mirror of
https://github.com/golang/go
synced 2024-10-05 06:21:24 -06:00
718da3339a
Fixes #549. R=adg CC=golang-dev https://golang.org/cl/1019042
472 lines
9.2 KiB
C
472 lines
9.2 KiB
C
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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#include "runtime.h"
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#include "defs.h"
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#include "os.h"
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extern SigTab sigtab[];
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static void
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unimplemented(int8 *name)
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{
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prints(name);
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prints(" not implemented\n");
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*(int32*)1231 = 1231;
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}
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// Thread-safe allocation of a semaphore.
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// Psema points at a kernel semaphore key.
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// It starts out zero, meaning no semaphore.
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// Fill it in, being careful of others calling initsema
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// simultaneously.
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static void
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initsema(uint32 *psema)
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{
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uint32 sema;
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if(*psema != 0) // already have one
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return;
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sema = mach_semcreate();
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if(!cas(psema, 0, sema)){
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// Someone else filled it in. Use theirs.
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mach_semdestroy(sema);
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return;
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}
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}
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// Blocking locks.
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// Implement Locks, using semaphores.
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// l->key is the number of threads who want the lock.
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// In a race, one thread increments l->key from 0 to 1
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// and the others increment it from >0 to >1. The thread
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// who does the 0->1 increment gets the lock, and the
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// others wait on the semaphore. When the 0->1 thread
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// releases the lock by decrementing l->key, l->key will
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// be >0, so it will increment the semaphore to wake up
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// one of the others. This is the same algorithm used
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// in Plan 9's user-level locks.
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void
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lock(Lock *l)
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{
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if(m->locks < 0)
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throw("lock count");
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m->locks++;
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if(xadd(&l->key, 1) > 1) { // someone else has it; wait
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// Allocate semaphore if needed.
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if(l->sema == 0)
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initsema(&l->sema);
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mach_semacquire(l->sema);
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}
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}
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void
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unlock(Lock *l)
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{
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m->locks--;
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if(m->locks < 0)
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throw("lock count");
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if(xadd(&l->key, -1) > 0) { // someone else is waiting
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// Allocate semaphore if needed.
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if(l->sema == 0)
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initsema(&l->sema);
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mach_semrelease(l->sema);
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}
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}
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void
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destroylock(Lock *l)
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{
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if(l->sema != 0) {
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mach_semdestroy(l->sema);
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l->sema = 0;
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}
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}
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// User-level semaphore implementation:
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// try to do the operations in user space on u,
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// but when it's time to block, fall back on the kernel semaphore k.
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// This is the same algorithm used in Plan 9.
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void
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usemacquire(Usema *s)
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{
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if((int32)xadd(&s->u, -1) < 0) {
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if(s->k == 0)
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initsema(&s->k);
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mach_semacquire(s->k);
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}
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}
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void
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usemrelease(Usema *s)
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{
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if((int32)xadd(&s->u, 1) <= 0) {
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if(s->k == 0)
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initsema(&s->k);
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mach_semrelease(s->k);
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}
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}
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// Event notifications.
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void
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noteclear(Note *n)
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{
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n->wakeup = 0;
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}
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void
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notesleep(Note *n)
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{
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while(!n->wakeup)
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usemacquire(&n->sema);
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}
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void
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notewakeup(Note *n)
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{
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n->wakeup = 1;
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usemrelease(&n->sema);
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}
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// BSD interface for threading.
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void
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osinit(void)
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{
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// Register our thread-creation callback (see {amd64,386}/sys.s)
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// but only if we're not using cgo. If we are using cgo we need
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// to let the C pthread libary install its own thread-creation callback.
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extern void (*libcgo_thread_start)(void*);
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if(libcgo_thread_start == nil)
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bsdthread_register();
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}
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void
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newosproc(M *m, G *g, void *stk, void (*fn)(void))
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{
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m->tls[0] = m->id; // so 386 asm can find it
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if(0){
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printf("newosproc stk=%p m=%p g=%p fn=%p id=%d/%d ostk=%p\n",
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stk, m, g, fn, m->id, m->tls[0], &m);
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}
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if(bsdthread_create(stk, m, g, fn) < 0)
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throw("cannot create new OS thread");
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}
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// Called to initialize a new m (including the bootstrap m).
