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// $Id$
// Purpose: This program uses ACE_FIFO wrappers to perform
// interprocess communication between a parent process and a child
// process. The parents reads from an input file and writes it into
// the fifo. The child reads from the ACE_FIFO and executes the more
// command.
#include "ace/FIFO_Recv.h"
#include "ace/FIFO_Send.h"
#define PERMS 0666
#define EXEC_NAME "more"
#define EXEC_COMMAND_ARG "more"
const char *FIFO_NAME = "/tmp/fifo";
int
do_child (ACE_FIFO_Recv &fifo_reader)
{
// Set child's stdin to read from the fifo.
if (ACE_OS::close (0) == -1 || ACE_OS::dup (fifo_reader.get_handle ()) == -1)
return -1;
char *argv[2];
argv[0] = EXEC_COMMAND_ARG;
argv[1] = 0;
if (ACE_OS::execvp (EXEC_NAME, argv) == -1)
return -1;
return 0;
}
int
do_parent (const char fifo_name[], char input_filename[])
{
int inputfd;
ACE_FIFO_Send fifo_sender (fifo_name, O_WRONLY | O_CREAT);
int len;
char buf[BUFSIZ];
if (fifo_sender.get_handle () == ACE_INVALID_HANDLE)
return -1;
if ((inputfd = ACE_OS::open (input_filename, O_RDONLY)) == -1)
return -1;
// Read from input file and write into input end of the fifo.
while ((len = ACE_OS::read (inputfd, buf, sizeof buf)) > 0)
if (fifo_sender.send (buf, len) != len)
return -1;
if (len == -1)
return -1;
if (fifo_sender.remove () == -1)
return -1;
return 0;
}
int
main (int argc, char *argv[])
{
ACE_LOG_MSG->open (argv[0]);
if (argc != 2)
ACE_ERROR ((LM_ERROR, "usage: %n input-file\n%a", 1));
ACE_FIFO_Recv fifo_reader (FIFO_NAME, O_RDONLY | O_CREAT, PERMS, 0);
if (fifo_reader.get_handle () == ACE_INVALID_HANDLE)
return -1;
pid_t child_pid;
switch (child_pid = ACE_OS::fork ())
{
case -1:
ACE_ERROR ((LM_ERROR, "%n: %p\n%a", "fork", 1));
case 0:
if (do_child (fifo_reader) == -1)
ACE_ERROR ((LM_ERROR, "%n: %p\n%a", "do_child", 1));
default:
if (do_parent (FIFO_NAME, argv[1]) == -1)
ACE_ERROR ((LM_ERROR, "%n: %p\n%a", "do_parent", 1));
// wait for child to ACE_OS::exit.
if (ACE_OS::waitpid (child_pid, (int *) 0, 0) == -1)
ACE_ERROR ((LM_ERROR, "%n: %p\n%a", "waitpid", 1));
}
return 0;
}
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