/* $FreeBSD$ */ /* * 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 #include #include #include #include #include #include #include #include #include #include #include #include static MALLOC_DEFINE(M_MSG, "msg", "SVID compatible message queues"); static void msginit __P((void)); static int msgunload __P((void)); static int sysvmsg_modload __P((struct module *, int, void *)); #define MSG_DEBUG #undef MSG_DEBUG_OK static void msg_freehdr __P((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 void msginit() { register int i; 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) { 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 */ msqids[i].msg_perm.mode = 0; } } 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); 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, 6); SYSCALL_MODULE_HELPER(msgctl, 3); SYSCALL_MODULE_HELPER(msgget, 2); SYSCALL_MODULE_HELPER(msgsnd, 4); SYSCALL_MODULE_HELPER(msgrcv, 5); 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; mtx_lock(&Giant); if (!jail_sysvipc_allowed && jailed(td->td_proc->p_ucred)) { error = ENOSYS; goto done2; } if (uap->which >= sizeof(msgcalls)/sizeof(msgcalls[0])) { error = EINVAL; goto done2; } error = (*msgcalls[uap->which])(td, &uap->a2); done2: mtx_unlock(&Giant); 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; #ifdef MSG_DEBUG_OK printf("call to msgctl(%d, %d, 0x%x)\n", msqid, cmd, user_msqptr); #endif mtx_lock(&Giant); if (!jail_sysvipc_allowed && jailed(td->td_proc->p_ucred)) { error = ENOSYS; goto done2; } 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 error = EINVAL; goto done2; } msqptr = &msqids[msqid]; if (msqptr->msg_qbytes == 0) { #ifdef MSG_DEBUG_OK printf("no such msqid\n"); #endif error = EINVAL; goto done2; } if (msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) { #ifdef MSG_DEBUG_OK printf("wrong sequence number\n"); #endif 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((caddr_t)msqptr); } break; case IPC_SET: if ((error = ipcperm(td, &msqptr->msg_perm, IPC_M))) goto done2; if ((error = copyin(user_msqptr, &msqbuf, sizeof(msqbuf))) != 0) goto done2; if (msqbuf.msg_qbytes > msqptr->msg_qbytes) { error = suser_td(td); if (error) goto done2; } 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 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))) { #ifdef MSG_DEBUG_OK printf("requester doesn't have read access\n"); #endif goto done2; } error = copyout((caddr_t)msqptr, user_msqptr, sizeof(struct msqid_ds)); break; default: #ifdef MSG_DEBUG_OK printf("invalid command %d\n", cmd); #endif error = EINVAL; goto done2; } if (error == 0) td->td_retval[0] = rval; done2: mtx_unlock(&Giant); 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_proc->p_ucred; register struct msqid_ds *msqptr = NULL; #ifdef MSG_DEBUG_OK printf("msgget(0x%x, 0%o)\n", key, msgflg); #endif mtx_lock(&Giant); if (!jail_sysvipc_allowed && jailed(td->td_proc->p_ucred)) { error = ENOSYS; goto done2; } 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 error = EEXIST; goto done2; } if ((error = ipcperm(td, &msqptr->msg_perm, msgflg & 0700 ))) { #ifdef MSG_DEBUG_OK printf("requester doesn't have 0%o access\n", msgflg & 0700); #endif goto done2; } 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 error = ENOSPC; goto done2; } #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_second; } else { #ifdef MSG_DEBUG_OK printf("didn't find it and wasn't asked to create it\n"); #endif error = ENOENT; goto done2; } found: /* Construct the unique msqid */ td->td_retval[0] = IXSEQ_TO_IPCID(msqid, msqptr->msg_perm); done2: mtx_unlock(&Giant); 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; #ifdef MSG_DEBUG_OK printf("call to msgsnd(%d, 0x%x, %d, %d)\n", msqid, user_msgp, msgsz, msgflg); #endif mtx_lock(&Giant); if (!jail_sysvipc_allowed && jailed(td->td_proc->p_ucred)) { error = ENOSYS; goto done2; } 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 error = EINVAL; goto done2; } msqptr = &msqids[msqid]; if (msqptr->msg_qbytes == 0) { #ifdef MSG_DEBUG_OK printf("no such message queue id\n"); #endif error = EINVAL; goto done2; } if (msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) { #ifdef MSG_DEBUG_OK printf("wrong sequence number\n"); #endif error = EINVAL; goto done2; } if ((error = ipcperm(td, &msqptr->msg_perm, IPC_W))) { #ifdef MSG_DEBUG_OK printf("requester