libcoro/coro.c

/*
 * Copyright (c) 2001-2008 Marc Alexander Lehmann <schmorp@schmorp.de>
 * 
 * Redistribution and use in source and binary forms, with or without modifica-
 * tion, are permitted provided that the following conditions are met:
 * 
 *   1.  Redistributions of source code must retain the above copyright notice,
 *       this list of conditions and the following disclaimer.
 * 
 *   2.  Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
 * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
 * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
 * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License ("GPL") version 2 or any later version,
 * in which case the provisions of the GPL are applicable instead of
 * the above. If you wish to allow the use of your version of this file
 * only under the terms of the GPL and not to allow others to use your
 * version of this file under the BSD license, indicate your decision
 * by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL. If you do not delete the
 * provisions above, a recipient may use your version of this file under
 * either the BSD or the GPL.
 *
 * This library is modelled strictly after Ralf S. Engelschalls article at
 * http://www.gnu.org/software/pth/rse-pmt.ps. So most of the credit must
 * go to Ralf S. Engelschall <rse@engelschall.com>.
 */

#include "coro.h"

#include <string.h>

#if !defined(STACK_ADJUST_PTR)
/* IRIX is decidedly NON-unix */
# if __sgi
#  define STACK_ADJUST_PTR(sp,ss) ((char *)(sp) + (ss) - 8)
#  define STACK_ADJUST_SIZE(sp,ss) ((ss) - 8)
# elif (__i386__ && CORO_LINUX) || (_M_IX86 && CORO_LOSER)
#  define STACK_ADJUST_PTR(sp,ss) ((char *)(sp) + (ss))
#  define STACK_ADJUST_SIZE(sp,ss) (ss)
# elif (__amd64__ && CORO_LINUX) || ((_M_AMD64 || _M_IA64) && CORO_LOSER)
#  define STACK_ADJUST_PTR(sp,ss) ((char *)(sp) + (ss) - 8)
#  define STACK_ADJUST_SIZE(sp,ss) (ss)
# else
#  define STACK_ADJUST_PTR(sp,ss) (sp)
#  define STACK_ADJUST_SIZE(sp,ss) (ss)
# endif
#endif

#if CORO_UCONTEXT
# include <stddef.h>
#endif

#if CORO_SJLJ || CORO_LOSER || CORO_LINUX || CORO_IRIX || CORO_ASM

# include <stdlib.h>

# if CORO_SJLJ
#  include <stdio.h>
#  include <signal.h>
#  include <unistd.h>
# endif

static volatile coro_func coro_init_func;
static volatile void *coro_init_arg;
static volatile coro_context *new_coro, *create_coro;

/* what we really want to detect here is wether we use a new-enough version of GAS */
/* instead, check for gcc 3, ELF and GNU/Linux and hope for the best */
# if __GNUC__ >= 3 && __ELF__ && __linux__
#  define HAVE_CFI 1
# endif

static void
coro_init (void)
{
  volatile coro_func func = coro_init_func;
  volatile void *arg = coro_init_arg;

  coro_transfer ((coro_context *)new_coro, (coro_context *)create_coro);

  func ((void *)arg);

  /* the new coro returned. bad. just abort() for now */
  abort ();
}

# if CORO_SJLJ

static volatile int trampoline_count;

/* trampoline signal handler */
static void
trampoline (int sig)
{
  if (setjmp (((coro_context *)new_coro)->env))
    {
#  if HAVE_CFI
      asm (".cfi_startproc");
#  endif
      coro_init (); /* start it */
#  if HAVE_CFI
      asm (".cfi_endproc");
#  endif
    }
  else
    trampoline_count++;
}

