PTR
get_pipe(char *name, int type, int *pid_ptr)
{
int the_pipe[2], local_fd, remote_fd;
if (pipe(the_pipe) == -1)
return (PTR) 0;
/*
* If this is an input-pipe then local_fd is reader, remote_fd is writer
* If this is an output-pipe then local_fd is writer, remote_fd is reader
*/
local_fd = the_pipe[type == PIPE_OUT];
remote_fd = the_pipe[type == PIPE_IN];
/* to keep output ordered correctly */
fflush(stdout);
fflush(stderr);
switch (*pid_ptr = fork()) {
case -1:
close(local_fd);
close(remote_fd);
return (PTR) 0;
case 0:
/*
* This is the child process. Close the unused end of the pipe, i.e,
* (local_fd) and then close the input/output file descriptor that
* corresponds to the direction we want to read/write.
*
* The dup() call uses the first unused file descriptor, which happens
* to be the one that we just closed, e.g., 0 or 1 for stdin and stdout
* respectively.
*/
close(local_fd);
close(type == PIPE_IN);
IGNORE_RC(dup(remote_fd));
close(remote_fd);
execl(shell, shell, "-c", name, (char *) 0);
errmsg(errno, "failed to exec %s -c %s", shell, name);
fflush(stderr);
_exit(128);
default:
close(remote_fd);
/* we could deadlock if future child inherit the local fd ,
set close on exec flag */
(void) CLOSE_ON_EXEC(local_fd);
break;
}
return ((type == PIPE_IN)
? (PTR) FINdopen(local_fd, 0)
: (PTR) fdopen(local_fd, "w"));
}
/* Adds file descriptors to the child structure to support output_sync; one
for stdout and one for stderr as long as they are open. If stdout and
stderr share a device they can share a temp file too.
Will reset output_sync on error. */
static void
setup_tmpfile (struct output *out)
{
/* Is make's stdout going to the same place as stderr? */
static int combined_output = -1;
if (combined_output < 0)
combined_output = sync_init ();
if (STREAM_OK (stdout))
{
int fd = output_tmpfd ();
if (fd < 0)
goto error;
CLOSE_ON_EXEC (fd);
out->out = fd;
}
if (STREAM_OK (stderr))
{
if (out->out != OUTPUT_NONE && combined_output)
out->err = out->out;
else
{
int fd = output_tmpfd ();
if (fd < 0)
goto error;
CLOSE_ON_EXEC (fd);
out->err = fd;
}
}
return;
/* If we failed to create a temp file, disable output sync going forward. */
error:
output_close (out);
output_sync = 0;
}
