47 lines
1.3 KiB
C
47 lines
1.3 KiB
C
#include <sys/mman.h>
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#include <sys/types.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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typedef struct {
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char name[4];
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int age;
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} people;
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int main(int argc, char **argv) {
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int i;
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people *p_map;
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char temp;
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pid_t pid;
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// parent shares memory with child through anonymous share memory
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p_map = (people *)mmap(NULL, sizeof(people)*10, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS, -1, 0);
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if ((pid = fork()) < 0) {
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printf("cannot fork!\n");
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return -1;
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} else if (pid == 0) { // child process
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sleep(2);
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for (i = 0; i < 5; i++) {
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printf("child read: age of the %d people %s is %d\n", i+1, (*(p_map+i)).name, (*(p_map+i)).age);
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}
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munmap(p_map, sizeof(people)*10); // share memory will end after process ends
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} else {
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temp = 'a';
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for (i = 0; i < 5; i++) {
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temp += 1;
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memcpy((*(p_map+i)).name, &temp, 1);
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(*(p_map+i)).age = 20 + i;
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}
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sleep(5);
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printf("parent read: the first people %s's age is %d\n", (*p_map).name, (*p_map).age);
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printf("umap\n");
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munmap(p_map, sizeof(people)*10);
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printf("umap ok\n");
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}
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return 0;
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}
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