Hello everybody.
I’m having a problem when I receive the return message from server using IPC and Shared Memory.
I have my server running forever with a while(1) and in a RECEIVE-BLOCKED state.
I send “Testing MessageClient” with the MsgSend command from my client to the server.
The server get the message (MsgReceive), puts it into the Shared Memory, add the text " - Reply from Server" and print it before the reply (until here no problem).
Then returns the content of the Shared Memory with MsgReply and my client shows “Ô}Testing MessageClient”. In other words my client don’t receive the full and correct message from my server.
Someone knows what’s happening?
Below the code:
— Client —
#include <cstdlib>
#include <iostream>
#include <sys/neutrino.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <string>
using namespace std;
int main(int argc, char *argv[]) {
char smsg[200] = "Testing MessageClient";
void * rmsg;
int coid, rMsgSend;
cout << "Welcome to the Client Message Passing\n" << endl;
/* Establish a connection*/
coid = ConnectAttach(0, 823315, 1, 0, 0);
if (coid == -1){
perror("Error during the ConnectAttach");
exit(EXIT_FAILURE);
}
/* Sending the message */
rMsgSend = MsgSend(coid, smsg, strlen(smsg) + 1, &rmsg, sizeof(&rmsg));
if (rMsgSend == -1){
//perror("Error during the MsgSend");
fprintf(stderr, "Error during the MsgSend: %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
if (sizeof(rmsg) > 0)
printf("The server returns the message:\n\t%s\n", &rmsg);
/* Unlink a Connection - It don't make trash's to the Server */
ConnectDetach(coid);
return EXIT_SUCCESS;
}— Server —
#include <cstdlib>
#include <iostream>
#include <errno.h> //Needed for the EOK in MsgReply
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/neutrino.h>
#include <string.h> //Needed for strcpy
#include <string>
#include <unistd.h> //Needed for sleep
using namespace std;
int main(int argc, char *argv[]) {
/* Message Passing */
int rcvid; //Receive ID
int chid; //Channel ID
int fd=0; // File Descriptor
int rMsgReply; //Return of MsgReply
int len=262144;
char message[200];
char * sharedMemoryName = "/tmp/SharedMemory";
void * addr; //It needs to be this because mmap returns void *
/* Creating a channel */
chid = ChannelCreate(0);
/* Server side */
while (1) {
rcvid = MsgReceive(chid, message, sizeof(message), NULL);
if (rcvid == -1)
MsgError(rcvid, ESRCH);
printf("Receive ID: %d\n", rcvid);
printf("Received the message: \n\t\"%s\"\n", message);
/* Creating a Shared Memory Object */
fd = shm_open(sharedMemoryName, O_RDWR|O_CREAT, 0777);
/* Mapping the Shared Memory Object*/
addr = mmap(NULL, sizeof(len), PROT_READ|PROT_WRITE|PROT_NOCACHE, MAP_PHYS|MAP_ANON, NOFD, 0);
if (addr == MAP_FAILED)
perror("Error memory mapping");
printf("Map address: %p\n", (void *) addr);
msync(&addr, sizeof(len), MS_SYNC);
shm_ctl(fd, SHMCTL_GLOBAL | SHMCTL_PHYS | SHMCTL_ANON, NULL, NULL);
/* Writing in the SharedMemory Object */
addr = strcat(message, " - Reply from Server");
printf("SHM content: \n\t\"%s\"\n", addr);
printf("+++ -------------------- +++\n\n");
/* Replying */
rMsgReply = MsgReply(rcvid, EOK, &addr, sizeof(&addr));
if (rMsgReply == -1)
MsgError(rcvid, ESRCH);
/* The memory object remains in the system after the close */
close(fd);
/* To remove a memory object you must unlink it like a file.
* This may be done by another process.*/
shm_unlink(sharedMemoryName);
}
return EXIT_SUCCESS;
}Thanks in advance!