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71 lines
2.4 KiB
C
71 lines
2.4 KiB
C
#if 0
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/*─────────────────────────────────────────────────────────────────╗
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│ To the extent possible under law, Justine Tunney has waived │
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│ all copyright and related or neighboring rights to this file, │
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│ as it is written in the following disclaimers: │
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│ • http://unlicense.org/ │
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│ • http://creativecommons.org/publicdomain/zero/1.0/ │
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╚─────────────────────────────────────────────────────────────────*/
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#endif
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#include <stdio.h>
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#include <stdlib.h>
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#include <ucontext.h>
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/**
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* @fileoverview swapcontext() and makecontext() example
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* @note adapted from the Linux man-pages project
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*/
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static ucontext_t uctx_main;
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static ucontext_t uctx_func1;
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static ucontext_t uctx_func2;
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#define say(s) write(1, s, strlen(s))
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#define handle_error(msg) \
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do { \
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perror(msg); \
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exit(EXIT_FAILURE); \
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} while (0)
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static void func1(void) {
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say("func1: started\n");
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say("func1: swapcontext(&uctx_func1, &uctx_func2)\n");
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if (swapcontext(&uctx_func1, &uctx_func2) == -1)
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handle_error("swapcontext");
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say("func1: returning\n");
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}
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static void func2(void) {
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say("func2: started\n");
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say("func2: swapcontext(&uctx_func2, &uctx_func1)\n");
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if (swapcontext(&uctx_func2, &uctx_func1) == -1)
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handle_error("swapcontext");
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say("func2: returning\n");
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}
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int main(int argc, char *argv[]) {
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char func1_stack[8192];
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char func2_stack[8192];
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if (getcontext(&uctx_func1) == -1)
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handle_error("getcontext");
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uctx_func1.uc_stack.ss_sp = func1_stack;
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uctx_func1.uc_stack.ss_size = sizeof(func1_stack);
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uctx_func1.uc_link = &uctx_main;
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makecontext(&uctx_func1, func1, 0);
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if (getcontext(&uctx_func2) == -1)
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handle_error("getcontext");
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uctx_func2.uc_stack.ss_sp = func2_stack;
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uctx_func2.uc_stack.ss_size = sizeof(func2_stack);
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/* Successor context is f1(), unless argc > 1 */
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uctx_func2.uc_link = (argc > 1) ? NULL : &uctx_func1;
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makecontext(&uctx_func2, func2, 0);
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say("main: swapcontext(&uctx_main, &uctx_func2)\n");
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if (swapcontext(&uctx_main, &uctx_func2) == -1)
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handle_error("swapcontext");
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say("main: exiting\n");
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exit(EXIT_SUCCESS);
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}
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