基于IPC的echo server

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Linux下使用共享内存和信号量来实现一个echo server。对共享内存的操作使用信号量来控制，类似于生产者和消费者的问题。下面附上server端和client端的代码。

Server.c

#include <stdio.h>

#include <string.h>

#include <errno.h>

#include <sys/mman.h>

#include <sys/types.h>

#include <fcntl.h>

#include <unistd.h>

#include <sys/shm.h>

#include <sys/stat.h>

#include <semaphore.h>

#include <assert.h>

#define MYSHM "myshm"

#define SEM_S "sem_s"

#define SEM_C "sem_c"

#define BUF_SIZE 200

typedef struct mydata {

int flag;

char buf[BUF_SIZE];

}mydata;

int main(int argc, char *argv[])

{

int shm_key;

int shm_id;

char name[50];

mydata *pdata;

char *ptr;

sem_t *sem_s, *sem_c;

strcpy(name, MYSHM);

shm_key = ftok(name, 0);

if (shm_key == -1)

{

perror("ftok error");

return -1;

}

shm_id = shmget(shm_key, sizeof(mydata), IPC_CREAT);

if (-1 == shm_id)

{

perror("shmget error.");

return -1;

}

ptr = shmat(shm_id, NULL, 0);

if ((char *)-1 == ptr)

{

perror("shmat error.");

return -1;

}

sem_s = sem_open(SEM_S, O_CREAT, 0644, 1);

if (sem_s == NULL)

perror("sem_open error.");

assert(sem_s != NULL);

int r1 = sem_init(sem_s, 1, 0);

assert(r1 == 0);

sem_c = sem_open(SEM_C, O_CREAT, 0644, 1);

assert(sem_c != NULL);

int r2 = sem_init(sem_c, 1, 0);

assert(r2 == 0);

pdata = (mydata *)ptr;

while (1)

{

//while (!pdata->flag);

sem_wait(sem_c);

pdata->flag = 0;

sem_post(sem_s);

}

shmdt(ptr);

return 0;

}

Client.c

#include <stdio.h>

#include <string.h>

#include <errno.h>

#include <sys/mman.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <unistd.h>

#include <sys/shm.h>

#include <semaphore.h>

#include <assert.h>

#define MYSHM "myshm"

#define SEM_S "sem_s"

#define SEM_C "sem_c"

#define BUF_SIZE 200

typedef struct mydata {

int flag;

char buf[BUF_SIZE];

}mydata;

int main(int argc, char *argv[])

{

int shm_key;

int shm_id;

char name[50];

mydata *pdata;

char *ptr;

sem_t *sem_s, *sem_c;

strcpy(name, MYSHM);

shm_key = ftok(name, 0);

if (shm_key == -1)

{

perror("ftok error");

return -1;

}

shm_id = shmget(shm_key, sizeof(mydata), IPC_CREAT);

if (-1 == shm_id)

{

perror("shmget error.");

return -1;

}

ptr = shmat(shm_id, NULL, 0);

if ((char *)-1 == ptr)

{

perror("shmat error.");

return -1;

}

sem_s = sem_open(SEM_S, O_CREAT, 0644, 1);

assert(sem_s != NULL);

int r1 = sem_init(sem_s, 1, 0);

assert(r1 == 0);

sem_c = sem_open(SEM_C, O_CREAT, 0644, 1);

assert(sem_c != NULL);

int r2 = sem_init(sem_c, 1, 0);

assert(r2 == 0);

pdata = (mydata *)ptr;

while (1)

{

fgets(pdata->buf, BUF_SIZE, stdin);

pdata->flag = 1;

//while (pdata->flag);

sem_post(sem_c);

sem_wait(sem_s);

printf("%s", pdata->buf);

}

shmdt(ptr);

return 0;

}

Makefile

all:

gcc -g -Wall ipc_echo_server.c -o ipc_echo_server -lpthread

gcc -g -Wall ipc_echo_client.c -o ipc_echo_client -lpthread

clean:

rm -f ipc_echo_server ipc_echo_client