Question

我写了一个简单的c程序。使用共享内存和信号量。当我编译程序服务器时，clang lsp警告shamt is invalid in c99。c

Undefined symbols for architecture x86_64:
  "_shamt", referenced from:
      _main in server-214a3e.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

但是我在server.c中有主要功能

代码如下：

#include <assert.h>
#include <errno.h>
#include <pthread.h>
#include <semaphore.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/shm.h>
#include <sys/sem.h>
#include <time.h>
#include <unistd.h>
#include <sys/ipc.h>
#include <sys/stat.h>
#include <fcntl.h>
#define MSG_MAX_SIZE 4096

char *server_memory, *client_memory;
sem_t *sig_server, *sig_client;
char message_client[MSG_MAX_SIZE];
char message_server[MSG_MAX_SIZE];

key_t generate_key(int ID) {
  key_t res;
  if ((res = ftok("/tmp", 'C')) == -1) {
    perror("ftok faild ");
    exit(1);
  }
  return res;
}

int get_shm_id(key_t key) {
  int res = shmget(key, sizeof(char) * MSG_MAX_SIZE, IPC_CREAT | 0666);
  if (res == -1) {
    perror("server: Failed to open/creat share memory");
    exit(2);
  }
  return res;
}

int main() {

  key_t key_client = generate_key('C');
  key_t key_server = generate_key('S');

  int shm_server_id = get_shm_id(key_server);
  int shm_client_id = get_shm_id(key_client);

  server_memory = shamt(shm_server_id, (void *)0, 0);
  client_memory = shamt(shm_client_id, (void *)0, 0);

  sig_server =
      sem_open("/tmp/signal_server", O_CREAT | 0666, S_IRUSR | S_IWUSR, 1);
  sig_client =
      sem_open("/tmp/signal_client", O_CREAT | 0666, S_IRUSR | S_IWUSR, 1);

  while (1) {
    printf("enter message,enter q to quit,enter p to pass input\n");
    fgets(message_server, MSG_MAX_SIZE, stdin);
    if (message_server[0] == 'q') {
      // ：TODO 
      exit(0);
    } else if (message_server[0] != 'p') {
      sem_wait(sig_client);
      strcpy(client_memory, message_server);
      sem_post(sig_client);
    }
    if (sem_trywait(sig_server) == -1) {
      printf("The client is typing\n");
      printf("enter r to reply and or w to wait The other party:");
      char c = getchar();
      if (c == 'w') {
        sem_wait(sig_server);
      } else if (c == 'r') {
        continue;
      } else {
        // :TODO 
      }
    }
    strcpy(message_client, server_memory);
    sem_post(sig_server);
    printf("message recived:%s\n", message_client);
  }

  return 0;
}

我也尝试在Ubuntu 18.04上编译代码，但是编译时出现了更多错误。

/tmp/ccrxmeXg.o: In function `main':
server.c:(.text+0xd5): undefined reference to `shamt'
server.c:(.text+0xf7): undefined reference to `shamt'
server.c:(.text+0x11e): undefined reference to `sem_open'
server.c:(.text+0x143): undefined reference to `sem_open'
server.c:(.text+0x19c): undefined reference to `sem_wait'
server.c:(.text+0x1bf): undefined reference to `sem_post'
server.c:(.text+0x1ce): undefined reference to `sem_trywait'
server.c:(.text+0x209): undefined reference to `sem_wait'
server.c:(.text+0x234): undefined reference to `sem_post'
collect2: error: ld returned 1 exit status

那么如何解决这个问题。我想在Mac OS以及Ubuntu上运行此程序。

请帮助我！

POSIX共享内存和信号量在Mac OS 10.14.6和Ubuntu 18.04上不起作用

0 个答案: