I have this two programs in C and I need to find a string value that I pass from the first one to the second and if the string value is in users.txt file, return value 1 or 0 (if the file does not contain the string value).
/*client.c*/
#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
struct message {
int result;
char *text;
};
int main(int argc, char *argv[]){
char fifo_name_client[] = "fifo-client";
char fifo_name_server[] = "fifo-server";
struct message send, result;
int fd_client = open(fifo_name_client, O_WRONLY);
int fd_server = open(fifo_name_server, O_RDONLY);
send.text = argv[1];
//printf("Sended: %s, send.text);
write(fd_client, &send, sizeof(send));
read(fd_server, &result, sizeof(result));
if(result.result = 1) printf("User found\n");
else printf("User not found\n");
close(fd_client); close(fd_server);
}
/*server.c*/
#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
struct message {
int result;
char *text;
};
int main(){
int fork_result, pid_child, pid_finished, status, child_exit_code;
char fifo_name_client[] = "fifo-client";
char fifo_name_server[] = "fifo-server";
char *user;
if(access(fifo_name_client, F_OK) != 0){
if(mknod(fifo_name_client, S_IFIFO | 0666, 0) == -1){
perror("mknod");
return EXIT_FAILURE;
}
}
if(access(fifo_name_server, F_OK) != 0){
if(mknod(fifo_name_server, S_IFIFO | 0666, 0) == -1){
perror("mknod");
return EXIT_FAILURE;
}
}
while(1){
FILE *fifo_client, *fifo_server;
fifo_client = fopen(fifo_name_client, "r");
if(fifo_client == NULL) return EXIT_FAILURE;
fifo_server = fopen(fifo_name_server, "w");
if(fifo_server == NULL) return EXIT_FAILURE;
if(setvbuf(fifo_server, NULL, _IONBF, 0) != 0){
printf("Error preventing buffering\n");
}
struct message send, result;
fread(&send, sizeof(send), 1, fifo_client);
user = send.text;
//printf("Received: %s\n", user); /*Segmentation fault*/
//printf("Received: %d\n", user);
fork_result = fork();
switch(fork_result){
case -1:
printf("Cant create\n");
break;
case 0:
execlp("grep", "grep", user, "users.txt", NULL);
break;
default:
pid_child = fork_result;
pid_finised = wait(&status);
if(pid_finished != pid_child) printf("Not equals\n");
else {
if(WIFEXITED(status)){
child_exit_code = WEXITSTATUS(status);
if(chil_exit_code == 0) result.result = 1;
else result.result = 0;
fwrite(&result, sizeof(result, 1, fifo_server);
}
}
break;
}
close(fifo_client); close(fifo_server);
}
}
My problem here, is that when printf what I receive from the ´client.c´ it appears as a integer value and not the initial string value I give to it in the beggining.
On the other hand, when I do execlp("grep",....) instead of use ´user´ value, I write it as "user1" (is in the file) and "user2" (is not in the file) and the value that comes back to ´client.c´ is correct.
If anyone knows why I get a integer value instead of the initial string I'd be really grateful.
Thank you, and sorry for my bad english
EDIT
I made it work and now the two programs look this way:
/*client.c*/
#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#define MAX_BUF 1024
int main(int argc, char *argv[]){
char fifo_name_client[] = "fifo-client";
char fifo_name_server[] = "fifo-server";
char *user;
char result[MAX_BUF];
int fd_client = open(fifo_name_client, O_WRONLY);
int fd_server = open(fifo_name_server, O_RDONLY);
user = argv[1];
//printf("Sended: %s\n", user);
write(fd_client, user, sizeof(user));
read(fd_server, result, MAX_BUF);
if(strcmp(result,"1") == 0) printf("User found\n");
else printf("User not found\n");
close(fd_client); close(fd_server);
}
/*server.c*/
#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#define MAX_BUF 1024
int main(){
int fork_result, pid_child, pid_finished, status, child_exit_code;
char fifo_name_client[] = "fifo-client";
char fifo_name_server[] = "fifo-server";
char *result;
if(access(fifo_name_client, F_OK) != 0){
if(mknod(fifo_name_client, S_IFIFO | 0666, 0) == -1){
perror("mknod");
return EXIT_FAILURE;
}
}
if(access(fifo_name_server, F_OK) != 0){
if(mknod(fifo_name_server, S_IFIFO | 0666, 0) == -1){
perror("mknod");
return EXIT_FAILURE;
}
}
while(1){
char user[MAX_BUF];
int fd_client = open(fifo_name_client, O_RDONLY);
int fd_server = open(fifo_name_server, O_WRONLY);
read(fd_client, user, MAX_BUF);
//printf("Received: %s\n", user);
fork_result = fork();
switch(fork_result){
case -1:
printf("Cant create\n");
break;
case 0:
execlp("grep", "grep", user, "users.txt", NULL);
break;
default:
pid_child = fork_result;
pid_finished = wait(&status);
if(pid_finished != pid_child) printf("Not equals\n");
else {
if(WIFEXITED(status)){
child_exit_code = WEXITSTATUS(status);
if(child_exit_code == 0) result = "1";
else result = "0";
write(fd_server, result, sizeof(result));
}
}
break;
}
close(fd_client); close(fd_server);
}
}
My problem now is that everytime I execute server.c and then client.c for some reason, execlp("grep", "grep", user, "users.txt", NULL); it executes twice and then server.c program stops because of "broke pipe error", and I don´t know how to solve that. Does someone know why is that and how to solve it? Thank you in advance