# endif

#endif

#if CORO_ASM

  asm (
       ".text\n"
       ".globl coro_transfer\n"
       ".type coro_transfer, @function\n"
       "coro_transfer:\n"
# if __amd64
#  define NUM_SAVED 6
       "\tpush %rbp\n"
       "\tpush %rbx\n"
       "\tpush %r12\n"
       "\tpush %r13\n"
       "\tpush %r14\n"
       "\tpush %r15\n"
       "\tmov  %rsp, (%rdi)\n"
       "\tmov  (%rsi), %rsp\n"
       "\tpop  %r15\n"
       "\tpop  %r14\n"
       "\tpop  %r13\n"
       "\tpop  %r12\n"
       "\tpop  %rbx\n"
       "\tpop  %rbp\n"
# elif __i386
#  define NUM_SAVED 4
       "\tpush %ebp\n"
       "\tpush %ebx\n"
       "\tpush %esi\n"
       "\tpush %edi\n"
       "\tmov  %esp, (%eax)\n"
       "\tmov  (%edx), %esp\n"
       "\tpop  %edi\n"
       "\tpop  %esi\n"
       "\tpop  %ebx\n"
       "\tpop  %ebp\n"
# else
#  error unsupported architecture
# endif
       "\tret\n"
  );

#endif

#if CORO_PTHREAD

/* this mutex will be locked by the running coroutine */
pthread_mutex_t coro_mutex = PTHREAD_MUTEX_INITIALIZER;

struct coro_init_args
{
  coro_func func;
  void *arg;
  coro_context *self, *main;
};

static pthread_t null_tid;

/* I'd so love to cast pthread_mutex_unlock to void (*)(void *)... */
static void
mutex_unlock_wrapper (void *arg)
{
  pthread_mutex_unlock ((pthread_mutex_t *)arg);
}

static void *
trampoline (void *args_)
{
  struct coro_init_args *args = (struct coro_init_args *)args_;
  coro_func func = args->func;
  void *arg = args->arg;

  pthread_mutex_lock (&coro_mutex);

  /* we try to be good citizens and use deferred cancellation and cleanup handlers */
  pthread_cleanup_push (mutex_unlock_wrapper, &coro_mutex);
    coro_transfer (args->self, args->main);
    func (arg);
  pthread_cleanup_pop (1);

  return 0;
}

void
coro_transfer (coro_context *prev, coro_context *next)
{
  pthread_cond_signal (&next->cv);
  pthread_cond_wait (&prev->cv, &coro_mutex);
}

void
coro_destroy (coro_context *ctx)
{
  if (!pthread_equal (ctx->id, null_tid))
    {
      pthread_cancel (ctx->id);
      pthread_mutex_unlock (&coro_mutex);
      pthread_join (ctx->id, 0);
      pthread_mutex_lock (&coro_mutex);
    }

  pthread_cond_destroy (&ctx->cv);
}

#endif

/* initialize a machine state */
void
coro_create (coro_context *ctx, coro_func coro, void *arg, void *sptr, long ssize)
{
#if CORO_UCONTEXT

  if (!coro)
    return;

  getcontext (&(ctx->uc));

  ctx->uc.uc_link           =  0;
  ctx->uc.uc_stack.ss_sp    = STACK_ADJUST_PTR (sptr,ssize);
  ctx->uc.uc_stack.ss_size  = (size_t)STACK_ADJUST_SIZE (sptr,ssize);
  ctx->uc.uc_stack.ss_flags = 0;

  makecontext (&(ctx->uc), (void (*)())coro, 1, arg);

#elif CORO_SJLJ || CORO_LOSER || CORO_LINUX || CORO_IRIX || CORO_ASM

# if CORO_SJLJ
  stack_t ostk, nstk;
  struct sigaction osa, nsa;
  sigset_t nsig, osig;
# endif
  coro_context nctx;

  if (!coro)
    return;

  coro_init_func = coro;
  coro_init_arg  = arg;

  new_coro    = ctx;
  create_coro = &nctx;

# if CORO_SJLJ
  /* we use SIGUSR2. first block it, then fiddle with it. */

  sigemptyset (&nsig);
  sigaddset (&nsig, SIGUSR2);
  sigprocmask (SIG_BLOCK, &nsig, &osig);

  nsa.sa_handler = trampoline;
  sigemptyset (&nsa.sa_mask);
  nsa.sa_flags = SA_ONSTACK;

  if (sigaction (SIGUSR2, &nsa, &osa))
    {
      perror ("sigaction");
      abort ();
    }

