text: // Copyright 2016 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  // +build cgo
  
  #include <pthread.h>
  #include <string.h>
  #include <signal.h>
  #include <ucontext.h>
  #include "libcgo.h"
  
  static void* threadentry(void*);
  static void (*setg_gcc)(void*);
  
  void
  x_cgo_init(G *g, void (*setg)(void*))
  {
  	ucontext_t ctx;
  
  	setg_gcc = setg;
  	if (getcontext(&ctx) != 0)
  		perror("runtime/cgo: getcontext failed");
  	g->stacklo = (uintptr_t)ctx.uc_stack.ss_sp;
  
  	// Solaris processes report a tiny stack when run with "ulimit -s unlimited".
  	// Correct that as best we can: assume it's at least 1 MB.
  	// See golang.org/issue/12210.
  	if(ctx.uc_stack.ss_size < 1024*1024)
  		g->stacklo -= 1024*1024 - ctx.uc_stack.ss_size;
  }
  
  void
  _cgo_sys_thread_start(ThreadStart *ts)
  {
  	pthread_attr_t attr;
  	sigset_t ign, oset;
  	pthread_t p;
  	void *base;
  	size_t size;
  	int err;
  
  	sigfillset(&ign);
  	pthread_sigmask(SIG_SETMASK, &ign, &oset);
  
  	pthread_attr_init(&attr);
  
  	if (pthread_attr_getstack(&attr, &base, &size) != 0)
  		perror("runtime/cgo: pthread_attr_getstack failed");
  	if (size == 0) {
  		ts->g->stackhi = 2 << 20;
  		if (pthread_attr_setstack(&attr, NULL, ts->g->stackhi) != 0)
  			perror("runtime/cgo: pthread_attr_setstack failed");
  	} else {
  		ts->g->stackhi = size;
  	}
  	pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
  	err = pthread_create(&p, &attr, threadentry, ts);
  
  	pthread_sigmask(SIG_SETMASK, &oset, nil);
  
  	if (err != 0) {
  		fprintf(stderr, "runtime/cgo: pthread_create failed: %s\n", strerror(err));
  		abort();
  	}
  }
  
  extern void crosscall1(void (*fn)(void), void (*setg_gcc)(void*), void *g);
  static void*
  threadentry(void *v)
  {
  	ThreadStart ts;
  
  	ts = *(ThreadStart*)v;
  	free(v);
  
  	crosscall1(ts.fn, setg_gcc, (void*)ts.g);
  	return nil;
  }
  