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struct msgctl_args {
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int msqid;
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int cmd;
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struct msqid_ds *user_msqptr;
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};
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int
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msgctl(p, uap, retval)
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struct proc *p;
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register struct msgctl_args *uap;
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int *retval;
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{
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int msqid = uap->msqid;
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int cmd = uap->cmd;
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struct msqid_ds *user_msqptr = uap->user_msqptr;
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struct ucred *cred = p->p_ucred;
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int rval, eval;
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struct msqid_ds msqbuf;
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register struct msqid_ds *msqptr;
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#ifdef MSG_DEBUG_OK
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printf("call to msgctl(%d, %d, 0x%x)\n", msqid, cmd, user_msqptr);
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#endif
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msqid = IPCID_TO_IX(msqid);
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if (msqid < 0 || msqid >= msginfo.msgmni) {
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#ifdef MSG_DEBUG_OK
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printf("msqid (%d) out of range (0<=msqid<%d)\n", msqid,
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msginfo.msgmni);
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#endif
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return(EINVAL);
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}
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msqptr = &msqids[msqid];
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if (msqptr->msg_qbytes == 0) {
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#ifdef MSG_DEBUG_OK
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printf("no such msqid\n");
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#endif
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return(EINVAL);
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}
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if (msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) {
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#ifdef MSG_DEBUG_OK
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printf("wrong sequence number\n");
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#endif
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return(EINVAL);
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}
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eval = 0;
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rval = 0;
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switch (cmd) {
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case IPC_RMID:
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{
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struct msg *msghdr;
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if ((eval = ipcperm(cred, &msqptr->msg_perm, IPC_M)))
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return(eval);
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/* Free the message headers */
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msghdr = msqptr->msg_first;
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while (msghdr != NULL) {
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struct msg *msghdr_tmp;
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/* Free the segments of each message */
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msqptr->msg_cbytes -= msghdr->msg_ts;
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msqptr->msg_qnum--;
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msghdr_tmp = msghdr;
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msghdr = msghdr->msg_next;
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msg_freehdr(msghdr_tmp);
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}
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if (msqptr->msg_cbytes != 0)
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panic("msg_cbytes is screwed up");
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if (msqptr->msg_qnum != 0)
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panic("msg_qnum is screwed up");
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msqptr->msg_qbytes = 0; /* Mark it as free */
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wakeup((caddr_t)msqptr);
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}
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break;
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case IPC_SET:
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if ((eval = ipcperm(cred, &msqptr->msg_perm, IPC_M)))
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return(eval);
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if ((eval = copyin(user_msqptr, &msqbuf, sizeof(msqbuf))) != 0)
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return(eval);
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if (msqbuf.msg_qbytes > msqptr->msg_qbytes && cred->cr_uid != 0)
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return(EPERM);
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if (msqbuf.msg_qbytes > msginfo.msgmnb) {
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#ifdef MSG_DEBUG_OK
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printf("can't increase msg_qbytes beyond %d (truncating)\n",
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msginfo.msgmnb);
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#endif
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msqbuf.msg_qbytes = msginfo.msgmnb; /* silently restrict qbytes to system limit */
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}
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if (msqbuf.msg_qbytes == 0) {
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#ifdef MSG_DEBUG_OK
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printf("can't reduce msg_qbytes to 0\n");
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#endif
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return(EINVAL); /* non-standard errno! */
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}
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msqptr->msg_perm.uid = msqbuf.msg_perm.uid; /* change the owner */
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msqptr->msg_perm.gid = msqbuf.msg_perm.gid; /* change the owner */
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msqptr->msg_perm.mode = (msqptr->msg_perm.mode & ~0777) |
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(msqbuf.msg_perm.mode & 0777);
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msqptr->msg_qbytes = msqbuf.msg_qbytes;
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msqptr->msg_ctime = time.tv_sec;
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break;
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case IPC_STAT:
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if ((eval = ipcperm(cred, &msqptr->msg_perm, IPC_R))) {
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#ifdef MSG_DEBUG_OK
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printf("requester doesn't have read access\n");
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#endif
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return(eval);
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}
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eval = copyout((caddr_t)msqptr, user_msqptr,
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sizeof(struct msqid_ds));
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break;
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default:
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#ifdef MSG_DEBUG_OK
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printf("invalid command %d\n", cmd);
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#endif
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return(EINVAL);
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}
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if (eval == 0)
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*retval = rval;
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return(eval);
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}
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struct msgget_args {
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key_t key;