doesn't have write access\n"); #endif goto done2; } 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 > msqptr->msg_qbytes) { #ifdef MSG_DEBUG_OK printf("msgsz > msqptr->msg_qbytes\n"); #endif error = EINVAL; goto done2; } 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 error = EAGAIN; goto done2; } 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 error = tsleep((caddr_t)msqptr, (PZERO - 4) | PCATCH, "msgwait", 0); #ifdef MSG_DEBUG_OK printf("good morning, error=%d\n", error); #endif if (we_own_it) msqptr->msg_perm.mode &= ~MSG_LOCKED; if (error != 0) { #ifdef MSG_DEBUG_OK printf("msgsnd: interrupted system call\n"); #endif error = EINTR; goto done2; } /* * Make sure that the msq queue still exists */ if (msqptr->msg_qbytes == 0) { #ifdef MSG_DEBUG_OK printf("msqid deleted\n"); #endif error = EIDRM; goto done2; } } 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 ((error = copyin(user_msgp, &msghdr->msg_type, sizeof(msghdr->msg_type))) != 0) { #ifdef MSG_DEBUG_OK printf("error %d copying the message type\n", error); #endif msg_freehdr(msghdr); msqptr->msg_perm.mode &= ~MSG_LOCKED; wakeup((caddr_t)msqptr); goto done2; } 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((caddr_t)msqptr); #ifdef MSG_DEBUG_OK printf("mtype (%d) < 1\n", msghdr->msg_type); #endif 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"); if ((error = copyin(user_msgp, &msgpool[next * msginfo.msgssz], tlen)) != 0) { #ifdef MSG_DEBUG_OK printf("error %d copying in message segment\n", error); #endif msg_freehdr(msghdr); msqptr->msg_perm.mode &= ~MSG_LOCKED; wakeup((caddr_t)msqptr); goto done2; } 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((caddr_t)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((caddr_t)msqptr); td->td_retval[0] = 0; done2: mtx_unlock(&Giant); 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; #ifdef MSG_DEBUG_OK printf("call to msgrcv(%d, 0x%x, %d, %ld, %d)\n", msqid, user_msgp, msgsz, msgtyp, msgflg); #endif mtx_lock(&Giant); if (!jail_sysvipc_allowed && jailed(td->td_proc->p_ucred)) { error = ENOSYS; goto done2; } 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 error = EINVAL; goto done2; } msqptr = &msqids[msqid]; if (msqptr->msg_qbytes == 0) { #ifdef MSG_DEBUG_OK printf("no such message queue id\n"); #endif error = EINVAL; goto done2; } if (msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) { #ifdef MSG_DEBUG_OK printf("wrong sequence number\n"); #endif error = EINVAL; goto done2; } if ((error = ipcperm(td, &msqptr->msg_perm, IPC_R))) { #ifdef MSG_DEBUG_OK printf("requester doesn't have read access\n"); #endif 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) { #ifdef MSG_DEBUG_OK printf("first message on the queue is too big (want %d, got %d)\n", msgsz, msghdr->msg_ts); #endif 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) { #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 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) { #ifdef MSG_DEBUG_OK printf("no appropriate message found (msgtyp=%d)\n", msgtyp); #endif /* The SVID says to return ENOMSG. */ error = ENOMSG; goto done2; } /* * Wait for something to happen */ #ifdef MSG_DEBUG_OK printf("msgrcv: goodnight\n"); #endif error = tsleep((caddr_t)msqptr, (PZERO - 4) | PCATCH, "msgwait", 0); #ifdef MSG_DEBUG_OK printf("msgrcv: good morning (error=%d)\n", error); #endif if (error != 0) { #ifdef MSG_DEBUG_OK printf("msgsnd: interrupted system call\n"); #endif 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)) { #ifdef MSG_DEBUG_OK printf("msqid deleted\n"); #endif 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). */ #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. */ error = copyout((caddr_t)&(msghdr->msg_type), user_msgp, sizeof(msghdr->msg_type)); if (error != 0) { #ifdef MSG_DEBUG_OK printf("error (%d) copying out message type\n", error); #endif msg_freehdr(msghdr); wakeup((caddr_t)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"); error = copyout((caddr_t)&msgpool[next * msginfo.msgssz], user_msgp, tlen); if (error != 0) { #ifdef MSG_DEBUG_OK printf("error (%d) copying out message segment\n", error); #endif msg_freehdr(msghdr); wakeup((caddr_t)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((caddr_t)msqptr); td->td_retval[0] = msgsz; done2: mtx_unlock(&Giant); 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");