29 lines
687 B
C
29 lines
687 B
C
#include <fcntl.h>
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#include <stdio.h>
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#include <string.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <unistd.h>
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#define FILE_SZ (5 * 1024 * 1024)
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static const char* msg1 = "1234567890abcdefghijklmnopqrstuvwxyz\n";
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int main()
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{
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int fd = open("test3.txt", O_RDWR | O_CREAT | O_TRUNC, 0664);
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char* file = mmap(0, FILE_SZ, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
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lseek(fd, FILE_SZ, SEEK_SET);
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write(fd, "", 1);
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printf("the file after mapping...\n");
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for (int i = 0; i < 10000; i += 1)
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memcpy(file + i * strlen(msg1), msg1, strlen(msg1));
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printf("the file after filling...\n");
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close(fd);
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return 0;
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}
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