  /* set the new stack */
  nstk.ss_sp    = STACK_ADJUST_PTR (sptr,ssize); /* yes, some platforms (IRIX) get this wrong. */
  nstk.ss_size  = STACK_ADJUST_SIZE (sptr,ssize);
  nstk.ss_flags = 0;

  if (sigaltstack (&nstk, &ostk) < 0)
    {
      perror ("sigaltstack");
      abort ();
    }

  trampoline_count = 0;
  kill (getpid (), SIGUSR2);
  sigfillset (&nsig); sigdelset (&nsig, SIGUSR2);

  while (!trampoline_count)
    sigsuspend (&nsig);

  sigaltstack (0, &nstk);
  nstk.ss_flags = SS_DISABLE;
  if (sigaltstack (&nstk, 0) < 0)
    perror ("sigaltstack");

  sigaltstack (0, &nstk);
  if (~nstk.ss_flags & SS_DISABLE)
    abort ();

  if (~ostk.ss_flags & SS_DISABLE)
    sigaltstack (&ostk, 0);

  sigaction (SIGUSR2, &osa, 0);

  sigprocmask (SIG_SETMASK, &osig, 0);

# elif CORO_LOSER

  setjmp (ctx->env);
#if __CYGWIN__
  ctx->env[7] = (long)((char *)sptr + ssize) - sizeof (long);
  ctx->env[8] = (long)coro_init;
#elif defined(_M_IX86)
  ((_JUMP_BUFFER *)&ctx->env)->Eip   = (long)coro_init;
  ((_JUMP_BUFFER *)&ctx->env)->Esp   = (long)STACK_ADJUST_PTR (sptr, ssize) - sizeof (long);
#elif defined(_M_AMD64)
  ((_JUMP_BUFFER *)&ctx->env)->Rip   = (__int64)coro_init;
  ((_JUMP_BUFFER *)&ctx->env)->Rsp   = (__int64)STACK_ADJUST_PTR (sptr, ssize) - sizeof (long);
#elif defined(_M_IA64)
  ((_JUMP_BUFFER *)&ctx->env)->StIIP = (__int64)coro_init;
  ((_JUMP_BUFFER *)&ctx->env)->IntSp = (__int64)STACK_ADJUST_PTR (sptr, ssize) - sizeof (long);
#else
# error "microsoft libc or architecture not supported"
#endif

# elif CORO_LINUX

  _setjmp (ctx->env);
#if __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 0 && defined (JB_PC) && defined (JB_SP)
  ctx->env[0].__jmpbuf[JB_PC] = (long)coro_init;
  ctx->env[0].__jmpbuf[JB_SP] = (long)STACK_ADJUST_PTR (sptr, ssize) - sizeof (long);
#elif __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 0 && defined (__mc68000__)
  ctx->env[0].__jmpbuf[0].__aregs[0] = (long int)coro_init;
  ctx->env[0].__jmpbuf[0].__sp = (int *)((char *)sptr + ssize) - sizeof (long);
#elif defined (__GNU_LIBRARY__) && defined (__i386__)
  ctx->env[0].__jmpbuf[0].__pc = (char *)coro_init;
  ctx->env[0].__jmpbuf[0].__sp = (void *)((char *)sptr + ssize) - sizeof (long);
#elif defined (__GNU_LIBRARY__) && defined (__amd64__)
  ctx->env[0].__jmpbuf[JB_PC]  = (long)coro_init;
  ctx->env[0].__jmpbuf[0].__sp = (void *)((char *)sptr + ssize) - sizeof (long);
#else
# error "linux libc or architecture not supported"
#endif

# elif CORO_IRIX

  setjmp (ctx->env);
  ctx->env[JB_PC] = (__uint64_t)coro_init;
  ctx->env[JB_SP] = (__uint64_t)STACK_ADJUST_PTR (sptr, ssize) - sizeof (long);

# elif CORO_ASM

  ctx->sp = (volatile void **)(ssize + (char *)sptr);
  *--ctx->sp = (void *)abort; /* needed for alignment only */
  *--ctx->sp = (void *)coro_init;
  ctx->sp -= NUM_SAVED;

