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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,143 @@ | ||
| //////////////////////////////////////////////////////////////////////// | ||
| // Copyright(c) libgreen contributors. See LICENSE file for details. // | ||
| //////////////////////////////////////////////////////////////////////// | ||
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| // Required for using ucontext. | ||
| #define _XOPEN_SOURCE 500 | ||
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|
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| #include <stdio.h> | ||
| #include <stdlib.h> | ||
| #include <ucontext.h> | ||
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| ucontext_t hub; | ||
| ucontext_t coro; | ||
| int coro_status = 0; | ||
| void * P = NULL; | ||
| int stack_size = 64 * 1024; // SIGSTKSZ is too small on linux. | ||
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| // NOTE: according to the ucontext specification, we can only pass int | ||
| // arguments to the coroutine. Use a pair of ints in case `sizeof(void*) | ||
| // != sizeof(int)`. | ||
| typedef union { | ||
| int i[2]; | ||
| void * p; | ||
| } coroutine_args; | ||
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| void coroutine(int i0, int i1) | ||
| { | ||
| // Decode pointer argument. | ||
| coroutine_args args; | ||
| args.i[0] = i0; | ||
| args.i[1] = i1; | ||
| void * p = args.p; | ||
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| int i = 0; | ||
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| fprintf(stderr, "coro: enter.\n"); | ||
| if (p != P) { | ||
| fprintf(stderr, "coro: p != P\n"); | ||
| coro_status = 1; | ||
| return; | ||
| } | ||
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| fprintf(stderr, "coro: yield.\n"); | ||
| i++; | ||
| if (swapcontext(&coro, &hub) < 0) { | ||
| fprintf(stderr, "coro: swapcontext()\n"); | ||
| coro_status = 1; | ||
| return; | ||
| } | ||
|
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| fprintf(stderr, "coro: check.\n"); | ||
| if (i != 1) { | ||
| fprintf(stderr, "coro: stack corruption detected.\n"); | ||
| coro_status = 1; | ||
| return; | ||
| } | ||
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| fprintf(stderr, "coro: leave.\n"); | ||
| } | ||
|
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| int main() | ||
| { | ||
| int i = 0; | ||
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| fprintf(stderr, "main: enter.\n"); | ||
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| // Store the pointer we pass as an argument to the coroutine to make sure | ||
| // the coroutine can check that it is passed safely. | ||
| P = &hub; | ||
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| // Encode pointer argument. | ||
| coroutine_args args; | ||
| args.p = &hub; | ||
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| // Spawn the coroutine (delayed start). | ||
| fprintf(stderr, "main: spawn.\n"); | ||
| if (getcontext(&coro) < 0) { | ||
| fprintf(stderr, "main: getcontext()\n"); | ||
| return EXIT_FAILURE; | ||
| } | ||
| void * stack = malloc(stack_size); | ||
| if (stack == NULL) { | ||
| fprintf(stderr, "main: malloc()\n"); | ||
| return EXIT_FAILURE; | ||
| } | ||
| coro.uc_link = &hub; | ||
| coro.uc_stack.ss_sp = stack; | ||
| coro.uc_stack.ss_size = stack_size; | ||
| makecontext(&coro, (void(*)())coroutine, 2, args.i[0], args.i[1]); | ||
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| fprintf(stderr, "main: stack @ %p.\n", coro.uc_stack.ss_sp); | ||
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| // Yield to the coroutine until it yields back. | ||
| i++; | ||
| fprintf(stderr, "main: yield (1).\n"); | ||
| if (swapcontext(&hub, &coro) < 0) { | ||
| fprintf(stderr, "main: getcontext()\n"); | ||
| return EXIT_FAILURE; | ||
| } | ||
| if (coro_status != 0) { | ||
| fprintf(stderr, "main: coroutine error\n"); | ||
| return EXIT_FAILURE; | ||
| } | ||
|
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| // Check for stack corruption. | ||
| fprintf(stderr, "main: check.\n"); | ||
| if (i != 1) { | ||
| fprintf(stderr, "main: stack corruption detected.\n"); | ||
| return EXIT_FAILURE; | ||
| } | ||
|
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| // Yield back to the coroutine to let it finish. | ||
| i++; | ||
| fprintf(stderr, "main: yield (2).\n"); | ||
| if (swapcontext(&hub, &coro) < 0) { | ||
| fprintf(stderr, "main: getcontext()\n"); | ||
| return EXIT_FAILURE; | ||
| } | ||
| if (coro_status != 0) { | ||
| fprintf(stderr, "main: coroutine error\n"); | ||
| return EXIT_FAILURE; | ||
| } | ||
|
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| // Check for stack corruption. | ||
| fprintf(stderr, "main: check.\n"); | ||
| if (i != 2) { | ||
| fprintf(stderr, "main: stack corruption detected.\n"); | ||
| return EXIT_FAILURE; | ||
| } | ||
|
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| // Release the coroutine's stack. | ||
| // | ||
| // NOTE: we can't rely on `coro.uc_stack.ss_sp` because the ucontext | ||
| // implementation is free to manipulate this at will and there is no | ||
| // guarantee that this will be the pointer we allocated. | ||
| fprintf(stderr, "main: cleanup.\n"); | ||
| fprintf(stderr, "main: stack @ %p.\n", coro.uc_stack.ss_sp); | ||
| free(stack); | ||
| coro.uc_stack.ss_sp = NULL; | ||
|
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| fprintf(stderr, "main: leave.\n"); | ||
| return EXIT_SUCCESS; | ||
| } |
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