我正在寫一個C程序,我正在向n個玩家發牌,由n個分叉過程表示。我希望他們都共用同一副牌,所以我試圖使用mmap()
來跟蹤牌組大小,但是我必須編譯該程序的機器不允許MAP_ANONYMOUS
或MAP_ANON
。是否還有另一種方法可以將共享內存中的全局變量存儲到C89/pre Linux 2.4中?C中的共享內存和MAP_ANONYMOUS缺失?
我的上下文程序:
static int *deck_size;
int pop(int *arr, int *size, int loc)
{
int i;
int val = arr[loc];
for(i = loc; i < (*size - 1); i++)
{
arr[i] = arr[(i+1)];
arr[*size] = '\0';
}
*size = *size-1;
return val;
}
int main(int argc, char* argv[])
{
pid_t pid, wpid;
int status, index, players, rdm_card;
char outbuf[100];
int deck[] =
{1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,6,6,6,6,7,7,7,7,8,8,8,8,9,9,9,9,10,10,10,10,11,11,11,11,12,12,12,12,13,13,13,13};
deck_size = mmap(NULL, sizeof *deck_size, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0);
*deck_size = 52;
/* reject an execution with no arguments */
if(argv[1] == NULL)
{
write(STDERR_FILENO, "Usage: dealer <n>\n", 18);
exit(EXIT_FAILURE);
}
else
{
if((players = atoi(argv[1])) < 1)
{
write(STDERR_FILENO, "n cannot be less than 1\n", 24);
exit(EXIT_FAILURE);
}
}
srand (time(NULL));
rdm_card = rand() % *deck_size;
for(index = 0; index < players; index++)
{
pid = fork();
if (pid == 0) {
sprintf(outbuf, "random card: %d\n", pop(deck, deck_size, rdm_card));
write(STDOUT_FILENO, outbuf, 17);
printf("size of deck %d!\n", *deck_size);
exit(EXIT_SUCCESS);
} else if (pid < 0) {
write(STDERR_FILENO, "fork error\n", 11);
exit(EXIT_FAILURE);
} else {
do {
wpid = waitpid(pid, &status, WUNTRACED);
} while (!WIFEXITED(status) && !WIFSIGNALED(status));
}
}
return 0;
}
你看'人2 shmget'?它描述了在POSIX shm –
之前使用的古老的System V共享內存接口,您記得要定義'_BSD_SOURCE'或'_SVID_SOURCE'來從 –
獲得MAP_ANONYMOUS您是否有一個特定的原因試圖在這裏使用分叉進程?除非這是項目需求(例如,對於編程任務),否則最好使用線程...... – duskwuff