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int msgflg;
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};
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int
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msgget(p, uap, retval)
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struct proc *p;
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register struct msgget_args *uap;
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int *retval;
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{
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int msqid, eval;
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int key = uap->key;
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int msgflg = uap->msgflg;
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struct ucred *cred = p->p_ucred;
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register struct msqid_ds *msqptr = NULL;
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#ifdef MSG_DEBUG_OK
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printf("msgget(0x%x, 0%o)\n", key, msgflg);
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#endif
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if (key != IPC_PRIVATE) {
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for (msqid = 0; msqid < msginfo.msgmni; msqid++) {
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msqptr = &msqids[msqid];
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if (msqptr->msg_qbytes != 0 &&
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msqptr->msg_perm.key == key)
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break;
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}
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if (msqid < msginfo.msgmni) {
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#ifdef MSG_DEBUG_OK
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printf("found public key\n");
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#endif
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if ((msgflg & IPC_CREAT) && (msgflg & IPC_EXCL)) {
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#ifdef MSG_DEBUG_OK
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printf("not exclusive\n");
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#endif
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return(EEXIST);
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}
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if ((eval = ipcperm(cred, &msqptr->msg_perm, msgflg & 0700 ))) {
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#ifdef MSG_DEBUG_OK
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printf("requester doesn't have 0%o access\n",
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msgflg & 0700);
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#endif
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return(eval);
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}
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goto found;
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}
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}
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#ifdef MSG_DEBUG_OK
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printf("need to allocate the msqid_ds\n");
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#endif
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if (key == IPC_PRIVATE || (msgflg & IPC_CREAT)) {
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for (msqid = 0; msqid < msginfo.msgmni; msqid++) {
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/*
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* Look for an unallocated and unlocked msqid_ds.
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* msqid_ds's can be locked by msgsnd or msgrcv while
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* they are copying the message in/out. We can't
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* re-use the entry until they release it.
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*/
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msqptr = &msqids[msqid];
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if (msqptr->msg_qbytes == 0 &&
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(msqptr->msg_perm.mode & MSG_LOCKED) == 0)
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break;
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}
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if (msqid == msginfo.msgmni) {
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#ifdef MSG_DEBUG_OK
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printf("no more msqid_ds's available\n");
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#endif
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return(ENOSPC);
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}
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#ifdef MSG_DEBUG_OK
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printf("msqid %d is available\n", msqid);
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#endif
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msqptr->msg_perm.key = key;
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msqptr->msg_perm.cuid = cred->cr_uid;
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msqptr->msg_perm.uid = cred->cr_uid;
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msqptr->msg_perm.cgid = cred->cr_gid;
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msqptr->msg_perm.gid = cred->cr_gid;
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msqptr->msg_perm.mode = (msgflg & 0777);
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/* Make sure that the returned msqid is unique */
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msqptr->msg_perm.seq++;
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msqptr->msg_first = NULL;
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msqptr->msg_last = NULL;
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msqptr->msg_cbytes = 0;
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msqptr->msg_qnum = 0;
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msqptr->msg_qbytes = msginfo.msgmnb;
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msqptr->msg_lspid = 0;
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msqptr->msg_lrpid = 0;
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msqptr->msg_stime = 0;
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msqptr->msg_rtime = 0;
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msqptr->msg_ctime = time.tv_sec;
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} else {
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#ifdef MSG_DEBUG_OK
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printf("didn't find it and wasn't asked to create it\n");
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#endif
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return(ENOENT);
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}
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found:
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/* Construct the unique msqid */
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*retval = IXSEQ_TO_IPCID(msqid, msqptr->msg_perm);
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return(0);
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}
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struct msgsnd_args {
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int msqid;
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void *user_msgp;
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size_t msgsz;
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int msgflg;
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};
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int
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msgsnd(p, uap, retval)
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struct proc *p;
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register struct msgsnd_args *uap;
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int *retval;
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{
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int msqid = uap->msqid;
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void *user_msgp = uap->user_msgp;
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size_t msgsz = uap->msgsz;
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int msgflg = uap->msgflg;
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int segs_needed, eval;
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struct ucred *cred = p->p_ucred;
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register struct msqid_ds *msqptr;
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register struct msg *msghdr;
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short next;
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#ifdef MSG_DEBUG_OK
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printf("call to msgsnd(%d, 0x%x, %d, %d)\n", msqid, user_msgp, msgsz,
