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https://github.com/golang/go
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e56c6e7535
SetPanicOnFault allows recovery from unexpected memory faults. This can be useful if you are using a memory-mapped file or probing the address space of the current program. LGTM=r R=r CC=golang-codereviews https://golang.org/cl/66590044
297 lines
6.9 KiB
C
297 lines
6.9 KiB
C
// Copyright 2011 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_GOOS_GOARCH.h"
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#include "os_GOOS.h"
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#include "signal_unix.h"
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#include "stack.h"
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#include "../../cmd/ld/textflag.h"
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extern SigTab runtime·sigtab[];
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extern int32 runtime·sys_umtx_op(uint32*, int32, uint32, void*, void*);
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// From FreeBSD's <sys/sysctl.h>
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#define CTL_HW 6
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#define HW_NCPU 3
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static Sigset sigset_none;
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static Sigset sigset_all = { ~(uint32)0, ~(uint32)0, ~(uint32)0, ~(uint32)0, };
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static int32
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getncpu(void)
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{
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uint32 mib[2];
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uint32 out;
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int32 ret;
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uintptr nout;
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// Fetch hw.ncpu via sysctl.
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mib[0] = CTL_HW;
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mib[1] = HW_NCPU;
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nout = sizeof out;
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out = 0;
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ret = runtime·sysctl(mib, 2, (byte*)&out, &nout, nil, 0);
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if(ret >= 0)
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return out;
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else
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return 1;
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}
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// FreeBSD's umtx_op syscall is effectively the same as Linux's futex, and
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// thus the code is largely similar. See linux/thread.c and lock_futex.c for comments.
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#pragma textflag NOSPLIT
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void
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runtime·futexsleep(uint32 *addr, uint32 val, int64 ns)
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{
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int32 ret;
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Timespec ts;
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if(ns < 0) {
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ret = runtime·sys_umtx_op(addr, UMTX_OP_WAIT_UINT, val, nil, nil);
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if(ret >= 0 || ret == -EINTR)
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return;
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goto fail;
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}
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// NOTE: tv_nsec is int64 on amd64, so this assumes a little-endian system.
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ts.tv_nsec = 0;
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ts.tv_sec = runtime·timediv(ns, 1000000000, (int32*)&ts.tv_nsec);
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ret = runtime·sys_umtx_op(addr, UMTX_OP_WAIT_UINT, val, nil, &ts);
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if(ret >= 0 || ret == -EINTR)
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return;
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fail:
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runtime·prints("umtx_wait addr=");
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runtime·printpointer(addr);
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runtime·prints(" val=");
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runtime·printint(val);
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runtime·prints(" ret=");
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runtime·printint(ret);
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runtime·prints("\n");
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*(int32*)0x1005 = 0x1005;
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}
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void
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runtime·futexwakeup(uint32 *addr, uint32 cnt)
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{
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int32 ret;
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ret = runtime·sys_umtx_op(addr, UMTX_OP_WAKE, cnt, nil, nil);
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if(ret >= 0)
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return;
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runtime·printf("umtx_wake addr=%p ret=%d\n", addr, ret);
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*(int32*)0x1006 = 0x1006;
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}
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void runtime·thr_start(void*);
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void
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runtime·newosproc(M *mp, void *stk)
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{
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ThrParam param;
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Sigset oset;
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if(0){
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runtime·printf("newosproc stk=%p m=%p g=%p id=%d/%d ostk=%p\n",
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stk, mp, mp->g0, mp->id, (int32)mp->tls[0], &mp);
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}
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runtime·sigprocmask(&sigset_all, &oset);
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runtime·memclr((byte*)¶m, sizeof param);
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param.start_func = runtime·thr_start;
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param.arg = (byte*)mp;
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// NOTE(rsc): This code is confused. stackbase is the top of the stack
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// and is equal to stk. However, it's working, so I'm not changing it.
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param.stack_base = (void*)mp->g0->stackbase;
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param.stack_size = (byte*)stk - (byte*)mp->g0->stackbase;
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param.child_tid = (intptr*)&mp->procid;
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param.parent_tid = nil;
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param.tls_base = (void*)&mp->tls[0];
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param.tls_size = sizeof mp->tls;
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mp->tls[0] = mp->id; // so 386 asm can find it
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runtime·thr_new(¶m, sizeof param);
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runtime·sigprocmask(&oset, nil);
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}
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void
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runtime·osinit(void)
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{
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runtime·ncpu = getncpu();
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}
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void
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runtime·get_random_data(byte **rnd, int32 *rnd_len)
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{
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static byte urandom_data[HashRandomBytes];
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int32 fd;
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fd = runtime·open("/dev/urandom", 0 /* O_RDONLY */, 0);
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if(runtime·read(fd, urandom_data, HashRandomBytes) == HashRandomBytes) {
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*rnd = urandom_data;
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*rnd_len = HashRandomBytes;
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} else {
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*rnd = nil;
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*rnd_len = 0;
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}
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runtime·close(fd);
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}
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void
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runtime·goenvs(void)
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{
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runtime·goenvs_unix();
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}
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// Called to initialize a new m (including the bootstrap m).
