| 1 | /* uipc_mu_msg.c Melb 4.3 82/12/28 */ |
| 2 | |
| 3 | #ifdef MUSH |
| 4 | #include "../h/param.h" |
| 5 | #include "../h/dir.h" |
| 6 | #include "../h/user.h" |
| 7 | #include "../h/proc.h" |
| 8 | |
| 9 | /* |
| 10 | * Melbourne Trivial IPC mechanism |
| 11 | * |
| 12 | * This is intended solely to serve for the 4.1bsd MUSH implementation |
| 13 | * until a better IPC scheme arrives from somewhere |
| 14 | * |
| 15 | * If it happens to be useful for other purposes, OK, but users |
| 16 | * should be prepared to change at short (no) notice. |
| 17 | * This is purposely kept as small as possible, with the expectation |
| 18 | * than anything done using this scheme should be able to be |
| 19 | * done easily in any other, with possibly a little more legwork. |
| 20 | * |
| 21 | * NB: we don't go fooling with spl's in here, as it is deliberately |
| 22 | * not intended that interrupt level code will ever call this |
| 23 | */ |
| 24 | |
| 25 | mu_msg() |
| 26 | { |
| 27 | register struct proc *p, *pp; |
| 28 | mmsgbuf mb; |
| 29 | register struct a { |
| 30 | msg_type cmd; |
| 31 | int wait; /* bit mask - see mu_msg.h */ |
| 32 | mmsgbuf * msgp; |
| 33 | } *uap; |
| 34 | |
| 35 | uap = (struct a *)u.u_ap; |
| 36 | p = u.u_procp; |
| 37 | |
| 38 | for (;;) { /* only loop if cmd == MSG_SNDW */ |
| 39 | switch (uap->cmd) { |
| 40 | |
| 41 | case MSG_ENAB: |
| 42 | p->p_msgflgs |= MSGENAB; |
| 43 | return; |
| 44 | |
| 45 | case MSG_DISB: |
| 46 | p->p_msgflgs &= ~MSGENAB; |
| 47 | /* |
| 48 | * Q: what should be done with a pending msg |
| 49 | * - for now we will just leave it, proc should |
| 50 | * do a MSG_RECV w/o waiting after MSG_DISB |
| 51 | */ |
| 52 | return; |
| 53 | |
| 54 | case MSG_RECV: |
| 55 | while (!p->p_mb.msg_val && (uap->wait & MSG_W_RCV)) { |
| 56 | p->p_msgflgs |= MSGOK; |
| 57 | sleep((caddr_t) &p->p_mb, MSGPRI); |
| 58 | } |
| 59 | u.u_error = copyout((caddr_t)&p->p_mb, |
| 60 | (caddr_t)uap->msgp, sizeof(mmsgbuf)); |
| 61 | p->p_msgflgs &= ~(MSGOK|MSGWRPLY); |
| 62 | if (p->p_mb.msg_rply) |
| 63 | p->p_msgflgs |= MSGRPLY; |
| 64 | else { |
| 65 | p->p_mb.msg_val = 0; |
| 66 | if (p->p_msgflgs & MSGWAIT) { |
| 67 | p->p_msgflgs &= ~MSGWAIT; |
| 68 | wakeup((caddr_t)&p->p_mb); |
| 69 | } |
| 70 | } |
| 71 | return; |
| 72 | |
| 73 | case MSG_SEND: |
| 74 | case MSG_SNDW: |
| 75 | case MSG_RPLY: |
| 76 | u.u_error = copyin((caddr_t)uap->msgp, (caddr_t)&mb, |
| 77 | sizeof(mmsgbuf)); |
| 78 | if (u.u_error) |
| 79 | return; |
| 80 | if (uap->cmd == MSG_RPLY) { |
| 81 | if (!(p->p_msgflgs & MSGRPLY) || |
| 82 | mb.msg_pid != p->p_mb.msg_pid) { |
| 83 | u.u_error = EINVAL; |
| 84 | return; |
| 85 | } |
| 86 | p->p_mb.msg_val = 0; |
| 87 | if (!mb.msg_rply && p->p_msgflgs & MSGWAIT) { |
| 88 | p->p_msgflgs &= ~MSGWAIT; |
