| /* Creating a Pipe |
| Copyright (C) 1991-2014 Free Software Foundation, Inc. |
| |
| This program is free software; you can redistribute it and/or |
| modify it under the terms of the GNU General Public License |
| as published by the Free Software Foundation; either version 2 |
| of the License, or (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program; if not, if not, see <http://www.gnu.org/licenses/>. |
| */ |
| |
| #include <sys/types.h> |
| #include <unistd.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| |
| /* Read characters from the pipe and echo them to @code{stdout}. */ |
| |
| void |
| read_from_pipe (int file) |
| { |
| FILE *stream; |
| int c; |
| stream = fdopen (file, "r"); |
| while ((c = fgetc (stream)) != EOF) |
| putchar (c); |
| fclose (stream); |
| } |
| |
| /* Write some random text to the pipe. */ |
| |
| void |
| write_to_pipe (int file) |
| { |
| FILE *stream; |
| stream = fdopen (file, "w"); |
| fprintf (stream, "hello, world!\n"); |
| fprintf (stream, "goodbye, world!\n"); |
| fclose (stream); |
| } |
| |
| int |
| main (void) |
| { |
| pid_t pid; |
| int mypipe[2]; |
| |
| /*@group*/ |
| /* Create the pipe. */ |
| if (pipe (mypipe)) |
| { |
| fprintf (stderr, "Pipe failed.\n"); |
| return EXIT_FAILURE; |
| } |
| /*@end group*/ |
| |
| /* Create the child process. */ |
| pid = fork (); |
| if (pid == (pid_t) 0) |
| { |
| /* This is the child process. |
| Close other end first. */ |
| close (mypipe[1]); |
| read_from_pipe (mypipe[0]); |
| return EXIT_SUCCESS; |
| } |
| else if (pid < (pid_t) 0) |
| { |
| /* The fork failed. */ |
| fprintf (stderr, "Fork failed.\n"); |
| return EXIT_FAILURE; |
| } |
| else |
| { |
| /* This is the parent process. |
| Close other end first. */ |
| close (mypipe[0]); |
| write_to_pipe (mypipe[1]); |
| return EXIT_SUCCESS; |
| } |
| } |