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// Called on the parent thread (main thread in case of bootstrap), can allocate memory.
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void
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runtime·mpreinit(M *mp)
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{
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mp->gsignal = runtime·malg(32*1024);
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}
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// Called to initialize a new m (including the bootstrap m).
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// Called on the new thread, can not allocate memory.
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void
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runtime·minit(void)
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{
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// Initialize signal handling
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runtime·signalstack((byte*)m->gsignal->stackguard - StackGuard, 32*1024);
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runtime·sigprocmask(&sigset_none, nil);
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}
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// Called from dropm to undo the effect of an minit.
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void
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runtime·unminit(void)
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{
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runtime·signalstack(nil, 0);
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}
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void
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runtime·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 || g->paniconfault) {
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if(g->sigpc == 0)
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runtime·panicstring("call of nil func value");
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runtime·panicstring("invalid memory address or nil pointer dereference");
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}
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runtime·printf("unexpected fault address %p\n", g->sigcode1);
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runtime·throw("fault");
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case SIGSEGV:
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if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000 || g->paniconfault) {
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if(g->sigpc == 0)
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runtime·panicstring("call of nil func value");
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runtime·panicstring("invalid memory address or nil pointer dereference");
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}
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runtime·printf("unexpected fault address %p\n", g->sigcode1);
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runtime·throw("fault");
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case SIGFPE:
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switch(g->sigcode0) {
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case FPE_INTDIV:
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runtime·panicstring("integer divide by zero");
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case FPE_INTOVF:
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runtime·panicstring("integer overflow");
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}
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runtime·panicstring("floating point error");
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}
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runtime·panicstring(runtime·sigtab[g->sig].name);
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}
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uintptr
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runtime·memlimit(void)
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{
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Rlimit rl;
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extern byte text[], end[];
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uintptr used;
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if(runtime·getrlimit(RLIMIT_AS, &rl) != 0)
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return 0;
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if(rl.rlim_cur >= 0x7fffffff)
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return 0;
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// Estimate our VM footprint excluding the heap.
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// Not an exact science: use size of binary plus
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// some room for thread stacks.
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used = end - text + (64<<20);
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if(used >= rl.rlim_cur)
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return 0;
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// If there's not at least 16 MB left, we're probably
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// not going to be able to do much. Treat as no limit.
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rl.rlim_cur -= used;
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if(rl.rlim_cur < (16<<20))
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return 0;
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return rl.rlim_cur - used;
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}
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extern void runtime·sigtramp(void);
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typedef struct sigaction {
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union {
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void (*__sa_handler)(int32);
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void (*__sa_sigaction)(int32, Siginfo*, void *);
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} __sigaction_u; /* signal handler */
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int32 sa_flags; /* see signal options below */
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Sigset sa_mask; /* signal mask to apply */
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} Sigaction;
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void
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runtime·setsig(int32 i, GoSighandler *fn, bool restart)
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{
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Sigaction sa;
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runtime·memclr((byte*)&sa, sizeof sa);
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sa.sa_flags = SA_SIGINFO|SA_ONSTACK;
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if(restart)
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sa.sa_flags |= SA_RESTART;
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sa.sa_mask.__bits[0] = ~(uint32)0;
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sa.sa_mask.__bits[1] = ~(uint32)0;
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sa.sa_mask.__bits[2] = ~(uint32)0;
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sa.sa_mask.__bits[3] = ~(uint32)0;
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if(fn == runtime·sighandler)
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fn = (void*)runtime·sigtramp;
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sa.__sigaction_u.__sa_sigaction = (void*)fn;
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runtime·sigaction(i, &sa, nil);
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}
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GoSighandler*
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runtime·getsig(int32 i)
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{
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Sigaction sa;
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runtime·memclr((byte*)&sa, sizeof sa);
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runtime·sigaction(i, nil, &sa);
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if((void*)sa.__sigaction_u.__sa_sigaction == runtime·sigtramp)
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return runtime·sighandler;
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return (void*)sa.__sigaction_u.__sa_sigaction;
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}
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void
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runtime·signalstack(byte *p, int32 n)
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{
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StackT st;
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st.ss_sp = (void*)p;
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st.ss_size = n;
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st.ss_flags = 0;
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if(p == nil)
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st.ss_flags = SS_DISABLE;
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runtime·sigaltstack(&st, nil);
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}
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void
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runtime·unblocksignals(void)
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{
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runtime·sigprocmask(&sigset_none, nil);
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}
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