# endif

  coro_transfer ((coro_context *)create_coro, (coro_context *)new_coro);

# elif CORO_PTHREAD

  static coro_context nctx;
  static int once;

  if (!once)
    {
      once = 1;

      pthread_mutex_lock (&coro_mutex);
      pthread_cond_init (&nctx.cv, 0);
      null_tid = pthread_self ();
    }

  pthread_cond_init (&ctx->cv, 0);

  if (coro)
    {
      pthread_attr_t attr;
      struct coro_init_args args;

      args.func = coro;
      args.arg  = arg;
      args.self = ctx;
      args.main = &nctx;

      pthread_attr_init (&attr);
      pthread_attr_setstack (&attr, sptr, (size_t)ssize);
      pthread_attr_setscope (&attr, PTHREAD_SCOPE_PROCESS);
      pthread_create (&ctx->id, &attr, trampoline, &args);

      coro_transfer (args.main, args.self);
    }
  else
    ctx->id = null_tid;

#else
# error unsupported backend
#endif
}

Revision:	1.38
Committed:	Fri Nov 7 20:12:26 2008 UTC (15 years, 6 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.37:	+125 -83 lines
Log Message:	* empty log message *
#	Content
1	/*
2	* Copyright (c) 2001-2008 Marc Alexander Lehmann <schmorp@schmorp.de>
3	*
4	* Redistribution and use in source and binary forms, with or without modifica-
5	* tion, are permitted provided that the following conditions are met:
6	*
7	* 1. Redistributions of source code must retain the above copyright notice,
8	* this list of conditions and the following disclaimer.
9	*
10	* 2. Redistributions in binary form must reproduce the above copyright
11	* notice, this list of conditions and the following disclaimer in the
12	* documentation and/or other materials provided with the distribution.
13	*
14	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
15	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
16	* CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
17	* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
18	* CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19	* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
20	* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
21	* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
22	* ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
23	* OF THE POSSIBILITY OF SUCH DAMAGE.
24	*
25	* Alternatively, the contents of this file may be used under the terms of
26	* the GNU General Public License ("GPL") version 2 or any later version,
27	* in which case the provisions of the GPL are applicable instead of
28	* the above. If you wish to allow the use of your version of this file
29	* only under the terms of the GPL and not to allow others to use your
30	* version of this file under the BSD license, indicate your decision
31	* by deleting the provisions above and replace them with the notice
32	* and other provisions required by the GPL. If you do not delete the
33	* provisions above, a recipient may use your version of this file under
34	* either the BSD or the GPL.
35	*
36	* This library is modelled strictly after Ralf S. Engelschalls article at
37	* http://www.gnu.org/software/pth/rse-pmt.ps. So most of the credit must
38	* go to Ralf S. Engelschall <rse@engelschall.com>.
39	*/
40
41	#include "coro.h"
42
