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author | dfr <dfr@FreeBSD.org> | 1994-09-13 14:47:38 +0000 |
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committer | dfr <dfr@FreeBSD.org> | 1994-09-13 14:47:38 +0000 |
commit | 580fe46632ff236a0f268c29705d04d44ad2f89a (patch) | |
tree | 0b43a166c9d31a9a5c55d5efd7085507563a3825 /sys/kern/sysv_msg.c | |
parent | a7c9d6c8b52a067267445732a70349e616440364 (diff) | |
download | FreeBSD-src-580fe46632ff236a0f268c29705d04d44ad2f89a.zip FreeBSD-src-580fe46632ff236a0f268c29705d04d44ad2f89a.tar.gz |
Added SYSV ipcs.
Obtained from: NetBSD and FreeBSD-1.1.5
Diffstat (limited to 'sys/kern/sysv_msg.c')
-rw-r--r-- | sys/kern/sysv_msg.c | 1006 |
1 files changed, 1006 insertions, 0 deletions
diff --git a/sys/kern/sysv_msg.c b/sys/kern/sysv_msg.c new file mode 100644 index 0000000..0d68840 --- /dev/null +++ b/sys/kern/sysv_msg.c @@ -0,0 +1,1006 @@ +/* $Id$ */ + +/* + * 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/param.h> +#include <sys/systm.h> +#include <sys/kernel.h> +#include <sys/proc.h> +#include <sys/msg.h> +#include <sys/malloc.h> + +#define MSG_DEBUG +#undef MSG_DEBUG_OK + +static int msgctl(), msgget(), msgsnd(), msgrcv(); + +int (*msgcalls[])() = { msgctl, msgget, msgsnd, msgrcv }; + +int nfree_msgmaps; /* # of free map entries */ +short free_msgmaps; /* head of linked list of free map entries */ +struct msg *free_msghdrs; /* list of free msg headers */ + +int +msginit() +{ + register int i; + vm_offset_t whocares1, whocares2; + + /* + * 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) { + printf("msginfo.msgssz=%d (0x%x)\n", msginfo.msgssz, + msginfo.msgssz); + panic("msginfo.msgssz not a small power of 2"); + } + + if (msginfo.msgseg > 32767) { + printf("msginfo.msgseg=%d\n", msginfo.msgseg); + panic("msginfo.msgseg > 32767"); + } + + if (msgmaps == NULL) + panic("msgmaps is NULL"); + + for (i = 0; i < msginfo.msgseg; i++) { + if (i > 0) + msgmaps[i-1].next = i; + msgmaps[i].next = -1; /* implies entry is available */ + } + free_msgmaps = 0; + nfree_msgmaps = msginfo.msgseg; + + if (msghdrs == NULL) + panic("msghdrs is NULL"); + + for (i = 0; i < msginfo.msgtql; i++) { + msghdrs[i].msg_type = 0; + if (i > 0) + msghdrs[i-1].msg_next = &msghdrs[i]; + msghdrs[i].msg_next = NULL; + } + free_msghdrs = &msghdrs[0]; + + if (msqids == NULL) + panic("msqids is NULL"); + + for (i = 0; i < msginfo.msgmni; i++) { + msqids[i].msg_qbytes = 0; /* implies entry is available */ + msqids[i].msg_perm.seq = 0; /* reset to a known value */ + } +} + +/* + * Entry point for all MSG calls + */ + +struct msgsys_args { + u_int which; +}; + +int +msgsys(p, uap, retval) + struct caller *p; + struct msgsys_args *uap; + int *retval; +{ + + if (uap->which >= sizeof(msgcalls)/sizeof(msgcalls[0])) + return (EINVAL); + return ((*msgcalls[uap->which])(p, &uap[1], retval)); +} + +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; +} + +struct msgctl_args { + int msqid; + int cmd; + struct msqid_ds *user_msqptr; +}; + +int +msgctl(p, uap, retval) + struct proc *p; + register struct msgctl_args *uap; + int *retval; +{ + int msqid = uap->msqid; + int cmd = uap->cmd; + struct msqid_ds *user_msqptr = uap->user_msqptr; + struct ucred *cred = p->p_ucred; + int i, rval, eval; + struct msqid_ds msqbuf; + register struct msqid_ds *msqptr; + +#ifdef MSG_DEBUG_OK + printf("call to msgctl(%d, %d, 0x%x)\n", msqid, cmd, user_msqptr); +#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 msqid\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); + } + + eval = 0; + rval = 0; + + switch (cmd) { + + case IPC_RMID: + { + struct msg *msghdr; + if ((eval = ipcperm(cred, &msqptr->msg_perm, IPC_M))) + return(eval); + /* 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((caddr_t)msqptr); + } + + break; + + case IPC_SET: + if ((eval = ipcperm(cred, &msqptr->msg_perm, IPC_M))) + return(eval); + if ((eval = copyin(user_msqptr, &msqbuf, sizeof(msqbuf))) != 0) + return(eval); + if (msqbuf.msg_qbytes > msqptr->msg_qbytes && cred->cr_uid != 0) + return(EPERM); + if (msqbuf.msg_qbytes > msginfo.msgmnb) { +#ifdef MSG_DEBUG_OK + printf("can't increase msg_qbytes beyond %d (truncating)\n", + msginfo.msgmnb); +#endif + msqbuf.msg_qbytes = msginfo.msgmnb; /* silently restrict qbytes to system limit */ + } + if (msqbuf.msg_qbytes == 0) { +#ifdef MSG_DEBUG_OK + printf("can't reduce msg_qbytes to 0\n"); +#endif + return(EINVAL); /* non-standard errno! */ + } + 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.tv_sec; + break; + + case