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void
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minit(void)
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{
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// Initialize signal handling.
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m->gsignal = malg(32*1024); // OS X wants >=8K, Linux >=2K
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signalstack(m->gsignal->stackguard, 32*1024);
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}
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// Mach IPC, to get at semaphores
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// Definitions are in /usr/include/mach on a Mac.
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static void
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macherror(int32 r, int8 *fn)
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{
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printf("mach error %s: %d\n", fn, r);
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throw("mach error");
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}
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enum
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{
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DebugMach = 0
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};
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static MachNDR zerondr;
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#define MACH_MSGH_BITS(a, b) ((a) | ((b)<<8))
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static int32
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mach_msg(MachHeader *h,
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int32 op,
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uint32 send_size,
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uint32 rcv_size,
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uint32 rcv_name,
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uint32 timeout,
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uint32 notify)
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{
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// TODO: Loop on interrupt.
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return mach_msg_trap(h, op, send_size, rcv_size, rcv_name, timeout, notify);
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}
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// Mach RPC (MIG)
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enum
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{
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MinMachMsg = 48,
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Reply = 100,
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};
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#pragma pack on
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typedef struct CodeMsg CodeMsg;
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struct CodeMsg
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{
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MachHeader h;
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MachNDR NDR;
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int32 code;
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};
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#pragma pack off
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static int32
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machcall(MachHeader *h, int32 maxsize, int32 rxsize)
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{
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uint32 *p;
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int32 i, ret, id;
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uint32 port;
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CodeMsg *c;
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if((port = m->machport) == 0){
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port = mach_reply_port();
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m->machport = port;
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}
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h->msgh_bits |= MACH_MSGH_BITS(MACH_MSG_TYPE_COPY_SEND, MACH_MSG_TYPE_MAKE_SEND_ONCE);
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h->msgh_local_port = port;
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h->msgh_reserved = 0;
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id = h->msgh_id;
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if(DebugMach){
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p = (uint32*)h;
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prints("send:\t");
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for(i=0; i<h->msgh_size/sizeof(p[0]); i++){
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prints(" ");
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·printpointer((void*)p[i]);
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if(i%8 == 7)
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prints("\n\t");
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}
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if(i%8)
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prints("\n");
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}
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ret = mach_msg(h, MACH_SEND_MSG|MACH_RCV_MSG,
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h->msgh_size, maxsize, port, 0, 0);
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if(ret != 0){
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if(DebugMach){
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prints("mach_msg error ");
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·printint(ret);
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prints("\n");
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}
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return ret;
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}
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if(DebugMach){
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p = (uint32*)h;
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prints("recv:\t");
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for(i=0; i<h->msgh_size/sizeof(p[0]); i++){
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prints(" ");
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·printpointer((void*)p[i]);
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if(i%8 == 7)
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prints("\n\t");
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}
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if(i%8)
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prints("\n");
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}
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if(h->msgh_id != id+Reply){
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if(DebugMach){
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prints("mach_msg reply id mismatch ");
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·printint(h->msgh_id);
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prints(" != ");
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·printint(id+Reply);
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prints("\n");
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}
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return -303; // MIG_REPLY_MISMATCH
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}
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// Look for a response giving the return value.
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// Any call can send this back with an error,
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// and some calls only have return values so they
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// send it back on success too. I don't quite see how
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// you know it's one of these and not the full response
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// format, so just look if the message is right.
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c = (CodeMsg*)h;
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if(h->msgh_size == sizeof(CodeMsg)
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&& !(h->msgh_bits & MACH_MSGH_BITS_COMPLEX)){
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if(DebugMach){
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prints("mig result ");
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·printint(c->code);
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prints("\n");
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}
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return c->code;
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}
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if(h->msgh_size != rxsize){
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if(DebugMach){
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prints("mach_msg reply size mismatch ");
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·printint(h->msgh_size);
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prints(" != ");
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·printint(rxsize);
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prints("\n");
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}
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return -307; // MIG_ARRAY_TOO_LARGE
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}
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return 0;
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}
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// Semaphores!
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enum
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{
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Tmach_semcreate = 3418,
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Rmach_semcreate = Tmach_semcreate + Reply,
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Tmach_semdestroy = 3419,
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Rmach_semdestroy = Tmach_semdestroy + Reply,
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// Mach calls that get interrupted by Unix signals
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// return this error code. We retry them.
