#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#define MAXLINE 4096
void client(int readfd, int writefd)
{
size_t len;
ssize_t n;
char buff[MAXLINE];
/* 4read pathname */
fgets(buff, MAXLINE, stdin);
len = strlen(buff); /* fgets() guarantees null byte at end */
if (buff[len-1] == '\n')
len--; /* delete newline from fgets() */
/* 4write pathname to IPC channel */
write(writefd, buff, len);
/* 4read from IPC, write to standard output */
while ( (n = read(readfd, buff, MAXLINE)) > 0)
write(STDOUT_FILENO, buff, n);
}
void server(int readfd, int writefd)
{
int fd;
ssize_t n;
char buff[MAXLINE+1];
/* 4read pathname from IPC channel */
if ( (n = read(readfd, buff, MAXLINE)) == 0)
printf("end-of-file while reading pathname");
buff[n] = '\0'; /* null terminate pathname */
if ( (fd = open(buff, O_RDONLY)) < 0) {
/* 4error: must tell client */
snprintf(buff + n, sizeof(buff) - n, ": can't open, %s\n",
strerror(errno));
n = strlen(buff);
write(writefd, buff, n);
} else {
/* 4open succeeded: copy file to IPC channel */
while ( (n = read(fd, buff, MAXLINE)) > 0)
write(writefd, buff, n);
close(fd);
}
}
int main(int argc, char **argv)
{
int pipe1[2], pipe2[2];
pid_t childpid;
pipe(pipe1); /* create two pipes */
pipe(pipe2);
if ( (childpid = fork()) == 0) { /* child */
close(pipe1[1]);
close(pipe2[0]);
server(pipe1[0], pipe2[1]);
exit(0);
}
/* 4parent */
close(pipe1[0]);
close(pipe2[1]);
client(pipe2[0], pipe1[1]);
waitpid(childpid, NULL, 0); /* wait for child to terminate */
exit(0);
}