| 89 | wakeup((caddr_t)&p->p_mb); |
| 90 | } |
| 91 | } else { |
| 92 | if (p->p_msgflgs & MSGRPLY) { |
| 93 | while (pp = mu_send(&p->p_mb, |
| 94 | (int)p->p_mb.msg_pid, 0)) { |
| 95 | pp->p_msgflgs |= MSGWAIT; |
| 96 | sleep((caddr_t)&pp->p_mb, |
| 97 | MSGPRI); |
| 98 | } |
| 99 | u.u_error = 0; /* not err if exited */ |
| 100 | p->p_mb.msg_val = 0; |
| 101 | if (!mb.msg_rply && |
| 102 | p->p_msgflgs & MSGWAIT) { |
| 103 | p->p_msgflgs &= ~MSGWAIT; |
| 104 | wakeup((caddr_t)&p->p_mb); |
| 105 | } |
| 106 | } |
| 107 | } |
| 108 | p->p_msgflgs &= ~MSGRPLY; |
| 109 | if (mb.msg_rply) { |
| 110 | if (p->p_mb.msg_val) { |
| 111 | u.u_error = ENOSPC; |
| 112 | return; |
| 113 | } |
| 114 | p->p_mb = mb; |
| 115 | p->p_mb.msg_rply = 0; |
| 116 | p->p_mb.msg_val = 0; |
| 117 | p->p_msgflgs |= MSGWRPLY; |
| 118 | } |
| 119 | mb.msg_uid = u.u_uid; |
| 120 | while ((pp = mu_send(&mb, (int)mb.msg_pid, p->p_pid)) && |
| 121 | uap->wait & MSG_W_POST) { |
| 122 | pp->p_msgflgs |= MSGWAIT; |
| 123 | sleep((caddr_t)&pp->p_mb, MSGPRI); |
| 124 | } |
| 125 | if (pp) |
| 126 | u.u_error = EBUSY; |
| 127 | if (u.u_error) { |
| 128 | if (mb.msg_rply) |
| 129 | p->p_msgflgs &= ~MSGWRPLY; |
| 130 | return; |
| 131 | } |
| 132 | if (uap->cmd == MSG_SNDW) { |
| 133 | uap->cmd = MSG_RECV; |
| 134 | break; |
| 135 | } |
| 136 | return; |
| 137 | |
| 138 | default: |
| 139 | u.u_error = EINVAL; |
| 140 | return; |
| 141 | } |
| 142 | } |
| 143 | } |
| 144 | |
| 145 | struct proc * |
| 146 | mu_send(mp, pid, from) |
| 147 | register mmsgbuf *mp; |
| 148 | register int pid, from; |
| 149 | { |
| 150 | register struct proc *p; |
| 151 | |
| 152 | p = pfind(pid); |
| 153 | |
| 154 | if (p == NULL || p->p_stat == SZOMB || |
| 155 | !(p->p_msgflgs & (MSGOK|MSGENAB|MSGWRPLY))) { |
| 156 | u.u_error = ESRCH; |
| 157 | return((struct proc *)0); |
| 158 | } |
| 159 | |
| 160 | if (p->p_mb.msg_val || |
| 161 | from != 0 && p->p_msgflgs&MSGWRPLY && from != p->p_mb.msg_pid) |
| 162 | return(p); |
| 163 | |
| 164 | p->p_mb = *mp; |
| 165 | p->p_mb.msg_val = 1; |
| 166 | p->p_mb.msg_pid = from; |
| 167 | if (from == 0) |
| 168 | p->p_mb.msg_rply = 0; |
| 169 | if (p->p_msgflgs & MSGOK) |
| 170 | wakeup((caddr_t)&p->p_mb); |
| 171 | else if (p->p_msgflgs & MSGENAB) |
| 172 | psignal(p, SIGMESG); |
| 173 | return((struct proc *)0); |
| 174 | } |
| 175 | |
| 176 | msgto(pid, data) |
| 177 | int pid; |
| 178 | DATA_T data; |
| 179 | { |
| 180 | register struct proc *p; |
| 181 | mmsgbuf mb; |
| 182 | |
| 183 | mb.msg_uid = 0; /* all msgs from system are from root */ |
| 184 | mb.msg_data = data; |
| 185 | mb.msg_rply = 0; |
| 186 | while (p = mu_send(&mb, pid, u.u_procp->p_pid)) { |
| 187 | p->p_msgflgs |= MSGWAIT; |
| 188 | sleep((caddr_t)&p->p_mb, MSGPRI); |
| 189 | } |
| 190 | } |
| 191 | #endif |