#include #include "ourhdr.h" static void sig_pipe(int); /* our signal handler */ int main(void) { int n, fd[2]; pid_t pid; char line[MAXLINE]; if (signal(SIGPIPE, sig_pipe) == SIG_ERR) err_sys("signal error"); if (s_pipe(fd) < 0) /* only need a single stream pipe */ err_sys("pipe error"); if ( (pid = fork()) < 0) err_sys("fork error"); else if (pid > 0) { /* parent */ close(fd[1]); while (fgets(line, MAXLINE, stdin) != NULL) { n = strlen(line); if (write(fd[0], line, n) != n) err_sys("write error to pipe"); if ( (n = read(fd[0], line, MAXLINE)) < 0) err_sys("read error from pipe"); if (n == 0) { err_msg("child closed pipe"); break; } line[n] = 0; /* null terminate */ if (fputs(line, stdout) == EOF) err_sys("fputs error"); } if (ferror(stdin)) err_sys("fgets error on stdin"); exit(0); } else { /* child */ close(fd[0]); if (fd[1] != STDIN_FILENO) { if (dup2(fd[1], STDIN_FILENO) != STDIN_FILENO) err_sys("dup2 error to stdin"); } if (fd[1] != STDOUT_FILENO) { if (dup2(fd[1], STDOUT_FILENO) != STDOUT_FILENO) err_sys("dup2 error to stdout"); } if (execl("./add2", "add2", NULL) < 0) err_sys("execl error"); } } static void sig_pipe(int signo) { printf("SIGPIPE caught\n"); exit(1); }