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KERN_ABORTED = 14,
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};
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typedef struct Tmach_semcreateMsg Tmach_semcreateMsg;
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typedef struct Rmach_semcreateMsg Rmach_semcreateMsg;
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typedef struct Tmach_semdestroyMsg Tmach_semdestroyMsg;
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// Rmach_semdestroyMsg = CodeMsg
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#pragma pack on
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struct Tmach_semcreateMsg
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{
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MachHeader h;
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MachNDR ndr;
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int32 policy;
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int32 value;
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};
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struct Rmach_semcreateMsg
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{
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MachHeader h;
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MachBody body;
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MachPort semaphore;
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};
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struct Tmach_semdestroyMsg
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{
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MachHeader h;
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MachBody body;
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MachPort semaphore;
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};
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#pragma pack off
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uint32
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mach_semcreate(void)
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{
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union {
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Tmach_semcreateMsg tx;
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Rmach_semcreateMsg rx;
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uint8 pad[MinMachMsg];
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} m;
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int32 r;
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m.tx.h.msgh_bits = 0;
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m.tx.h.msgh_size = sizeof(m.tx);
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m.tx.h.msgh_remote_port = mach_task_self();
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m.tx.h.msgh_id = Tmach_semcreate;
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m.tx.ndr = zerondr;
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m.tx.policy = 0; // 0 = SYNC_POLICY_FIFO
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m.tx.value = 0;
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while((r = machcall(&m.tx.h, sizeof m, sizeof(m.rx))) != 0){
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if(r == KERN_ABORTED) // interrupted
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continue;
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macherror(r, "semaphore_create");
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}
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if(m.rx.body.msgh_descriptor_count != 1)
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unimplemented("mach_semcreate desc count");
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return m.rx.semaphore.name;
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}
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void
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mach_semdestroy(uint32 sem)
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{
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union {
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Tmach_semdestroyMsg tx;
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uint8 pad[MinMachMsg];
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} m;
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int32 r;
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m.tx.h.msgh_bits = MACH_MSGH_BITS_COMPLEX;
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m.tx.h.msgh_size = sizeof(m.tx);
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m.tx.h.msgh_remote_port = mach_task_self();
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m.tx.h.msgh_id = Tmach_semdestroy;
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m.tx.body.msgh_descriptor_count = 1;
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m.tx.semaphore.name = sem;
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m.tx.semaphore.disposition = MACH_MSG_TYPE_MOVE_SEND;
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m.tx.semaphore.type = 0;
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while((r = machcall(&m.tx.h, sizeof m, 0)) != 0){
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if(r == KERN_ABORTED) // interrupted
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continue;
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macherror(r, "semaphore_destroy");
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}
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}
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// The other calls have simple system call traps in sys.s
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int32 mach_semaphore_wait(uint32 sema);
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int32 mach_semaphore_timedwait(uint32 sema, uint32 sec, uint32 nsec);
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int32 mach_semaphore_signal(uint32 sema);
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int32 mach_semaphore_signal_all(uint32 sema);
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void
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mach_semacquire(uint32 sem)
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{
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int32 r;
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while((r = mach_semaphore_wait(sem)) != 0) {
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if(r == KERN_ABORTED) // interrupted
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continue;
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macherror(r, "semaphore_wait");
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}
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}
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void
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mach_semrelease(uint32 sem)
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{
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int32 r;
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while((r = mach_semaphore_signal(sem)) != 0) {
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if(r == KERN_ABORTED) // interrupted
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continue;
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macherror(r, "semaphore_signal");
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}
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}
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void
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sigpanic(void)
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{
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switch(g->sig) {
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case SIGBUS:
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if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000)
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panicstring("invalid memory address or nil pointer dereference");
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break;
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case SIGSEGV:
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if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR) && g->sigcode1 < 0x1000)
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panicstring("invalid memory address or nil pointer dereference");
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break;
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case SIGFPE:
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switch(g->sigcode0) {
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case FPE_INTDIV:
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panicstring("integer divide by zero");
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case FPE_INTOVF:
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panicstring("integer overflow");
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}
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panicstring("floating point error");
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}
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panicstring(sigtab[g->sig].name);
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}
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