1/*
2 * Copyright (c) 2001-2012,2015 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 * This coroutine library is very much stripped down. You should either
41 * build your own process abstraction using it or - better - just use GNU
42 * Portable Threads, http://www.gnu.org/software/pth/.
43 *
44 */
45
46/*
47 * 2006-10-26 Include stddef.h on OS X to work around one of its bugs.
48 * Reported by Michael_G_Schwern.
49 * 2006-11-26 Use _setjmp instead of setjmp on GNU/Linux.
50 * 2007-04-27 Set unwind frame info if gcc 3+ and ELF is detected.
51 * Use _setjmp instead of setjmp on _XOPEN_SOURCE >= 600.
52 * 2007-05-02 Add assembly versions for x86 and amd64 (to avoid reliance
53 * on SIGUSR2 and sigaltstack in Crossfire).
54 * 2008-01-21 Disable CFI usage on anything but GNU/Linux.
55 * 2008-03-02 Switched to 2-clause BSD license with GPL exception.
56 * 2008-04-04 New (but highly unrecommended) pthreads backend.
57 * 2008-04-24 Reinstate CORO_LOSER (had wrong stack adjustments).
58 * 2008-10-30 Support assembly method on x86 with and without frame pointer.
59 * 2008-11-03 Use a global asm statement for CORO_ASM, idea by pippijn.
60 * 2008-11-05 Hopefully fix misaligned stacks with CORO_ASM/SETJMP.
61 * 2008-11-07 rbp wasn't saved in CORO_ASM on x86_64.
62 * introduce coro_destroy, which is a nop except for pthreads.
63 * speed up CORO_PTHREAD. Do no longer leak threads either.
64 * coro_create now allows one to create source coro_contexts.
65 * do not rely on makecontext passing a void * correctly.
66 * try harder to get _setjmp/_longjmp.
67 * major code cleanup/restructuring.
68 * 2008-11-10 the .cfi hacks are no longer needed.
69 * 2008-11-16 work around a freebsd pthread bug.
70 * 2008-11-19 define coro_*jmp symbols for easier porting.
71 * 2009-06-23 tentative win32-backend support for mingw32 (Yasuhiro Matsumoto).
72 * 2010-12-03 tentative support for uclibc (which lacks all sorts of things).
73 * 2011-05-30 set initial callee-saved-registers to zero with CORO_ASM.
74 * use .cfi_undefined rip on linux-amd64 for better backtraces.
75 * 2011-06-08 maybe properly implement weird windows amd64 calling conventions.
76 * 2011-07-03 rely on __GCC_HAVE_DWARF2_CFI_ASM for cfi detection.
77 * 2011-08-08 cygwin trashes stacks, use pthreads with double stack on cygwin.
78 * 2012-12-04 reduce misprediction penalty for x86/amd64 assembly switcher.
79 * 2012-12-05 experimental fiber backend (allocates stack twice).
80 * 2012-12-07 API version 3 - add coro_stack_alloc/coro_stack_free.
81 * 2012-12-21 valgrind stack registering was broken.
82 * 2015-12-05 experimental asm be for arm7, based on a patch by Nick Zavaritsky.
83 * use __name__ for predefined symbols, as in libecb.
84 * enable guard pages on arm, aarch64 and mips.
85 */
86
87#ifndef CORO_H
88#define CORO_H
89
90#if __cplusplus
91extern "C" {
92#endif
93
94/*
95 * This library consists of only three files
96 * coro.h, coro.c and LICENSE (and optionally README)
97 *
98 * It implements what is known as coroutines, in a hopefully
99 * portable way.
100 *
101 * All compiletime symbols must be defined both when including coro.h
102 * (using libcoro) as well as when compiling coro.c (the implementation).
103 *
104 * You can manually specify which flavour you want. If you don't define
105 * any of these, libcoro tries to choose a safe and fast default:
106 *
107 * -DCORO_UCONTEXT
108 *
109 * This flavour uses SUSv2's get/set/swap/makecontext functions that
110 * unfortunately only some unices support, and is quite slow.
111 *
112 * -DCORO_SJLJ
113 *
114 * This flavour uses SUSv2's setjmp/longjmp and sigaltstack functions to
115 * do it's job. Coroutine creation is much slower than UCONTEXT, but
116 * context switching is a bit cheaper. It should work on almost all unices.
117 *
118 * -DCORO_LINUX
119 *
120 * CORO_SJLJ variant.
121 * Old GNU/Linux systems (<= glibc-2.1) only work with this implementation
122 * (it is very fast and therefore recommended over other methods, but
123 * doesn't work with anything newer).
124 *
125 * -DCORO_LOSER
126 *
127 * CORO_SJLJ variant.
128 * Microsoft's highly proprietary platform doesn't support sigaltstack, and
129 * this selects a suitable workaround for this platform. It might not work
130 * with your compiler though - it has only been tested with MSVC 6.
