Thread feeding other MultiThreading
- by alaamh
I see it's easy to open pipe between two process using fork, but how we can passing open pipe to threads.
Assume we need to pass out of PROGRAM A to PROGRAM B "may by more than one thread",
PROGRAM B send his output to PROGRAM C
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
struct targ_s {
char* reader;
};
void *thread1(void *arg) {
struct targ_s *targ = (struct targ_s*) arg;
int status, fd[2];
pid_t pid;
pipe(fd);
pid = fork();
if (pid == 0) {
int fd = fileno( targ->fd_reader );
dup2(STDIN_FILENO, fd);
close(fd[0]);
dup2(fd[1], STDOUT_FILENO);
close(fd[1]);
execvp ("PROGRAM B", NULL);
exit(1);
} else {
close(fd[1]);
dup2(fd[0], STDIN_FILENO);
close(fd[0]);
execl("PROGRAM C", NULL);
wait(&status);
return NULL;
}
}
int main(void) {
FILE *fpipe;
char *command = "PROGRAM A";
char buffer[1024];
if (!(fpipe = (FILE*) popen(command, "r"))) {
perror("Problems with pipe");
exit(1);
}
char* outfile = "out.dat";
FILE* f = fopen (outfile, "wb");
int fd = fileno( f );
struct targ_s targ;
targ.fd_reader = outfile;
pthread_t thid;
if (pthread_create(&thid, NULL, thread1, &targ) != 0) {
perror("pthread_create() error");
exit(1);
}
int len;
while (read(fpipe, buffer, sizeof (buffer)) != 0) {
len = strlen(buffer);
write(fd, buffer, len);
}
pclose(fpipe);
return (0);
}
