问在带有XCode 4.6的MacOSX 10.8.2下写入mmap会导致程序崩溃

EN

#include <stdio.h>
#include <string.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <unistd.h>
int main(int argc, const char * argv[]) {
int input, output;
size_t size;

char *source, *target;

input = open("SEK2.txt", O_RDONLY);
if (input == -1) {
    printf("Open source file failed");
    return -1;
}
output = open("test.txt", O_RDWR|O_CREAT|O_TRUNC);
if (output == -1) {
    printf("Open Output file failed");
    return -1;
}

size = lseek(input, 0, SEEK_END);
printf("File size = %d\n", size);

source = (char*)mmap(0, size, PROT_READ, MAP_PRIVATE, input, 0);
if ( source == (void*)-1) {
    printf("Source MMap Error\n");
    return -1;
}

target = (char*)mmap(0, size, PROT_EXEC, MAP_PRIVATE, output, 0);
if ( target == (void*)-1 ) {
    printf( "Target MMap Error\n");
    return -1;
}

memcpy(target, source, size); // EXC_BAD_ACCESS to "target"
munmap(source, size);
munmap(target, size);

close(input);
close(output);

printf("Successed");
return 0;