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msgflg);
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#endif
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msqid = IPCID_TO_IX(msqid);
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if (msqid < 0 || msqid >= msginfo.msgmni) {
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#ifdef MSG_DEBUG_OK
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printf("msqid (%d) out of range (0<=msqid<%d)\n", msqid,
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msginfo.msgmni);
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#endif
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return(EINVAL);
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}
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msqptr = &msqids[msqid];
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if (msqptr->msg_qbytes == 0) {
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#ifdef MSG_DEBUG_OK
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printf("no such message queue id\n");
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#endif
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return(EINVAL);
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}
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if (msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) {
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#ifdef MSG_DEBUG_OK
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printf("wrong sequence number\n");
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#endif
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return(EINVAL);
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}
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if ((eval = ipcperm(cred, &msqptr->msg_perm, IPC_W))) {
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#ifdef MSG_DEBUG_OK
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printf("requester doesn't have write access\n");
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#endif
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return(eval);
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}
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segs_needed = (msgsz + msginfo.msgssz - 1) / msginfo.msgssz;
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#ifdef MSG_DEBUG_OK
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printf("msgsz=%d, msgssz=%d, segs_needed=%d\n", msgsz, msginfo.msgssz,
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segs_needed);
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#endif
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for (;;) {
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int need_more_resources = 0;
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/*
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* check msgsz
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* (inside this loop in case msg_qbytes changes while we sleep)
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*/
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if (msgsz > msqptr->msg_qbytes) {
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#ifdef MSG_DEBUG_OK
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printf("msgsz > msqptr->msg_qbytes\n");
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#endif
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return(EINVAL);
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}
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if (msqptr->msg_perm.mode & MSG_LOCKED) {
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#ifdef MSG_DEBUG_OK
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printf("msqid is locked\n");
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#endif
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need_more_resources = 1;
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}
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if (msgsz + msqptr->msg_cbytes > msqptr->msg_qbytes) {
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#ifdef MSG_DEBUG_OK
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printf("msgsz + msg_cbytes > msg_qbytes\n");
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#endif
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need_more_resources = 1;
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}
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if (segs_needed > nfree_msgmaps) {
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#ifdef MSG_DEBUG_OK
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printf("segs_needed > nfree_msgmaps\n");
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#endif
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need_more_resources = 1;
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}
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if (free_msghdrs == NULL) {
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#ifdef MSG_DEBUG_OK
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printf("no more msghdrs\n");
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#endif
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need_more_resources = 1;
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}
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if (need_more_resources) {
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int we_own_it;
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if ((msgflg & IPC_NOWAIT) != 0) {
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#ifdef MSG_DEBUG_OK
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printf("need more resources but caller doesn't want to wait\n");
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#endif
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return(EAGAIN);
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}
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if ((msqptr->msg_perm.mode & MSG_LOCKED) != 0) {
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#ifdef MSG_DEBUG_OK
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printf("we don't own the msqid_ds\n");
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#endif
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we_own_it = 0;
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} else {
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/* Force later arrivals to wait for our
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request */
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#ifdef MSG_DEBUG_OK
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printf("we own the msqid_ds\n");
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#endif
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msqptr->msg_perm.mode |= MSG_LOCKED;
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we_own_it = 1;
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}
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#ifdef MSG_DEBUG_OK
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printf("goodnight\n");
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#endif
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eval = tsleep((caddr_t)msqptr, (PZERO - 4) | PCATCH,
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"msgwait", 0);
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#ifdef MSG_DEBUG_OK
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printf("good morning, eval=%d\n", eval);
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#endif
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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!
|
|
*/
|
|
|
|
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");
|
|
#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;
|
|
if (next <= -1)
|
|
panic("next too low #2");
|
|
if (next >= msginfo.msgseg)
|
|
panic("next out of range #2");
|
|
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;
|
|
}
|
|
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((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);
|
|
}
|
|
|
|
struct msgrcv_args {
|
|
int msqid;
|
|
void *msgp;
|
|
size_t msgsz;
|
|
long msgtyp;
|
|
int msgflg;
|
|
};
|
|
|
|
int
|
|
msgrcv(p, uap, retval)
|
|
struct proc *p;
|
|
register struct msgrcv_args *uap;
|
|
int *retval;
|
|
{
|
|
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;
|
|
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, 0x%x, %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(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);
|
|
}
|
|
|
|
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;
|
|
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) {
|
|
#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) {
|
|
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) {
|
|
#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(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;
|
|
if (next <= -1)
|
|
panic("next too low #3");
|
|
if (next >= msginfo.msgseg)
|
|
panic("next out of range #3");
|
|
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);
|
|
}
|