IPC_STAT: + if ((eval = ipcperm(cred, &msqptr->msg_perm, IPC_R))) { +#ifdef MSG_DEBUG_OK + printf("requester doesn't have read access\n"); +#endif + return(eval); + } + eval = copyout((caddr_t)msqptr, user_msqptr, + sizeof(struct msqid_ds)); + break; + + default: +#ifdef MSG_DEBUG_OK + printf("invalid command %d\n", cmd); +#endif + return(EINVAL); + } + + if (eval == 0) + *retval = rval; + return(eval); +} + +struct msgget_args { + key_t key; + int msgflg; +}; + +int +msgget(p, uap, retval) + struct proc *p; + register struct msgget_args *uap; + int *retval; +{ + int msqid, eval; + int key = uap->key; + int msgflg = uap->msgflg; + struct ucred *cred = p->p_ucred; + register struct msqid_ds *msqptr; + +#ifdef MSG_DEBUG_OK + printf("msgget(0x%x, 0%o)\n", key, msgflg); +#endif + + 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) { +#ifdef MSG_DEBUG_OK + printf("found public key\n"); +#endif + if ((msgflg & IPC_CREAT) && (msgflg & IPC_EXCL)) { +#ifdef MSG_DEBUG_OK + printf("not exclusive\n"); +#endif + return(EEXIST); + } + if ((eval = ipcperm(cred, &msqptr->msg_perm, msgflg & 0700 ))) { +#ifdef MSG_DEBUG_OK + printf("requester doesn't have 0%o access\n", + msgflg & 0700); +#endif + return(eval); + } + goto found; + } + } + +#ifdef MSG_DEBUG_OK + printf("need to allocate the msqid_ds\n"); +#endif + 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) { +#ifdef MSG_DEBUG_OK + printf("no more msqid_ds's available\n"); +#endif + return(ENOSPC); + } +#ifdef MSG_DEBUG_OK + printf("msqid %d is available\n", msqid); +#endif + 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 { +#ifdef MSG_DEBUG_OK + printf("didn't find it and wasn't asked to create it\n"); +#endif + return(ENOENT); + } + +found: + /* Construct the unique msqid */ + *retval = IXSEQ_TO_IPCID(msqid, msqptr->msg_perm); + return(0); +} + +struct msgsnd_args { + int msqid; + void *user_msgp; + size_t msgsz; + int msgflg; +}; + +int +msgsnd(p, uap, retval) + struct proc *p; + register struct msgsnd_args *uap; + int *retval; +{ + int msqid = uap->msqid; + void *user_msgp = uap->user_msgp; + size_t msgsz = uap->msgsz; + int msgflg = uap->msgflg; + int segs_needed, eval; + struct ucred *cred = p->p_ucred; + register struct msqid_ds *msqptr; + register struct msg *msghdr; + short next; + +#ifdef MSG_DEBUG_OK + printf("call to msgsnd(%d, 0x%x, %d, %d)\n", msqid, user_msgp, msgsz, + 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_W))) { +#ifdef MSG_DEBUG_OK + printf("requester doesn't have write access\n"); +#endif + return(eval); + } + + segs_needed = (msgsz + msginfo.msgssz - 1) / msginfo.msgssz; +#ifdef MSG_DEBUG_OK + printf("msgsz=%d, msgssz=%d, segs_needed=%d\n", msgsz, msginfo.msgssz, + segs_needed); +#endif + for (;;) { + int need_more_resources = 0; + + /* + * check msgsz + * (inside this loop in case msg_qbytes changes while we sleep) + */ + + if (msgsz < 0 || msgsz > msqptr->msg_qbytes) { +#ifdef MSG_DEBUG_OK + printf("msgsz > msqptr->msg_qbytes\n"); +#endif + return(EINVAL); + } + + if (msqptr->msg_perm.mode & MSG_LOCKED) { +#ifdef MSG_DEBUG_OK + printf("msqid is locked\n"); +#endif + need_more_resources = 1; + } + if (msgsz + msqptr->msg_cbytes > msqptr->msg_qbytes) { +#ifdef MSG_DEBUG_OK + printf("msgsz + msg_cbytes > msg_qbytes\n"); +#endif + need_more_resources = 1; + } + if (segs_needed > nfree_msgmaps) { +#ifdef MSG_DEBUG_OK + printf("segs_needed > nfree_msgmaps\n"); +#endif + need_more_resources = 1; + } + if (free_msghdrs == NULL) { +#ifdef MSG_DEBUG_OK + printf("no more msghdrs\n"); +#endif + need_more_resources = 1; + } + + if (need_more_resources) { + int we_own_it; + + if ((msgflg & IPC_NOWAIT) != 0) { +#ifdef MSG_DEBUG_OK + printf("need more resources but caller doesn't want to wait\n"); +#endif + return(EAGAIN); + } + + if ((msqptr->msg_perm.mode & MSG_LOCKED) != 0) { +#ifdef MSG_DEBUG_OK + printf("we don't own the msqid_ds\n"); +#endif + we_own_it = 0; + } else { + /* Force later arrivals to wait for our + request */ +#ifdef MSG_DEBUG_OK + printf("we own the msqid_ds\n"); +#endif + msqptr->msg_perm.mode |= MSG_LOCKED; + we_own_it = 1; + } +#ifdef MSG_DEBUG_OK + printf("goodnight\n"); +#endif + eval = tsleep((caddr_t)msqptr, (PZERO - 4) | PCATCH, + "msgwait", 0); +#ifdef MSG_DEBUG_OK + printf("good morning, eval=%d\n", eval); +#endif + 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); + } + + if (msgsz < 0) { +#ifdef MSG_DEBUG_OK + printf("msgsz < 0\n"); +#endif + return(EINVAL); + } + + 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); +} |