（原标题：帮忙给看一下！我的程序怎么回事了！）
gcc -o sem1 sem1.c
sem1.c: In function `set_semvalue':
sem1.c:67: storage size of `sem_union' isn't known
sem1.c: In function `del_semvalue':
sem1.c:77: storage size of `sem_union' isn't known
/* semun.h */
#ifdef _SEMUN_H
#define _SEMUN_H
union semun {
int val; /* value for SETVAL */
struct semid_ds *buf; /* buffer for IPC_STAT, IPC_SET */
unsigned short int *array; /* array for GETALL, SETALL */
struct seminfo *__buf; /* buffer for IPC_INFO */
};
#endif
/* sem1.c */
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include "semun.h"
static int set_semvalue(void);
static void del_semvalue(void);
static int semaphore_p(void);
static int semaphore_v(void);
static int sem_id;
int main(int argc, char *argv[])
{
int i;
int pause_time;
char op_char = 'O';
srand((unsigned int)getpid());
sem_id = semget((key_t)1234, 1, 0666 | IPC_CREAT);
if(argc > 1)
{
if(!set_semvalue())
{
fprintf(stderr, "Failed ot initialize semaphore\n");
exit(EXIT_FAILURE);
}
op_char = 'X';
sleep(2);
}
for(i = 0; i < 10; i++)
{
if(!semaphore_p())
exit(EXIT_FAILURE);
printf("%C", op_char);
fflush(stdout);
pause_time = rand() % 3;
sleep(pause_time);
printf("%C", op_char);
fflush(stdout);
if(!semaphore_v())
exit(EXIT_FAILURE);
pause_time = rand() % 2;
sleep(pause_time);
}
printf("\n%d - finished\n", getpid());
if(argc > 1)
{
sleep(10);
del_semvalue();
}
exit(EXIT_SUCCESS);
}
static int set_semvalue(void)
{
union semun sem_union;
sem_union.val = 1;
if(semctl(sem_id, 0, SETVAL, sem_union) == -1)
return (0);
return (1);
}
static void del_semvalue(void)
{
union semun sem_union;
if(semctl(sem_id, 0, IPC_RMID, sem_union) == -1)
fprintf(stderr, "Failed to delete semaphore\n");
}
static int semaphore_p(void)
{
struct sembuf sem_b;
sem_b.sem_num = 0;
sem_b.sem_op = -1;
sem_b.sem_flg = SEM_UNDO;
if(semop(sem_id, &sem_b, 1) == -1)
{
fprintf(stderr, "semaphore_p failed\n");
return (0);
}
return (1);
}
static int semaphore_v(void)
{
struct sembuf sem_b;
sem_b.sem_num = 0;
sem_b.sem_op = 1; /* V() */
sem_b.sem_flg = SEM_UNDO;
if(semop(sem_id, &sem_b, 1) == -1)
{
fprintf(stderr, "semaphore_v failed\n");
return (0);
}
return (1);
}
[ 本帖最后由 langue 于 2006-12-27 20:45 编辑 ]
lenovo 回复于：2006-12-27 19:25:35
在semun.h中
加入一行：
#include <sys/sem.h>
试试。
wyaccent 回复于：2006-12-27 19:33:08
#ifdef _SEMUN_H
#define _SEMUN_H
union semun {
int val; /* value for SETVAL */
struct semid_ds *buf; /* buffer for IPC_STAT, IPC_SET */
unsigned short int *array; /* array for GETALL, SETALL */
struct seminfo *__buf; /* buffer for IPC_INFO */
};
#endif
#ifdef _SEMUN_H 这个条件编译在编译时定义了吗？？或者在你的头文件里面有定义吗，检查一下
wyaccent 回复于：2006-12-27 19:33:48
#ifdef _SEMUN_H
是不是应该改为#ifndef跟合理？？
lenovo 回复于：2006-12-27 19:35:12
引用：原帖由 wyaccent 于 2006-12-27 19:33 发表
#ifdef _SEMUN_H
是不是应该改为#ifndef跟合理？？
汗，就应该是你说的，
我没仔细看。
yyying 回复于：2006-12-27 20:29:44
确实是wyaccent所说的那样，编译通过了；但小弟不明白为什么要改那里，能帮忙给些解释吗？
yyying 回复于：2006-12-27 20:35:39
man semctl 是这样说的
This function has three or four arguments. When there are four, the
call is semctl(semid,semnum,cmd,arg); where the fourth argument arg has
a type union semun defined as follows:
#if defined(__GNU_LIBRARY__) && !defined(_SEM_SEMUN_UNDEFINED)
/* union semun is defined by including <sys/sem.h> */
#else
/* according to X/OPEN we have to define it ourselves */
union semun {
int val; /* value for SETVAL */
struct semid_ds *buf; /* buffer for IPC_STAT, IPC_SET */
unsigned short *array; /* array for GETALL, SETALL */
/* Linux specific part: */
struct seminfo *__buf; /* buffer for IPC_INFO */
};
#endif
langue 回复于：2006-12-27 20:39:41
对啦，就是这里。看代码的时候，无论是条件编译指令，还是实际代码，都自己在脑子里过一遍，看看逻辑上有没有问题。这样能消除不少错误。
/* semun.h */
#ifdef _SEMUN_H
#define _SEMUN_H
union semun {
int val; /* value for SETVAL */
struct semid_ds *buf; /* buffer for IPC_STAT, IPC_SET */
unsigned short int *array; /* array for GETALL, SETALL */
struct seminfo *__buf; /* buffer for IPC_INFO */
};
#endif
把 #ifdef 改成 #ifndef
想想，自己写这些 #if(n)def ... #define ... #endif，到底为了什么。这样就不难明白为什么要换为 #ifndef 啦。
:)
[ 本帖最后由 langue 于 2006-12-27 20:47 编辑 ]
langue 回复于：2006-12-27 20:45:49
另外，我保留了本帖，修改了标题，方便大家查找。如有冒犯之处，还请原谅 :)
yyying 回复于：2006-12-27 20:46:06
谢谢助为了，小弟明白了！
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