Linux信号灯C语言编程示例(包含信号灯回滚,信号等取值和初始化操作)

#include <stdio.h> #include <sys/types.h> #include <sys/sem.h> #include <sys/ipc.h> //#include <linux/sem.h> #include <unistd.h> #include <errno.h> #include "mysem.h" #define SEM_KEY 7589 #define SEMSIZE 5 static int mysem_id = -1; union semun{ int val; struct semid_ds *buf; unsigned short *array; }; void init_mysem(int ini_flag) { key_t key; int i; struct sembuf op; union semun arg; // op.sem_num = s_id; op.sem_op = 1; op.sem_flg = 0; // key=ftok(PATHNAME,'O'); if((mysem_id=semget(SEM_KEY,SEMSIZE,IPC_CREAT|0666))==-1){ perror("semget err!\n"); exit(-1); } if(ini_flag == 1){ arg.array = (unsigned short *) calloc(SEMSIZE,sizeof(unsigned short)); if(arg.array == NULL){ printf("No enough memory to calloc!\n"); exit(-1); } for(i=0;i<SEMSIZE;i++){ arg.array[i] = 1; } if(semctl(mysem_id,0,SETALL,arg) == -1){ perror("semctl err:"); exit(-1); } } } void init_mysemvalue(int s_id,int ini_value) { key_t key; int i; struct sembuf op; union semun arg; // op.sem_num = s_id; op.sem_op = 1; op.sem_flg = 0; // key=ftok(PATHNAME,'O'); if(mysem_id == -1){ if((mysem_id=semget(SEM_KEY,SEMSIZE,IPC_CREAT|0666))==-1){ perror("semget err!\n"); exit(-1); } } /*arg.array = (unsigned short *) calloc(SEMSIZE,sizeof(unsigned short)); if(arg.array == NULL){ printf("No enough memory to calloc!\n"); exit(-1); } arg.array[s_id] = ini_value;*/ arg.val = ini_value; if(semctl(mysem_id,s_id,SETVAL,arg) == -1){ perror("semctl err:"); exit(-1); } } int getmysemvalue(int s_id) { int i_value; if(mysem_id == -1){ if((mysem_id=semget(SEM_KEY,SEMSIZE,IPC_CREAT|0666))==-1){ perror("semget err!\n"); exit(-1); } } i_value = semctl(mysem_id,s_id,GETVAL); if(i_value == -1){ perror("semctl err:"); exit(-1); } return i_value; } void mywait(int s_id) { struct sembuf op; int i_result; op.sem_num = s_id; op.sem_op = -1; op.sem_flg = SEM_UNDO; if(mysem_id == -1) init_mysem(0); while((i_result = semop(mysem_id,&op,1)) == -1 && errno == EINTR) usleep(5000); if(i_result==-1){ printf("mywait sid = %d errno = %d %s\n",s_id,errno,strerror(errno)); if(errno == ERANGE){ printf("semval = %d\n",getmysemvalue(s_id)); } perror("semop err!\n"); exit(-1); } } void mysignal(int s_id) { struct sembuf op; int i_result; op.sem_num = s_id; op.sem_op = 1; op.sem_flg = SEM_UNDO; if(mysem_id == -1) init_mysem(0); while((i_result = semop(mysem_id,&op,1)) == -1 && errno == EINTR) usleep(5000); if(i_result==-1){ printf("mysignal s_id = %d errno = %d %s\n",s_id,errno,strerror(errno)); if(errno == ERANGE){ printf("semval = %d\n",getmysemvalue(s_id)); } perror("semop err!\n"); exit(-1); } } void myuwait(int s_id) { struct sembuf op; int i_result; op.sem_num = s_id; op.sem_op = -1; op.sem_flg = 0; if(mysem_id == -1) init_mysem(0); while((i_result = semop(mysem_id,&op,1)) == -1 && errno == EINTR) usleep(5000); if(i_result==-1){ printf("myuwait s_id = %d errno = %d %s\n",s_id,errno,strerror(errno)); if(errno == ERANGE){ printf("semval = %d\n",getmysemvalue(s_id)); } perror("semop err!\n"); exit(-1); } } void myusignal(int s_id) { struct sembuf op; int i_result; op.sem_num = s_id; op.sem_op = 1; op.sem_flg = 0; if(mysem_id == -1) init_mysem(0); while((i_result = semop(mysem_id,&op,1)) == -1 && errno == EINTR) usleep(5000); if(i_result==-1){ printf("myusignal s_id = %d errno = %d %s\n",s_id,errno,strerror(errno)); if(errno == ERANGE){ printf("semval = %d\n",getmysemvalue(s_id)); } perror("semop err!\n"); exit(-1); } }