131 *
132 * -DCORO_FIBER
133 *
134 * Slower, but probably more portable variant for the Microsoft operating
135 * system, using fibers. Ignores the passed stack and allocates it internally.
136 * Also, due to bugs in cygwin, this does not work with cygwin.
137 *
138 * -DCORO_IRIX
139 *
140 * CORO_SJLJ variant.
141 * For SGI's version of Microsoft's NT ;)
142 *
143 * -DCORO_ASM
144 *
145 * Hand coded assembly, known to work only on a few architectures/ABI:
146 * GCC + arm7/x86/IA32/amd64/x86_64 + GNU/Linux and a few BSDs. Fastest
147 * choice, if it works.
148 *
149 * -DCORO_PTHREAD
150 *
151 * Use the pthread API. You have to provide <pthread.h> and -lpthread.
152 * This is likely the slowest backend, and it also does not support fork(),
153 * so avoid it at all costs.
154 *
155 * If you define neither of these symbols, coro.h will try to autodetect
156 * the best/safest model. To help with the autodetection, you should check
157 * (e.g. using autoconf) and define the following symbols: HAVE_UCONTEXT_H
158 * / HAVE_SETJMP_H / HAVE_SIGALTSTACK.
159 */
160
161/*
162 * Changes when the API changes incompatibly.
163 * This is ONLY the API version - there is no ABI compatibility between releases.
164 *
165 * Changes in API version 2:
166 * replaced bogus -DCORO_LOOSE with grammatically more correct -DCORO_LOSER
167 * Changes in API version 3:
168 * introduced stack management (CORO_STACKALLOC)
169 */
170#define CORO_VERSION 3
171
172#include <stddef.h>
173
174/*
175 * This is the type for the initialization function of a new coroutine.
176 */
177typedef void (*coro_func)(void *);
178
179/*
180 * A coroutine state is saved in the following structure. Treat it as an
181 * opaque type. errno and sigmask might be saved, but don't rely on it,
182 * implement your own switching primitive if you need that.
183 */
184typedef struct coro_context coro_context;
185
186/*
187 * This function creates a new coroutine. Apart from a pointer to an
188 * uninitialised coro_context, it expects a pointer to the entry function
189 * and the single pointer value that is given to it as argument.
190 *
191 * Allocating/deallocating the stack is your own responsibility.
192 *
193 * As a special case, if coro, arg, sptr and ssze are all zero,
194 * then an "empty" coro_context will be created that is suitable
195 * as an initial source for coro_transfer.
196 *
197 * This function is not reentrant, but putting a mutex around it
198 * will work.
199 */
200void coro_create (coro_context *ctx, /* an uninitialised coro_context */
201 coro_func coro, /* the coroutine code to be executed */
202 void *arg, /* a single pointer passed to the coro */
203 void *sptr, /* start of stack area */
204 size_t ssze); /* size of stack area in bytes */
205
206/*
207 * The following prototype defines the coroutine switching function. It is
208 * sometimes implemented as a macro, so watch out.
209 *
210 * This function is thread-safe and reentrant.
211 */
212#if 0
213void coro_transfer (coro_context *prev, coro_context *next);
214#endif
215
216/*
217 * The following prototype defines the coroutine destroy function. It
218 * is sometimes implemented as a macro, so watch out. It also serves no
219 * purpose unless you want to use the CORO_PTHREAD backend, where it is
220 * used to clean up the thread. You are responsible for freeing the stack
221 * and the context itself.
222 *
223 * This function is thread-safe and reentrant.
224 */
225#if 0
226void coro_destroy (coro_context *ctx);
227#endif
228
229/*****************************************************************************/
230/* optional stack management */
231/*****************************************************************************/
232/*
233 * You can disable all of the stack management functions by
234 * defining CORO_STACKALLOC to 0. Otherwise, they are enabled by default.
235 *
236 * If stack management is enabled, you can influence the implementation via these
237 * symbols:
238 *
239 * -DCORO_USE_VALGRIND
240 *
241 * If defined, then libcoro will include valgrind/valgrind.h and register
242 * and unregister stacks with valgrind.
243 *
244 * -DCORO_GUARDPAGES=n
245 *
246 * libcoro will try to use the specified number of guard pages to protect against
247 * stack overflow. If n is 0, then the feature will be disabled. If it isn't
248 * defined, then libcoro will choose a suitable default. If guardpages are not
249 * supported on the platform, then the feature will be silently disabled.
250 */
251#ifndef CORO_STACKALLOC
252# define CORO_STACKALLOC 1
253#endif
254
255#if CORO_STACKALLOC
256
257/*
258 * The only allowed operations on these struct members is to read the
259 * "sptr" and "ssze" members to pass it to coro_create, to read the "sptr"
260 * member to see if it is false, in which case the stack isn't allocated,
261 * and to set the "sptr" member to 0, to indicate to coro_stack_free to
262 * not actually do anything.