43	#include <string.h>
44
45	#if !defined(STACK_ADJUST_PTR)
46	/* IRIX is decidedly NON-unix */
47	# if __sgi
48	# define STACK_ADJUST_PTR(sp,ss) ((char *)(sp) + (ss) - 8)
49	# define STACK_ADJUST_SIZE(sp,ss) ((ss) - 8)
50	# elif (__i386__ && CORO_LINUX) \|\| (_M_IX86 && CORO_LOSER)
51	# define STACK_ADJUST_PTR(sp,ss) ((char *)(sp) + (ss))
52	# define STACK_ADJUST_SIZE(sp,ss) (ss)
53	# elif (__amd64__ && CORO_LINUX) \|\| ((_M_AMD64 \|\| _M_IA64) && CORO_LOSER)
54	# define STACK_ADJUST_PTR(sp,ss) ((char *)(sp) + (ss) - 8)
55	# define STACK_ADJUST_SIZE(sp,ss) (ss)
56	# else
57	# define STACK_ADJUST_PTR(sp,ss) (sp)
58	# define STACK_ADJUST_SIZE(sp,ss) (ss)
59	# endif
60	#endif
61
62	#if CORO_UCONTEXT
63	# include <stddef.h>
64	#endif
65
66	#if CORO_SJLJ \|\| CORO_LOSER \|\| CORO_LINUX \|\| CORO_IRIX \|\| CORO_ASM
67
68	# include <stdlib.h>
69
70	# if CORO_SJLJ
71	# include <stdio.h>
72	# include <signal.h>
73	# include <unistd.h>
74	# endif
75
76	static volatile coro_func coro_init_func;
77	static volatile void *coro_init_arg;
78	static volatile coro_context new_coro, create_coro;
79
80	/* what we really want to detect here is wether we use a new-enough version of GAS */
81	/* instead, check for gcc 3, ELF and GNU/Linux and hope for the best */
82	# if __GNUC__ >= 3 && __ELF__ && __linux__
83	# define HAVE_CFI 1
84	# endif
85
86	static void
87	coro_init (void)
88	{
89	volatile coro_func func = coro_init_func;
90	volatile void *arg = coro_init_arg;
91
92	coro_transfer ((coro_context )new_coro, (coro_context )create_coro);
93
94	func ((void *)arg);
95
96	/* the new coro returned. bad. just abort() for now */
97	abort ();
98	}
99
100	# if CORO_SJLJ
101
102	static volatile int trampoline_count;
103
104	/* trampoline signal handler */
105	static void
106	trampoline (int sig)
107	{
108	if (setjmp (((coro_context *)new_coro)->env))
109	{
110	# if HAVE_CFI
111	asm (".cfi_startproc");
112	# endif
113	coro_init (); /* start it */
114	# if HAVE_CFI
115	asm (".cfi_endproc");
116	# endif
117	}
118	else
119	trampoline_count++;
120	}
121
122	# endif
123
124	#endif
125
126	#if CORO_ASM
127
128	asm (
129	".text\n"
130	".globl coro_transfer\n"
131	".type coro_transfer, @function\n"
132	"coro_transfer:\n"
133	# if __amd64
134	# define NUM_SAVED 6
135	"\tpush %rbp\n"
136	"\tpush %rbx\n"
137	"\tpush %r12\n"
138	"\tpush %r13\n"
139	"\tpush %r14\n"
140	"\tpush %r15\n"
141	"\tmov %rsp, (%rdi)\n"
142	"\tmov (%rsi), %rsp\n"
143	"\tpop %r15\n"
144	"\tpop %r14\n"
145	"\tpop %r13\n"
146	"\tpop %r12\n"
147	"\tpop %rbx\n"
148	"\tpop %rbp\n"
149	# elif __i386
150	# define NUM_SAVED 4
151	"\tpush %ebp\n"
152	"\tpush %ebx\n"
153	"\tpush %esi\n"
154	"\tpush %edi\n"
155	"\tmov %esp, (%eax)\n"
156	"\tmov (%edx), %esp\n"
157	"\tpop %edi\n"
158	"\tpop %esi\n"
159	"\tpop %ebx\n"
160	"\tpop %ebp\n"
161	# else
162	# error unsupported architecture
163	# endif
164	"\tret\n"
165	);
166
167	#endif
168
169	#if CORO_PTHREAD
170
171	/* this mutex will be locked by the running coroutine */
172	pthread_mutex_t coro_mutex = PTHREAD_MUTEX_INITIALIZER;
173
174	struct coro_init_args
175	{
176	coro_func func;
177	void *arg;
178	coro_context self, main;
179	};
180