263 */
264
265struct coro_stack
266{
267 void *sptr;
268 size_t ssze;
269#if CORO_USE_VALGRIND
270 int valgrind_id;
271#endif
272};
273
274/*
275 * Try to allocate a stack of at least the given size and return true if
276 * successful, or false otherwise.
277 *
278 * The size is *NOT* specified in bytes, but in units of sizeof (void *),
279 * i.e. the stack is typically 4(8) times larger on 32 bit(64 bit) platforms
280 * then the size passed in.
281 *
282 * If size is 0, then a "suitable" stack size is chosen (usually 1-2MB).
283 */
284int coro_stack_alloc (struct coro_stack *stack, unsigned int size);
285
286/*
287 * Free the stack allocated by coro_stack_alloc again. It is safe to
288 * call this function on the coro_stack structure even if coro_stack_alloc
289 * failed.
290 */
291void coro_stack_free (struct coro_stack *stack);
292
293#endif
294
295/*
296 * That was it. No other user-serviceable parts below here.
297 */
298
299/*****************************************************************************/
300
301#if !defined CORO_LOSER && !defined CORO_UCONTEXT \
302 && !defined CORO_SJLJ && !defined CORO_LINUX \
303 && !defined CORO_IRIX && !defined CORO_ASM \
304 && !defined CORO_PTHREAD && !defined CORO_FIBER
305# if defined WINDOWS && (defined __i386__ || (__x86_64__ || defined _M_IX86 || defined _M_AMD64))
306# define CORO_ASM 1
307# elif defined WINDOWS || defined _WIN32
308# define CORO_LOSER 1 /* you don't win with windoze */
309# elif __linux && (__i386__ || (__x86_64__ && !__ILP32__) || (__arm__ && __ARCH_ARCH == 7))
310# define CORO_ASM 1
311# elif defined HAVE_UCONTEXT_H
312# define CORO_UCONTEXT 1
313# elif defined HAVE_SETJMP_H && defined HAVE_SIGALTSTACK
314# define CORO_SJLJ 1
315# else
316error unknown or unsupported architecture
317# endif
318#endif
319
320/*****************************************************************************/
321
322#if CORO_UCONTEXT
323
324# include <ucontext.h>
325
326struct coro_context
327{
328 ucontext_t uc;
329};
330
331# define coro_transfer(p,n) swapcontext (&((p)->uc), &((n)->uc))
332# define coro_destroy(ctx) (void *)(ctx)
333
334#elif CORO_SJLJ || CORO_LOSER || CORO_LINUX || CORO_IRIX
335
336# if defined(CORO_LINUX) && !defined(_GNU_SOURCE)
337# define _GNU_SOURCE /* for glibc */
338# endif
339
340# if !CORO_LOSER
341# include <unistd.h>
342# endif
343
344/* solaris is hopelessly borked, it expands _XOPEN_UNIX to nothing */
345# if __sun
346# undef _XOPEN_UNIX
347# define _XOPEN_UNIX 1
348# endif
349
350# include <setjmp.h>
351
352# if _XOPEN_UNIX > 0 || defined (_setjmp)
353# define coro_jmp_buf jmp_buf
354# define coro_setjmp(env) _setjmp (env)
355# define coro_longjmp(env) _longjmp ((env), 1)
356# elif CORO_LOSER
357# define coro_jmp_buf jmp_buf
358# define coro_setjmp(env) setjmp (env)
359# define coro_longjmp(env) longjmp ((env), 1)
360# else
361# define coro_jmp_buf sigjmp_buf
362# define coro_setjmp(env) sigsetjmp (env, 0)
363# define coro_longjmp(env) siglongjmp ((env), 1)
364# endif
365
366struct coro_context
367{
368 coro_jmp_buf env;
369};
370
371# define coro_transfer(p,n) do { if (!coro_setjmp ((p)->env)) coro_longjmp ((n)->env); } while (0)
372# define coro_destroy(ctx) (void *)(ctx)
373
374#elif CORO_ASM
375
376struct coro_context
377{
378 void **sp; /* must be at offset 0 */
379};
380
381#if __i386__ || __x86_64__
382void __attribute__ ((__noinline__, __regparm__(2)))
383#else
384void __attribute__ ((__noinline__))
385#endif
386coro_transfer (coro_context *prev, coro_context *next);
387
388# define coro_destroy(ctx) (void *)(ctx)
389
390#elif CORO_PTHREAD
391
392# include <pthread.h>
393
394extern pthread_mutex_t coro_mutex;
395
396struct coro_context
397{
398 pthread_cond_t cv;
399 pthread_t id;
400};
401
402void coro_transfer (coro_context *prev, coro_context *next);
403void coro_destroy (coro_context *ctx);
404
405#elif CORO_FIBER
406
407struct coro_context
408{
409 void *fiber;
410 /* only used for initialisation */
411 coro_func coro;
412 void *arg;
413};
414
415void coro_transfer (coro_context *prev, coro_context *next);
416void coro_destroy (coro_context *ctx);
417
418#endif
419
420#if __cplusplus
421}
422#endif
423
424#endif
425
426