181	static pthread_t null_tid;
182
183	/* I'd so love to cast pthread_mutex_unlock to void ()(void )... */
184	static void
185	mutex_unlock_wrapper (void *arg)
186	{
187	pthread_mutex_unlock ((pthread_mutex_t *)arg);
188	}
189
190	static void *
191	trampoline (void *args_)
192	{
193	struct coro_init_args args = (struct coro_init_args )args_;
194	coro_func func = args->func;
195	void *arg = args->arg;
196
197	pthread_mutex_lock (&coro_mutex);
198
199	/* we try to be good citizens and use deferred cancellation and cleanup handlers */
200	pthread_cleanup_push (mutex_unlock_wrapper, &coro_mutex);
201	coro_transfer (args->self, args->main);
202	func (arg);
203	pthread_cleanup_pop (1);
204
205	return 0;
206	}
207
208	void
209	coro_transfer (coro_context prev, coro_context next)
210	{
211	pthread_cond_signal (&next->cv);
212	pthread_cond_wait (&prev->cv, &coro_mutex);
213	}
214
215	void
216	coro_destroy (coro_context *ctx)
217	{
218	if (!pthread_equal (ctx->id, null_tid))
219	{
220	pthread_cancel (ctx->id);
221	pthread_mutex_unlock (&coro_mutex);
222	pthread_join (ctx->id, 0);
223	pthread_mutex_lock (&coro_mutex);
224	}
225
226	pthread_cond_destroy (&ctx->cv);
227	}
228
229	#endif
230
231	/* initialize a machine state */
232	void
233	coro_create (coro_context ctx, coro_func coro, void arg, void *sptr, long ssize)
234	{
235	#if CORO_UCONTEXT
236
237	if (!coro)
238	return;
239
240	getcontext (&(ctx->uc));
241
242	ctx->uc.uc_link = 0;
243	ctx->uc.uc_stack.ss_sp = STACK_ADJUST_PTR (sptr,ssize);
244	ctx->uc.uc_stack.ss_size = (size_t)STACK_ADJUST_SIZE (sptr,ssize);
245	ctx->uc.uc_stack.ss_flags = 0;
246
247	makecontext (&(ctx->uc), (void (*)())coro, 1, arg);
248
249	#elif CORO_SJLJ \|\| CORO_LOSER \|\| CORO_LINUX \|\| CORO_IRIX \|\| CORO_ASM
250
251	# if CORO_SJLJ
252	stack_t ostk, nstk;
253	struct sigaction osa, nsa;
254	sigset_t nsig, osig;
255	# endif
256	coro_context nctx;
257
258	if (!coro)
259	return;
260
261	coro_init_func = coro;
262	coro_init_arg = arg;
263
264	new_coro = ctx;
265	create_coro = &nctx;
266
267	# if CORO_SJLJ
268	/* we use SIGUSR2. first block it, then fiddle with it. */
269
270	sigemptyset (&nsig);
271	sigaddset (&nsig, SIGUSR2);
272	sigprocmask (SIG_BLOCK, &nsig, &osig);
273
274	nsa.sa_handler = trampoline;
275	sigemptyset (&nsa.sa_mask);
276	nsa.sa_flags = SA_ONSTACK;
277
278	if (sigaction (SIGUSR2, &nsa, &osa))
279	{
280	perror ("sigaction");
281	abort ();
282	}
283
284	/* set the new stack */
285	nstk.ss_sp = STACK_ADJUST_PTR (sptr,ssize); /* yes, some platforms (IRIX) get this wrong. */
286	nstk.ss_size = STACK_ADJUST_SIZE (sptr,ssize);
287	nstk.ss_flags = 0;
288
289	if (sigaltstack (&nstk, &ostk) < 0)
290	{
291	perror ("sigaltstack");
292	abort ();
293	}
294
295	trampoline_count = 0;
296	kill (getpid (), SIGUSR2);
297	sigfillset (&nsig); sigdelset (&nsig, SIGUSR2);
298
299	while (!trampoline_count)
300	sigsuspend (&nsig);
301
302	sigaltstack (0, &nstk);
303	nstk.ss_flags = SS_DISABLE;
304	if (sigaltstack (&nstk, 0) < 0)
305	perror ("sigaltstack");
306
307	sigaltstack (0, &nstk);
308	if (~nstk.ss_flags & SS_DISABLE)
309	abort ();
310
311	if (~ostk.ss_flags & SS_DISABLE)
312	sigaltstack (&ostk, 0);
313
314	sigaction (SIGUSR2, &osa, 0);
315
316	sigprocmask (SIG_SETMASK, &osig, 0);
317
318	# elif CORO_LOSER
319
320	setjmp (ctx->env);
321	#if __CYGWIN__
322	ctx->env[7] = (long)((char *)sptr + ssize) - sizeof (long);
323	ctx->env[8] = (long)coro_init;
324	#elif defined(_M_IX86)
325	((_JUMP_BUFFER *)&ctx->env)->Eip = (long)coro_init;
326	((_JUMP_BUFFER *)&ctx->env)->Esp = (long)STACK_ADJUST_PTR (sptr, ssize) - sizeof (long);
327	#elif defined(_M_AMD64)
328	((_JUMP_BUFFER *)&ctx->env)->Rip = (__int64)coro_init;
329	((_JUMP_BUFFER *)&ctx->env)->Rsp = (__int64)STACK_ADJUST_PTR (sptr, ssize) - sizeof (long);
330	#elif defined(_M_IA64)
331	((_JUMP_BUFFER *)&ctx->env)->StIIP = (__int64)coro_init;
332	((_JUMP_BUFFER *)&ctx->env)->IntSp = (__int64)STACK_ADJUST_PTR (sptr, ssize) - sizeof (long);
333	#else
334	# error "microsoft libc or architecture not supported"
335	#endif
336
337	# elif CORO_LINUX
338
339	_setjmp (ctx->env);
340	#if __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 0 && defined (JB_PC) && defined (JB_SP)
341	ctx->env[0].__jmpbuf[JB_PC] = (long)coro_init;
342	ctx->env[0].__jmpbuf[JB_SP] = (long)STACK_ADJUST_PTR (sptr, ssize) - sizeof (long);
343	#elif __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 0 && defined (__mc68000__)
344	ctx->env[0].__jmpbuf[0].__aregs[0] = (long int)coro_init;
345	ctx->env[0].__jmpbuf[0].__sp = (int )((char )sptr + ssize) - sizeof (long);
346	#elif defined (__GNU_LIBRARY__) && defined (__i386__)
347	ctx->env[0].__jmpbuf[0].__pc = (char *)coro_init;
348	ctx->env[0].__jmpbuf[0].__sp = (void )((char )sptr + ssize) - sizeof (long);
349	#elif defined (__GNU_LIBRARY__) && defined (__amd64__)
350	ctx->env[0].__jmpbuf[JB_PC] = (long)coro_init;
351	ctx->env[0].__jmpbuf[0].__sp = (void )((char )sptr + ssize) - sizeof (long);
352	#else
353	# error "linux libc or architecture not supported"
354	#endif
355
356	# elif CORO_IRIX
357
358	setjmp (ctx->env);
359	ctx->env[JB_PC] = (__uint64_t)coro_init;
360	ctx->env[JB_SP] = (__uint64_t)STACK_ADJUST_PTR (sptr, ssize) - sizeof (long);
361
362	# elif CORO_ASM
363
364	ctx->sp = (volatile void *)(ssize + (char )sptr);
365	--ctx->sp = (void )abort; /* needed for alignment only */
366	--ctx->sp = (void )coro_init;
367	ctx->sp -= NUM_SAVED;
368
369	# endif
370
371	coro_transfer ((coro_context )create_coro, (coro_context )new_coro);
372
373	# elif CORO_PTHREAD
374
375	static coro_context nctx;
376	static int once;
377
378	if (!once)
379	{
380	once = 1;
381
382	pthread_mutex_lock (&coro_mutex);
383	pthread_cond_init (&nctx.cv, 0);
384	null_tid = pthread_self ();
385	}
386
387	pthread_cond_init (&ctx->cv, 0);
388
389	if (coro)
390	{
391	pthread_attr_t attr;
392	struct coro_init_args args;
393
394	args.func = coro;
395	args.arg = arg;
396	args.self = ctx;
397	args.main = &nctx;
398
399	pthread_attr_init (&attr);
400	pthread_attr_setstack (&attr, sptr, (size_t)ssize);
401	pthread_attr_setscope (&attr, PTHREAD_SCOPE_PROCESS);
402	pthread_create (&ctx->id, &attr, trampoline, &args);
403
404	coro_transfer (args.main, args.self);
405	}
406	else
407	ctx->id = null_tid;
408
409	#else
410	# error unsupported backend
411	#endif
412	}
413